# Antiproliferative, Anti-Inflammatory Activities, and Molecular Docking Studies of Secondary Metabolites fromMacrosolen tricolor

Authors: Van Son Dang; Kieu Hung Le; Thi Hong Tuoi Do; Le Thanh Tuyen Nguyen; Thi Phuong Lan Vu; Thi Kim Chi Huynh; Thi Kim Dung Hoang; Quan Hien Nguyen; Trong Nghia Ngo; Diep Xuan Ky Nguyen; Nhat Minh Phan; Trong Dat Bui; Dinh Tri Mai; Tan Phat Nguyen
Journal: Journal of Chemistry
 (2023)

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## Abstract

In Vietnam,Macrosolen tricolor is used for the treatment of bloating, broken bones, cough, diarrhea, diuretic, rheumatism, and laxative effects. The study aimed to identify the in vitro antiproliferation and anti-inflammation of all fractions and purified compounds from the M. tricolor whole plants, as well as the in silico molecular docking of the potentially cytotoxic compounds. As the results, fractions (MTH.I, MTH.II, MTE.I, and MTE.II) strongly demonstrated antiproliferative properties against three tested cells, MDA-MB-231, RD, and HepG2 (IC50 values ranged from 4.00 ± 0.20 to 70.60 ± 1.44 μg/mL), as well as anti-inflammatory effects (IC50 values ranged from 4.45 ± 0.08 to 23.00 ± 1.18 μg/mL), whereas other fractions meaningfully evidenced selective cytotoxicity and/or anti-inflammation. Therefore, the phytochemical compositions of the active fractions were illuminated, leading to the characterization of eighteen compounds. Compounds (3–5) revealed the most cytotoxic effects towards all examined cells (IC50 values ranged from 6.88 ± 0.12 to 71.64 ± 1.17 μM) and the strongest anti-inflammatory properties (IC50 values of 16.30 ± 0.92, 7.31 ± 0.55, and 9.23 ± 0.60 μM, respectively). Compound 11 showed potential cytotoxicity against MDA-MB-231, RD, and HepG2 cells (IC50 values of 24.42 ± 0.28, 20.60 ± 0.25, and 3.20 ± 0.02 μM, respectively). Furthermore, compounds (4, 5, and 11) interacted with the active site of the apoptosis regulator Bcl-2 protein (PDB ID: 2O2F), were comparable to PAC, and were compatible with their anticancer activity. This project suggests that M. tricolor is a good source of natural antiproliferative and anti-inflammatory agents and contributes to understanding the biological activities of Macrosolen species in traditional Vietnamese medicine.


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## Body

## 1. Introduction

Inflammation, characterized as the first protective response of the immune system, is a common and highly dynamic process in the body. The extent of the inflammatory response is seriously important. Chronic inflammation results from an insufficient inflammatory response, which is implicated in the pathophysiology of cancers [1, 2]. In this process, macrophages express the vital administration of many immune-pathological phenomena, including the overproduction of major inflammatory mediators such as NO [2, 3]. Therefore, the investigation of bioactive components from herbal medicines possessing antiproliferation [4] and anti-inflammation properties against NO overproduction [5, 6] is very essential and of most concern today.Macrosolen tricolor, belonging to the Loranthaceae family, is a hemiparasitic shrub, ca. 30–50 cm. The branches are grayish. The leaves are blade obovate to narrowly obovate, 3.5–5.5 × 1.3–2 cm, have 2 or 3 pairs of lateral veins, and the petiole is 2–3 mm long. The flowers consist of solitary or paired inflorescences, a peduncle of ca. 1 mm, and a mature bud of 2.5–3.5 cm. The corolla is red with a green band at the top of the tube, slightly curved, tube inflated, lobes greenish, lanceolate, 6–9 mm, reflexed. Berries are dark purple, globose, ca. 7 mm, and smooth. The plant is used in traditional Vietnamese medicine for treatments such as bloating, broken bones, cough, diarrhea, diuretic, rheumatism, and laxative effects [7, 8].In vivo pharmacological studies on rats demonstrated that the liquid of the M. tricolor whole plants provided hepatoprotection against paracetamol-induced hepatotoxicity, as evidenced by decreased liver weight and aspartate aminotransferase (ALT) and alanine aminotransferase (AST) concentrations in the blood (at the doses of 30 g/kg and 60 g/kg, which were compared to silymarin at a dose of 70 mg/kg) [9, 10]. M. tricolor whole plant liquid was also found to have anti-inflammatory effects on carrageenan-induced paw oedema and carrageenan plus formaldehyde-induced abdominal writhing (at a dose of 40 g/kg, compared to the aspirin drug’s dose of 150 mg/kg) [11, 12].Lupeol, 3β-nonadecanoyllup-20(29)-ene-7β-ol, 3β-nonadecanoyllup-20(29)-ene-7β,15α-diol, quercetin 3-rhamnoside, and methyl brevifolin carboxylate were discovered in the M. tricolor whole plants [3–5]. In our earlier papers, one diarylpropanoid, three diarylheptanoids, three phenolics, three flavonoids, and two steroids were characterized from this species [7, 8].There is no report on thein vitro antiproliferative and anti-inflammatory properties of this species. Continuing our exciting studies on the cytotoxic constituents of the Vietnam plants [13–15] and the Macrosolen genus [16–19], this study disclosed the in vitro cytotoxic efficacy on MDA-MB-231, RD, HepG2, and RAW264.7 cells and anti-inflammatory evaluation against NO production in LPS-induced inflammation of fractions and separated compounds using MTT assay, as well as the in silico molecular docking studies on the Bcl-2-regulated apoptosis protein for the most cytotoxic isolates.


## 2. Materials and Methods

### 2.1. Plant Material

TheMacrosolen tricolor whole plants, certificated by Dr. Dang Van-Son, Institute of Tropical Biology, were collected in Ba Ria-Vung Tau Province (December 2018) and further deposited in the Bioactive Compounds Laboratory, Institute of Chemical Technology (voucher herbarium specimen No. VH/PHAT-MT1218).


