bluuebunny/crossref_metadata_2025 huggingface dataset:
New Gallotannin and other Phytochemicals from Sycamore Maple (Acer pseudoplatanus) Leaves
Authors: Zhang Lu , Tu Zong-Cai , Yuan Tao , Ma Hang , Niesen Daniel B. , Wang Hui , Seeram Navindra P.
Published: March 2019

The maple (Acer) genus is a reported source of bioactive (poly)phenols, including gallotannins, but several of its members, such as the sycamore maple (A. pseudoplatanus). remain uninvestigated. Herein, thirty-nine compounds, including a new gallotannin, 1,2,3-tri- O-galloyl-6- O-( p-hydroxybenzoyl)-β-D-glucopyranoside (1), and thirty-eight (2-39) known compounds, consisting of four gallotannins, one ellagitannin, thirteen flavonoids, eight hydroxycinnamic acids, ten benzoic acid derivatives, and two sesquiterpenoids, were isolated from sycamore maple leaves. Their structures were determined based on NMR and mass spectral analyses. The isolates were evaluated for α-glucosidase inhibitory and antioxidant activities. Among the isolates, the gallotannins were the most potent α-glucosidase inhibitors with thirteen-fold more potent activity compared with the clinical drug, acarbose (IC50 = 16–31 vs. 218 μM). Similarly, the gallotannins showed the highest antioxidant activities, followed by the other phenolic sub-classes, while the sesquiterpenoids were inactive.
Volatile Constituents of Three Piper Species from Vietnam
Authors: Hieu Le D. , Hoi Tran M. , Thang Tran D. , Ogunwande Isiaka A.
Published: March 2019

The chemical compositions of the essential oils obtained by hydrodistillation of three Piper plants grown in Vietnam are reported. The analysis was achieved by means of gas chromatography with flame ionization detection (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The main constituents of the leaf oil of Piper majusculum Blume were β-caryophyllene (20.7%), germacrene D (18.6%) and β-elemene (11.3%). The quantitatively significant compounds of the volatile oils of P. harmandii C. DC were sabinene (leaves, 14.5%; stems, 16.2%), benzyl benzoate (leaves, 20.0%; stems, 29.40%) and benzyl salicylate (leaves, 14.1%; stems, 24.3%). Also, α-cadinol (17.0%) was identified in large proportion in the leaf oil. However, sabinene (leaves, 17.9%; stems, 13.5%), benzyl benzoate (leaves, 20.5%; stems, 32.5%) and β-eudesmol (leaves, 13.8%; stems, 8.4%) were the main constituents of P. brevicaule C. DC. This is the first report on the volatile constituents of both P. harmandii and P. brevicaule.
Volatile Constituents from the Flowers of Spathodea campanulata from the Venezuelan Andes
Authors: Villarreal Silvana , Jaimez Deisy , Moreno Sindy , Rojas Luis B. , Usubillaga Alfredo , Rodríguez María
Published: March 2019

The chemical composition is reported of the essential oil obtained by hydrodistillation of Spathodea campanulata P. Beauv. (Bignoniaceae) flowers collected in the Andes region of Venezuela. Thirty compounds were characterized, representing 96.5% of the total oil composition; benzyl benzoate (17.5%) was the major constituent. Others major components were a mixture of geranyl acetone with α-humulene (12.7%), β-caryophyllene (9.5%), farnesyl acetone (6.0%), aromadendrene (4.3%), α-gurjunene (3.9%) and tricosane (3.7%). This is the first report related to the chemical composition of the essential oil of S. campanulata flowers.
Isoprenylated Flavonoids with PTP1B Inhibition from Ficus tikoua
Authors: Wu Lu-Qin , Lei Chun , Gao Li-Xin , Liao Hai-Bing , Li Jing-Ya , Li Jia , Hou Ai-Jun
Published: March 2019

Two new isoprenylated flavanones, ficustikousins A and B (1 and 2), together with seven known compounds (3–9) were isolated from the whole plant of Ficus tikoua (Moraceae). The structures of the new compounds were elucidated on the basis of spectroscopic methods. Compounds 1–7 exhibited moderate inhibitory activities against PTP1B in vitro.
Synthesis of (6R,12R)-6,12-Dimethylpentadecan-2-one, the Female-Produced Sex Pheromone from Banded Cucumber Beetle Diabrotica balteata, Based on a Chiron Approach
Authors: Shen Wei , Hao Xiang , Shi Yong , Tian Wei-Sheng
Published: March 2019

Herein we describe a synthesis of (6 R,12 R)-6,12-dimethylpentadecan-2-one (5), the female produced sex pheromone of banded cucumber beetle Diabrotica balteata Le Conte, from ( R)-4-methyl-δ-valerolactone, a methyl-branched chiron.
Re-evaluation of ABTS•+ Assay for Total Antioxidant Capacity of Natural Products
Authors: Dong Jian-Wei , Cai Le , Xing Yun , Yu Jing , Ding Zhong-Tao
Published: March 2019

2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS•+) is a stable free radical frequently used for estimating the total antioxidant capacity (TAC) of natural products. The existing methods for ABTS•+ radical-scavenging activity assays are diverse in pre-diluting solvents and reaction time, which lead to errors in the TAC estimations. To develop an effective and universal method for estimating the ABTS•+ capacity accurately and reasonably, five pre-dilution solvents [methanol, ethanol, phosphate buffer (Na2HPO4-NaH2PO4, 200 mM, pH = 7.4), PBS buffer (Na2HPO4-NaH2PO4-NaCl, 200 mM, pH = 7.4), and distilled water] and different reaction times were investigated in ABTS•+ assays of five typical antioxidants. The results showed that the solvent effects were very significant. When using different pre-diluting solvents, different detection wavelengths should be selected. ABTS-+ assay could be measured within 2–10 min to obtain a rough result, which was mostly 6 min in the literature. However, full and accurate evaluation of antioxidant reactivity rather than capacity requires recording ABTS•+ loss continuously during the whole reaction period. The present study makes a recommendation for estimating the ABTS•+ capacity accurately and reasonably.
Synergistic Effects of Dietary Natural Products as Anti-Prostate Cancer Agents
Authors: Vue Bao , Zhang Sheng , Chen Qiao-Hong
Published: March 2019

