Polyanxanthone A, B and C, three xanthones from the wood trunk of Garcinia polyantha Oliv.

Three xanthones, polyanxanthone A (1), B (2) and C (3) have been isolated from the methanol extract of the wood trunk of Garcinia polyantha, along with five known xanthones: 1,3,5-trihydroxyxanthone (4); 1,5-dihydroxyxanthone (5); 1,3,6,7-tetrahydroxyxanthone (6); 1,6-dihydroxy-5-methoxyxanthone (7) and 1,3,5,6-tetrahydroxyxanthone (8). Their structures were determined by means of 1D- and 2D-NMR techniques. Some of the above compounds were screened for their anticholinesterase activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes.

Inhibitory effect of macabarterin, a polyoxygenated ellagitannin from Macaranga barteri, on human neutrophil respiratory burst activity.

An ellagitannin with a 2,4-acyl group, named macabarterin (1), and a new ellagic acid glycoside, 3-O-methylellagic acid 4-O-ß-d-xylopyranoside (2), were isolated from the stem bark extract of Macaranga barteri along with five known phenolic compounds, ellagic acid (3), 3-O-methylellagic acid (4), gallic acid (5), methyl gallate (6), and scopoletin (7). The structures of 1 and 2, as well as those of the known compounds, were elucidated on the basis of spectroscopic data and by comparison with reported data. Compounds 1-5 and 7 were tested for their anti-inflammatory potential in a cell-based respiratory burst assay, compound 1 being found an inhibitor of the superoxides produced in the cellular system.

Antimalarial compounds from the root bark of Garcinia polyantha Olv.

Eight compounds were isolated from the roots of Garcinia polyantha, and identified. Two of them, the xanthone garciniaxanthone I (1), and the triterpene, named garcinane (2), are reported as new natural products. The structures of the new compounds were elucidated on the basis of 1D and 2D NMR spectroscopic studies. The structure of compound 1 was confirmed by X-ray crystallography. Among the remaining six known compounds, three were known xanthones [smeathxanthone A (3), smeathxanthone B (4), and chefouxanthone (5)], one benzophenone [isoxanthochymol (6)], one triterpene [magnificol], and one sterol [beta-sitosterol]. The in vitro antimalarial activity of isoxanthochymol (6) against Plasmodium falciparum shows strong chemosuppression of parasitic growth.

Bafoudiosbulbins A, and B, two anti-salmonellal clerodane diterpenoids from Dioscorea bulbifera L. var sativa.

Two clerodane diterpenoids, Bafoudiosbulbins A 1, and B 2, together with five known compounds: tetracosanoic acid, 1-(tetracosanoyl)-glycerol, trans-tetracosanylferulate, beta-sitosterol and 3-O-beta-D-glucopyranosyl-beta-sitosterol were isolated from the tubers of Dioscorea bulbifera L. var sativa. Their structures were established by spectroscopic methods (1D and 2D-NMR, MS) and X-ray crystallographic diffraction analysis of compound 1. The CH2Cl2-soluble portion of the crude extract and the two clerodanes were screened for anti-bacterial activity using both agar diffusion and broth dilution techniques against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi A and Salmonella paratyphi B. They both showed significant activities against P. aeruginosa, S. typhi, S. paratyphi A and S. paratyphi B.

Xanthones from Garcinia smeathmannii (Oliver) and their antimicrobial activity.

Two new xanthones, smeathxanthone A (1) (2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone) and smeathxanthone B (2) (5,7,10-trihydroxy-2-methyl-2-(4-methylpent-3-enyl)[2H, 6H]pyrano[3,2-b]xanthen-6-one), have been isolated from the stem bark of Garcinia smeathmannii, and their structures elucidated on the basis of 1D and 2D NMR experiments. 1,3,5-Trihydroxyxanthone and 1,5-dihydroxyxanthone were also obtained. The compounds showed only modest activity against a range of bacteria and yeasts.

In vivo anti-nociceptive and anti-inflammatory effect of the two triterpenes, ursolic acid and 23-hydroxyursolic acid, from Cussonia bancoensis.

Triterpenoids, ursolic acid (1) and 23-hydroxyursolic acid (2) were obtained from the hydrolysis of BuOH fraction of Cussonia bancoensis extract to test antinociceptive and anti-inflammatory effect of C. bancoensis (Araliaceae). Compound 1 and 2 exhibited anti-nociceptive effects, which were determined by acetic acid-induced writhing test and hot plate test. The effect of 2 was much more potent in acetic acid-induced writhing test than in hot plate test. Compound 1 and 2 significantly inhibited 1%-carrageenan-induced edema in the rat. These results suggest that the two triterpenes, ursolic acid and 23-hydroxyursolic acid, are responsible for the anti-nociceptive and anti-inflammatory effect of C. bancoesnsis.

