# Review of the Chemical Composition, Pharmacological Effects, Pharmacokinetics, and Quality Control ofBoswellia carterii

Authors: Kai Huang; Yanrong Chen; Kaiyong Liang; Xiaoyan Xu; Jing Jiang; Menghua Liu; Fenghua Zhou
Journal: Evidence-Based Complementary and Alternative Medicine
 (2022)

---

## Abstract

Objective. This review aimed to systematically summarize studies that investigated the bioactivities of compounds and extracts from Boswellia. Methods. A literature review on the pharmacological properties and phytochemicals of B. carterii was performed. The information was retrieved from secondary databases such as PubMed, Chemical Abstracts Services (SciFinder), Google Scholar, and ScienceDirect. Results. The various Boswellia extracts and compounds demonstrated pharmacological properties, such as anti-inflammatory, antitumour, and antioxidant activities. B. carterii exhibited a positive effect on the treatment and prevention of many ageing diseases, such as diabetes, cancer, cardiovascular disease, and neurodegenerative diseases. Conclusion. Here, we highlight the pharmacological properties and phytochemicals of B. carterii and propose further evidence-based research on plant-derived remedies and compounds.


---

## Body

## 1. Introduction

Frankincense resin comes from the tree of the genusBoswellia (family Burseraceae). Boswellia resins are recorded in texts with their traditional medical practices in an ancient civilization such as ancient China, Persia, and India. It was subsequently included in Chinese Pharmacopoeia Volume I. B. carterii was firstly used as a traditional Chinese medicine for treating urticaria. Modern pharmacological studies confirmed that B. carterii could be not only anti-inflammation, antioxidation, antiviral, antimalarial, and antitumour, but also protect liver and nerve. 3-O-Acetyl-11-keto-β-boswellic acid, 3α-acetoxy-8,24-dienetirucallic acid, and 3α-acetoxy-7,24-dienetirucallic acid are related to its anti-inflammatory effect. Incensole acetate plays an important role in its neuroprotective effect.According to previous comments and reports [1–4], volatile oils and terpenes are the main components of B. carterii. However, although many chemical components have been isolated and identified from B. carterii, the toxicology and pharmacokinetic studies of Boswellia long-term use are lacking. Some review articles on B. carterii have been published, mainly concerning its chemical composition and pharmacological activity [1, 5–9]. In this review, we strictly analyze the current state of knowledge of phytochemistry, quality control, pharmacological effects, and pharmacokinetics. It is hoped that this review will fill the knowledge gap, complement the published review on its chemical composition and pharmacological activity, and provide support and perspectives on future research and clinical application of B. carterii.


## 2. Methods

A literature search was performed to collect relevant information of the traditional uses, as well as pharmacological properties and phytochemicals ofB. carterii. Electronic databases were searched, including Google Scholar, SciFinder, PubMed, and ScienceDirect, and several literature articles published before August 2019 were reviewed. Additional primary data such as books were examined, including “The Compendium of Materia Medica” and “Chinese Pharmacopoeia.” Searching for relevant information on B. carterii was performed using multiple keywords, such as “B. carterii”; “Traditional uses”; “Phytochemistry”; “Pharmacological activities”; “Anti-tumour”; “Anti-inflammatory”; “Wound-healing properties”; and “Hepatoprotective.” All chemical structures were drawn using ChemBioDraw Ultra 14.0 software.


### 2.1. Phytochemistry

The chemical structure ofB. carterii is primarily composed of terpenoids. A total of 304 compounds were identified, including 148 triterpenes, 94 diterpenes, and 62 compounds classified as volatile oils. All identified compounds are listed and numbered in Table 1.Table 1
Compounds identified from Boswellia carterii.
CompoundsNo.ReferenceVolatile oilo-Methyl anisole1[2]Octanol2[2]2,6-Dimethoxy toluene3[2]Octyl formate4[2]Geranyl acetate5[2]Hexyl hexanoate6[2]Decyl acetate7[2]Farnesyl acetate (E, E)8[2]Benzyl benzoate9[2]α-Pinene10[2]Olibanumol A11[10]β-Pinene12[2]Isoterpinolene13[2]α-Phellandrene14[2]β-Phellandrene15[2]Sabinene16[2]β-Myrcene17[2]d-Limonene18[2]cis-Ocimene19[2]Octyl acetate20[2]β-Citronellol21[2]cis-Carveol22[2]Carvone23[2]Piperitone24[2]1-Decanol25[2]Isopinocampheol26[2]Bornyl acetate27[2]trans-Terpin28[2]Citronellyl acetate29[2]Neryl acetate30[2]Olibanumol B31[10]Olibanumol C32[10]3,6-Dihydroxy-p-menth-1-ene33[10]p-Menth-1-en-4a,6b-diol34[10](-)-trans-Sobrerol35[10]p-Menth-4-en-1,2-diol36[10]p-Menth-5-en-1,2-diol37[10]α-Copaene38[2]δ-Selinene39[2]Maaliene40[2]Viridiflorol41[2]α-Muurolol42[2]β-Bisabolene43[2]cis-Calamenene (1S)44[2]Spathulenol45[2]cis-Nerolidol46[2]β-Caryophyllene oxide47[11]Palmitic acid48[12]1-Hexanol49[3]3,5-Dimethoxytoluene50[3]Chrysanthenone51[3]cis-Verbenol52[3]Hexyl acetate53[3]Linalool54[3]Myrtenal55[3]Terpinene-4-ol56[3]trans-Pinocarveol57[3]trans-Verbenol58[3]Z-β-Ocimene59[3]α-Pinene epoxide60[3]β-Bourbonene61[3]β-Thujone62[3]Monocyclic diterpenoidDuva-3,9,13-triene-1α-hydroxy-5,8-oxide-1-acetate63[2]Duva-3,9,13-triene-1,5α-diol-1-acetate64[2]Cembrene C65[13]Boscartin A66[14]Boscartin P67[4]Cembrene A68[13]Isoincensole acetate69[13]Cembrene70[2]Isocembrene71[2]9-cis-Retinal72[2]Duva-4,8,13-triene-1,3α-diol73[2]Thunbergol74[2]Duva-3,9,13-triene-1,5α-diol75[2]Serratol76[11]Cembrene A77[15]Incensole78[15]Boscartin B79[14]Boscartin C80[14]Boscartin D81[14]Boscartin E82[14]Boscartin F83[14]Boscartin G84[14]Boscartin H85[14]Boscartin Q86[4]Boscartin R87[4]Boscartin S88[4]Boscartin T89[4]Boscartin U90[4]Boscartin V91[4]Boscartin W92[4]Boscartin X93[4]Boscartin Y94[4]Boscartin Z95[4]Boscartin AA96[4]Boscartin AB97[4]Boscartin AC98[4]Boscartin AD99[4]Boscartin AE100[4]Boscartin AF101[4]Boscartin AG102[4]Incensole acetate103[15]Incensole oxide104[14](rel)-(1S,5 R,7E,11 E)-1-Isopropyl-8,12-dimethyl-4-methylenecyclotetradeca-7,11-diene-1,5-diol105[16]1,4-Epoxy-8,13-cembrandien-5,12-diol106[16]Boscartin C107[16]Boscartin E108[16]Boscartin I109[16]Boscartin J110[16]Boscartin K111[16]Myrcene112[17]Δ-3-Carene113[17]Dicyclic diterpenoidVerticiol114[2]Sclarene115[2]Naphthalene decahydro-1,1,4a-trimethyl-6-methylene-5-(3-methyl-2-pentenyl)116[2]Verticilla-4(20),7,11-triene117[15](-)-Limonene118[17](R)-Linalool119[17]1,8-Cineole120[17]1-Octanol121[17]ent-13-epi-Verticillanediol122[3]ent-Isoverticillenol123[3]ent-Verticillanediol124[3]ent-Verticillol125[3]E-β-Ocimene126[17]Isoverticillene127[3]p-Cymene128[17]Verticillene129[3]Verticillol130[3]α-Terpineol131[17]Tricyclic diterpenoidOlibanumol D132[18]Boscartol A133[19]Phenanthrene-7-ethenyl-1,2,3,4,4a,5,6,7,8,9,10,10a-dodecahydro-1,1,4a,7-tetramethyl134[2]Boscartol B135[19]Boscartol C136[19]Boscartol D137[19]Boscartol E138[19]Boscartol F139[19]Boscartol H140[19]Boscartol I141[19]Boscartol K142[20]Boscartol L143[20]Boscartol M144[20]Boscartol N145[20]Boscartol F146[20]Boscartol B147[20]Boscartol A148[20]Boscartol C149[20]Boscartol E150[20]Boscartol H151[20]α-Thujene152[17]Camphene153[17]Tetracyclic diterpenoidIsophyllocladene (kaur-15-ene)154[2]Beyerene155[2]Boscartol G156[19]Tetracyclic triterpenoid3α-O-Acetyl-8,24-dien-tirucallic acid157[15]3α-Acetoxytirucalla-7,24-dien-21-oic acid158[21]3α-Hydroxytirucalla-7,24-dien-21-oic acid159[21]3-Oxo-tirucallic acid160[22]3-Oxotirucalla-7,9(11),24-trien-21-oic acid161[23]3-Oxo-8,24-dien-tirucallic acid162[11]Boscartene A163[24]3β-Hydroxytirucalla-8,24-dien-21-oic acid164[21]α-Elemolic acid165[21]Olibanumol J166[10]3-α-Acetoxy-tirucallic acid167[22]3-β-Acetoxy-tirucallic acid168[22]Dammarenediol169[25]Dammarenediol acetate170[25]3-O-Acetyl-3β,20S,24-trihydeoxy-dammar-25-ene171[25]Isofouquierol172[25]Isofouquierol acetate173[25]Ocotillol acetate174[25]3β-Hydroxymansumbin-13(17)-en-16-one175[25]Mansumbinol176[25]Isomasticadienonic acid177[26]Masticadienonic acid178[26]3,4-Seco-olean-12-en-3,28-dioic acid179[26]3,4-Seco-olean-18-en-3,28-dioic acid180[26]Elemonic acid181[27]3-α-Hydroxy-8,24-dienetirucallic acid182[28]3α-Acetoxy-8,24-dienetirucallic acid183[28]3-β-Hydroxy-8,24-dienetirucallic acid184[28]3-Oxo-8,24-dienetirucallic acid185[28]3-α-Hydroxy-7,24-dienetirucallic acid186[28]3α-Acetoxy-7,24-dienetirucallic acid187[28]Roburic acid188[28]4, (23)-Dihydroroburic acid189[28]4, (23)-Dihydro-11-keto-roburic acid190[28]4, (23)-Dihydronyc-tanthic acid191[28]Boscartene B192[24]Boscartene C193[24]Boscartene D194[24]Boscartene E195[24]Boscartene F196[24]Boscartene G197[24]Boscartene H198[24]Boscartene I199[24]Isoflindissone lactone200[24]Boscartene J201[24]Boscartene K202[24]3-Hydroxy-tirucallic acid203[12]Boscartene L204[29]Boscartene M205[29]Boscartene N206[29]Trametenolic acid B207[29]3-Oxotirucalla-7, 9 (11), 24-trien-21-oic acid208[29](20S)-3,7-Dioxo-tirucalla-8,24-dien-21-oic acid209[29]20,21-Dinortirucalla-8,24-diene-3β-ol-7-one210[16]3-Oxo-tirucalla-8, 24-dien-21-oic acid211[16]3β-Hydroxytirucalla-8, 24-dien-21-oic acid212[16]3α-Hydroxytirucalla-8, 24-dien-21-oic acid213[16]Pentacyclic triterpeneLup-20-ene-3α-acetoxy-24-acid214[30]α-Boswellic acid acetate215[31]3-O-Acetyl-11-hydroxy-β-boswellic acid216[28]β-Boswellic acid acetate217[32]3α-Acetyl-11-keto-α-boswellic acid218[33]24-Noroleana-3,12-diene219[34]3-O-Oxalyl-11-β-keto-boswellic acid220[35]3-O-Acetyl-α-boswellic acid221[26]3-Acetyl-11-keto-β-boswellic acid222[36]3-O-Acetyl-11-methoxy-β-boswellic acid223[28]3-O-Acetyl-9,11-dehydro-β-boswellic acid224[28]3α-Acetyl-11-keto-β-boswellic acid225[33]24-Norursa-3,12-diene226[34]24-Norlupa-3,20(29)-diene227[34]Neoilexonol acetate228[25]Triptohypol F229[18]Lupenyl formate230[18]3-O-Acetyl-11-keto-β-boswellic acid231[11]β-Acetyl-boswellic acid232[11]α-Acetyl-boswellic acid233[11]3-O-Acetyl-lupeolic acid234[28]3-O-Acetyl-28-hydroxy-lupeolic acid235[28]Acetyl-11-dien-β-boswellic acid236[37]Acetyl-lupeolic acid237[38]α-Amyrin238[39]3-O-Acetyl-boswellic acid239[40]Olibanumol K240[25]3-Oxalyl-β-boswellic acid241[41]Acetyl-hydroxy-lupeolic acid242[42]3-O-Acetyl-9,11-dehydro-β-boswellic acid243[43]9,11-Dehydro-β-boswellic acid244[44]11-Keto-α-boswellic acid245[27]3-O-Acetyl-β-boswellic acid246[28]Acetyl-β-boswellic acid247[45]11-Keto-β-boswellic acid248[46]Acetyl-11α-methoxy-β-boswellic acid249[21]Oleanolic acid250[39]Betulin251[39]Betulinic acid252[39]11-Keto-boswellic acid253[40]Olibanumol H254[10]Olibanumol I255[10]Isofpuquierol256[10]3-Epi-α-amyrin257[25]Olibanumol L258[25]Olibanumol M259[25]Olibanumol N260[25]Epilupeol261[25]Epilupeol acetate262[25]Lup-20(30)-ene-3α,29-diol263[25]Glochidiol264[25]Lupeol265[25]Lup-20(29)-ene-2α,3β-diol266[25]3β-Acetoxylup-20(29)-en-11β-ol267[25]Lupenone268[25]Urs-9(11),12-dien-3β-ol269[25]Neoilexonol270[25]Urs-12-ene-3β,11α-diol271[25]Urs-12-ene-3α,11α-diol272[25]Olibanumol E273[18]Olibanumol F274[18]Olibanumol G275[18]18Hα,3β,20β-ursanediol276[23]3-Oxalyl-11-keto-β-boswellic acid277[41]3-Succinoyl-β-boswellic acid278[41]3-Succinoyl-11-keto-β-boswellic acid279[41]3-Glutaroyl-β-boswellic acid280[41]3-Glutaroyl-11-keto-β-boswellic acid281[41]3-Carboxymethylenoxy-β-boswellic acid282[41]3-Carboxymethylenoxy-11-keto-β-boswellic acid283[41]11-Keto-β-boswellic acid284[11]β-Boswellic acid285[11]α-Boswellic acid286[11]3-O-Acetyl-11-hydroxy-β-boswellic acid287[43]Acetyl-9,11-dehydro-β-boswellic acid288[44]Acetyl-9,11-dehydro-α-boswellic acid289[44]9,11-Dehydro-α-boswellic acid290[44]Acetyl-lupeolic acid291[44]Moronic acid292[26]Oleanonic acid293[26]Acetyl-α-boswellic acid294[27]Acetyl-11-keto-α-boswellic acid295[27]3-Acetyl-9,11-dehydro-α-boswellic acid296[27]3-Acetyl-9,11-dehydro-β-boswellic acid297[27]3-O-Acetyl-11-keto-β-boswellic acid298[28]Lupeolic acid299[28]β-Boswellic acid300[45]α-Boswellic acid301[46]Acetyl-11-keto-β-boswellic acid302[12]3-O-Acetyl-11-keto-boswellic acid303[16]21β-Hydroxy-3-O-acetyl-11-keto-boswellic acid304[16]The bold values refer to the relationship corresponding to the chemical structural formula in Schemes 1–7.