This review is to describe synergistic effects of various combinations of dietary natural products including curcumin, quercetin, soybean isoflavones, silibinin, and EGCG that have potential for the treatment of prostate cancer. These data can provide valuable insights into the future rational design and development of synergistic and/or hybrid agents for potential treatment of prostate cancer.
Chemical Constituents and LC-profile of Fresh Formosan Lonicera Japonica Flower Buds
Authors: Lo I-Wen , Cheng Yuan-Bin , Hsieh Yi-Jin , Hwang Tsong-Long , Shieh Deng-En , Chang Fang-Rong , Wu Yang-Chang
Published: March 2019

One new secoiridoid glucoside, ethylsecologanin dimethyl acetal (1), along with 15 known compounds, comprising six iridoid glucosides (2–7), six flavonoids (8–13), two sterol glucosides (14 and 15), and chlorogenic acid (16) were isolated from the flower buds of Formosan Lonicera japonica. The structures of these isolates were determined on the basis of mass and spectroscopic analyzes. In addition, the chemical profiles of fresh Formosan honeysuckle buds and the dried Chinese one were compared by HPLC with a PDA detector. The calibration curve of the active component, chlorogenic acid, was also provided. As a result of the constituent similarity, Formosan L. japonica can be an alternative to the Chinese honeysuckles.
Phytochemical and Biological Investigations of Conradina Canescens
Authors: Dosoky Noura S. , Moriarity Debra M. , Setzer William N.
Published: March 2019

Conradina canescens (Lamiaceae) is an endemic evergreen shrub native to Florida, Mississippi and Alabama, with no phytochemical or biological studies registered in the literature. Thus, a phytochemical study and a toxicity analysis of the chloroform extract obtained from the leaves of C. canescens were performed for the first time. In our preliminary screening, the crude extract and its fractions were subjected to cytotoxicity, antimicrobial and antileishmanial bioassays. The crude extract showed substantial cytotoxic, antimicrobial and antileishmanial activities. A total of six compounds, namely ursolic acid (62.4%), betulin (8.4%), β-amyrin (4.6%), myrtenic acid (2.9%), n-tetracosane (1.4%), and oleanolic acid (1.1%), were isolated. The structures of the isolated compounds were established by spectroscopic studies using NMR and IR spectroscopy.
Cordycepin, a Natural Antineoplastic Agent, Induces Apoptosis of Breast Cancer Cells via Caspase-dependent Pathways
Authors: Wang Di , Zhang Yongfeng , Lu Jiahui , Wang Yang , Wang Junyue , Meng Qingfan , Lee Robert J. , Wang Di , Teng Lesheng
Published: March 2019

Cordycepin, a major compound separated from Cordyceps sinensis, is known as a potential novel candidate for cancer therapy. Breast cancer, the most typical cancer diagnosed among women, remains a global health problem. In this study, the anti-breast cancer property of cordycepin and its underlying mechanisms was investigated. The direct effects of cordycepin on breast cancer cells both in in vitro and in vivo experiments were evaluated. Cordycepin exerted cytotoxicity in MCF-7 and MDA-MB-231 cells confirmed by reduced cell viability, inhibition of cell proliferation, enhanced lactate dehydrogenase release and reactive oxygen species accumulation, induced mitochondrial dysfunction and nuclear apoptosis in human breast cancer cells. Cordycepin increased the activation of pro-apoptotic proteins, including caspase-8, caspase-9, caspase-3 and Bax, and suppressed the expression of the anti-apoptotic protein, B-cell lymphoma 2 (Bcl-2). The inhibition on MCF-7-xenografted tumor growth in nude mice further confirmed cordycepin's anti-breast cancer effect. These aforementioned results reveal that cordycepin induces apoptosis in human breast cancer cells via caspase-dependent pathways. The data shed light on the possibility of cordycepin being a safe agent for breast cancer treatment.
Antifungal and Cytotoxic Assessment of Lapachol Derivatives Produced by Fungal Biotransformation
Authors: Silva Eliane O. , Ruano-González Antonio , Dos Santos Raquel A. , Sánchez-Maestre Rosario , Furtado Niege A. J. C. , Collado Isidro G. , Aleu Josefina
Published: March 2019

In the screening for biological active compounds, the biotransformation processes catalyzed by filamentous fungi are useful because they can provide information about the possible appearance of toxic metabolites after oral administration and also generate new leads. In this paper, biotransformation of lapachol (1) by three fungal strains, Mucor circinelloides NRRL3631, Botrytis cinerea UCA992 and Botrytis cinerea 2100, has been investigated for the first time. Lapachol (1) was biotransformed into avicequinone-A (2) by M. circinelloides, 3′-hydroxylapachol (3) by B. cinerea, and into dehydro-α-lapachone (4) by both fungi. All these compounds were evaluated for their cytotoxic activities. The metabolite 2 displayed non-selective cytotoxicity against tumor and normal cell lines, 3 did not show cytotoxicity against the same cells, while 4 showed higher cytotoxicity against cancer cell lines than lapachol (1). The transformation of 1 into harmless and reactive metabolites evidences the importance of the evaluation of drug metabolism in the drug discovery process. Antifungal potential of lapachol (1) and its metabolites 2 and 4 against B. cinerea has also been evaluated. Dehydro-α-lapachone (4) has been shown to be less toxic to fungal growth than lapachol (1), which indicates a detoxification mechanism of the phytopathogen.
Chemical Composition of the Essential Oil of Bupleurum Fontanesii (Apiaceae) Growing Wild in Sicily and its Activity on Microorganisms Affecting Historical Art Crafts
Authors: Casiglia Simona , Bruno Maurizio , Senatore Federica , Senatore Felice
Published: March 2019

Hydrodistillation of the flowers (BpFl) of and fruits (BpFr) of Bupleurum fontanesii Guss. ex Caruel gave two oils that were analyzed by GC and GC-MS. The main components were α-elemol (16.7%), caryophyllene oxide (16.4%) and heptacosane (15.9%) in BpFl, and spathulenol (16.8%), caryophylladienol I (13.2%) and α-elemol (12.8%) in BpFr. A good antimicrobial activity against several microorganisms, including Bacillus subtilis, Staphylococcus aureus, Fusarium oxysporum and Aspergillus niger, all infesting historical art craft, was also determined.
In Vivo Cytotoxicity Studies of Amaryllidaceae Alkaloids
Authors: Nair Jerald J. , Bastida Jaume , van Staden Johannes
Published: March 2019

