A new coumarin from stem bark of Mesua hexapetala

A new alkylated coumarin derivative, hexapetarin (1) along with three other xanthones, trapezifolixanthone (2), cudraxanthone G (3) and 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4), and four common triterpenoids, friedelin (5), stigmasterol (6), beta-sitosterol (7) and gamma-sitosterol (8) were isolated from the stem bark of Mesua hexapetala (Clusiaceae), a plant, native to Malaysia. The structures of these compounds were elucidated and determined using spectroscopic techniques such as NMR and MS. Anti-inflammatory activity assay indicated hexapetarin (1) to possess moderate anti-inflammatory activity, while 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4) gave very good activity.     

Soulamarin, a new coumarin from stem bark of Calophyllum soulattri

The extracts of the stem bark of Calophyllum soulattri gave a new pyranocoumarin, soulamarin (1), together with five other xanthones caloxanthone B (2), caloxanthone C (3), macluraxanthone (4), trapezifolixanthone (5) and brasixanthone B (6) one common triterpene, friedelin (7), and the steroidal triterpene stigmasterol (8). The structures of these compounds were established based on spectral evidence (1D and 2D NMR).     

A new benzophenone from the stem bark of Garcinia benthami

From the stem bark of Garcinia benthami a new benzophenone, named Salimbenzophenone, was isolated. The structure was determined by means of spectroscopic analysis.     

A new diterpenoid from the stem bark of Populus davidiana

A new diterpenoid, named populusol A （1）, was isolated from the methanolic extraction of the stem bark of Populus davidiana. The structure was elucidated on the basis of extensive 1D and 2D NMR as well as HRFAB-MS spectroscopic analysis.     

A new salicin derivative from the stem bark of Populus davidiana

Phytochemical study on the BuOH-soluble fraction of the stem bark of Populus davidiana resulted in the isolation of a new salicin derivative(1),named davidianoside.The structure was elucidated on the basis of extensive physicochemical and spectroscopic analyses.     

A new chromanone acid from the stem bark of Calophyllum teysmannii

A new chromanone acid, namely caloteysmannic acid (1), along with three known compounds, calolongic acid (2), isocalolongic acid (3) and stigmasterol (4) were isolated from the stem bark of Calophyllum teysmannii. All these compounds were evaluated for their cytotoxic and antioxidant activities in the MTT and DPPH assays, respectively. The structure of compound 1 was determined by means of spectroscopic methods including 1D and 2D NMR experiments as well as HR-EIMS spectrometry. The stereochemical assignment of compound 1 was done based on the NMR results and X-ray crystallographic analysis. The preliminary assay results revealed that all the test compounds displayed potent inhibitory activity against HeLa cancer cell line, in particular with compound 1 which exhibited the highest cytotoxic activity comparable to the positive control used, cisplatin. However, no significant antioxidant activity was observed for all the test compounds in the DPPH radical scavenging capacity assay.     

Phenylpropanoids from the stem bark of Jacaranda mimosaefolia

Two new compounds: 2-(3',4'-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-p-hydroxyphenylacetyl-6-O-caffeoyl-β-D-glucopyranoside and 2-(3',4'-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-piperidine-3-carboxylic acid-6-O-caffeoyl-β-D-glucopyranoside were isolated from the stem bark of Jacaranda mimosaefolia. In addition, the known compounds lupeol, betulinaldehyde, terminic acid, betulinic acid, maslinic acid, β-sitosterol glucoside and isoacteoside were isolated and identified.     

A novel antimicrobial flavonoid from the stem bark of Commiphora pedunculata (Kotschy & Peyr.) Engl.