#### 2.1.1. Volatile Oil

Volatile oil, also known as an essential oil, is a general term for a class of oily compounds with aromatic odors. It can volatilize at average temperature and can be distilled with water vapor. Volatile oil fromB. carterii primarily contains monoterpenes, sesquiterpenes, and ester compounds. It is worth mentioning that the classification here does not contain volatile diterpenoids and triterpenes, and we have described them in the corresponding classification (Scheme 1).Scheme 1
Chemical structural formula of volatile oil.
(a)(b)(c)


#### 2.1.2. Diterpenoid

Diterpenoid refers to a group of compounds whose molecular skeleton contains four isoprene units and 20 carbon atoms.It contains monocyclic diterpenoids, dicyclic diterpenoids, tricyclic diterpenoids, and tetracyclic diterpenoids. Fifty-one kinds of monocyclic diterpenoids, eighteen kinds of dicyclic diterpenoids, twenty-two kinds of tricyclic diterpenoids, and three kinds of tetracyclic diterpenoids were extracted fromB. carterii.(1) Monocyclic Diterpenoid. Monocyclic diterpenoid is a group of diterpenoids with one closed-loop carbon atom (Scheme 2).Scheme 2
Chemical structural formula of monocyclic diterpenoid.
(a)(b)(c)(2) Dicyclic Diterpenoid. Dicyclic diterpenoid is a group of diterpenoids with two closed-loop carbon atoms (Scheme 3).Scheme 3
Chemical structural formula of dicyclic diterpenoid.(3) Tricyclic Diterpenoid. Tricyclic diterpenoid is a group of diterpenoids with three closed-loop carbon atoms (Scheme 4).Scheme 4
Chemical structural formula of tricyclic diterpenoid.(4) Tetracyclic Diterpenoid. Tetracyclic diterpenoid is a group of diterpenoids with four closed-loop carbon atoms (Scheme 5).Scheme 5
Chemical structural formula of tetracyclic diterpenoid.


#### 2.1.3. Triterpenoid

The triterpenoid is a terpenoid composed of 30 carbon atoms. According to the “Isoprene Rule,” most triterpenes consist of the condensation of 6 isoprene units (30 carbons). It can be divided into tetracyclic triterpenoids and pentacyclic triterpenoids. Fifty-seven tetracyclic triterpenes and ninety-one pentacyclic triterpenes were identified fromB. carterii.(1) Tetracyclic Triterpenoid. Tetracyclic triterpenoid is a group of triterpenoids with four closed-loop carbon atoms (Scheme 6).Scheme 6
Chemical structural formula of tetracyclic triterpenoid.
(a)(b)(c)(d)(2) Pentacyclic Triterpene. A pentacyclic triterpenoid is a group of triterpenoids with five closed-loop carbon atoms (Scheme 7).Scheme 7
Chemical structural formula of pentacyclic triterpenoid.
(a)(b)(c)(d)(e)(f)