### 2.2. Extraction

The whole plants ofM. tricolor were washed, dried, and powdered (50 mesh). The ground powder sample (4.3 kg) was macerated using 96% ethanol at room temperature to deliver the crude extract (MTEt). The MTEt extract (1.1 kg) was applied to two liquid-phase separations and consecutively fractionated with n-hexane (n-H) and ethyl acetate, respectively, to obtain MTH (100 g), MTE (106 g) extracts, and water layer (1000 g).The MTH extract was separated on a silica gel column and eluted withn-H/EtOAc (100/0–0/100, v/v) to yield five fractions: MTH.I (10.0 g), MTH.II (50.0 g), MTH.III (5.0 g), MTH.IV (15.0 g), and MTH.V (12.0 g). Similarly, the MTE extract was segregated on normal-phase column chromatography (CC) eluting with n-H/EtOAc/MeOH (25/75/0–0/90/10, v/v/v) to get five fractions: MTE.I (18.0 g), MTE.II (5.2 g), MTE.III (18.2 g), MTE.IV (30.0 g), and MTE.V (9.0 g). Those were stored at 4°C for further investigation.


### 2.3. Chemicals and Reagents

Penicillin (PEN),L-glutamine (GLU), phosphate buffer, streptomycin (STR), carbon tetrachloride (CCl4), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and PAC were purchased from Sigma-Aldrich. Fetal calf serum (FCS), Eagle’s Minimum Essential Medium (EMEM), and trypsin-Ethylene Diamine Tetracetic Acid (EDTA) were ordered from Gibco. Isopropanol, ethanol, and dimethyl sulfoxide were delivered from Merck. All chemicals met regulatory requirements.


### 2.4. Cell Culture

All tested cell lines (RAW264.7, MDA-MB-231, RD, and HepG2 cells) required from the ATCC organization in Virginia were seeded and cultured in EMEM including 2 mM GLU, 10% FCS (v/v), 100 IU/mL PEN, and 100µg/mL STR (in 5% CO2 at 37°C).


### 2.5. MTT Assay

Thein vitro cytotoxic effects were observed against four tumor cells: MDA-MB-231, RD, HepG2, and RAW264.7 of all MTH, MTE fractions, and pure compounds were exposed by the MTT test, as described in our previous papers [15, 16].Cancer cells (MDA-MB-231, RD, and HepG2) were harvested and seeded in 96-wells at 4.0 × 104 cells/cm2 in EMEM or DMEM medium supplemented with 2 mM GLU, 10% FCS, 100 µg/mL STR, and 100 IU/mL PEN. Cells were treated with tested fractions, purified compounds at different concentrations, PAC, and blank control (DMSO), after 24 h of incubation (in 5% CO2 at 37°C). Cell media were removed from the plate, the cells were washed using 200 µL buffered saline (PBS), and MTT solution was added to each well, after 72 h of incubation (in 5% CO2 at 37°C). Succinate dehydrogenase (SDH) activity was detected after 4 h of incubation at 37°C, which is converted into formazan dissolved in isopropanol by agitation for 10 min at room temperature. The absorbance was measured at 570 nm. The IC50 values were calculated by regressing the concentrations of the tested fractions (at 12.5, 25.0, 50.0, and 100.0 µg/mL) and the cell inhibition percentages. The positive drug, PAC was purposed.


### 2.6. NO Assay

Thein vitroanti-inflammation of LPS-induced inflammatory effect using RAW264.7 cells of all MTH, MTE fractions, and isolated compounds were communicated as in previous papers [7, 20].RAW264.7 cells derived from mice bone marrow were seeded into 96-well plates. Cells were incubated for 3 hours and then treated with 04 high testers at the different concentrations for 30 minutes. The cells were then treated without or with a 1μg/mL LPS to induce inflammation, and incubated for 24 hours (in 5% CO2 at 37°C). After 24 hours, each well received 100 μL of culture medium and 100 μL of Griess reagent. The nitrite concentration was measured in the supernatants of tissue homogenate with 1% bovine serum albumin. Then an equal volume of the sample with Griess reagent (1% sulphanilamide in 5% H3PO4 and 0.1% N-[1-Napthyl]-ethylenediamine) was mixed. The absorbance was measured (at 450 nm) to determine the amount of NO. The amount of nitrite was obtained by extrapolation from a standard curve with NaNO2 and expressed as μmol/mg tissue. The positive control, QUE, was serviced.


### 2.7. General Experimental Procedures for Isolation and Structural Elucidation

The high-resolution mass spectroscopy (HRMS) using the electrospray ionization technique (ESI) was measured on a Sciex spectrometer (Modem X500R-QTOF). The 1D and 2D NMR spectra were recorded on a Bruker Avance spectrometer (Modem AM500, 500 MHz). CC was carried out using normal-phase silica gel (230–400 mesh) and reversed-phase silica gel RP-C18 (Merck, Germany). Thin-layer chromatography (TLC) was applied to silica gel 60 F254 plates (Merck, Germany). The compounds were sprayed with the H2SO4 10%/ethanol reagent and visualized by heating (3–5 min).