The plant family Amaryllidaceae is recognizable for its esthetic floral characteristics, its widespread usage in traditional medicine as well as its unique alkaloid principles. Few alkaloid-producing families rival the Amaryllidaceae in terms of the diversity of its structures as well as their wide applicability on the biological landscape. In particular, cytotoxic effects have come to be a dominant theme in the biological properties of Amaryllidaceae alkaloids. To this extent, a significant number of structures have been subjected to in vitro studies in numerous cell lines from which several targets have been identified as promising chemotherapeutics. By contrast, in vivo models of study involving these alkaloids have been carried out to a lesser extent and should prove crucial in the continued development of a clinical target such as pancratistatin. This survey examines the cytotoxic effects of Amaryllidaceae alkaloids in vivo and contrasts these against the corresponding in vitro effects.
Chemical Constituents of Ligularia Wilsoniana Collected in Chongqing, China
Authors: Okamoto Yasuko , Taniguchi Mizuho , Nakashima Katsuyuki , Gong Xun , Hanai Ryo , Kuroda Chiaki , Tori Motoo
Published: March 2019

The chemical constituents of Ligularia wilsoniana were studied for the first time, using four samples collected in Chongqing City, China. Two new compounds, 6β-(2′,3′-epoxy-2′-methylpropanoyloxy)-1β,10β-epoxyfuranoeremophilane and 11αH-6β-(2′-hydroxymethylacryloyloxy)-1β,10β;7β,8β-diepoxyeremophilanolide, as well as eight known compounds, were isolated from one of the samples, while three to four known furanoeremophilanes were isolated from the other three samples. No compound was common to the two classes of the samples, demonstrating the presence of at least two chemotypes of this species.
Terpenoids, Flavonoids and Acetogenins from Some Malagasy Plants
Authors: Nagashima Fumihiro , Tabuchi Yuki , Ito Takuya , Harinantenaina Liva , Asakawa Yoshinori
Published: March 2019

Humulanes, drimanes, ent-kaurane, lupane, cycloartane, flavanone, flavones and quinol derivatives were isolated from Malagasy Cussonia vantsilana, Helichrysum gymnocephalum, Phyllarthron madagascariense, Gomphocarpus fructicosus, Cinnamosma sp. and C. fragrans, and their structures elucidated by using extensive NMR analysis. A mixture of a few flavones and/or lupane triterpene showed antimicrobial activity against Mycobacterium smegmatis and Pseudomonas aeruginosa.
Triterpene Galloyl Esters from Edible Acorn of Castanopsis Cuspidata
Authors: Ogata Misaki , Saito Yoshinori , Matsuo Yosuke , Maeda Hajime , Tanaka Takashi
Published: March 2019

Polyphenols of edible acorns of Castanopsis cuspidata were examined and two triterpene galloyl esters were isolated. Based on two-dimensional NMR spectroscopic evidence the structures were determined to be 3,24-di- O-galloyl-2α,3β-23,24-tetrahydroxyolean-12-en-28-oic acid (1) and 3,24-di- O-galloyl-2α,3β-23,24-tetrahydroxyurs-12-en-28-oic acid (2). The triterpene hexahydroxydiphenoyl esters, which had been found in the leaves, were not detected in the acoms.
Glycosylation of Trans-Resveratrol by Cultured Plant Cells under Illumination of LEDs
Authors: Uesugi Daisuke , Hamada Hiroki , Shimoda Kei
Published: March 2019

Incubation of cultured cells of Strophantus gratus with trans-resveratrol gave its 4′- O-β-D-glucoside as the major product in addition to its 3- O-β-D-glucoside under white and red light-emitting diodes (LEDs). Use of blue LEDs as light sources for biotransformation of trans-resveratrol much improved the yield of its β-Dglycosides and changed the composition of products, that is, 3- O-β-Dglucoside was the major product and 4′- O-β-D-glucoside was the minor one.
A New Neolignan from Coix Lachryma-jobi var. Mayuen
Authors: Kim Sun Young , Choi Chun Whan , Hong Seong Su , Shin HyungSeok , Oh Joa Sub
Published: March 2019

A new neolignan, named coixide A (1), along with fifteen known compounds, (7 R,8 S)-3′-demethyl-dehydrodiconiferyl alcohol-3′- O-β-glucopyranoside (2), (7 R,8 S)-3′-demethyl-9′-butoxy-dehydrodiconiferyl-3′- O-β-glucopyranoside (3),adenosine (4), 2- O-caffeoyl isocitricacid (5), pseudolaroside A (6), 2-hydroxy-7-methoxy-(2 H)-1,4-benzoxazin-3(4 H)-one (7), 2- O-β-glucopyranosyl-7-methoxy-2 H-1,4-benzoxazin-3(4 H)-one (8), 2- O-β-glucopyranosyl-4-hydroxy-7-methoxy-2 H-1,4-benzoxazin-3(4 H)-one (9), 2- O-β-D-glucopyranosyl-7-hydroxy-2 H-1,4-benzoxazin-3(4 H)-one (10), p-coumaric acid ethyl ester (11), caffeic acid ethyl ester (12), p-coumaric acid (13), cis-N-p-coumaroyltyramine (14) trans-N-p-coumaroyltyramine (15), and coixol (16) have been isolated from Coix lachryma-jobi var. mayuen. Their chemical structures were elucidated by chemical evidence on the basis of spectroscopic and MS data, and as well as by comparison with those reported.
Bioactive Constituents and Antioxidant Activity of Some Carpathian Basin Honeys
Authors: Gyergyák Kinga , Boros Borbála , Marton Krisztina , Felinger Attila , Papp Nóra , Farkas Ágnes
Published: March 2019