## 2.1. Phytochemistry

The chemical structure ofB. carterii is primarily composed of terpenoids. A total of 304 compounds were identified, including 148 triterpenes, 94 diterpenes, and 62 compounds classified as volatile oils. All identified compounds are listed and numbered in Table 1.Table 1
Compounds identified from Boswellia carterii.
CompoundsNo.ReferenceVolatile oilo-Methyl anisole1[2]Octanol2[2]2,6-Dimethoxy toluene3[2]Octyl formate4[2]Geranyl acetate5[2]Hexyl hexanoate6[2]Decyl acetate7[2]Farnesyl acetate (E, E)8[2]Benzyl benzoate9[2]α-Pinene10[2]Olibanumol A11[10]β-Pinene12[2]Isoterpinolene13[2]α-Phellandrene14[2]β-Phellandrene15[2]Sabinene16[2]β-Myrcene17[2]d-Limonene18[2]cis-Ocimene19[2]Octyl acetate20[2]β-Citronellol21[2]cis-Carveol22[2]Carvone23[2]Piperitone24[2]1-Decanol25[2]Isopinocampheol26[2]Bornyl acetate27[2]trans-Terpin28[2]Citronellyl acetate29[2]Neryl acetate30[2]Olibanumol B31[10]Olibanumol C32[10]3,6-Dihydroxy-p-menth-1-ene33[10]p-Menth-1-en-4a,6b-diol34[10](-)-trans-Sobrerol35[10]p-Menth-4-en-1,2-diol36[10]p-Menth-5-en-1,2-diol37[10]α-Copaene38[2]δ-Selinene39[2]Maaliene40[2]Viridiflorol41[2]α-Muurolol42[2]β-Bisabolene43[2]cis-Calamenene (1S)44[2]Spathulenol45[2]cis-Nerolidol46[2]β-Caryophyllene oxide47[11]Palmitic acid48[12]1-Hexanol49[3]3,5-Dimethoxytoluene50[3]Chrysanthenone51[3]cis-Verbenol52[3]Hexyl acetate53[3]Linalool54[3]Myrtenal55[3]Terpinene-4-ol56[3]trans-Pinocarveol57[3]trans-Verbenol58[3]Z-β-Ocimene59[3]α-Pinene epoxide60[3]β-Bourbonene61[3]β-Thujone62[3]Monocyclic diterpenoidDuva-3,9,13-triene-1α-hydroxy-5,8-oxide-1-acetate63[2]Duva-3,9,13-triene-1,5α-diol-1-acetate64[2]Cembrene C65[13]Boscartin A66[14]Boscartin P67[4]Cembrene A68[13]Isoincensole acetate69[13]Cembrene70[2]Isocembrene71[2]9-cis-Retinal72[2]Duva-4,8,13-triene-1,3α-diol73[2]Thunbergol74[2]Duva-3,9,13-triene-1,5α-diol75[2]Serratol76[11]Cembrene A77[15]Incensole78[15]Boscartin B79[14]Boscartin C80[14]Boscartin D81[14]Boscartin E82[14]Boscartin F83[14]Boscartin G84[14]Boscartin H85[14]Boscartin Q86[4]Boscartin R87[4]Boscartin S88[4]Boscartin T89[4]Boscartin U90[4]Boscartin V91[4]Boscartin W92[4]Boscartin X93[4]Boscartin Y94[4]Boscartin Z95[4]Boscartin AA96[4]Boscartin AB97[4]Boscartin AC98[4]Boscartin AD99[4]Boscartin AE100[4]Boscartin AF101[4]Boscartin AG102[4]Incensole acetate103[15]Incensole oxide104[14](rel)-(1S,5 R,7E,11 E)-1-Isopropyl-8,12-dimethyl-4-methylenecyclotetradeca-7,11-diene-1,5-diol105[16]1,4-Epoxy-8,13-cembrandien-5,12-diol106[16]Boscartin C107[16]Boscartin E108[16]Boscartin I109[16]Boscartin J110[16]Boscartin K111[16]Myrcene112[17]Δ-3-Carene113[17]Dicyclic diterpenoidVerticiol114[2]Sclarene115[2]Naphthalene decahydro-1,1,4a-trimethyl-6-methylene-5-(3-methyl-2-pentenyl)116[2]Verticilla-4(20),7,11-triene117[15](-)-Limonene118[17](R)-Linalool119[17]1,8-Cineole120[17]1-Octanol121[17]ent-13-epi-Verticillanediol122[3]ent-Isoverticillenol123[3]ent-Verticillanediol124[3]ent-Verticillol125[3]E-β-Ocimene126[17]Isoverticillene127[3]p-Cymene128[17]Verticillene129[3]Verticillol130[3]α-Terpineol131[17]Tricyclic diterpenoidOlibanumol D132[18]Boscartol A133[19]Phenanthrene-7-ethenyl-1,2,3,4,4a,5,6,7,8,9,10,10a-dodecahydro-1,1,4a,7-tetramethyl134[2]Boscartol B135[19]Boscartol C136[19]Boscartol D137[19]Boscartol E138[19]Boscartol F139[19]Boscartol H140[19]Boscartol I141[19]Boscartol K142[20]Boscartol L143[20]Boscartol M144[20]Boscartol N145[20]Boscartol F146[20]Boscartol B147[20]Boscartol A148[20]Boscartol C149[20]Boscartol E150[20]Boscartol H151[20]α-Thujene152[17]Camphene153[17]Tetracyclic diterpenoidIsophyllocladene (kaur-15-ene)154[2]Beyerene155[2]Boscartol G156[19]Tetracyclic triterpenoid3α-O-Acetyl-8,24-dien-tirucallic acid157[15]3α-Acetoxytirucalla-7,24-dien-21-oic acid158[21]3α-Hydroxytirucalla-7,24-dien-21-oic acid159[21]3-Oxo-tirucallic acid160[22]3-Oxotirucalla-7,9(11),24-trien-21-oic acid161[23]3-Oxo-8,24-dien-tirucallic acid162[11]Boscartene A163[24]3β-Hydroxytirucalla-8,24-dien-21-oic acid164[21]α-Elemolic acid165[21]Olibanumol J166[10]3-α-Acetoxy-tirucallic acid167[22]3-β-Acetoxy-tirucallic acid168[22]Dammarenediol169[25]Dammarenediol acetate170[25]3-O-Acetyl-3β,20S,24-trihydeoxy-dammar-25-ene171[25]Isofouquierol172[25]Isofouquierol acetate173[25]Ocotillol acetate174[25]3β-Hydroxymansumbin-13(17)-en-16-one175[25]Mansumbinol176[25]Isomasticadienonic acid177[26]Masticadienonic acid178[26]3,4-Seco-olean-12-en-3,28-dioic acid179[26]3,4-Seco-olean-18-en-3,28-dioic acid180[26]Elemonic acid181[27]3-α-Hydroxy-8,24-dienetirucallic acid182[28]3α-Acetoxy-8,24-dienetirucallic acid183[28]3-β-Hydroxy-8,24-dienetirucallic acid184[28]3-Oxo-8,24-dienetirucallic acid185[28]3-α-Hydroxy-7,24-dienetirucallic acid186[28]3α-Acetoxy-7,24-dienetirucallic acid187[28]Roburic acid188[28]4, (23)-Dihydroroburic acid189[28]4, (23)-Dihydro-11-keto-roburic acid190[28]4, (23)-Dihydronyc-tanthic acid191[28]Boscartene B192[24]Boscartene C193[24]Boscartene D194[24]Boscartene E195[24]Boscartene F196[24]Boscartene G197[24]Boscartene H198[24]Boscartene I199[24]Isoflindissone lactone200[24]Boscartene J201[24]Boscartene K202[24]3-Hydroxy-tirucallic acid203[12]Boscartene L204[29]Boscartene M205[29]Boscartene N206[29]Trametenolic acid B207[29]3-Oxotirucalla-7, 9 (11), 24-trien-21-oic acid208[29](20S)-3,7-Dioxo-tirucalla-8,24-dien-21-oic acid209[29]20,21-Dinortirucalla-8,24-diene-3β-ol-7-one210[16]3-Oxo-tirucalla-8, 24-dien-21-oic acid211[16]3β-Hydroxytirucalla-8, 24-dien-21-oic acid212[16]3α-Hydroxytirucalla-8, 24-dien-21-oic acid213[16]Pentacyclic triterpeneLup-20-ene-3α-acetoxy-24-acid214[30]α-Boswellic acid acetate215[31]3-O-Acetyl-11-hydroxy-β-boswellic acid216[28]β-Boswellic acid acetate217[32]3α-Acetyl-11-keto-α-boswellic acid218[33]24-Noroleana-3,12-diene219[34]3-O-Oxalyl-11-β-keto-boswellic acid220[35]3-O-Acetyl-α-boswellic acid221[26]3-Acetyl-11-keto-β-boswellic acid222[36]3-O-Acetyl-11-methoxy-β-boswellic acid223[28]3-O-Acetyl-9,11-dehydro-β-boswellic acid224[28]3α-Acetyl-11-keto-β-boswellic acid225[33]24-Norursa-3,12-diene226[34]24-Norlupa-3,20(29)-diene227[34]Neoilexonol acetate228[25]Triptohypol F229[18]Lupenyl formate230[18]3-O-Acetyl-11-keto-β-boswellic acid231[11]β-Acetyl-boswellic acid232[11]α-Acetyl-boswellic acid233[11]3-O-Acetyl-lupeolic acid234[28]3-O-Acetyl-28-hydroxy-lupeolic acid235[28]Acetyl-11-dien-β-boswellic acid236[37]Acetyl-lupeolic acid237[38]α-Amyrin238[39]3-O-Acetyl-boswellic acid239[40]Olibanumol K240[25]3-Oxalyl-β-boswellic acid241[41]Acetyl-hydroxy-lupeolic acid242[42]3-O-Acetyl-9,11-dehydro-β-boswellic acid243[43]9,11-Dehydro-β-boswellic acid244[44]11-Keto-α-boswellic acid245[27]3-O-Acetyl-β-boswellic acid246[28]Acetyl-β-boswellic acid247[45]11-Keto-β-boswellic acid248[46]Acetyl-11α-methoxy-β-boswellic acid249[21]Oleanolic acid250[39]Betulin251[39]Betulinic acid252[39]11-Keto-boswellic acid253[40]Olibanumol H254[10]Olibanumol I255[10]Isofpuquierol256[10]3-Epi-α-amyrin257[25]Olibanumol L258[25]Olibanumol M259[25]Olibanumol N260[25]Epilupeol261[25]Epilupeol acetate262[25]Lup-20(30)-ene-3α,29-diol263[25]Glochidiol264[25]Lupeol265[25]Lup-20(29)-ene-2α,3β-diol266[25]3β-Acetoxylup-20(29)-en-11β-ol267[25]Lupenone268[25]Urs-9(11),12-dien-3β-ol269[25]Neoilexonol270[25]Urs-12-ene-3β,11α-diol271[25]Urs-12-ene-3α,11α-diol272[25]Olibanumol E273[18]Olibanumol F274[18]Olibanumol G275[18]18Hα,3β,20β-ursanediol276[23]3-Oxalyl-11-keto-β-boswellic acid277[41]3-Succinoyl-β-boswellic acid278[41]3-Succinoyl-11-keto-β-boswellic acid279[41]3-Glutaroyl-β-boswellic acid280[41]3-Glutaroyl-11-keto-β-boswellic acid281[41]3-Carboxymethylenoxy-β-boswellic acid282[41]3-Carboxymethylenoxy-11-keto-β-boswellic acid283[41]11-Keto-β-boswellic acid284[11]β-Boswellic acid285[11]α-Boswellic acid286[11]3-O-Acetyl-11-hydroxy-β-boswellic acid287[43]Acetyl-9,11-dehydro-β-boswellic acid288[44]Acetyl-9,11-dehydro-α-boswellic acid289[44]9,11-Dehydro-α-boswellic acid290[44]Acetyl-lupeolic acid291[44]Moronic acid292[26]Oleanonic acid293[26]Acetyl-α-boswellic acid294[27]Acetyl-11-keto-α-boswellic acid295[27]3-Acetyl-9,11-dehydro-α-boswellic acid296[27]3-Acetyl-9,11-dehydro-β-boswellic acid297[27]3-O-Acetyl-11-keto-β-boswellic acid298[28]Lupeolic acid299[28]β-Boswellic acid300[45]α-Boswellic acid301[46]Acetyl-11-keto-β-boswellic acid302[12]3-O-Acetyl-11-keto-boswellic acid303[16]21β-Hydroxy-3-O-acetyl-11-keto-boswellic acid304[16]The bold values refer to the relationship corresponding to the chemical structural formula in Schemes 1–7.


