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Pauridiantha paucinervis var. Lyalli (Rubiaceae)[1][2] is a plant abounding in alkaloid compounds[3] of which the quinoline derivatives are the majority. An alkaloid quinoline has been isolated for the first time of this plant. The chemical formula of this compound is C26H30N2O9 while its mass is M = 514. This plant can be found and bought everywhere at the markets and at the herbalists on the island. It is a widely known plant of the Malagasy traditional medicine. The structure has been clarified by analyses of its NMR 1D and 2D as well as ESI-MS (coupled with HPLC) spectral data. The test with the DDPH reagent on a thin layer of silica gel chromatogram revealed that the isolated substance has antioxidant activity [4]-[8].

New cardenolide glycoside 1 and steroid glycoside 2, named respectively corotoxigenin-3-O-β- digitalopyranosyl-(1–4)-O-β-digitoxopyanoside and 5∆-pregnene-3β,16α,20(S)-diol 20-O-[β-Ddigitalopyranosyl (1→2)-β-D-glucopyranoside], have been isolated from the leaves of Alafia sp. (Apocynaceae). Compound 2 was isolated for the first time in its natural state, together with the known compounds digitoxin, corotoxigenin, and β-sitosteryl-3-O-β-D-glycopyranoside. The structures of compounds 1 and 2 were elucidated through spectroscopic techniques and chemical methods.

A new gentisic acid derivative named micronyc acid (1) and a new 1,4-benzoquinone derivative named micronone (2) have been isolated from the root of Micronychia tsiramiramy together with the known compounds gallic acid (3), methyl gallate (4), moronic acid (5), masticadienolic acid (6), and masticadienediol (7). The structures of 1 and 2 were established using MS and NMR. Compound 1 was tested for antiplasmodial activity in vitro against the chloroquine-resistant strain Plasmodium falciparum W2 and displayed moderate antiplasmodial activity in vitro with an IC50 value of 25.6 μ m. Compounds 1 and its acetyl derivative 1a were also tested for their cytotoxicity against the human cervix carcinoma cell line KB-3-1 and still showed moderate activity.

In addition to lupeol (1a), three long-chain alkanoic acid esters of lupeol, in which two were new, were isolated from the hexane and ethyl acetate twigs extract of Dorstenia harmsiana Engl. (Moraceae). The structures of the new compounds were elucidated on the basis of 1D and 2D NMR experiments. Some isolated compounds were evaluated for their antimicrobial activities. The lupeol and its three long-chain alkanoic acid esters showed antifungal and antibacterial activities.

A new flavonol glycoside, 3′-(4′''-(3′''',4′'''-dihydroxyphenoxy)-2′''-hydroxyphenoxy)acanthophorin B (1a) together with 3′-(2′'',4′''-dihydroxyphenoxy)acanthophorin B (1), acanthophorin B (2), vismiaquinone (3), rheochrysidin (3a), lupeol acetate and fatty acid were isolated from the chloroform extract of the stem bark of Psorospermum androsaemifolium Baker (Clusiaceae). The structure of 1a was determined on the basis of detailed spectroscopic analysis and comparison with the literature. Compounds 1a and 3a showed moderate antimicrobial activity.

This study was designed to evaluate the antimycobacterial, antibacterial and antifungal activities of the methanol extract from the stem bark of Thecacoris annobonae Pax & K. Hoffm, that of aristolochic acid I (1) and other isolated compounds. The microplate alamar blue assay (MABA) and the broth microdilution method were used to determine the minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of the above samples. The H+-ATPase-mediated proton pumping assay was used to evaluate a possible mechanism of action for both the methanol extract and aristolochic acid I. The results of the MIC determinations showed that the methanol extract and aristolochic acid I prevent the growth of all studied organisms. The results obtained in this study also showed that the methanol extract as well as aristolochic acid I inhibited the H+-ATPase activity. The overall results provided evidence that the methanol extract of T. annobonae might be a potential source of new antimicrobial drug against tuberculosis, and some bacterial and fungal diseases, but should be consumed with caution, bearing in mind that the main active component, aristolochic acid I is a potentially toxic compound.

A new flavonol glycoside (I) is isolated from the stem bark of the endemic Madagascan plant P.

Two new flavonoid glycosides, namely 3'-(2'',4''-dihydroxybenzyloxy)acanthophorin B (1b) and beta,2,3',4,4',6-hexahydroxy-alpha-(alpha-L-rhamnopyranosyl)dihydrochalcone (2) were isolated from the leaves of Psorospermum androsaemifolium together with quercetin (1), acanthophorin B (1a), alpha- (3) and beta-amyrine (3a), vismiaquinone (4), 12-hentriacontanol and hentriacontane. The structures of these secondary metabolites were established using detailed spectroscopic analysis and by comparison with published data. Compounds 1, 1a, 1b, 2, 3, 3a and 4 showed weak antifungal and antibacterial activities.

Two new flavonoid glycosides, namely 3'-(2'',4''-dihydroxybenzyloxy)acanthophorin B (1b) and beta,2,3',4,4',6-hexahydroxy-alpha-(alpha-L-rhamnopyranosyl)dihydrochalcone (2) were isolated from the leaves of Psorospermum androsaemifolium together with quercetin (1), acanthophorin B (1a), alpha- (3) and beta-amyrine (3a), vismiaquinone (4), 12-hentriacontanol and hentriacontane. The structures of these secondary metabolites were established using detailed spectroscopic analysis and by comparison with published data. Compounds 1, 1a, 1b, 2, 3, 3a and 4 showed weak antifungal and antibacterial activities.