Unifloral honeys have a high commercial value and should undergo a strict quality control before marketing. This study aimed at determining floral origin, polyphenolic compounds and antioxidant activity in 7 samples marketed as lavender and thyme honeys. The samples were subjected to pollen analysis to confirm their botanical origin. Coupled chromatographic techniques (HPLC-DAD-ESI-MS) were optimized for the separation and identification of polyphenolic compounds. The antioxidant properties of the samples were determined by spectrophotometric methods. Pollen profile analysis revealed that only 3 out of 5 alleged lavender honeys contained a low percentage (0.6-1.5) of lavender pollen; and there were only traces (0.1–0.6%) of thyme pollen in the alleged thyme honeys. Polyphenolic constituents did not allow for the clear separation of honey samples, revealing no marker compounds previously associated with lavender and thyme honeys. All samples contained large amounts of chlorogenic acid, chrysin, hesperetin, kaempferol and p-coumaric acid; as well as abscisic acid, a plant hormone known to be present in floral nectar and honey. Our results suggest that only one of five alleged lavender honeys and neither of the two alleged thyme honeys are true unifloral honeys. However, they can still provide various health benefits, such as being good sources of antioxidants. There was no relationship between the antioxidant activity and the uni- or multifloral character of the honey samples. Total phenolic content and antioxidant activity was the lowest in the honey sample with lavender and the highest in one of the alleged lavender honeys. Our findings highlight the importance of microscopical and phytochemical analyses of honeys before marketing, to ensure satisfactory quality for customers.
Comparative Study of the Volatile Components of Fresh and Fermented Flowers of Alnus sieboldiana (Betulaceae)
Authors: Ghani Nurunajah Ab , Ismail Nor Hadiani , Asakawa Yoshinori
Published: March 2019

Analysis of the volatile components present in the fresh male and female flowers and young leaves shows that 2-phenylethanol is the major component in all these three organs, which play a significant role in the strong resinous aromatic odor. The male flowers contained styrene as a second major compound. The level of styrene does not affect the male flowers odor concentration. The level of β-phenylethyl cinnamate and trans-methyl cinnamate in the fermented male flowers decreased as the fermentation time increased. This was due to the Penicillium enzymatic action on the fermented male flowers.
A Review of Traditional Medicinal Plants from Kachin State, Northern Myanmar
Authors: Aung Hnin Thanda , Sein Myint Myint , Aye Mya Mu , Thu Zaw Min
Published: March 2019

Medicinal plants are a vital source of medication in developing countries. In Kachin State, Northern Myanmar, the people have a long history of the use of traditional plants for medicinal purposes. This article deals with the 25 most used medicinal plants in Kachin State. They are: Drynaria fortunei, Tetrastigma serrulatum, Bauhinia championii, Goniothalamus cheliensis, Juglans regia, Houttuynia cordata, Osmanthus fragrans, Pothos chinensis, Tabemaemontana coronaria, Eryngium foetidum, Chloranthus spicatus, Peperomia pellucida, Zanthoxylum armatum, Polygonum fagopyrum, Cymbidium floribundum, Amomum kravanh, Coscinium fenestratum, Solanum nigrum, Gnetum parvifolium, Desmodium triquetum, Begonia augustinec, Mappianthus iodoides, Erycibe obtusifolia, Schefflera venulosa, Holarrhena antidysenterica. The different traditional applications, the known chemical constituents and medicinal properties are reported for each plant. The efficacy of several of these plants has been supported by some scientific evidence, while other plants have to be submitted to further investigations to prove the beneficial medicinal properties attributed to them.
Diterpenoids from Leaves of Rubus Chingii
Authors: Shu Jicheng , Huang Yingzheng , Cui Hangqing , Peng Caiying , Liu Jianqun , Huang Huilian
Published: March 2019

The leaves of Rubus chingii were examined for their phytochemical composition and anti-yeast activity. In the process, seven diterpenoids (compounds 1–7), including a new natural compound (14β, 16-epoxy-7-pimarene-3α, 15β-diol, 1), were isolated and elucidated. Compound 1 exhibited moderate anti- Candida activity.
Synthesis of 5,19-(2,6-Dimethylpyridin-4-yl)-trisnorlupane and Oleanane
Authors: Salimova Elena V. , Tretyakova Elena V. , Parfenova Lyudmila V. , Odinokov Victor N.
Published: March 2019

Acetylation of the 3,4-seco-derivatives of betulin, allobetulin and 28-oxyallobetulone gave the 5,19-(2,6-dimethylpyridin-4-yl)-4,23,24,20,29,30-hexanorlupane, and 5-(2,6-dimethylpyridin-4-yl)-4,23,24-trisnor-derivatives of oleanane and ursane.
Cytotoxic Aporphines from Artabotrys Crassifolius
Authors: Kwan Tan Kok , Shipton Fiona , Azman Nadiah Syafiqah Nor , Hossan Shahadat , Jin Khoo Ten , Wiart Christophe
Published: March 2019

Artabotrys crassifolius Hook. f. & Thomson is a medicinal plant used in Malaysia. The cytotoxic effects of the hexane, chloroform and ethanol extracts of the leaves and bark were examined in vitro against MCF-7, MDA-468 and HCT-116 cells. The chloroform extract of the bark inhibited the growth of all cell lines with GI50 values ranging from 4.2 μg/mL to 9.4 μg/mL. Silica gel column chromatography of this extract yielded artabotrine, liridine, atherospermidine and lysicamine. Artabotrine and lysicamine inhibited the growth of HCT-116 and MCF-7 cells with GI50 values ranging from 3.3 μM to 3.9 μM. These alkaloids were not toxic to human embryonic kidney cells (HEK297) up to a concentration of 50 μg/mL.
Comparison of Seeds of Colchicum Speciosum and Gloriosa Superba in Respect to Colchicine and Colchicoside Contents by RP-LC
Authors: Gumustas Mehmet , Polat Derya Çiçek , Kılıç Ceyda S. , Akalın Kemalettin , Ozkan Sibel A. , Coşkun Maksut
Published: March 2019

In this study, colchicine (CLN) and colchicoside (CLS) contents of the methanolic extracts of the seeds of Colchicum speciosum Steven that were collected from Uzungöl, Trabzon and also the seeds belonging to two different samples of Gloriosa superba Linn. imported from India were compared by using RP-LC (Reversed Phase High Pressure Liquid Chromatography). This proposed method is advantageous in terms of sample preparation and selective separation of the compounds. Also the method was successfully validated in accordance with the International Conference on Harmonization (ICH) guideline acceptance criteria for system suitability, linearity and range, precision, specificity and accuracy. As a conclusion of this analysis, the colchicoside and colchicine contents of G. superba (GSI), G. superba (GSII) and C. speciosum (CS) were found to be 312.9 mg/100 g and 333.1 mg/100 g; 434.0 mg/100 g and 471.1 mg/100 g, and 51.9 mg/100 g and 75.9 mg/100 g, respectively.
Secondary Metabolites from an Actinomycete from Vietnam's East Sea
Authors: Thi Quyen Vu , Tran Van Hieu , Mai Huong Doan Thi , Le Cong Vinh , Hong Minh Le Thi , Murphy Brian T. , Chau Van Minh , Pham Van Cuong
Published: March 2019