### 2.1.1. Volatile Oil

Volatile oil, also known as an essential oil, is a general term for a class of oily compounds with aromatic odors. It can volatilize at average temperature and can be distilled with water vapor. Volatile oil fromB. carterii primarily contains monoterpenes, sesquiterpenes, and ester compounds. It is worth mentioning that the classification here does not contain volatile diterpenoids and triterpenes, and we have described them in the corresponding classification (Scheme 1).Scheme 1
Chemical structural formula of volatile oil.
(a)(b)(c)


### 2.1.2. Diterpenoid

Diterpenoid refers to a group of compounds whose molecular skeleton contains four isoprene units and 20 carbon atoms.It contains monocyclic diterpenoids, dicyclic diterpenoids, tricyclic diterpenoids, and tetracyclic diterpenoids. Fifty-one kinds of monocyclic diterpenoids, eighteen kinds of dicyclic diterpenoids, twenty-two kinds of tricyclic diterpenoids, and three kinds of tetracyclic diterpenoids were extracted fromB. carterii.(1) Monocyclic Diterpenoid. Monocyclic diterpenoid is a group of diterpenoids with one closed-loop carbon atom (Scheme 2).Scheme 2
Chemical structural formula of monocyclic diterpenoid.
(a)(b)(c)(2) Dicyclic Diterpenoid. Dicyclic diterpenoid is a group of diterpenoids with two closed-loop carbon atoms (Scheme 3).Scheme 3
Chemical structural formula of dicyclic diterpenoid.(3) Tricyclic Diterpenoid. Tricyclic diterpenoid is a group of diterpenoids with three closed-loop carbon atoms (Scheme 4).Scheme 4
Chemical structural formula of tricyclic diterpenoid.(4) Tetracyclic Diterpenoid. Tetracyclic diterpenoid is a group of diterpenoids with four closed-loop carbon atoms (Scheme 5).Scheme 5
Chemical structural formula of tetracyclic diterpenoid.


### 2.1.3. Triterpenoid

The triterpenoid is a terpenoid composed of 30 carbon atoms. According to the “Isoprene Rule,” most triterpenes consist of the condensation of 6 isoprene units (30 carbons). It can be divided into tetracyclic triterpenoids and pentacyclic triterpenoids. Fifty-seven tetracyclic triterpenes and ninety-one pentacyclic triterpenes were identified fromB. carterii.(1) Tetracyclic Triterpenoid. Tetracyclic triterpenoid is a group of triterpenoids with four closed-loop carbon atoms (Scheme 6).Scheme 6
Chemical structural formula of tetracyclic triterpenoid.
(a)(b)(c)(d)(2) Pentacyclic Triterpene. A pentacyclic triterpenoid is a group of triterpenoids with five closed-loop carbon atoms (Scheme 7).Scheme 7
Chemical structural formula of pentacyclic triterpenoid.
(a)(b)(c)(d)(e)(f)


## 2.1.1. Volatile Oil

Volatile oil, also known as an essential oil, is a general term for a class of oily compounds with aromatic odors. It can volatilize at average temperature and can be distilled with water vapor. Volatile oil fromB. carterii primarily contains monoterpenes, sesquiterpenes, and ester compounds. It is worth mentioning that the classification here does not contain volatile diterpenoids and triterpenes, and we have described them in the corresponding classification (Scheme 1).Scheme 1
Chemical structural formula of volatile oil.
(a)(b)(c)


## 2.1.2. Diterpenoid

Diterpenoid refers to a group of compounds whose molecular skeleton contains four isoprene units and 20 carbon atoms.It contains monocyclic diterpenoids, dicyclic diterpenoids, tricyclic diterpenoids, and tetracyclic diterpenoids. Fifty-one kinds of monocyclic diterpenoids, eighteen kinds of dicyclic diterpenoids, twenty-two kinds of tricyclic diterpenoids, and three kinds of tetracyclic diterpenoids were extracted fromB. carterii.(1) Monocyclic Diterpenoid. Monocyclic diterpenoid is a group of diterpenoids with one closed-loop carbon atom (Scheme 2).Scheme 2
Chemical structural formula of monocyclic diterpenoid.
(a)(b)(c)(2) Dicyclic Diterpenoid. Dicyclic diterpenoid is a group of diterpenoids with two closed-loop carbon atoms (Scheme 3).Scheme 3
Chemical structural formula of dicyclic diterpenoid.(3) Tricyclic Diterpenoid. Tricyclic diterpenoid is a group of diterpenoids with three closed-loop carbon atoms (Scheme 4).Scheme 4
Chemical structural formula of tricyclic diterpenoid.(4) Tetracyclic Diterpenoid. Tetracyclic diterpenoid is a group of diterpenoids with four closed-loop carbon atoms (Scheme 5).Scheme 5
Chemical structural formula of tetracyclic diterpenoid.


## 2.1.3. Triterpenoid

The triterpenoid is a terpenoid composed of 30 carbon atoms. According to the “Isoprene Rule,” most triterpenes consist of the condensation of 6 isoprene units (30 carbons). It can be divided into tetracyclic triterpenoids and pentacyclic triterpenoids. Fifty-seven tetracyclic triterpenes and ninety-one pentacyclic triterpenes were identified fromB. carterii.(1) Tetracyclic Triterpenoid. Tetracyclic triterpenoid is a group of triterpenoids with four closed-loop carbon atoms (Scheme 6).Scheme 6
Chemical structural formula of tetracyclic triterpenoid.
(a)(b)(c)(d)(2) Pentacyclic Triterpene. A pentacyclic triterpenoid is a group of triterpenoids with five closed-loop carbon atoms (Scheme 7).Scheme 7
Chemical structural formula of pentacyclic triterpenoid.
(a)(b)(c)(d)(e)(f)


## 3. Quality Control

It is vital that quality control is for the safety and effectiveness of traditional Chinese medicine (TCM). Many rapid, sensitive, and stable technologies have been applied for quality analysis ofB. carterii. A thin-layer chromatography method is developed to differentiate and identify three crucial Boswellia species [11]. A total of twenty compounds, which contained two tricyclic diterpenes, twelve triterpenes, and six volatile oil, were detected by GC, GC/MS, SPME, TRSDMC [47], TLC, and HPLC. We summarized the information in Table 2.Table 2
Quantitative analysis for the quality control ofBoswellia carterii.
CompoundsMethodResultReferenceAcetyl-11-keto-β-boswellic acidAcetyl-β-boswellic acidβ-Boswellic acidα-Boswellic acidAcetyl-α-boswellic acid11-Keto-β-boswellic acidAcetyl-lupeolic acidLupeolic acidAcetyl-9,11-dehydro-α-boswellic acid9,11-Dehydro-α-boswellic acidAcetyl-9,11-dehydro-β-boswellic acid9,11-Dehydro-β-boswellic acidHPLCThe contents of acetyl-11-keto-β-boswellic acid, acetyl-β-boswellic acid, ß-boswellic acid, α-boswellic acid, acetyl-α-boswellic acid, 11-keto-β-boswellic acid, acetyl-lupeolic acid, lupeolic acid, acetyl-9,11-dehydro-α-boswellic acid, 9,11-dehydro-α-boswellic acid, acetyl-9,11-dehydro-β-boswellic acid, and 9,11-dehydro-β-boswellic acid were 40.0, 39.8, 37.2, 26.9, 21.1, 10.1, 7.8, 2.3, 0.28, 0.15, 0.06, and 0.04 mg/g, respectively[44]α-Thujeneα-Pineneα-PhellandreneGC-MSTheα-thujene (69.16%), α-pinene (7.20%), and α-phellandrene (6.78%) were the major components of tested essential oil by GC-MS analysis[47]α-PineneGC/MS, UVB. carterii can be distinguished from B. scar by comparing optical rotation and chirality. However, storage time and storage conditions increase the variability of the α-pinene content, which is related to its optical rotation[48]α-Pineneα-PhellandreneSabineneBornyl acetateGC/MSThe contents ofα-pinene, α-phellandrene, sabinene, and bornyl acetate were 3.11%, 0.03%, 0.26%, and 0.09%, respectively[2]α-PineneIsoincensole acetateGC/MSThe fibre coating material, sampling temperature, and sampling time will affect the test results. The polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre ageing was found as the most effective method to capture the diterpene characteristics of olibanum, with a sampling time of 1 h and a sampling temperature of 80°C. The contents ofα-pinene and isoincensole acetate in PDMS/DVB fraction were 4.0% and 8.2%, respectively[13]α-PineneIsoincensole acetateGC/MSThe contents ofα-pinene and isoincensole acetate in CH2Cl2 extraction of B. carterii were 3.6% and 40.4%, respectivelyß-Caryophyllene oxideTLCß-caryophyllene oxide was a significant marker compound ofB. carterii/sacra[11]α-Pineneα-ThujeneMethoxydecaneGC-MSEnvironmental and human factors resulted in 42 samples ofB. carterii essential oil exhibited three different chemotypes[49]