### 2.8. Isolation

The fractionMTH.I (10.0 g) was subjected to silica gel CC eluted with the solvent systems of n-H/EtOAc (5/95–30/70, v/v) to provide four subfractions (MTH.I.1–MTH.I.4). Subfraction MTH.I.2 (4.5 g) was isolated by normal-phase CC using CHCl3/MeOH (99/1, v/v) to yield 1 (350 mg).The fractionMTH.II (50.0 g) was eluted over a silica gel column with n-H/EtOAc systems (20/80–45/55, v/v) to get six subfractions (MTH.II.1–MTH.II.6). Subfraction MTH.II.1 (6.5 g) was chromatographed on normal-phase silica gel using CHCl3/MeOH (99/1, v/v) and on reversed-phase silica gel eluting MeOH/H2O (20/80, v/v) to afford 1 (160 mg), 2 (8 mg), 3 (5 mg), 4 (4.5 mg), and 5 (7 mg).The fractionMTH.III (5.0 g) was fractioned on a normal-phase column with an n-H/EtOAc gradient (30/70–50/50, v/v) to collect five subfractions (MTH.III.1–MTH.III.5). Subfraction MTH.III.1 (2.4 g) was rechromatographed on CC with CHCl3/MeOH solvents (99/1, v/v) and on RP-C18 with MeOH/H2O (30/70, v/v) to give 3 (4 mg), 4 (4 mg), 5 (4 mg), and 6 (4.5 mg).The fractionMTH.IV (15.0 g) was divided into four subfractions (MTH.IV.1–MTH.IV.4) using n-H/EtOAc solvents (40/60–70/30, v/v). Subfraction MTH.IV.2 (6.0 g) was purified with CHCl3/MeOH (98/2, v/v) to deliver 7 (8 mg) and 8 (100 mg).In the same way, fractionMTE.I was subjected to CC using n-H/EtOAc mixtures (25/75–0/100, v/v) to furnish compounds 1 (200 mg), 8 (35 mg), and a mixture of 3–5 (40 mg). Compounds 9 (6 mg), 10 (4 mg), 11 (40 mg), 12 (7 mg), 13 (3.5 mg), 14 (8 mg), 15 (10 mg), and 16 (4 mg) were supplied from fraction MTE.II. Finally, compounds 17 (5 mg) and 18 (40 mg) were donated from fraction MTE.IV.


### 2.9. Molecular Docking Studies

#### 2.9.1. Preparation of Compounds

The 2D and 3D chemical structures of compounds4, 5, 11, and PAC were constructed using ChemDraw 19.1 and MOE 2015.10 software. The structural compounds were optimized by energy minimization and molecular dynamic functions in Sybyl-X 1.1. In energy minimization, the method of minimizing was a conjugate gradient, and the structures of compounds were optimized until a minimal energy change of 0.001 kcal/mol was reached. Gasteiger-Huckel charges were applied to the structure atoms, and the maximal number of iterations was fixed at 10,000 to be performed during minimization. The simulated annealing method was used in this process, and the compounds were heated at 700°K for 1000 femtoseconds and then cooled to 200°K for the same period to achieve stable states from which their final conformations were obtained. This action was conducted in five cycles to discover the different required structures. Lastly, the energy minimization procedure was conducted one more time, and the minimal energy of the final conformations was explored.


#### 2.9.2. Preparation of Protein

The X-ray crystallographic structure of the antiapoptotic protein Bcl-2 in complex with an acyl-sulfonamide-based ligand was collected from the Protein Data Bank (PDB ID: 2O2F) and performed as the receptor model [21]. The 3D structure of the crystallographic complex was established in AutoDock 4.2.6 software [22] to add hydrogen, protonate, and delete unbound waters. The active site was defined by considering a grid box of appropriate size around the bound co-crystal ligand. The grid box dimensions were as follows: no. of grid points 65 × 65 × 65; center (xyz coordinates) −0.024, 3.142, −0.361; grid point spacing (Å) 0.375. The compounds were docked using AutoDock 4.2.6 software.


#### 2.9.3. Evaluation of Docking Results

The docking experiment was organized using the Lamarckian genetic algorithm, with an initial population of 150 randomly placed individuals, a maximum number of 2.5 × 106 energy evaluations, a mutation rate of 0.02, and a crossover rate of 0.8. One hundred independent docking runs were detailed for each compound. Conformation clustering was carried out considering a root mean square deviation (RMSD) cut-off of 2.0 Å clustered, and the most possible binding modes were described using the lowest free energy of binding (ΔG) and the lowest inhibition constant (Ki). The most favorable binding conformation was selected and evaluated for molecular interaction with their receptors using LigPlot + version 1.4.5 software [23]. To establish that the binding pose of the docked compound defines a probable and valid perspective conformation, the docking parameters and methods were confirmed by redocking the cocrystal ligand against their specific targets. 3D poses of compounds with the antiapoptotic protein Bcl-2 in the complex were displayed using PyMOL 2.5.


## 2.1. Plant Material

TheMacrosolen tricolor whole plants, certificated by Dr. Dang Van-Son, Institute of Tropical Biology, were collected in Ba Ria-Vung Tau Province (December 2018) and further deposited in the Bioactive Compounds Laboratory, Institute of Chemical Technology (voucher herbarium specimen No. VH/PHAT-MT1218).


## 2.2. Extraction

The whole plants ofM. tricolor were washed, dried, and powdered (50 mesh). The ground powder sample (4.3 kg) was macerated using 96% ethanol at room temperature to deliver the crude extract (MTEt). The MTEt extract (1.1 kg) was applied to two liquid-phase separations and consecutively fractionated with n-hexane (n-H) and ethyl acetate, respectively, to obtain MTH (100 g), MTE (106 g) extracts, and water layer (1000 g).The MTH extract was separated on a silica gel column and eluted withn-H/EtOAc (100/0–0/100, v/v) to yield five fractions: MTH.I (10.0 g), MTH.II (50.0 g), MTH.III (5.0 g), MTH.IV (15.0 g), and MTH.V (12.0 g). Similarly, the MTE extract was segregated on normal-phase column chromatography (CC) eluting with n-H/EtOAc/MeOH (25/75/0–0/90/10, v/v/v) to get five fractions: MTE.I (18.0 g), MTE.II (5.2 g), MTE.III (18.2 g), MTE.IV (30.0 g), and MTE.V (9.0 g). Those were stored at 4°C for further investigation.


## 2.3. Chemicals and Reagents

Penicillin (PEN),L-glutamine (GLU), phosphate buffer, streptomycin (STR), carbon tetrachloride (CCl4), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and PAC were purchased from Sigma-Aldrich. Fetal calf serum (FCS), Eagle’s Minimum Essential Medium (EMEM), and trypsin-Ethylene Diamine Tetracetic Acid (EDTA) were ordered from Gibco. Isopropanol, ethanol, and dimethyl sulfoxide were delivered from Merck. All chemicals met regulatory requirements.


## 2.4. Cell Culture

All tested cell lines (RAW264.7, MDA-MB-231, RD, and HepG2 cells) required from the ATCC organization in Virginia were seeded and cultured in EMEM including 2 mM GLU, 10% FCS (v/v), 100 IU/mL PEN, and 100µg/mL STR (in 5% CO2 at 37°C).