Analysis of an antimicrobial extract prepared from culture broth of the marine-derived actinomycete Nocardiopsis sp. (strain G057) led to the isolation of twelve compounds, 1–12. Compound 1 (2-[(2 R-hydroxypropanoyl)amino]benzamide) was found to be a new enantiomeric isomer while compounds 2 (3-acetyl-4-hydroxycinnoline) and 3 (3,3′-bis-indole) were isolated from a natural source for the first time. The structures of 1 – 12 were determined by analyses of MS and 2D NMR data. All compounds were evaluated for their antimicrobial activity against a panel of clinically significant microorganisms. Compound 1 selectively inhibited Escherichia coli (MIC: 16 μg/mL). Compounds 2 and 3 exhibited antimicrobial activity against several strains of both Gram-positive and Gram-negative bacteria, and the yeast Candida albicans. Cytotoxic evaluation of compounds 1 – 3 against four cancer cell lines (KB, LU-1, HepG-2 and MCF-7) indicated that compound 3 produced a weak inhibition against KB and LU cell lines. Two remaining compounds, 1 and 2 were not cytotoxic, even at the concentration of 128 μg/mL.
Cytotoxic Activity of Lomatiol and 7-(3′-Hydroxymethyl-3′-methylallyloxy)coumarin
Authors: Fiorito Serena , Genovese Salvatore , Epifano Francesco , Mathieu Veronique , Kiss Robert , Taddeo Vito Alessandro
Published: March 2019

7-(3′-Hydroxymethyl-3′-methylallyloxy)coumarin, bearing a 3′-hydroxy-3′-methylallyl group as the O-side chain, and lomatiol, a lapachol derivative sharing the same structural feature, were tested for their in vitro growth inhibitory activities on six cancer cell lines using the MTT colorimetric assay, along with the respective 3′,3′-dimethylallyl derivatives and unprenylated products used for comparison. Data revealed that lomatiol displayed the strongest growth inhibitory activities in vitro although not as efficient as the parent compound lapachol. The oxidized O-prenylcoumarin recorded better growth inhibitory capacities than the prenylated and unprenylated parent products.
Compositional and Enantiomeric Analysis of the Essential Oil of Taxodium Distichum from India
Authors: Padalia Rajendra C. , Verma Ram S. , Chauhan Amit , Goswami Prakash , Chanotiya Chandan S.
Published: March 2019

The leaf essential oil composition of Taxodium distichum L., collected from the foothills of Uttarakhand, India was analyzed using gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) equipped with DB-5 (5% diphenyl-95% dimethyl polysiloxane) and β-cyclodextrin (6-tertiarybutyldimethylsiliyl-2,3-diethyl-β-cyclodextrin) capillary columns. Seventeen constituents, representing 90.3 to 99.4% of composition were identified in the essential oils from different seasons, viz. spring, summer, rainy, autumn and winter. The essential oil composition was mainly dominated by monoterpene hydrocarbons, represented mainly by α-pinene (81.9–94.3%). Other constituents of the oil were myrcene (0.5–4.7%), β-pinene (2.2–2.9%), limonene (0.5–1.5%), camphene (≤0.03–1.5%), and α-terpineol (upto 1.6%). Chiral analysis of T. dstichum essential oil on an ethyl substituted β-cyclodextrin capillary column revealed the presence of α-pinene in racemic form, with an enantiomeric ratio of 49.3% for (1 R)-(+)- and 50.7% for (1 S)-(-)-α-pinene.
Aerobic Decomposition of Trialkylquercetins: Structure Characterization and Antiproliferative Effect
Authors: Al-Jabban Sami M.R. , Zhang Xiaojie , Chen Guanglin , Rakotondraibe Liva Harinantenaina , Chen Qiao-Hong
Published: March 2019

The aerobic decomposition of 3,4′,7- O-trialkylquercetins was first reported in this paper. The structures of four new decomposed products were characterized by analyzing the 1D and 2D NMR data, as well as their high resolution mass spectroscopic data. Their antiproliferative activity toward human prostate cancer cells has been assessed through WST-1 cell proliferation assay. The decomposition mechanism was also proposed.
Two New Anthraquinones from the Roots of Prismatomeris connata
Authors: Wang Chun-Xiang , Zhao Sa-Na , Feng Shi-Xiu , Zhang Xiao-Ping , Chen Tao
Published: March 2019

Two new anthraquinones, 4-hydroxy-1,2,3-trimethoxy-7-hydroxymethylanthracene-9,10-dione (1) and 1,2,3-trimethoxy-7-hydroxymethylanthracene-9,10-dione (2), were isolated from the roots of Prismatomeris connata, a Chinese medicinal herb. Their structures were elucidated by spectroscopic analysis. Compound 1 exhibited cytotoxicity against a panel of H1229, HTB179, A549 and H520 lung tumor cell lines with IC50 values ranging from 12.3 to 20 μM.
A New Succinate Derivative from Ajuga decumbens
Authors: Fan Gai-Xia , Zhi De-Juan , Ren Hui , Li Zheng-Yu , Hu Qiao-Ling , Liu Ying-Hong , Zhang Zhan-Xin , Fei Dong-Qing
Published: March 2019

A new succinate derivative, ethyl (5-formylfuran-2-yl)methyl succinate (1), along with three known compounds (2–4) have been isolated from the whole plants of Ajuga decumbens Thunb. Their structures were elucidated by extensive spectroscopic (1D and 2D NMR) and HR-ESI-MS data analysis, and literature values. Compound 1 was isolated as a new succinate derivative, and compounds 2 and 3 were for the first time separated from A. decumbens.
Chlorogenic Acid Interaction with Cisplatin and Oxaliplatin: Studies in Cervical Carcinoma Cells
Authors: Catanzaro Daniela , Filippini Raffaella , Vianello Caterina , Carrara Maria , Ragazzi Eugenio , Montopoli Monica
Published: March 2019