## 4. Pharmacology

B. carterii has acted as an ethnodrug for a long history because of its pharmacological effects. Boswellia contains biologically active compounds that exhibit pharmacological activities (Table 3).Table 3
Pharmacological effects ofB. carterii.
ModelsConstituent/ExtractMechanismReferenceAnti-inflammatory effectsAdjuvant-induced arthritis in Lewis ratsAqueous acetone extractThe extract significantly decreased arthritic scores, reduced paw oedema, and restrained the expression of TNF-α and IL-1β[50]12-O-Tetradecanoylphorbol-13-acetate(TPA)-induced inflammation in specific pathogen-free female ICR miceMeOH extract,n-hexane-soluble fractionEtOAc-soluble fraction, n-BuOH-soluble fractionH2O-soluble fractionβ-Boswellic acidAcetyl-β-boswellic acid11-Keto-β-boswellic acidAcetyl-11-keto-β-boswellic acidAcetyl-11α-methoxy-β-boswellic acid9,11-Dehydro-β-boswellic acidAcetyl-9,11-dehydro-β-boswellic acidα-Boswellic acidAcetyl-α-boswellic acidLupeolic acidAcetyl-lupeolic acidα-Elemolic acidElemonic acid3α-Hydroxytirucalla-7,24-dien-21-oic acid3α-Acetoxytirucalla-7,24-dien-21-oic acid3β-Hydroxytirucalla-8,24-dien-21-oic acidIncensoleThe H2O-soluble fraction and EtOAc-soluble fraction showed the strongest and the weakest anti-inflammatory effects in the fraction group, respectively. All compounds showed an anti-inflammatory effect[38]HeLa cells, 293T cells, RAW 264.7 macrophage cell, Jurkat T leukemia cells, 5.1 Jurkat and HeLa-Tat-Luc cell lines, A549 cells, human peripheral monocytes, female Sabra miceIncensole acetate (IA)Incensole (IN)IA and IN (3-280μM) inhibited IκBα degradation. IA inhibited IκBα and p65 phosphorylation by impairment of IKK activation and interfered with TAK/TAB-mediated phosphorylation of IKKα/β activation loop. IA inhibited NF-κB accumulation in cell nuclei and DNA binding, which may be related to its inhibition of gene expression by NF-κB[51]LPS-induced inflammatory in rat C6 glioma cell and human peripheral monocytesIncensole acetate (IA)100μmol/L IA, restraining the expression of IL-1b and TNF-α mRNA, inhibited the activation and mRNA level of NF-κB in human peripheral blood monocytes and C6 glioma cells[52]Lipopolysaccharide-activated mouse peritoneal macrophagesOlibanumol AOlibanumol BOlibanumol COlibanumol HOlibanumol I3,6-Dihydroxy-p-menth-1-ene p-menth-1-en-4α,6β-diol(-)-trans-sobrerol p-menth-4-en-1,2-diolp-Menth-5-en-1,2-diolIsofpuquierolEpilupeolTwelve compounds inhibited the production of NO[10]Lipopolysaccharide-activated mouse peritoneal macrophagesOlibanumol DOlibanumol ETwo compounds exhibited nitric oxide production inhibitory activity[18]Carrageenan-induced paw oedema and Carrageenan-induced pleurisy in adult male CD1 mice and Wistar Han ratsA549 cells and human whole bloodα-Amyrin3-O-Acetyl-β-boswellic acid3-O-Acetyl-11-keto-β-boswellic acidβ-Boswellic acid11-Keto-β-boswellic acid3-O-Oxalyl-11-β-keto-boswellic acidHuman mPGES-1 was identified as one of theβ-boswellic acid-binding proteins. The boswellic acid is capable of reversibly inhibiting the conversion of prostaglandin (PG) H2 to PGE2, which is mediated by mPGES-1. Besides, in A549 cells, boswellic acids restrained PGE2 generation, and in human whole blood, β-boswellic acid diminished PGE2 biosynthesis induced by LPS. β-boswellic acid (1 mg/kg) can inhibit pleurisy in rats, accompanied by decreasing levels of PGE2, and can also reduce paw oedema in mice[35]Cooperation-induced cerebral ischemic injury in C57BL/6 mice and TRPV 3-deficient miceIncensole acetate (IA)0-50 mg/kg IA reduced the levels of TNF-α, IL-1β, and TGF-β, the activity of NF-κB, and the expression of GFAP in the brain of model mice in a dose-dependent manner[53]Formalin and carrageenan-induced paw oedema in mice and oxytocin-induced dysmenorrhea in miceWater extract of frankincense (FWE)FWE significantly inhibited PGE2 production, and 5.2 g/kg FWE inhibited nitrite production[54]Neutrophils, monocytes, and platelets from human bloodLupeolic acid (LA)Acetyl-lupeolic acid (Ac-LA)Acetyl-hydroxy-lupeolic acid (Ac–OH–LA)Ac–OH–LA, which may directly hamper with cPLA2a activity (IC50 = 3.6μM), lowered the biosynthesis of COX-, 5-LO-, and 12-LO-derived eicosanoids, with consistent IC50 value ranging from 2.3 to 6.9 μM.[42]A549 cells3-α-Hydroxy-8,24-dienetirucallic acid3α-Acetoxy-8,24-dienetirucallic acid3-β-Hydroxy-8,24-dienetirucallic acid3-Oxo-8,24-dienetirucallic acid3-α-Hydroxy-7,24-dienetirucallic acid3α-Acetoxy-7,24-dienetirucallic acidRoburic acid4, (23)-Dihydroroburic acid4, (23)-Dihydro-11-keto-roburic acidLupeolic acid3-O-Acetyl-lupeolic acid3-O-Acetyl-28-hydroxy-lupeolic acidTwelve compounds suppressed mPGES-1 with increased potencies. 3α-Acetoxy-7,24-dienetirucallic acid and 3α-acetoxy-8,24-dienetirucallic acid suppressed mPGES-1 activity with IC50 = 0.4 μM, each[28]Xylene-induced ear oedema model and formalin-inflamed hind paw model in Kunming miceFrankincense oil extract (FOE)α-PineneLinalool1-OctanolFOE and three compounds restrained inflammatory infiltrates and COX-2 overexpression induced by the nociceptive stimulus[55]LPS-induced NO production in RAW 264.7 cellBoscartol KBoscartol LBoscartol FBoscartol K, boscartol L, and boscartol F inhibited NO production.[20]LPS-induced NO production in RAW 264.7 cell(rel)-(1S,5 R,7E,11 E)-1-Isopropyl-8,12-dimethyl-4-methylenecyclotetradeca-7,11-diene-1,5-diol3-Oxo-tirucalla-8, 24-dien-21-oic acid3β-Hydroxytirucalla-8,24-dien-21-oic acid3-O-Acetyl-11-keto-boswellic acidFour compounds restrained NO production with IC50 values of 1.32, 3.04, 1.42, and 3.25μM, respectively[16]Antioxidant effects5-Lipoxygenase3-O-Acetyl-9,11-dehydro-β-boswellic acid3-O-Acetyl-11-methoxy-β-boswellic acid9,11-Dehydro-β-boswellic acidThree compounds inhibited 5-LO activity to varying degrees, of which 3-O-acetyl-9,11-dehydro-β-boswellic acid almost completely abolished 5-LO activity[28]ABTS radical cationMethanol extract1000μg/kg extract exhibited a weak antioxidant activity[56]Antitumour effectsThe human glioblastoma cells, U251 and U87-MGU87-MG-induced tumour model in BALB/c-nu nude mice3-O-Acetyl-11-keto-β-boswellic acid3-O-Acetyl-11-keto-β-boswellic acid, via the p21/FOXM1/cyclin B1 pathway, stop glioblastoma cells at the G2/M phase, which was related to the inhibition of mitosis through Aurora B/TOP2A pathway and the induction of mitochondrial-dependent apoptosis[57]LNCaP and PC-3 cellAcetyl-keto-β-boswellic acid20μg/ml acetyl-keto-β-boswellic acid induced apoptosis in LNCaP and PC-3 cell via a DR5 regulated pathway, which induced the expression of CAAT/enhancer-binding protein homologous protein[58]PC-3 cellMDA-MB-231 cellAcetyl-lupeolic acidDirectly bound to the pleckstrin homology domain, acetyl-lupeolic acid (0-20μg/mL) advertised hindrance of phosphorylation of following targets of the Akt signalling pathway and nuclear accumulation of the mTOR target p70 ribosome and p65/NF-κB, β-catenin and c-Myc six protein kinase[59]B16F10 cellHT-1080 cellBoswellic acid acetateIn B16F10 cells, boswellic acid acetate (25μM) inhibited cell migration activity, lured cell differentiation, blocked the cell population in the G1 phase, and restrained topoisomerase II activity. Boswellic acid acetate lured apoptosis of HT-1080 cells and prevented the secretion of MMPs from HT-1080 cells[60]Myeloid leukemia cells HL-60, U937, ML-1, erythrocyte leukemia cells DS-19 and K562BC-4, a mixture containedα- and β-boswellic acid acetateIn myeloid leukemia cells, BC-4 (24.2μM) lured monocytic differentiation. BC-4 also increased specific and nonspecific esterases. Besides, BC-4 dose- and time-dependently inhibited growth of all cell lines tested[31]IMR-32, NB-39, and SK-N-SH cellβ-Boswellic acid, acetyl-β-boswellic acid, 11-keto-β-boswellic acid, acetyl-11-keto-β-boswellic acid, acetyl-11α-methoxy-β-boswellic acid, 9,11-dehydro-β-boswellic acidAcetyl-9,11-dehydro-β-boswellic acid, acetylα-boswellic acid, lupeolic acid, acetyl-lupeolic acid, elemonic acid, 3α-hydroxytirucalla-7,24-dien-21-oic acid, 3α-acetoxytirucalla-7,24-dien-21-oic acid, incensoleIncensole acetateIn the above cells, these fifteen compounds exhibited potent cytotoxic activities[21]Text of activation of NOR1Acetyl-9,11-dehydro-β-boswellic acidElemonic acid3α-Hydroxytirucalla-7,24-dien-21-oic acid3β-Acetoxytirucalla-7,24-dien-21-oic acid3α-Hydroxytirucalla-8,24-dien-21-oic acidFive compounds indicated potent inhibitory effects of the activation of (-/+)-(E)-methyl-2[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexemide (NOR 1).[21]PC-3 cell3α-Acetyl-11-keto-α-boswellic acid3α-acetyl-11-keto-α-boswellic acid inhibited the proliferation of human PC-3 cells and induced apoptosis, as shown by the activation of caspase-3 and the induction of DNA fragmentation. Furthermore, 3α-acetyl-11-keto-α-boswellic acid inhibited the proliferation and induced apoptosis of PC-3 xenografted to the chorioallantoic membrane of the chicken chorioallantoic membrane.[33]Bladder cancer cell J82Immortalized normal bladder cell UROtsaFrankincense essential oil (FEO)FEO-activated signal of IL-6, histone core proteins, and heat shock proteins. FEO induced selective cancer cell death through NRF-2-mediated oxidative stress.[61]Jurkat cellBoswellia water extractBoswellia extract (200 μg/ml) promoted apoptosis of Jurkat cells and stopped cell differentiation in the G1 phase.[62]Bladder cancer cell J82Frankincense oilThrough activating genes responsible for cell apoptosis, cell growth inhibition, and cell cycle arrest, frankincense oil inhibited the cell viability of J82 cells, but cell death did not result in DNA fragmentation.[63]N-2A cellsEthanol fraction of frankincenseEthanol fraction showed cytotoxicity to neuro-2A cell with LC50 of 0.081 mg/mL.[64]Prostate cancer cells LNCaP and PC-3Acetyl-11-keto-β-boswellic acidBased on the binding activity of Sp1, the active compound downregulated AR short promoter and hindered cellular proliferation. Luring p21 (WAF1/CIP1) and preventing cyclin D1 in cells, the compound (20-40μM) induced G1 phase cell cycle arrest.