Structure-activity relationship of triterpenoids isolated from Mitragyna stipulosa on cytotoxicity.

Chromatographic separation of the stem bark extract of Mitragyna stipulosa afforded triterpene derivatives ursolic acid (1), quinovic acid (2), quinivic acid 3-O-beta-D-glucopyranoside (3, quinovin glycoside C), quinovic acid 3-O-[(2-O-sulfo)-beta-D-quinovopyranoside] (4, zygophyloside D) and quinovic acid 3-O-beta-D-quinovopyranosyl-27-O-beta-D-glucopyranosyl ester (5, zygophyloside B). These five compounds were subjected to the cytotoxicity on MTT assay system. Compound 1 among tested showed the most potent cytotoxicity. Quinovic acid showed less potent cytotoxicity than ursolic acid and sugar linkages to 2 decreased the cytotoxicity. Compound 4 more potent than 3 with indicate that the sulfonyl group significantly enhances the activity. This indicates that the glycosidic linkage in ursane-type triterpenoids has mainly negative effect on cytotoxicity unlike in oleanane-type glycosides.

Antibacterial activities of the extracts and conessine from Holarrhena floribunda G. Don. (Apocynaceae).

The methanolic extract and conessine isolated from the stem bark of Holarrhena floribunda (Hf) were tested for their antibacterial activities on Bacillus: Bacillus cereus, Bacillus subtilis, Bacillus megaterium and Bacillus stearothermophilus using the disc diffusion method. Phytochemical analysis of the crude extract and fractions was also conducted. The inhibition parameters of the crude methanol extract and the total alkaloid fraction were determined using the macrodilution method. The results showed that the crude extract, the total alkaloid fraction and conessine exhibited a significant antibacterial effect against all the strains studied. The antibacterial effect of conessine is almost similar to that of chloramphenicol used as reference. The ratio of the minimal bactericidal concentration (MBC) over the minimal inhibitive concentration (MIC) indicates the bactericidal effect of the plant. These results support common use of stem bark of Hf and conessine isolated from Hf in the treatment of some infectious diseases.

Quinovic acid glycosides from Mitragyna stipulosa--first examples of natural inhibitors of snake venom phosphodiesterase I.

Phytochemical investigations on the non-alkaloidal extracts of Mitragyna stipulosa bark has led to the isolation of a series of triterpenoids mainly consisting of quinovic acid ([structure: see text]) and its glycoside derivatives [structure: see text] and [structure: see text]. The other constituents isolated include alpha-amyrin, 3beta-acetyl ursolic acid and a mixture of oleanolic and ursolic acid and beta-sitosterol glucopyranoside. Their structures were identified by spectral and chemical studies and compounds [structure: see text] and [structure: see text] were, respectively, identified as quinovic acid 3-O-[beta-D-glucopyranoside] (quinovin glycoside C) and quinovic acid 3-O-[beta-D-quinovopyranoside]-27-O-[beta-D-glucopyranosyl] ester. Compounds [structure: see text] and [structure: see text] showed significant inhibitory activity against snake venom phosphodiesterase I.

Triterpenes from Maesopsis eminii.

Two pentacyclic triterpenes, 1alpha,3beta-dihydroxybauer-7-en-28-oic acid (1) and 3beta-hydroxybauer-7-en-28-oic acid (2), together with sitosterol-3-beta-O-d-glucopyranoside and stigmasterol have been isolated from the bark of the plant Maesopsis eminii. Their structures have been elucidated by spectroscopic methods. One of the triterpenes (1) is new, and its structure was confirmed by X-ray crystallographic analysis. This new triterpene displayed moderate antibacterial activity against Bacillus subtilis ATCC 6633.

Saponins from Cussonia bancoensis and their inhibitory effects on nitric oxide production.

Two new triterpenoid saponins (1 and 2) were isolated from the stem bark of Cussonia bancoensis together with the known stigmasterol, ursolic acid, 23-hydroxyursolic acid (3), and 3beta-hydroxylup-20(29)-en-28-oic acid. On the basis of their spectroscopic data and on chemical transformations, the structures of the new saponins have been established as 3-O-(alpha-Ll-arabinopyranosyl)-23-hydroxyursolic acid (1) and 3-O-(beta-D-glucopyranosyl)-23-hydroxyursolic acid (2). In a nitric oxide (NO)-production bioassay, compound 3 exhibited significant NO inhibitory activity, while compounds 1 and 2 were less potent than 3.