The antiproliferative effect of the naturally occurring polyphenol chlorogenic acid (CGA) was evaluated in combination with either cisplatin or oxaliplatin in human cervical carcinoma cell lines that were either sensitive (A431) or resistant to cisplatin (A431Pt), in order to provide evidence to overcome drug resistance. Cytotoxicity of platinating drugs (IC50 ~ 10−6 - 10−5 M) was enhanced by 1–2 orders of magnitude by increasing incubation times (1, 4, and 24 hours) in the two cell lines. CGA treatment presented low cytotoxicity per se (IC50 ~ 10−4 M at 24 h) if compared with platinum drugs and its activity was similar in A431Pt cells and in their sensitive A431 counterpart. The combination of the platinating drugs with CGA (10−6 - 10−4 M) indicated variable effects on cytotoxicity, ranging from potentiation to various degrees of antagonism (in A431 cells) and no effect (in A431Pt cells). In order to explain the different cytotoxic activity elicited by oxaliplatin and cisplatin in association with CGA, the possible presence of chemical interactions was investigated by HPLC analysis. The drug association with CGA caused evident changes in their chromatographic profile, suggesting occurrence of in vitro chemical interactions.
Chemical Constituents of Trichilia hirta (Meliaceae)
Authors: Vieira Milena G. Curcino , dos Santos Frances R. , Filho Raimundo Braz , Vieira Ivo J. Curcino
Published: March 2019

A novel oleanane-type triterpene, 15-chloro-β-amyrone (1), was isolated from Trichilia hirta, together with the known compounds taraxer-3-one (2) and β-taraxerol (3), along with two novel esters, 3-(isobutyryloxy)-2,2,4-trimethylpentyl palmitate (4) and 3-(isobutyryloxy)-2,2,3-trimethylpentyl stearate (5), and the known 3-hydroxy-2,2,4-trimethylpentyl isobutyrate (6). These compounds were characterized on the basis of their spectroscopic and HRSEIMS data and by comparison with literature data.
Phytochemical Analysis and Gastroprotective Activity of the Root Bark from Maytenus robusta
Authors: Benvenutti Danyela Francine , Monache Franco Delle , Filho Valdir Cechinel , de Andrade Sérgio Faloni , Niero Rivaldo
Published: March 2019

The present work evaluated the chemical composition and antiulcerogenic potential of the crude extract, fractions and pure compounds isolated of roots barks from Maytenus robusta Reiss, using different pharmacological models in mice. 3,12-Dioxofriedelane (1) and 11-hydroxylup-20 (29)-en-3-one (2) were isolated from the n-hexane fraction, and mayteine (3) and 3,7-dioxofriedelane (4) from the dichloromethane fraction. The crude extract (50, 259, 500 mg/kg), all the fractions (250 mg/kg) and cimetidine (100 mg/kg) significantly reduced the lesion index, total lesion area, and percentage of lesions, in comparison with the control group ( p< 0.05), by ethanol and NSAID-induced ulcer models. All the isolated compounds also presented significant pharmacological effects at 30 mg/kg. These results show that the root bark of M. robusta may be a promising source of molecules with applicability in the treatment of gastric disorders.
Activity of Flavanones Isolated from Rhododendron hainanense against Plant Pathogenic Fungi
Authors: Li Ya , Zhao Jie , Gao Kun
Published: March 2019

In a search for naturally occurring antimicrobial compounds in medicinal plants and herbs, seven flavanones were isolated from the aerial parts of Rhododendron hainanense and were tested for their antimicrobial activities against six bacteria and six plant pathogenic fungi. Within the series of flavanones tested, farrerol (1) displayed moderate antibacterial activities against Bacillus cereus, B. subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Erwinia carotovora, with MICs ranging from 15.6 to 125 μg/mL. Furthermore, farrerol (1) exhibited excellent inhibitory activities against six plant pathogenic fungi: Fusarium oxysporum f. sp. niveum, Colletotrichum gloeosporioides, Penicillium italicum, Rhizoctonia solani, Fusarium oxysporum f. sp. cubenserace and Phytophthora melonis, with EC50 values of 9, 18, 35, 39, 46 and 66 μg/mL, respectively. This is the first report on farrerol with anti-plant pathogenic fungal activities.
HPLC-DPPH Screening Method for Evaluation of Antioxidant Compounds in Corylus Species
Authors: Riethmüller Eszter , Könczöl Árpád , Szakál Dorottya , Végh Krisztina , Balogh György T. , Kéry Ágnes
Published: March 2019

Corylus avellana L., C. colurna L. and C. maxima Mill. have been used in traditional medicine for a long time for the treatment of various diseases, such as phlebitis, varicose veins, haemorrhoidal symptoms and eczema. Our previous studies indicated the presence of flavonol-3- O-glycosides, diarylheptanoids and caffeic acid derivatives in the bark and leaf extracts of the three species mentioned above. Comparison of in vitro DPPH scavenging activity of the Corylus extracts prepared with ethyl acetate and methanol to those of well-known antioxidant phenolics was performed. The contribution of certain compounds to the total antioxidant activity of the extracts was investigated by developing a HPLC method coupled to the DPPH radical scavenging assay.
A New Bibenzyl-phenanthrene Derivative from Dendrobium signatum and its Cytotoxic Activity
Authors: Mittraphab Arparporn , Muangnoi Chawanphat , Likhitwitayawuid Kittisak , Rojsitthisak Pornchai , Sritularak Boonchoo
Published: March 2019

From the whole plant of Dendrobium signatum, a new bibenzyl-dihydrophenanthrene derivative, named dendrosignatol was isolated, together with the known compounds 3,4-dihydroxy-3,4′-dimethoxybibenzyl, dendrocandin B, dendrocandin I and dendrofalconerol A. The structure of the new compound was elucidated through analysis of its spectroscopic and mass spectrometric data. All of the isolates showed appreciable cytotoxic activity against three human cancer cell lines, including MDA-231, HepG2 and HT-29 cells.
Synthesis of 5-Methoxy-6-isopropyl-1-tetralone
Authors: Vera William J. , Banerjee Ajoy K.
Published: March 2019

1-Hydroxytetralin was converted into 5-methoxy-6-isopropyl-1-tetralone in six steps.
Chemical Composition, Antioxidant, and Antimicrobial Activities of Essential Oils of Endlicheria arenosa (Lauraceae) from the Amazon
Authors: da Silva Joyce Kelly R. , da Trindade Rafaela C. S. , Maia José Guilherme S. , Setzer William N.
Published: March 2019