## 2.5. MTT Assay

Thein vitro cytotoxic effects were observed against four tumor cells: MDA-MB-231, RD, HepG2, and RAW264.7 of all MTH, MTE fractions, and pure compounds were exposed by the MTT test, as described in our previous papers [15, 16].Cancer cells (MDA-MB-231, RD, and HepG2) were harvested and seeded in 96-wells at 4.0 × 104 cells/cm2 in EMEM or DMEM medium supplemented with 2 mM GLU, 10% FCS, 100 µg/mL STR, and 100 IU/mL PEN. Cells were treated with tested fractions, purified compounds at different concentrations, PAC, and blank control (DMSO), after 24 h of incubation (in 5% CO2 at 37°C). Cell media were removed from the plate, the cells were washed using 200 µL buffered saline (PBS), and MTT solution was added to each well, after 72 h of incubation (in 5% CO2 at 37°C). Succinate dehydrogenase (SDH) activity was detected after 4 h of incubation at 37°C, which is converted into formazan dissolved in isopropanol by agitation for 10 min at room temperature. The absorbance was measured at 570 nm. The IC50 values were calculated by regressing the concentrations of the tested fractions (at 12.5, 25.0, 50.0, and 100.0 µg/mL) and the cell inhibition percentages. The positive drug, PAC was purposed.


## 2.6. NO Assay

Thein vitroanti-inflammation of LPS-induced inflammatory effect using RAW264.7 cells of all MTH, MTE fractions, and isolated compounds were communicated as in previous papers [7, 20].RAW264.7 cells derived from mice bone marrow were seeded into 96-well plates. Cells were incubated for 3 hours and then treated with 04 high testers at the different concentrations for 30 minutes. The cells were then treated without or with a 1μg/mL LPS to induce inflammation, and incubated for 24 hours (in 5% CO2 at 37°C). After 24 hours, each well received 100 μL of culture medium and 100 μL of Griess reagent. The nitrite concentration was measured in the supernatants of tissue homogenate with 1% bovine serum albumin. Then an equal volume of the sample with Griess reagent (1% sulphanilamide in 5% H3PO4 and 0.1% N-[1-Napthyl]-ethylenediamine) was mixed. The absorbance was measured (at 450 nm) to determine the amount of NO. The amount of nitrite was obtained by extrapolation from a standard curve with NaNO2 and expressed as μmol/mg tissue. The positive control, QUE, was serviced.


## 2.7. General Experimental Procedures for Isolation and Structural Elucidation

The high-resolution mass spectroscopy (HRMS) using the electrospray ionization technique (ESI) was measured on a Sciex spectrometer (Modem X500R-QTOF). The 1D and 2D NMR spectra were recorded on a Bruker Avance spectrometer (Modem AM500, 500 MHz). CC was carried out using normal-phase silica gel (230–400 mesh) and reversed-phase silica gel RP-C18 (Merck, Germany). Thin-layer chromatography (TLC) was applied to silica gel 60 F254 plates (Merck, Germany). The compounds were sprayed with the H2SO4 10%/ethanol reagent and visualized by heating (3–5 min).


## 2.8. Isolation

The fractionMTH.I (10.0 g) was subjected to silica gel CC eluted with the solvent systems of n-H/EtOAc (5/95–30/70, v/v) to provide four subfractions (MTH.I.1–MTH.I.4). Subfraction MTH.I.2 (4.5 g) was isolated by normal-phase CC using CHCl3/MeOH (99/1, v/v) to yield 1 (350 mg).The fractionMTH.II (50.0 g) was eluted over a silica gel column with n-H/EtOAc systems (20/80–45/55, v/v) to get six subfractions (MTH.II.1–MTH.II.6). Subfraction MTH.II.1 (6.5 g) was chromatographed on normal-phase silica gel using CHCl3/MeOH (99/1, v/v) and on reversed-phase silica gel eluting MeOH/H2O (20/80, v/v) to afford 1 (160 mg), 2 (8 mg), 3 (5 mg), 4 (4.5 mg), and 5 (7 mg).The fractionMTH.III (5.0 g) was fractioned on a normal-phase column with an n-H/EtOAc gradient (30/70–50/50, v/v) to collect five subfractions (MTH.III.1–MTH.III.5). Subfraction MTH.III.1 (2.4 g) was rechromatographed on CC with CHCl3/MeOH solvents (99/1, v/v) and on RP-C18 with MeOH/H2O (30/70, v/v) to give 3 (4 mg), 4 (4 mg), 5 (4 mg), and 6 (4.5 mg).The fractionMTH.IV (15.0 g) was divided into four subfractions (MTH.IV.1–MTH.IV.4) using n-H/EtOAc solvents (40/60–70/30, v/v). Subfraction MTH.IV.2 (6.0 g) was purified with CHCl3/MeOH (98/2, v/v) to deliver 7 (8 mg) and 8 (100 mg).In the same way, fractionMTE.I was subjected to CC using n-H/EtOAc mixtures (25/75–0/100, v/v) to furnish compounds 1 (200 mg), 8 (35 mg), and a mixture of 3–5 (40 mg). Compounds 9 (6 mg), 10 (4 mg), 11 (40 mg), 12 (7 mg), 13 (3.5 mg), 14 (8 mg), 15 (10 mg), and 16 (4 mg) were supplied from fraction MTE.II. Finally, compounds 17 (5 mg) and 18 (40 mg) were donated from fraction MTE.IV.


## 2.9. Molecular Docking Studies

### 2.9.1. Preparation of Compounds

The 2D and 3D chemical structures of compounds4, 5, 11, and PAC were constructed using ChemDraw 19.1 and MOE 2015.10 software. The structural compounds were optimized by energy minimization and molecular dynamic functions in Sybyl-X 1.1. In energy minimization, the method of minimizing was a conjugate gradient, and the structures of compounds were optimized until a minimal energy change of 0.001 kcal/mol was reached. Gasteiger-Huckel charges were applied to the structure atoms, and the maximal number of iterations was fixed at 10,000 to be performed during minimization. The simulated annealing method was used in this process, and the compounds were heated at 700°K for 1000 femtoseconds and then cooled to 200°K for the same period to achieve stable states from which their final conformations were obtained. This action was conducted in five cycles to discover the different required structures. Lastly, the energy minimization procedure was conducted one more time, and the minimal energy of the final conformations was explored.