[65]HT-29, HCT-116, SW480, and LS174 T colon cancer cell lines3-acetyl-11-keto-β-boswellic acid3-acetyl-11-keto-β-boswellic acid (30 μM) could activate the PI3K/Akt pathway. However, when we inhibited the PI3K pathway, the cell apoptosis induced by 3-acetyl-11-keto-β-boswellic acid would enhance[66]Hep-G2 cellVerticilla-4(20),7,11-trieneVerticilla-4(20),7,11-triene showed an inhibitory effect against the proliferation of Hep-G2 cell line[15]PTEN-overexpressing PC-3 cellsPeripheral blood mononuclear cellsLNCaP cellPC-3 tumours xenografted to nude mice and chick chorioallantoic membranes3-Oxo-tirucallic acid3-α-Acetoxy-tirucallic acid3-β-Acetoxy-tirucallic acidTirucallic acids inhibited Akt activity, downregulated the pathway of Akt activation, and induced apoptosis in prostate cancer cell lines. However, 3-β-acetoxy-tirucallic acid showed no significant activation of Akt1, which lacks the pleckstrin homology domain. The compounds inhibited the proliferation and induced apoptosis of tumours xenografted to the allantoic membrane of chicken veins, and postponed the progression of pre-established prostate tumours in nude mice without causing systemic toxicity[22]Antiviral effectsHepatitis C virusBoswellia carteriiB. carterii showed toxicity to the hepatitis C virus with IC50 of 23 mg/mL, which may be related to its inhibition of hepatitis C virus protease.[67]TPA-induced production of EBV-EA in Raji cellβ-Boswellic acidLupeolic acidAcetyl-lupeolic acidElemonic acid3α-Hydroxytirucalla-7,24-dien-21-oic acid3α-Acetoxytirucalla-7,24-dien-21-oic acid3β-Hydroxytirucalla-8,24-dien-21-oic acidIn Raji cells, the above compounds show dose-dependent inhibition of EBV-EA induction induced by TPA[21]Antimicrobial effectsStaphylococcus aureus (S. aureus) ATCC 29213S. aureus ATCC 25923S. aureus ATCC 43866S. epidermidis DSM 3269Escherichia coli (E. coli) ATCC 25922Pseudomonas aeruginosa (P. aeruginosa) ATCC 9027Candida albicans (C. albicans) ATCC 10231C. tropicalis ATCC 13803Oleo gum resin oilThe antibacterial activity of the oleo gum resin oils fromB. carterii was identified and found to show antibacterial activity to the above bacterial[68]Trichosporon ovoidesEssential oil (EO)EO showed antibacterial activity against trichosporon ovoides with MIC and MIF of 25μl/ml and 50 μl/ml, respectively[69]Neuroprotective effectsThe Sabra line mice were selected to be compliant for 10 generations.Incensole acetate (IA)IA has shown potent TRPV3 agonists, which caused anti-anxiety-like and anti-depression-like behavioural effects, with changes in c-Fos activation in the brain[70]Anterior cerebral artery ligation-induced cerebral ischemic injury in C57BL/6 mice and TRPV 3-deficient miceIncensole acetate (IA)0-50 mg/kg IA dose-dependently reduced the cerebral infarction area and the contents of TNF-α, IL-1β, and TGF-β in the brain of the model mice, the activity of NF-κB, and the expression of GFAP in the brain. The behavioural assessment found that IA dose-dependently reduced nerve damage. Interestingly, IA showed only partial neuroprotective effects in TRPV3-deficient mice[52]LPS-induced inflammatory in rat C6 glioma cell and human peripheral monocytesIncensole acetate (IA)Incensole acetate (100μmol/L) downregulated NF-κB activation and mRNA level in both human peripheral monocytes and C6 glioma cells. Moreover, it impaired the inflammatory reaction in human peripheral monocytes[52]Weight drop device-induced closed head injury in male Sabra miceIncensole acetate (IA)IA (50 mg/kg) alleviated inflammation and neurodegeneration in the hippocampus by inhibiting the mRNA level of TNF-α and IL-1β after closed head injury. Incensole acetate induced a mild hypothermic effect, but it did not affect tissue oedema formation[52]HEK293 cells, female Sabra mice, wild-type C57BL/6, and TRPV3(KO) female miceIncensole acetate (IA)IA (50 mg/kg) regulated the expression of c-Fos in mice brain areas, including that related to anxiety and depression. IA (500μM) activated TRPV3 channels as determined by calcium imaging. IA activated a TRPV3 current in HEK293 cells and relieved depression and anxiety in wild-type but not in TRPV3 KO mice[70]The mice fed by breast milk which was generated from the Boswellia-fed miceB. carteriiPregnancy or lactation mother mice receivingB. carterii injection upregulated CaMKII mRNA in the hippocampus of offspring, but no significant change in hippocampal CaMKIV mRNA expression[71]Kidney protective effectsOral adenine-induced chronic renal failure model in adult male albino rats ischemia-reperfusion injury-induced acute renal failure model in adult male albino ratsBoswelliaProphylactic oral administration ofBoswellia decreased serum urea, blood urea nitrogen, and the activity of C-reactive protein[72]Hepatoprotective effectsD-galactosamine-induced toxicity in HL-7702 cellBoscartol A, boscartol B, boscartol C, boscartol E, boscartol F, boscartol H, and boscartol ISeven compounds (10μM) reduced cytotoxicity, which may be the basis of its liver protection[19]D-galactosamine-induced cytotoxic in HL-7702 cellAcetyl-α-elemolic acid3β-Hydroxytirucalla-8,24-dien-21-oic acid3α-Hydroxytirucalla-8,24-dien-21-oic acid3β-Hydroxy-mansumbin-13(17)-en-16-oneFour compounds reduced cytotoxic and increased the survival rate in cell[24]D-galactosamine-induced toxicity in HL-7702Boscartin P, boscartin U, boscartin V, boscartin W, boscartin X, boscartin Y, boscartin AA, boscartin AB, boscartin AE, boscartin AF, incensole, incensole oxide acetate, incensole oxide, 1,4-epoxy-8,13-cembrandien-5,12-diol, 4,8-epoxy-8,12-cembrandien-5,12-diolFifteen compounds (10μM) showed hepatoprotective effect against HL-7702 cell injury induced by D-galactosamine[4]Immunomodulatory effectsTh17 CD4+T cell, Th1, Th2, and Treg cellAcetyl-11-keto-β-boswellic acidSlightly increasing the differentiation of Th2 and Treg cells, acetyl-11-keto-β-boswellic acid (1 or 5 μM) reduced the differentiation of human CD4 (+) T cells. Further, acetyl-11-keto-β-boswellic acid reduced IL-17A released from memory Th17 cells triggered by IL-1β, which may involve IL-1β signalling by inhibiting the phosphorylation of IL-1 receptor-associated kinase 1 and STAT3[73]Peripheral blood lymphocytesPalmitic acid, lupeol,β-boswellic acid, 11-keto-β-boswellic acid, acetyl-β-boswellic acid, acetyl-11-keto-β-boswellic acid, acetyl-α-boswellic acid, 3-oxo-tirucallic acid, 3-hydroxy-tirucallic acidNine compounds promoted the transformation of peripheral blood lymphocytes[12]Murine splenocytesEthanol extract and sesame oil extractUsing ethanol as a solvent to deliver resin extracts resulted in significant cytotoxicity, which was not seen when ethanol was added alone. In contrast, when delivered by sesame oil solvent, resin extract dose-dependently inhibited TH1 cytokines and dose-dependently enhanced TH2 cytokines[37]Wister albino miceBoswellia carterii smokeThe smoke resulted that alveolar capillaries were damaged, neutrophil nucleus contracted, mitochondria swelled and elongated in type 2 lung cells, type 2 lung cells were shed, most microvilli were shed, and leukocyte neutrophils were exuded in the alveolar cavity[74]Other effectsEpinephrine hydrochloride and cool water bath-induced acute cold blood model in SD ratsStir-fried frankincense (SFF)Vinegar-processed frankincense (VPF)Frankincense oral administration (FRA)Frankincense (2.7 g/kg) presented more anticoagulant function than its processed products. FRA reduced the levels of DD and TAT and increased the content of PGI2. The processing of frankincense resulted in changes in its absorption and pharmacokinetics[36]Myeloid leukemia cells HL-60, U937, and ML-1, and erythrocyte leukemia cells DS-19 and K562Boswellic acid acetateThe compounds advertised a time- and dose-dependent induction and differentiation on myeloid leukemia cells expressed significant pro-apoptotic effects above 15 mg/ml. They also enriched the red blood cell line leukemia cells DS-19 and K562 at the G1 phase[31]Jurkat cellBoswellia carterii Birdw. extractFrankincense extract induced Jurkat cell apoptosis, promoted Jurkat cell apoptosis, and stopped cell differentiation at G1 phase[74]Myeloid leukemia cells NB4, SKNO-1, K562, U937, ML-1, and HL-60Boswellic acid acetate (BAA)BAA, under the condition of 20μg/ml for 24 h, decreased cell membrane potential, and p53 mutation did not affect the pro-apoptotic effect of boswellic acid acetate. Also, BCL-2, Bax, and Bcl-X do not participate in the process of BAA-induced cell membrane potential decline[32]Jack bean urease3-O-Acetyl-9,11-dehydro-β-boswellic acid3-O-Acetyl-11-hydroxy-β-boswellic acid3-O-Acetyl-11-keto-β-boswellic acid11-Keto-β-boswellic acidFour compounds presented an inhibitory effect on Jack bean urease with IC50 of 6.27, 9.21, 16.34, and 85.23μmol/L, respectively. The inhibitory force may be because of the formation of appropriate hydrogen bonds and the hydrophobic interaction between 3-O-acetyl-9,11-dehydro-β-boswellic acid and the urease active site[43]Callosobruchus chinensis (C. chinensis) and C. maculatusB. carterii essential oil (BEO)The essential oil showed toxicity toC. chinensis with LC50 and LC90 of 0.066 and 0.096 μL/mL, respectively. It expressed the same effect in C. maculatus with LC50 and LC90 of 0.050 and 0.075 μL/mL. BEO showed a concentration-dependent inhibitory effect on its spawning, growth, and development behaviour. It was found that the essential oil induced an increase in the levels of ROS, SOD, and CAT in pests. It also decreased the level of GSH and GSH/GSSG[47]Wistar male albino ratsAlcohol extract of olibanumAt a concentration of 1,000μg/kg, the alcohol extract of olibanum, advertising dose-dependence NO-scavenging action, resulted in a marked increase in the serum levels of LDH, AST, and CK-MB, as well as MDA[56]Side effectsMale albino ratBoswellic smokeHistopathological sections and ultrastructure of the testis showed adverse effects on sperm development. Sperm analysis revealed that sperm counts, viability, and speed decreased in varying degrees, and the proportion of abnormal sperm increased[75]Wistar male albino ratBoswellic smokeThe smoke resulted that fructose levels in epididymal fluid and prostate fluid were decreased. The histopathological sections and morphological analysis of the epididymis showed an adverse effect on sperm development[75]Wistar male albino ratBoswellic smokeThe smoke caused a decrease in follicle-stimulating hormone, luteinizing hormone, testosterone and protein, sialic acid, and carnitine. Also, the smoke resulted in a decrease in sperm count, reduced vitality, and reduced speed. The testicular ultrastructure showed adverse changes to sperm[76]