A new flavonoid, 2-(3,5-dihydroxy-4-methoxy-phenyl)-3,5-dihydroxy-8,8-dimethyl-2,3-dihydro-8H-pyrano[3,2]chromen-4-one, together with previously reported epicatechin was isolated from the ethyl acetate soluble fraction of the methanol extract of the stem bark of Commiphora pedunculata. The structures of these compounds were elucidated based on extensive analysis of their spectral data, including 1 and 2D NMR. The compounds were active against 9 out of 12 tested microorganisms including a resistant strain; vancomycin-resistant entrococci (VRE), Escherichia coli, Staphylococcus aureus and Candida albicans. The zones of inhibition ranged between 22 and 34 mm against the microorganisms. The minimum inhibitory concentration was as low as 6.25 μg/mL against Shigella dysentriae, Bacillus cereus and S. aureus while the minimum bactericidal concentration was as low as 50 μg/mL against Pseudomonas aeruginosa, VRE and C. albicans. This is the first report of the isolation of the compound.     

A novel synthesis of coumarin derivatives

The chemical behaviors of 3-ethynylcoumarin towards benzyl bromide,diazonium chic ride,hydrogen chloride,ethyl magnesium bromide and its self-coupling are reported.     

A novel bacteriohopanoid from Celtis australis L.bark

A novel bacteriohopanoid elucidated as 3β-hydroxy-35-(cyclohexyl-5’-propan-7’-one)-33-ethyl-34-methyl-bactereohopane(1) has been isolated from the bark of Celtis australis(Ulmaceae) together with three known compounds apigenin,quercetin and its glucoside.The structure of 1 was characterized by means of chemical and spectral methods including advanced 2D NMR studies.     

<em>Mesua beccariana </em>(Clusiaceae), A Source of Potential Anti-cancer Lead Compounds in Drug Discovery

An investigation on biologically active secondary metabolites from the stem bark of Mesua beccariana was carried out. A new cyclodione, mesuadione (1), along with several known constituents which are beccamarin (2), 2,5-dihydroxy-1,3,4-trimethoxy anthraquinone (3), 4-methoxy-1,3,5-trihydroxyanthraquinone (4), betulinic acid (5) and stigmasterol (6) were obtained from this ongoing research. Structures of these compounds were elucidated by extensive spectroscopic methods, including 1D and 2D-NMR, GC-MS, IR and UV techniques. Preliminary tests of the in vitro cytotoxic activities of all the isolated metabolites against a panel of human cancer cell lines Raji (lymphoma), SNU-1 (gastric carcinoma), K562 (erythroleukemia cells), LS-174T (colorectal adenocarcinoma), HeLa (cervical cells), SK-MEL-28 (malignant melanoma cells), NCI-H23 (lung adenocarcinoma), IMR-32 (neuroblastoma) and Hep-G2 (hepatocellular liver carcinoma) were carried out using an MTT assay. Mesuadione (1), beccamarin (2), betulinic acid (5) and stigmasterol (6) displayed strong inhibition of Raji cell proliferation, while the proliferation rate of SK-MEL-28 and HeLa were strongly inhibited by stigmasterol (6) and beccamarin (2), indicating these secondary metabolites could be anti-cancer lead compounds in drug discovery.     

Phenolic glycosides from the stem bark of Albizzia julibrissin

From the stem bark of Albizzia julibrissin DURAZZ (Leguminosae), two new phenolic glycosides (albibrissinosides A and B) were isolated. Their structures were determined by spectroscopic analysis. The albibrissinoside B was found to be a radical scavenger on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.     

Stilbenoids isolated from stem bark of Shorea hemsleyana

Two new stilbene glucosides [(+)-alpha-viniferin 13b-O-beta-glucopyranoside and resveratrol 12-C-beta-glucopyranoside] and two new resveratrol oligomers, hemsleyanols A and B, were isolated from the bark of Shorea hemsleyana along with four known resveratrol oligomers. The structures of the isolates, including the relative configurations, were established by spectroscopic data involving long-range coupling and nuclear Overhauser effect experiments.     