### 2.9.2. Preparation of Protein

The X-ray crystallographic structure of the antiapoptotic protein Bcl-2 in complex with an acyl-sulfonamide-based ligand was collected from the Protein Data Bank (PDB ID: 2O2F) and performed as the receptor model [21]. The 3D structure of the crystallographic complex was established in AutoDock 4.2.6 software [22] to add hydrogen, protonate, and delete unbound waters. The active site was defined by considering a grid box of appropriate size around the bound co-crystal ligand. The grid box dimensions were as follows: no. of grid points 65 × 65 × 65; center (xyz coordinates) −0.024, 3.142, −0.361; grid point spacing (Å) 0.375. The compounds were docked using AutoDock 4.2.6 software.


### 2.9.3. Evaluation of Docking Results

The docking experiment was organized using the Lamarckian genetic algorithm, with an initial population of 150 randomly placed individuals, a maximum number of 2.5 × 106 energy evaluations, a mutation rate of 0.02, and a crossover rate of 0.8. One hundred independent docking runs were detailed for each compound. Conformation clustering was carried out considering a root mean square deviation (RMSD) cut-off of 2.0 Å clustered, and the most possible binding modes were described using the lowest free energy of binding (ΔG) and the lowest inhibition constant (Ki). The most favorable binding conformation was selected and evaluated for molecular interaction with their receptors using LigPlot + version 1.4.5 software [23]. To establish that the binding pose of the docked compound defines a probable and valid perspective conformation, the docking parameters and methods were confirmed by redocking the cocrystal ligand against their specific targets. 3D poses of compounds with the antiapoptotic protein Bcl-2 in the complex were displayed using PyMOL 2.5.


## 2.9.1. Preparation of Compounds

The 2D and 3D chemical structures of compounds4, 5, 11, and PAC were constructed using ChemDraw 19.1 and MOE 2015.10 software. The structural compounds were optimized by energy minimization and molecular dynamic functions in Sybyl-X 1.1. In energy minimization, the method of minimizing was a conjugate gradient, and the structures of compounds were optimized until a minimal energy change of 0.001 kcal/mol was reached. Gasteiger-Huckel charges were applied to the structure atoms, and the maximal number of iterations was fixed at 10,000 to be performed during minimization. The simulated annealing method was used in this process, and the compounds were heated at 700°K for 1000 femtoseconds and then cooled to 200°K for the same period to achieve stable states from which their final conformations were obtained. This action was conducted in five cycles to discover the different required structures. Lastly, the energy minimization procedure was conducted one more time, and the minimal energy of the final conformations was explored.


## 2.9.2. Preparation of Protein

The X-ray crystallographic structure of the antiapoptotic protein Bcl-2 in complex with an acyl-sulfonamide-based ligand was collected from the Protein Data Bank (PDB ID: 2O2F) and performed as the receptor model [21]. The 3D structure of the crystallographic complex was established in AutoDock 4.2.6 software [22] to add hydrogen, protonate, and delete unbound waters. The active site was defined by considering a grid box of appropriate size around the bound co-crystal ligand. The grid box dimensions were as follows: no. of grid points 65 × 65 × 65; center (xyz coordinates) −0.024, 3.142, −0.361; grid point spacing (Å) 0.375. The compounds were docked using AutoDock 4.2.6 software.


## 2.9.3. Evaluation of Docking Results

The docking experiment was organized using the Lamarckian genetic algorithm, with an initial population of 150 randomly placed individuals, a maximum number of 2.5 × 106 energy evaluations, a mutation rate of 0.02, and a crossover rate of 0.8. One hundred independent docking runs were detailed for each compound. Conformation clustering was carried out considering a root mean square deviation (RMSD) cut-off of 2.0 Å clustered, and the most possible binding modes were described using the lowest free energy of binding (ΔG) and the lowest inhibition constant (Ki). The most favorable binding conformation was selected and evaluated for molecular interaction with their receptors using LigPlot + version 1.4.5 software [23]. To establish that the binding pose of the docked compound defines a probable and valid perspective conformation, the docking parameters and methods were confirmed by redocking the cocrystal ligand against their specific targets. 3D poses of compounds with the antiapoptotic protein Bcl-2 in the complex were displayed using PyMOL 2.5.


## 3. Results and Discussion

### 3.1. Antiproliferative Activity against Tumor Cells

Thein vitro anticancer effects of all fractions of the MTH and MTE extracts were recognized against four tumor cell lines, MDA-MB-231, RD, HepG2, and RAW264.7, following the MTT assay (Table 1).Table 1
The cytotoxic activity of all fractions ofM. tricolor.
NoSamplesIC50 (μg/mL)MDA-MB-231RDHepG2RAW264.71MTH.I27.98 ± 2.4724.64 ± 1.1228.51 ± 0.59>1002MTH.II10.24 ± 1.737.09 ± 0.4434.16 ± 1.15>1003MTH.III31.24 ± 3.1242.14 ± 2.74>100>1004MTH.IV57.72 ± 2.1773.94 ± 1.89>100>1005MTH.V>10031.49 ± 0.31>100>1006MTE.I4.00 ± 0.205.53 ± 0.5133.00 ± 1.11>1007MTE.II27.33 ± 1.7920.70 ± 0.2470.60 ± 1.44>1008MTE.III>10096.03 ± 1.89>100>1009MTE.IV>100>100>100>10010MTE.V>100>100>100>10011PAC8.38 ± 0.75 (μM)5.73 ± 0.27 (μM)16.38 ± 0.50 (μM)Bold values should be the IC50 values below <100.As the testification, fractions (MTH.I, MTH.II, MTE.I, and MTE.II) evidenced meaningful properties against three tested cells, MDA-MB-231, RD, and HepG2 (IC50 values ranged from 4.00 ± 0.20 to 70.60 ± 1.44 μg/mL). Moreover, fractions (MTH.III and MTH.IV) evidenced selective cytotoxicity against MDA-MB-231 and RD (IC50 values ranged from 31.24 ± 3.12 to 73.94 ± 1.89 μg/mL), as well as fractions (MTH.V and MTE III), which proved moderate activity against RD (IC50 values of 31.49 ± 0.31 and 96.03 ± 1.89 μg/mL, respectively). It is the first time that the in vitro cytotoxic effects of fractions of M. tricolor have been reported. Besides, all fractions did not exhibit cytotoxicity toward RAW264.7.Therefore, thein vitroanti-inflammation of LPS-induced NO production in RAW264.7 cells of all MTH and MTE fractions were further examined.