### 4.1. Anti-Inflammatory Effects

It was recorded thatB. carterii resin has been applied to treat various inflammatory diseases such as rheumatoid arthritis. Boswellic acids, the most well-known active components of B. carterii resin, were identified to have anti-inflammatory properties. Boswellic acids, in particular 3-O-acetyl-11-keto-β-boswellic acid, interfered with COX-1 and could regulate the anti-inflammatory effect in the way of inhibiting the expression of 5-lipoxygenases (5-LO) and 12-lipoxygenases (12-LO) and the suppression of cyclooxygenases, especially COX-1 [77]. 3-O-Acetyl-11-keto-β-boswellic acid reduced Th17 differentiation by interrupting IL-1ß-mediated IRAK1 signal, which may regulate IL-1ß signal by inhibiting the phosphorylation of IL-1 receptor-related kinase 1 and STAT3 [73].Microsomal prostaglandin E2 synthase-1 (mPGES-1) was confirmed to be a boswellic acid-interacting protein, and boswellic acid inhibited mPGES-1-mediated prostaglandin (PG) H2 conversion to PGE2 [35]. Besides boswellic acids, other known triterpene acids, particularly 3α-acetoxy-8,24-dienetirucallic acid, and 3α-acetoxy-7,24-dienetirucallic acid, isolated from B. carterii suppressed mPGES-1 [28]. The pull-down experiments and selective inhibition of the expression of iNOS induced by LPS suggested that ß-boswellic acid could be anti-inflammation through inhibiting LPS activity [41]. Incensole acetate inhibited cytokine secretion and LPS-induced NF-κB activation through suppressing IκB kinase (IKK) phosphorylation [51]. Incensole acetate reduced the activation of glial cells, the expression of TGF-β, IL-1β, and TNF-α mRNA, and the activation of NF-κB. Incensole acetate induced macrophages dead in closed head injury mice [52]. The above studies indicate that incensole acetate could inhibit inflammation and protect neurons and may show potential effects against ischemia and reperfusion. Furthermore, 3α-acetoxy-28-hydroxy-lup-20(29)-en-4β-oic acid inhibited the biosynthesis of COX-, 5-LO-, and 12-LO-derived eicosanoids, acting as an efficient inhibitor of cPLA2α, and consequently suppressed eicosanoid biosynthesis in intact cells [42].


### 4.2. Antioxidant Effects

Research on the antioxidative effects ofB. carterii has focused on the compounds 3-O-acetyl-9, 11-dehydro-β-mastic acid [28] and alcohol extracts [56]. The antioxidative effects were observed by inhibiting 5-lipoxygenase [28], scavenging oxygen free radicals [78], and inhibiting a significant increase in the lipid peroxidation marker malondialdehyde (MDA) [56]. Besides, the extracts from B. carterii showed antioxidant effects using the DPPH- and ABTS-free radical scavenging methods [79]. Interestingly, the methanol fraction of the mastic-containing complex showed anti-inflammatory and antioxidant effects and promoted angiogenesis and epithelial regeneration in mice that had epithelial damage [79]. Oxidative damage is one of the causes of human ageing, and the antioxidant effect of frankincense helps to slow down this process.


### 4.3. Antitumour Effects

B. carterii compounds and extracts showed adverse effects on glioblastoma, prostate cancer, fibrosarcoma, neuroblastoma, bladder cancer, leukemia, colon cancer, breast cancer, and liver cancer, which are partly related to the ageing [31, 57, 59, 60]. The cellular pathways modulated by B. carterii to exert anticancer effects are involved in the following aspects. B. carterii regulated the p21/FOXM1/cyclin B1 pathway, downregulated Aurora B, and upregulated the p53 signalling pathway [57]. Acetyl-lupeolic acid primarily inhibited Akt by directly binding the pleckstrin homology domain. Acetyl-lupeolic acid could lead to three results, namely, the loss of mitochondrial membrane potential, the hindrance of phosphorylation of following targets of the Akt pathway, and the inhibition of the mTOR target p70 ribosomal hexaprotein kinase and β-catenin, p65/NF-κB, and c-Myc [59]. B. carterii was also shown to significantly inhibit c-Myc expression [80] and block Sp1 DNA-binding activity to inhibit Sp1-stimulated androgen receptor promoter activity [65]. At both Ser473 and Thr308 positions, 3-acetyl-11-keto-β-boswellic acid induced Akt phosphorylation [66]. Tirucallic acids functioned in combination with the pleckstrin homeodomain of Akt to inhibit Akt activation and downregulate the pathway that activates Akt [22]. B. carterii diterpenoids selectively docked with HIV-1 reverse transcriptase [81]. B. carterii triterpenoids target cancer-related proteins, including poly (ADP-ribose) polymerase-1, tankyrase, and the folate receptor [81]. ß-Boswellic acid could target cancer-associated proteins, such as proteasomes, 14-3-3 proteins, heat shock proteins, and ribosomal proteins [82]. B. carterii essential oil activated heat shock proteins and histone core proteins [61].Clinically, the combination ofB. carterii, betaine, and inositol could reduce breast density, relieve pain in benign breast masses, reduce anxiety, and reduce masses in menopausal women [83–85]. Besides, B. carterii prolonged the survival of patients with lung cancer [86], reduced fatigue, enhanced vitality, and reduced insulin use in patients with pancreatic cancer [87]. B. carterii also exhibited a beneficial effect for patients with bilateral lung and metastatic bladder cancers [88].


### 4.4. Antiviral Effects

Then-hexane-soluble mixture, MeOH extract, EtOAc-soluble mixture, n-BuOH-soluble mixture, water extract, and H2O-soluble mixture of B. carterii showed an antiviral effect by inhibiting the hepatitis C virus protease [67] and the Epstein–Barr virus early antigen [21].


### 4.5. Antimicrobial Effects

An antimicrobial effect ofB. carterii for bacteria (Gram-positive and Gram-negative) and fungi was associated with its essential oils and its smoke [68, 69, 89, 90].


### 4.6. Neuroprotective Effects

A neuroprotective effect has been associated withB. carterii extracts that demonstrated antidepressant properties, resistance to inflammation caused by cerebral ischemia, promotion of neurodevelopment, and resistance to Alzheimer’s disease [81]. Research in this area has focused on incensole acetate and gum resin from Boswellia. The TPRV3 pathway was associated with the antidepressant effect of B. carterii [52, 70]. The ability of B. carterii to promote nerve development may be related to its ability to increase CaMKII mRNA expression [71]. Incensole acetate reduced NF-κB activity, and GFAP expression in the brain [53] showed an antidepressant effect in acute and chronic treatment cases [91] and reduced the inflammatory response of nerve tissues via the NF-κB pathway [52]. Also, triterpene acids showed cytotoxicity in neuroblastoma [21].


### 4.7. Hepatoprotective Effects

The compounds ofB. carterii showed a liver protective effect by inhibiting damage from D-galactosamine to HL-7702 cells [4, 19, 24].


### 4.8. Kidney Protective Effects

Prophylactic treatments usingB. carterii showed benefits in anti-acute and anti-chronic renal failure cases. Oral administration of B. carterii induced a reduction in serum creatinine, serum urea, blood urea nitrogen, and C-reactive protein activity [72].


### 4.9. Immunomodulatory Effects

The compounds and fractions ofB. carterii promoted the transformation of peripheral blood lymphocytes, regulated the expression of lymphokines in mouse spleen cells, dose-dependently inhibited the expression of Th1 cytokines, and dose-dependently promoted the expression of Th2 cytokines [37]. Furthermore, acetyl-11-keto-β-boswellic acid, by preventing IL-1R-related kinase 1 phosphorylation and subsequently inhibiting STAT3 phosphorylation, affected the IL-1β signalling, thereby inhibiting Th17 cell differentiation [73]. Moreover, it is interesting that the purified compounds showed carrier-dependent immunomodulation in vitro and that the purified compounds are less active than the total compounds [12].


### 4.10. Other Effects

B. carterii compounds showed an effect on the lung cell structure of rats [74], affected the development of Callosobruchus species by increasing oxidative stress [47], and reduced the level of oxidation to promote cardiovascular protection [56].


### 4.11. Side Effects

The side effects refer to the pharmacological effects of a drug beyond its therapeutic purpose following the application of a therapeutic amount of the drug. Understanding drug side effects is required to formulate a clinical medication plan and to avoid health risks. The side effects ofB. carterii are primarily related to smoke-induced reproductive toxicity. Histopathological sections and ultrastructure of the testis and epididymis showed adverse effects on sperm development. Sperm counts, viability, and speed decreased in varying degrees, and the proportion of abnormal sperm increased. Fructose levels in epididymal fluid and prostate fluid were reduced, and also, a luteinizing hormone, testosterone, and follicle-stimulating hormone levels in plasma and protein were reduced [75, 92]. Other studies have shown that sialic acid and carnitine in cauda epididymal plasma are reduced [76].


## 4.1. Anti-Inflammatory Effects

It was recorded thatB. carterii resin has been applied to treat various inflammatory diseases such as rheumatoid arthritis. Boswellic acids, the most well-known active components of B. carterii resin, were identified to have anti-inflammatory properties. Boswellic acids, in particular 3-O-acetyl-11-keto-β-boswellic acid, interfered with COX-1 and could regulate the anti-inflammatory effect in the way of inhibiting the expression of 5-lipoxygenases (5-LO) and 12-lipoxygenases (12-LO) and the suppression of cyclooxygenases, especially COX-1 [77]. 3-O-Acetyl-11-keto-β-boswellic acid reduced Th17 differentiation by interrupting IL-1ß-mediated IRAK1 signal, which may regulate IL-1ß signal by inhibiting the phosphorylation of IL-1 receptor-related kinase 1 and STAT3 [73].Microsomal prostaglandin E2 synthase-1 (mPGES-1) was confirmed to be a boswellic acid-interacting protein, and boswellic acid inhibited mPGES-1-mediated prostaglandin (PG) H2 conversion to PGE2 [35]. Besides boswellic acids, other known triterpene acids, particularly 3α-acetoxy-8,24-dienetirucallic acid, and 3α-acetoxy-7,24-dienetirucallic acid, isolated from B. carterii suppressed mPGES-1 [28]. The pull-down experiments and selective inhibition of the expression of iNOS induced by LPS suggested that ß-boswellic acid could be anti-inflammation through inhibiting LPS activity [41]. Incensole acetate inhibited cytokine secretion and LPS-induced NF-κB activation through suppressing IκB kinase (IKK) phosphorylation [51]. Incensole acetate reduced the activation of glial cells, the expression of TGF-β, IL-1β, and TNF-α mRNA, and the activation of NF-κB. Incensole acetate induced macrophages dead in closed head injury mice [52]. The above studies indicate that incensole acetate could inhibit inflammation and protect neurons and may show potential effects against ischemia and reperfusion. Furthermore, 3α-acetoxy-28-hydroxy-lup-20(29)-en-4β-oic acid inhibited the biosynthesis of COX-, 5-LO-, and 12-LO-derived eicosanoids, acting as an efficient inhibitor of cPLA2α, and consequently suppressed eicosanoid biosynthesis in intact cells [42].