The essential oils (EOs) of leaves and twigs of Endlicheria arenosa Chanderb. were obtained by hydrodistillation using a Clevenger-type apparatus and the chemical composition was determined by GC and GC-MS. In total, 47 constituents were identified and sesquiterpene hydrocarbons (77.6%) were the main compounds found in the leaf EO, such as bicyclogermacrene (42.2%), germacrene D (12.5%) and β-caryophyllene (10.1%). Limonene (33.2%), terpinen-4-ol (15.6%) and δ-cadinol (6.9%) were the predominant constituents in the EO of the twigs. Using the DPPH radical-scavenging method, the EO of the leaves showed the greater radical-scavenging activity (216.5 ± 11.6 mg Trolox equivalents (TE)/mL compared to the EO of the twigs (122.6 ± 6.8 mg TE/mL). Also, the EO of leaves displayed promising antimicrobial activity against Escherichia coli (MIC 19.5 μg•mL−1). The present study is the first report about evaluation of volatile oils for this species.
A New Cassane-type Diterpene from the Seed of Caesalpinia Sappan
Authors: Nguyen Hai Xuan , Nguyen Nhan Trung , Dang Phu Hoang , Thi Phuoc Ho , Nguyen Mai Thanh Thi , Van Can Mao , Dibwe Dya Fita , Ueda Jun-ya , Matsumoto Kinzo , Awale Suresh
Published: March 2019

Phytochemical investigation of the CH2C12 extract of the Vietnamese medicinal plant Caesalpinia sappan Linn resulted in the isolation of a new cassane-type diterpene named tomocin I (1). Its chemical structure was determined by NMR spectroscopic and mass spectrometric analysis.
Steroid Sulfates from Ophiuroids (Brittle Stars): Action on Some Factors of Innate and Adaptive Immunity
Authors: Gazha Anna K , Ivanushko Lyudmila A. , Levina Eleonora V. , Fedorov Sergey N. , Zaporozets Tatyana S. , Stonik Valentin A. , Besednova Nataliya N.
Published: March 2019

The action of seven polyhydroxylated sterol mono- and disulfates (1-7), isolated from ophiuroids, on innate and adaptive immunity was examined in in vitro and in vivo experiments. At least, three of them (1, 2 and 4) increased the functional activities of neutrophils, including levels of oxygen-dependent metabolism, adhesive and phagocytic properties, and induced the expression of pro-inflammatory cytokines TNF-α and IL-8. Compound 4 was the most active for enhancing the production of antibody forming cells in the mouse spleen.
A Novel Heterodimer from Crotalaria ferruginea
Authors: Zou Yi-Hong , Liu Xin , Liu Ye-Na , Tang Gui-Hua , Yin Sheng
Published: March 2019

A new compound was isolated from the traditional Chinese folk herb Crotalaria ferruginea. The structure of the new compound was identified as (±)-crotaferruphenol (1) based on analyses of its spectroscopic data including NMR, MS, and specific rotation values. (±)-Crotaferruphenol was a novel heterodimer characteristic of a unique spiroketal moiety, which was produced by the condensation reaction of a chromanone and a 2-isopropenybenzofuran. (±)-Crotaferruphenol exhibited inhibitory activity (IC50 = 6.57 μM.) against phosphodiesterase-4 (PDE4), a drug target for the treatment of chronic obstructive pulmonary disease and asthma.
A New Neolignan, and the Cytotoxic and Anti-HIV-1 Activities of Constituents from the Roots of Dasymaschalon sootepense
Authors: Hongthong Sakchai , Kuhakarn Chutima , Jaipetch Thaworn , Piyachaturawat Pawinee , Jariyawat Surawat , Suksen Kanoknetr , Limthongkul Jitra , Nuntasaen Narong , Reutrakul Vichai
Published: March 2019

Bioassay-guided isolation from the ethyl acetate extract of Dasymaschalon sootepense roots led to the isolation of twelve compounds including a new dihydrobenzo-furan neolignan, (+)-(2S’,3S)-2,3-dihydro-2-(3,4-dimethoxyphenyl)-3-methylbenzofuran-5-carbaldehyde (5), and eleven known compounds (1-4, and 6-12). The chemical structures and stereochemistry of all the isolated compounds were established by spectroscopic techniques. The known compounds 4 and 6 have been fully characterized spectroscopically, including their absolute configurations. Cytotoxic and anti-HIV-1 reverse transcriptase (RT) activities of compounds 1-3, 5 and 8-12 were determined. Among compounds screened, compounds 2, 3 and 10 displayed weak cytotoxic activity with ED50 values ranging from 9.6-47.5 μM and only compound 2 was found weakly active against HIV-1 RT with an IC50 value of 323.2 μM.
Proteomic Analysis of the Antibacterial Mechanism of Action of Juglone against Staphylococcus aureus
Authors: Wang Jiayi , Wang Zixue , Wu Rina , Jiang Donghua , Bai Bing , Tan Dehong , Yan Tingcai , Sun Xiyun , Zhang Qi , Wu Zhaoxia
Published: March 2019

Juglone is a plant-derived 1,4-naphthoquinone with confirmed antibacterial activity. However, the mechanism of action of juglone against Staphylococcus aureus remains unclear. Possible mechanisms were explored by a proteomic analysis of S. aureus proteins that are inhibited by juglone. Two-dimensional gel electrophoresis revealed that 21 protein spots were differentially expressed between juglone-treated and untreated cells of which 13 were identified. A bioinformatic analysis revealed that proteins participating in protein synthesis, the tricarboxylic acid cycle, as well as DNA and RNA synthesis were inhibited by juglone, thus leading to cell collapse. These findings provide clues regarding the mechanism of action of juglone, which can be effective for treating cases of S. aureus infection.
Composition of the Leaf Essential Oil of Phoebe formosana from Taiwan and its in vitro Cytotoxic, Antibacterial, and Antifungal Activities
Authors: Su Yu-Chang , Ho Chen-Lung
Published: March 2019

