A triterpenoidal saponin and sphingolipids from Pteleopsis hylodendron.

From the stem bark of Pteleopsis hylodendron, a triterpenoidal saponin bellericagenin [B 3-O-[beta-D-glucopyranosyl-(1-->2)-alpha-D-glucopyranoside] (1) (Pteleopsoside)] and two sphingolipids, hylodendroside-I (2), and hylodendroside-II (3) were isolated, along with a synthetically known compound, [2alpha, 3beta, 23-triacetoxy-19alpha-hydroxyolean-12-en-28-oic acid (4)]. Other known compounds, friedelin (5), beta-carotene (6), lupeol (7), sitosterol (8), and stigmasterol (9), were also obtained. Their structures were deduced with the help of detailed spectroscopic studies.

Securidacaxanthone A, a heptaoxygenated xanthone from Securidaca longepedunculata.

From the root bark of Securidaca longepedunculata, a heptaoxygenated xanthone (1) has been isolated as well as two known xanthones (2) and (3) and two salicylic acid derivatives (4) and (5). The structure of 1 has been elucidated from 1H and 13C-NMR spectral data.

Antimicrobial activity of the methanolic extract from the stem bark of Tridesmostemon omphalocarpoides (Sapotaceae).

The methanolic extract and fractions from the stem bark of Tridesmostemon omphalocarpoides were investigated for their in vitro antimicrobial properties as well as their phytochemical constituents. The stem bark was collected from Yaoundé, in the Centre Province of Cameroon. The antimicrobial activity of the extract and fractions against two Candida species and seven aerobic bacteria was evaluated on the basis of the inhibition zones (IZ) using agar hole diffusion method, the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC) by the macrodilution method. The results indicated significant anticandidal and antibacterial effect of the methanolic extract and fractions against all the nine microorganisms tested. Preliminary phytochemical analysis of methanolic extract showed the presence of biologically active components namely alkaloids, steroids, tannins, saponins, phenols, polyphenols and flavonoids. The acute toxicity of the methanolic extract was also studied. This was found to be non-toxic to the inbred Wistar rats treated per os. The results of this study suggested that the stem bark of this plant could be safely used in the treatment of some infectious diseases.

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.

Bioactive constituents from Boswellia papyrifera.

Phytochemical investigation of the stem bark extract of Boswellia papyrifera afforded two new stilbene glycosides, trans-4',5-dihydroxy-3-methoxystilbene-5-O-{alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (1), trans-4',5-dihydroxy-3-methoxystilbene-5-O-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranoside (2), and a new triterpene, 3alpha-acetoxy-27-hydroxylup-20(29)-en-24-oic acid (3), along with five known compounds, 11-keto-beta-boswellic acid (4), beta-elemonic acid (7), 3alpha-acetoxy-11-keto-beta-boswellic acid (8), beta-boswellic acid (9), and beta-sitosterol (10). The stilbene glycosides exhibited significant inhibition of phosphodiesterase I and xanthine oxidase. The triterpenes (3-9) exhibited prolyl endopeptidase inhibitory activities.

New antioxidant and antimicrobial ellagic acid derivatives from Pteleopsis hylodendron.

Bioassay-guided isolation of two new compounds, 3,4-methylenedioxy-3'-O-methyl-4'-O-glucoside ellagic acid (1) and the pteleoellagic acid derivative (2), from the stem bark of Pteleopsis hylodendron is reported along with 3,4-methylenedioxy-3'-O-methyl ellagic acid (3), 3,3'-di-O-methyl ellagic acid (4) and 3,3',4'-tri-O-methyl ellagic acid (5), which were obtained for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic studies. Compounds 1 and 4 were found to have significant antioxidant activity, while compounds 1-4 showed antibacterial activity against different pathogenic bacteria.

New isoflavones from Ceiba pentandra.

Two new isoflavones, pentandrin (1) and pentandrin glucoside (2), were isolated from the stem barks of Ceiba pentandra along with beta-sitosterol and its 3-O-beta-D-glucopyranoside, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic techniques, while the structure of 1 was unambiguously confirmed by single-crystal X-ray diffraction studies.

Myrianthiphyllin, The First Lignan Cinnamate from Myrianthus arboreus.

Studies of the methylated ethyl acetate extract of the trunk wood of MYRIANTHUS ARBOREUS (Cec-ropiaceae) have resulted in the isolation of five known pentacyclic triterpenes and a new lignan cinnamate. The structural elucidation of the new compound has been effected on grounds of the interpretation of spectroscopic data and alkaline hydrolysis.