Four new isoflavonoids from the stem bark of Erythrina variegata

Bioassay-directed fractionation of the stem bark extract of Erythrina variegata L. has resulted in the isolation of three new isoflavones: 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-methoxyisopropylfurano[4,5:6,7]isoflavone (1), 5,7,4'-trihydroxy-6-(3,3-dimethylallyloxiranylmethyl)isoflavone (2), 5,4'-dihydroxy-8-(3,3-dimethylallyl)-2'-hydroxymethyl-2'-methylpyrano[5,6:6,7]isoflavone (3) and a new isoflavanone, 5,4'-dihydroxy-2'-methoxy-8-(3,3-dimethylallyl)-2',2'-dimethylpyrano[5,6:6,7]isoflavanone (4) together with seven known compounds, euchrenone b10 (5), isoerysenegalensein E (6), wighteone (7), laburnetin (8), lupiwighteone (9), erythrodiol (10), and oleanolic acid (11). The structures were determined on the basis of spectroscopic analyses and chemical evidence. The effect of these compounds on the proliferation of rat osteogenic sarcoma (UMR106) is also reported.     

New labdane diterpenes from the stem bark of Larix laricina

Two new labdane diterpenes, cis-19-hydroxyabienol (1) and 8alpha-hydroxy-12Z,14-labdadien-19-al (2), along with another labdane described for the first time in the genus Larix, 19-acetoxy-13S-hydroxy-8(17),14-labdadiene (3) and a stilbene, 3-methoxy-3,3',5'-trihydroxystilbene (4), were isolated from the stem bark of Larch (Larix laricina). Their structures were established by standard chemical and spectroscopic methods. Compounds 2 and 3 were shown to be moderately cytotoxic against A-549, DLD-1 and normal skin fibroblast cell lines, WS1. Compound 1 was found to be selectively active against colon carcinoma cell lines, DLD-1.     

Two new xanthones isolated from the stem bark of Garcinia lancilimba

Two new xanthones, 1,5,6-trihydroxy-6',6'-dimethyl-2H-pyrano(2',3':3,4)-2-(3-methylbut-2-enyl)xanthone (1) and 1,6,7-trihydroxy-6',6'-dimethyl-2H-pyrano(2',3':3,2)-4-(3-methylbut-2-enyl)xanthone (2), have been isolated from the stem bark of Garcinia lancilimba (Guttiferae), together with six known xanthones. Their structures were identified on the basis of extensive spectral evidence including detailed 2D NMR and HR-MS data. Two new compounds showed moderate inhibitory effect on human breast cancer MDA-MB-435S cell line.     

Alkaloids from the stem bark of Turraeanthus africanus (Meliaceae)

Fractionation of the methanol extract of the stem bark of Turraeanthus africanus led to the isolation of two new alkaloids designated turraeanthin A and B, together with two known alkaloids. The structures of the new alkaloids were elucidated by means of spectroscopic analysis and characterized as 10-O-demethyl-17-O-methyl isoarnottianamide and 11-demethoxyl-12-methoxyl oxynitidine respectively.     

Anti-fatigue activity of extracts of stem bark from Acanthopanax senticosus

In the present study, we investigated the anti-fatigue activity in male Kunming mice of extracts of stem bark from Acanthopanax senticosus (ASSE) using a forced swimming test. Mice were divided into four groups (three ASSE administered groups and the control group). The control group were gavaged with distilled water and ASSE administered groups were gavaged with ASSE (100, 200 and 400 mg/kg). After four weeks, a forced swimming test was performed and the biochemical parameters related to fatigue were examined. The results suggested that ASSE could extend the swimming time to exhaustion of the mice, as well as increase the tissue glycogen contents, while decreasing the blood lactate and serum urea nitrogen contents. This indicated that ASSE had anti-fatigue activity and could elevate the exercise tolerance.     

Alkaloids from the stem bark of an Australian population of Zanthoxylum ovalifolium

The aerial parts of Zanthoxylum ovalifolium (Rutaceae) have yielded the two novel benzo[c]phenanthridine alkaloids terihanine (8-demethylnitidine) and isoterihanine (9-demethylnitidine) together with nitidine, the unusual furoquinoline 5-methoxydictamnine, canthin-6-one and several common furocoumarins. The finding of benzo[c]phenanthridine and furoquinoline alkaloids in Australian material of this species confirms its chemical homogeneity throughout its range from India to Australia.