## 4.2. Antioxidant Effects

Research on the antioxidative effects ofB. carterii has focused on the compounds 3-O-acetyl-9, 11-dehydro-β-mastic acid [28] and alcohol extracts [56]. The antioxidative effects were observed by inhibiting 5-lipoxygenase [28], scavenging oxygen free radicals [78], and inhibiting a significant increase in the lipid peroxidation marker malondialdehyde (MDA) [56]. Besides, the extracts from B. carterii showed antioxidant effects using the DPPH- and ABTS-free radical scavenging methods [79]. Interestingly, the methanol fraction of the mastic-containing complex showed anti-inflammatory and antioxidant effects and promoted angiogenesis and epithelial regeneration in mice that had epithelial damage [79]. Oxidative damage is one of the causes of human ageing, and the antioxidant effect of frankincense helps to slow down this process.


## 4.3. Antitumour Effects

B. carterii compounds and extracts showed adverse effects on glioblastoma, prostate cancer, fibrosarcoma, neuroblastoma, bladder cancer, leukemia, colon cancer, breast cancer, and liver cancer, which are partly related to the ageing [31, 57, 59, 60]. The cellular pathways modulated by B. carterii to exert anticancer effects are involved in the following aspects. B. carterii regulated the p21/FOXM1/cyclin B1 pathway, downregulated Aurora B, and upregulated the p53 signalling pathway [57]. Acetyl-lupeolic acid primarily inhibited Akt by directly binding the pleckstrin homology domain. Acetyl-lupeolic acid could lead to three results, namely, the loss of mitochondrial membrane potential, the hindrance of phosphorylation of following targets of the Akt pathway, and the inhibition of the mTOR target p70 ribosomal hexaprotein kinase and β-catenin, p65/NF-κB, and c-Myc [59]. B. carterii was also shown to significantly inhibit c-Myc expression [80] and block Sp1 DNA-binding activity to inhibit Sp1-stimulated androgen receptor promoter activity [65]. At both Ser473 and Thr308 positions, 3-acetyl-11-keto-β-boswellic acid induced Akt phosphorylation [66]. Tirucallic acids functioned in combination with the pleckstrin homeodomain of Akt to inhibit Akt activation and downregulate the pathway that activates Akt [22]. B. carterii diterpenoids selectively docked with HIV-1 reverse transcriptase [81]. B. carterii triterpenoids target cancer-related proteins, including poly (ADP-ribose) polymerase-1, tankyrase, and the folate receptor [81]. ß-Boswellic acid could target cancer-associated proteins, such as proteasomes, 14-3-3 proteins, heat shock proteins, and ribosomal proteins [82]. B. carterii essential oil activated heat shock proteins and histone core proteins [61].Clinically, the combination ofB. carterii, betaine, and inositol could reduce breast density, relieve pain in benign breast masses, reduce anxiety, and reduce masses in menopausal women [83–85]. Besides, B. carterii prolonged the survival of patients with lung cancer [86], reduced fatigue, enhanced vitality, and reduced insulin use in patients with pancreatic cancer [87]. B. carterii also exhibited a beneficial effect for patients with bilateral lung and metastatic bladder cancers [88].


## 4.4. Antiviral Effects

Then-hexane-soluble mixture, MeOH extract, EtOAc-soluble mixture, n-BuOH-soluble mixture, water extract, and H2O-soluble mixture of B. carterii showed an antiviral effect by inhibiting the hepatitis C virus protease [67] and the Epstein–Barr virus early antigen [21].


## 4.5. Antimicrobial Effects

An antimicrobial effect ofB. carterii for bacteria (Gram-positive and Gram-negative) and fungi was associated with its essential oils and its smoke [68, 69, 89, 90].


## 4.6. Neuroprotective Effects

A neuroprotective effect has been associated withB. carterii extracts that demonstrated antidepressant properties, resistance to inflammation caused by cerebral ischemia, promotion of neurodevelopment, and resistance to Alzheimer’s disease [81]. Research in this area has focused on incensole acetate and gum resin from Boswellia. The TPRV3 pathway was associated with the antidepressant effect of B. carterii [52, 70]. The ability of B. carterii to promote nerve development may be related to its ability to increase CaMKII mRNA expression [71]. Incensole acetate reduced NF-κB activity, and GFAP expression in the brain [53] showed an antidepressant effect in acute and chronic treatment cases [91] and reduced the inflammatory response of nerve tissues via the NF-κB pathway [52]. Also, triterpene acids showed cytotoxicity in neuroblastoma [21].


## 4.7. Hepatoprotective Effects

The compounds ofB. carterii showed a liver protective effect by inhibiting damage from D-galactosamine to HL-7702 cells [4, 19, 24].


## 4.8. Kidney Protective Effects

Prophylactic treatments usingB. carterii showed benefits in anti-acute and anti-chronic renal failure cases. Oral administration of B. carterii induced a reduction in serum creatinine, serum urea, blood urea nitrogen, and C-reactive protein activity [72].


## 4.9. Immunomodulatory Effects

The compounds and fractions ofB. carterii promoted the transformation of peripheral blood lymphocytes, regulated the expression of lymphokines in mouse spleen cells, dose-dependently inhibited the expression of Th1 cytokines, and dose-dependently promoted the expression of Th2 cytokines [37]. Furthermore, acetyl-11-keto-β-boswellic acid, by preventing IL-1R-related kinase 1 phosphorylation and subsequently inhibiting STAT3 phosphorylation, affected the IL-1β signalling, thereby inhibiting Th17 cell differentiation [73]. Moreover, it is interesting that the purified compounds showed carrier-dependent immunomodulation in vitro and that the purified compounds are less active than the total compounds [12].


## 4.10. Other Effects

B. carterii compounds showed an effect on the lung cell structure of rats [74], affected the development of Callosobruchus species by increasing oxidative stress [47], and reduced the level of oxidation to promote cardiovascular protection [56].


## 4.11. Side Effects

The side effects refer to the pharmacological effects of a drug beyond its therapeutic purpose following the application of a therapeutic amount of the drug. Understanding drug side effects is required to formulate a clinical medication plan and to avoid health risks. The side effects ofB. carterii are primarily related to smoke-induced reproductive toxicity. Histopathological sections and ultrastructure of the testis and epididymis showed adverse effects on sperm development. Sperm counts, viability, and speed decreased in varying degrees, and the proportion of abnormal sperm increased. Fructose levels in epididymal fluid and prostate fluid were reduced, and also, a luteinizing hormone, testosterone, and follicle-stimulating hormone levels in plasma and protein were reduced [75, 92]. Other studies have shown that sialic acid and carnitine in cauda epididymal plasma are reduced [76].


## 5. Pharmacokinetics

Pharmacokinetics offers scientific support for the clinical use ofB. carterii. The experiments have shown that 3-acetyl-11-keto-β-boswellic acid and 11-keto-β-boswellic acid are absorbed more by laboratory animals when administered in processed frankincense forms. Using HPLC, the Cmax of 3-acetyl-11-keto-β-boswellic acid and 11-keto-β-boswellic acid was 3.197 μg/mL and 2.037 μg/mL for vinegar-processed frankincense (VPF), respectively, and 0.987 μg/mL and 1.937 μg/mL for frankincense oral administration (FRA), respectively [36]. The processed and nonprocessed products exhibited a significant difference in absorption. Meanwhile, 3-acetyl-11-keto-β-boswellic acid was absorbed more easily than 11-keto-β-boswellic acid, and the values of Cmax were observed in the order of VPF > SFF (stir-fried frankincense) > FRA. The levels of plasma 11-keto-β-boswellic acid and 3-acetyl-11-keto-β-boswellic acid reduced slowly, especially for the VPF group compared with the FRA group. In the VPF group, pharmacokinetic parameters of 11-keto-β-boswellic acid and 3-acetyl-11-keto-β-boswellic acid, such as Cmax, AUC0-t, and AUC0–∞, were greatly increased, while V/F and CL/F values were decreased [36]. These results show that the clinical use value of frankincense can be further enhanced [36].


## 6. Discussion

The resins ofB. carterii have been used for the treatment of inflammation-related diseases, such as traumatic injury and inflammatory pain in China for a long time. Recently, the traditional medicine had become a hot research topic, while more positive effects and other potential medical values have been found. In this study, we listed the isolated components of Boswellia resin by category according to previous research and summarized their pharmacological effect on a different model. The different components of Boswellia resin have found a series of beneficial effects on many diseases when applied in laboratory research, and some have been approved for clinical use. We hope more research about quality control, and the novel component can be conducted in the future.


## 7. Conclusion

This article reviewed the research performed on the components ofB. carterii in terms of quality control, phytochemistry, pharmacological effects (including side effects), and pharmacokinetics. We highlighted studies showing that frankincense exhibits anti-inflammatory, antitumour, and antioxidant activities, including some important organ-protective effects on the heart, liver, and kidney. We also found that B. carterii exhibits a good effect on the treatment and prevention of geriatric diseases. The review also presented studies showing that pure compounds could exhibit lower immunomodulatory activities than the crude extract, with some progress being made in identifying the mechanisms involved. However, we found that some studies did not investigate relevant toxicology and pharmacokinetic aspects.Furthermore, the studies did not provide an in-depth evaluation of the bioactivity of the extracts and the isolated compounds, orin vivo experiments that might indicate therapeutic relevance. Based on the above research and deficiencies, clinicians should remain cautious when using this plant as a therapeutic drug until further research demonstrates the safety, quality, and efficacy of B. carterii. As such, extensive pharmacological and chemical experiments, including human metabolism studies, require future investigations.



---

*Source: 6627104-2022-01-13.xml*