### 3.2. Anti-Inflammatory Activity on LPS-Induced NO Production in RAW264.7 Cells

Thein vitroanti-inflammatory properties of LPS-induced inflammation using RAW264.7 cells of all MTH and MTE fractions were certified (Table 2).Table 2
The anti-inflammatory activity of all fractions ofM. tricolor.
NoSamplesIC50 (μg/mL)1MTH.I12.64 ± 0.772MTH.II9.78 ± 0.583MTH.III32.81 ± 3.024MTH.IV27.42 ± 2.075MTH.V51.12 ± 4.516MTE.I4.45 ± 0.087MTE.II23.00 ± 1.188MTE.III>1009MTE.IV85.76 ± 8.0710MTE.V83.90 ± 8.0511QUE10.46 ± 0.16The bold values should be the IC50 values below 100.As a result, all MTH and MTE fractions except fractionMTE.III expressed a significant anti-inflammatory effect (IC50 values ranged from 4.45 ± 0.08 to 85.76 ± 8.07 μg/mL). Particularly, fractions (MTE.I and MTH.II) revealed more powerful efficacy against NO production (IC50 values of 4.45 ± 0.08 and 9.78 ± 0.58 μg/mL, respectively) than QUE (IC50 value of 10.46 ± 0.16 μg/mL). In vivoanti-inflammation of M. tricolor whole plant liquid against carrageenan-induced and carrageenan plus formaldehyde-induced in rats was reported [5, 6]. However, it is the first time that the in vitroanti-inflammatory activities of fractions from this species were perceived against NO production in RAW264.7 cells. Thus, the active fractions were further elaborated on in terms of phytochemical composition.


### 3.3. Phytochemical Ingredients of the Active Fractions

Thein vitroanti-inflammatory and anticancer fractions from the whole plants of M. tricolor were administered in normal-phase and reversed-phase CC to afford eighteen compounds (Figure 1).Figure 1
Chemical structures of isolated compounds (1–18) from M. tricolor.The HRMS (ESI technique) and NMR spectra of those compounds were consistent with the data in the published literature for lupeol (1) [24]; macrotricolorin A (2); bisdemethoxycurcumin (3); desmethoxycurcumin (4); curcumin (5) [7]; 24-methylenecycloartanol (6) [25]; 6′-O-margaroyldaucosterol (7); daucosterol (8); ursolic acid (9) [26]; 1-oxooleanolic acid (10) [27]; gallic acid (11); bisacurone A (12) [28]; a mixture of (1E, 4E)-1,5-bis(4-hydroxy-3-methoxyphenyl)penta-1,4-dien-3-one (13a); and pinoresinol (13b) [29]; 3,3′-di-O-methylellagic acid (14); 3,3′-di-O-methyl-4-O-β-D-xylopyranosylellagic acid (15); kaempferol (16); vitexin (17); and orientin (18) [30].


### 3.4. Antiproliferation and Anti-Inflammation of Purified Compounds

The antiproliferation against MDA-MB-231, RD, and HepG2 cells, and therefore the anti-inflammation against NO production on RAW264.7 cells of purified compounds (1–11) are shown (Table 3).Table 3
The antiproliferative and anti-inflammatory activities of compounds (1–11) from M. tricolor.
NoCompoundsIC50 (μM)MDA-MB-231RDHepG2NO production1157.78 ± 1.9574.25 ± 0.46>100—22>100>100>10027.54 ± 1.75∗3359.01 ± 1.2422.79 ± 0.4271.64 ± 1.1716.30 ± 0.924417.28 ± 0.276.88 ± 0.1228.04 ± 0.417.31 ± 0.555522.89 ± 0.099.57 ± 0.1819.92 ± 0.559.23 ± 0.6066#>50>50>50>5071124.42 ± 0.2820.60 ± 0.253.20 ± 0.02>100814>10095.60 ± 1.03>100>100914>100>100>100>1001017>100>100>100>1001118>10065.73 ± 5.05>100>10012PAC8.38 ± 0.755.73 ± 0.2716.38 ± 0.50—13QUE10.46 ± 0.16Bold values should be the IC50 values below <100.Compounds (3–5) certificated the strong activity in both antiproliferation against MDA-MB-231, RD, and HepG2 cells (IC50 values ranged from 6.88 ± 0.12 to 71.64 ± 1.17 μM), and anti-inflammatory activity against NO production on LPS-inducedanti-inflammation using RAW264.7 (IC50 values of 16.30 ± 0.92, 7.31 ± 0.55, and 9.23 ± 0.60 μM, respectively). Likewise, compound 11 meaningfully showed a cytotoxic effect on all examined cells (IC50 values of 24.42 ± 0.28, 20.60 ± 0.25, and 3.20 ± 0.02 μM, respectively); however, it didn’t display anti-inflammatory activity. Additionally, compound 1 exhibited selective properties against MDA-MB-231 and RD cells (IC50 values of 57.78 ± 1.95 and 74.25 ± 0.46 μM, respectively), while compounds (14 and 18) revealed a moderate effect on RD cells (IC50 values of 95.60 ± 1.03 and 65.73 ± 5.05 μM, respectively).Distinctly, compounds (4, 5, and 11) possessed potential cytotoxicity against MDA-MB-231, RD, and HepG2 cells with IC50 values less than 30 μM, which were demonstrated at the active binding site of the Bcl-2 protein (PDB ID: 2O2F) (Figure 2).Figure 2
3D interaction models in the active site of the Bcl-2 protein and compounds4 (a), 5 (b), and 11 (c).
(a)(b)(c)