The essential oil from the leaves of Phoebe formosana from Taiwan was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. Seventy-one compounds were identified, representing 100% of the oil. The main components identified were α-humulene (16.8%), τ-cadinol (8.9%), α-pinene (8.4%), α-cadinol (8.1%), β-caryophyllene (8.0%), β-phellandrene (6.0%), and β-eudesmol (5.8%). The oil exhibited cytotoxic activity against human lung, liver and oral cancer cells. The active compounds were β-caryophyllene, α-humulene, τ-cadinol, β-eudesmol, and α-cadinol. The antibacterial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against eight bacterial species. The oil exhibited moderate growth suppression against Gram-positive bacteria with inhibition zones of 28 to 36 mm, and MIC values of 250 to 375 μg/mL. The active antibacterial compounds were determined to be τ-cadinol, β-eudesmol, and α-cadinol. The leaf oil displayed excellent antifungal activity with the active compounds determined as α-cadinol, β-eudesmol, τ-cadinol, α-humulene, and β-caryophyllene.
Antioxidant and Anti-inflammatory Activities of Essential Oils of Actinodaphne macrophylla and A. pruinosa (Lauraceae)
Authors: Salleh Wan Mohd Nuzul Hakimi Wan , Ahmad Farediah
Published: March 2019

The essential oils of Actinodaphne macrophylla and A. pruinosa were analyzed by GC and GC-MS and evaluated for their antioxidant and anti-inflammatory activities. The essential oil of the leaves of A. macrophylla was characterized by the presence of 31 components (78.2%), with germacrene B (16.8%) and globulol (16.0%) as the major components. A total of 28 components (71.6%) were characterized in the leaf oil of A. pruinosa with the most abundant components being globulol (17.8%) and spathulenol (12.0%). The antioxidant activity was determined by DPPH radical scavenging and total phenolic content, while anti-inflammatory activity by lipoxygenase assay. The essential oil of A. pruinosa demonstrated significant activity on DPPH (IC50 85.6 μg/mL), phenolic content (190.2 mg GA/g) and in the lipoxygenase (IC5085.2 μM) assays.
Guaiane Sesquiterpenoids from the Gorgonian Menella woodin
Authors: Lyakhova Ekaterina G. , Diep Chau Ngoc , Berdyshev Dmitrii V. , Kolesnikova Sophia A. , Kalinovsky Anatoly L , Dmitrenok Pavel S. , Tu Vu Anh , Cuong Nguyen Xuan , Van Thanh Nguyen , Nam Nguyen Hoai , Van Kiem Phan , Stonik Valentin A. , Van Minh Chau
Published: March 2019

Two new guaiane derivatives (1 and 2) along with six known sesquiterpenoids (3-8) were isolated from the gorgonian Menella woodin. Their structures were elucidated by ID and 2D NMR and HRESIMS data as well as by comparison of their spectra with those in the literature. Relative configurations of asymmetric centers in 1 and 2 were suggested on the basis of NOESY and ID NOE correlations, absolute stereochemistry of these compounds was proposed in result of comparison of calculated (for both enatiomers) and experimental ECD. Some suggestions were made regarding a biosynthesis of guaiane sesquiterpenoids in this species. All the compounds were firstly isolated from M woodin.
Oxygenated Diterpenes from the Indo-Pacific Nudibranchs Goniobranchus splendidus and Ardeadoris egretta
Authors: White Andrew M. , Dewi Ariyanti S. , Cheney Karen L. , Winters Anne E. , Blanchfield Joanne T. , Garson Mary J.
Published: March 2019

Five new diterpenes (1-5), each with a highly oxygenated spongian framework, were characterized from an organic extract of a specimen of the nudibranch Goniobranchus splendidus collected from Eastern Australia. The new diterpene 7α-hydroxydendrillol-3 (6) was identified from specimens of Ardeodoris egretta. The structures and relative configurations of the six new metabolites have been elucidated by analysis of their spectroscopic data.
Structure Revision of (22E)-24-Methylcholesta-8(14),22-diene-3β,5α,6β,7α-tetraol from the Marine-Derived Fungus Penicillium sp
Authors: Yaoita Yasunori , Machida Koichi
Published: March 2019

Careful reexamination of the published 1H- and 13C-NMR spectral data of (22 E)-24-methylcholesta-8(14),22-diene-3β,5α,6β,7α-tetraol (1), isolated from the marine-derived fungus Penicillium sp., indicates that, in reality, the compound is 5α,6α-epoxy-(22 E,24 R)-24-methylcholesta-8(14),22-diene-3β,7α-diol (5).
Anticandidal Effects of Thymoquinone: Mode of Action Determined by Transmission Electron Microscopy (TEM)
Authors: İşcan Gökalp , İşcan Arzu , Demirci Fatih
Published: March 2019

Thymoquinone (TQ) is one of the bioactive constituents of black cumin seed ( Nigella sativa L.) oil. It is well known that this natural volatile quinone has remarkable antimicrobial effects, especially against Candida species. Consequently, in this present study TQ was evaluated for its anticandidal effects against 14 different pathogenic Candida strains by using the in vitro, partly modified, microdilution CLSI M27-A2 method. After TQ treatment at the minimum inhibitory concentration (MIC), ultra-thin sections of C. albicans cells were thoroughly evaluated by transmission electron microscopy (TEM). The mode of action of TQ on different Candida cells was elaborated, where their disintegration and disorganization with amorphous nucleus were observed microscopically.
Chemical Composition and Antimicrobial Activity of Populus nigra Shoot Resin
Authors: Paetz Christian , Hammerbacher Almuth , Menezes Riya C. , Feistel Felix , Weigel Christiane , Voigt Kerstin , Schneider Bernd
Published: March 2019

The chemical composition of Populus nigra shoot resin has been investigated by chromatographic and spectroscopic methods. The analyses resulted in identification of 19 known compounds. The resin exhibited low activity against selected microorganisms.
Synthesis of Piceatannol, an Oxygenated Analog of Resveratrol
Authors: Tashiro Takuya , Honzawa Shinobu , Sugihara Takumichi
Published: March 2019

Piceatannol (3,3′,4,5′-tetrahydroxy- trans-stilbene, 2), an oxygenated analog of resveratrol (1), was synthesized. It is one of the naturally occurring polyphenolic stilbenoids contained in red wine, and possesses many kinds of beneficial effects such as anticancer activity. The trans-stilbene skeleton of 2 was constructed by Pd-catalyzed Suzuki-Miyaura cross coupling reaction of triflate 8 with ( E)-alkenylboronoate 13. The key intermediate 13 was prepared diastereoselectively by acid-catalyzed hydroboration of pinacolborane 12 to alkyne 11.