### 3.5. Molecular Docking Studies for Potential Cytotoxic Compounds

As a result, the docking scores of compounds4, 5, and PAC were −6.31, −6.92, and −6.08 kJ.mol−1, respectively. On the other hand, compound 11 had a low docking score (−3.39 kJ.mol−1) and interacted with the amino acids via the hydrogen bonds formed by Val130 and Ala146 (Figure 3), which are not important.Figure 3
2D interaction models in the active site of Bcl-2 protein and compound11.This model contradictsin vitro cytotoxicity in three cancer cell lines, and it implies that 11 displays a different binding pocket for 11 in the Bcl-2 protein and makes a distinction from that of PAC. On the other hand, 4 and 5 interacted through hydrogen bonds with crucial amino acids as follows: Phe109, Arg143, Ala97 (4), Phe109, Arg143 (5), into the active site of the Bcl-2 protein (Figure 4). The other amino acids had hydrophobic interactions with 4 (Phe101) and 5 (Ala146, Phe101, Gly142, and Val145). Specifically, they formed the same amino acid Arg143 interaction as PAC.Figure 4
2D interaction models in the active site of Bcl-2 protein and compounds4 (a) and 5 (b).
(a)(b)Consequently, binding models4 and 5 were compatible with their in vitro anticancer activity. In addition, these results were further consistent with the in vitro inhibitions of these compounds against cell proliferation and the expression of the antiapoptotic protein Bcl-2 [31, 32] or the expression of NO production and proteins of tumor necrosis factor-alpha (TNF-α) [32, 33].


## 3.1. Antiproliferative Activity against Tumor Cells

Thein vitro anticancer effects of all fractions of the MTH and MTE extracts were recognized against four tumor cell lines, MDA-MB-231, RD, HepG2, and RAW264.7, following the MTT assay (Table 1).Table 1
The cytotoxic activity of all fractions ofM. tricolor.
NoSamplesIC50 (μg/mL)MDA-MB-231RDHepG2RAW264.71MTH.I27.98 ± 2.4724.64 ± 1.1228.51 ± 0.59>1002MTH.II10.24 ± 1.737.09 ± 0.4434.16 ± 1.15>1003MTH.III31.24 ± 3.1242.14 ± 2.74>100>1004MTH.IV57.72 ± 2.1773.94 ± 1.89>100>1005MTH.V>10031.49 ± 0.31>100>1006MTE.I4.00 ± 0.205.53 ± 0.5133.00 ± 1.11>1007MTE.II27.33 ± 1.7920.70 ± 0.2470.60 ± 1.44>1008MTE.III>10096.03 ± 1.89>100>1009MTE.IV>100>100>100>10010MTE.V>100>100>100>10011PAC8.38 ± 0.75 (μM)5.73 ± 0.27 (μM)16.38 ± 0.50 (μM)Bold values should be the IC50 values below <100.As the testification, fractions (MTH.I, MTH.II, MTE.I, and MTE.II) evidenced meaningful properties against three tested cells, MDA-MB-231, RD, and HepG2 (IC50 values ranged from 4.00 ± 0.20 to 70.60 ± 1.44 μg/mL). Moreover, fractions (MTH.III and MTH.IV) evidenced selective cytotoxicity against MDA-MB-231 and RD (IC50 values ranged from 31.24 ± 3.12 to 73.94 ± 1.89 μg/mL), as well as fractions (MTH.V and MTE III), which proved moderate activity against RD (IC50 values of 31.49 ± 0.31 and 96.03 ± 1.89 μg/mL, respectively). It is the first time that the in vitro cytotoxic effects of fractions of M. tricolor have been reported. Besides, all fractions did not exhibit cytotoxicity toward RAW264.7.Therefore, thein vitroanti-inflammation of LPS-induced NO production in RAW264.7 cells of all MTH and MTE fractions were further examined.


## 3.2. Anti-Inflammatory Activity on LPS-Induced NO Production in RAW264.7 Cells

Thein vitroanti-inflammatory properties of LPS-induced inflammation using RAW264.7 cells of all MTH and MTE fractions were certified (Table 2).Table 2
The anti-inflammatory activity of all fractions ofM. tricolor.
NoSamplesIC50 (μg/mL)1MTH.I12.64 ± 0.772MTH.II9.78 ± 0.583MTH.III32.81 ± 3.024MTH.IV27.42 ± 2.075MTH.V51.12 ± 4.516MTE.I4.45 ± 0.087MTE.II23.00 ± 1.188MTE.III>1009MTE.IV85.76 ± 8.0710MTE.V83.90 ± 8.0511QUE10.46 ± 0.16The bold values should be the IC50 values below 100.As a result, all MTH and MTE fractions except fractionMTE.III expressed a significant anti-inflammatory effect (IC50 values ranged from 4.45 ± 0.08 to 85.76 ± 8.07 μg/mL). Particularly, fractions (MTE.I and MTH.II) revealed more powerful efficacy against NO production (IC50 values of 4.45 ± 0.08 and 9.78 ± 0.58 μg/mL, respectively) than QUE (IC50 value of 10.46 ± 0.16 μg/mL). In vivoanti-inflammation of M. tricolor whole plant liquid against carrageenan-induced and carrageenan plus formaldehyde-induced in rats was reported [5, 6]. However, it is the first time that the in vitroanti-inflammatory activities of fractions from this species were perceived against NO production in RAW264.7 cells. Thus, the active fractions were further elaborated on in terms of phytochemical composition.


## 3.3. Phytochemical Ingredients of the Active Fractions

Thein vitroanti-inflammatory and anticancer fractions from the whole plants of M. tricolor were administered in normal-phase and reversed-phase CC to afford eighteen compounds (Figure 1).Figure 1
Chemical structures of isolated compounds (1–18) from M. tricolor.The HRMS (ESI technique) and NMR spectra of those compounds were consistent with the data in the published literature for lupeol (1) [24]; macrotricolorin A (2); bisdemethoxycurcumin (3); desmethoxycurcumin (4); curcumin (5) [7]; 24-methylenecycloartanol (6) [25]; 6′-O-margaroyldaucosterol (7); daucosterol (8); ursolic acid (9) [26]; 1-oxooleanolic acid (10) [27]; gallic acid (11); bisacurone A (12) [28]; a mixture of (1E, 4E)-1,5-bis(4-hydroxy-3-methoxyphenyl)penta-1,4-dien-3-one (13a); and pinoresinol (13b) [29]; 3,3′-di-O-methylellagic acid (14); 3,3′-di-O-methyl-4-O-β-D-xylopyranosylellagic acid (15); kaempferol (16); vitexin (17); and orientin (18) [30].


## 3.4. Antiproliferation and Anti-Inflammation of Purified Compounds

The antiproliferation against MDA-MB-231, RD, and HepG2 cells, and therefore the anti-inflammation against NO production on RAW264.7 cells of purified compounds (1–11) are shown (Table 3).Table 3
The antiproliferative and anti-inflammatory activities of compounds (1–11) from M. tricolor.
NoCompoundsIC50 (μM)MDA-MB-231RDHepG2NO production1157.78 ± 1.9574.25 ± 0.46>100—22>100>100>10027.54 ± 1.75∗3359.01 ± 1.2422.79 ± 0.4271.64 ± 1.1716.30 ± 0.924417.28 ± 0.276.88 ± 0.1228.04 ± 0.417.31 ± 0.555522.89 ± 0.099.57 ± 0.1819.92 ± 0.559.23 ± 0.6066#>50>50>50>5071124.42 ± 0.2820.60 ± 0.253.20 ± 0.02>100814>10095.60 ± 1.03>100>100914>100>100>100>1001017>100>100>100>1001118>10065.73 ± 5.05>100>10012PAC8.38 ± 0.755.73 ± 0.2716.38 ± 0.50—13QUE10.46 ± 0.16Bold values should be the IC50 values below <100.Compounds (3–5) certificated the strong activity in both antiproliferation against MDA-MB-231, RD, and HepG2 cells (IC50 values ranged from 6.88 ± 0.12 to 71.64 ± 1.17 μM), and anti-inflammatory activity against NO production on LPS-inducedanti-inflammation using RAW264.7 (IC50 values of 16.30 ± 0.92, 7.31 ± 0.55, and 9.23 ± 0.60 μM, respectively). Likewise, compound 11 meaningfully showed a cytotoxic effect on all examined cells (IC50 values of 24.42 ± 0.28, 20.60 ± 0.25, and 3.20 ± 0.02 μM, respectively); however, it didn’t display anti-inflammatory activity. Additionally, compound 1 exhibited selective properties against MDA-MB-231 and RD cells (IC50 values of 57.78 ± 1.95 and 74.25 ± 0.46 μM, respectively), while compounds (14 and 18) revealed a moderate effect on RD cells (IC50 values of 95.60 ± 1.03 and 65.73 ± 5.05 μM, respectively).Distinctly, compounds (4, 5, and 11) possessed potential cytotoxicity against MDA-MB-231, RD, and HepG2 cells with IC50 values less than 30 μM, which were demonstrated at the active binding site of the Bcl-2 protein (PDB ID: 2O2F) (Figure 2).Figure 2
3D interaction models in the active site of the Bcl-2 protein and compounds4 (a), 5 (b), and 11 (c).
(a)(b)(c)


## 3.5. Molecular Docking Studies for Potential Cytotoxic Compounds

As a result, the docking scores of compounds4, 5, and PAC were −6.31, −6.92, and −6.08 kJ.mol−1, respectively. On the other hand, compound 11 had a low docking score (−3.39 kJ.mol−1) and interacted with the amino acids via the hydrogen bonds formed by Val130 and Ala146 (Figure 3), which are not important.Figure 3
2D interaction models in the active site of Bcl-2 protein and compound11.This model contradictsin vitro cytotoxicity in three cancer cell lines, and it implies that 11 displays a different binding pocket for 11 in the Bcl-2 protein and makes a distinction from that of PAC. On the other hand, 4 and 5 interacted through hydrogen bonds with crucial amino acids as follows: Phe109, Arg143, Ala97 (4), Phe109, Arg143 (5), into the active site of the Bcl-2 protein (Figure 4). The other amino acids had hydrophobic interactions with 4 (Phe101) and 5 (Ala146, Phe101, Gly142, and Val145). Specifically, they formed the same amino acid Arg143 interaction as PAC.Figure 4
2D interaction models in the active site of Bcl-2 protein and compounds4 (a) and 5 (b).
(a)(b)Consequently, binding models4 and 5 were compatible with their in vitro anticancer activity. In addition, these results were further consistent with the in vitro inhibitions of these compounds against cell proliferation and the expression of the antiapoptotic protein Bcl-2 [31, 32] or the expression of NO production and proteins of tumor necrosis factor-alpha (TNF-α) [32, 33].


## 4. Conclusions

The systematic investigation, including sample collection, sample authentication, bioassay-guided separation, and structural characterization of antiproliferative and anti-inflammatory compounds from the Vietnamese herbMacrosolen tricolor, was conducted for the first time. Additionally, the in vitro cytotoxicity against MDA-MB-231, RD, HepG2, and RAW264.7 cells and anti-inflammation against NO production on LPS-induced inflammation of all fractions and purified metabolites, as well as the in silico molecular docking studies of potentially cytotoxic compounds from M. tricolor, were detailed for the first time.A phytochemical study on the active fractions fromM. tricolor affirmed that the diarylalkanoids (2–5) present in this species accounted for their anti-inflammatory activities, whereas the main compounds, triterpenoid 1 and phenolic 11, revealed their cytotoxic properties. Furthermore, molecular docking studies provided evidence to support the good cytotoxicity of compounds 4, 5, and 11 as compared with PAC via inhibition of the Bcl-2-regulated apoptotic protein.The present study proposes thatM. tricolor plant is a good source of natural antiproliferative and anti-inflammatory agents and supports understanding the ethnopharmacological aspect of Macrosolen species in Vietnam.



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*Source: 7977620-2023-01-02.xml*