Estrogenic activity of chemical constituents from Tephrosia candida.

In a continued investigation of medicinal plants from the genus Tephrosia, phytochemical analysis of a methylene chloride-methanol (1:1) extract of the air-dried aerial parts of Tephrosia candida afforded two new 8-prenylated flavonoids, namely, tephrocandidins A (1) and B (2), a new prenylated chalcone, candidachalcone (3), a new sesquiterpene (4), and a previously reported pea flavonoid phytoalexin, pisatin (5). The structures of 1-4 were established by spectroscopic methods, including HREIMS, and 1H, 13C, DEPT, HMQC, and HMBC NMR experiments. The most potent estrogenic activity of these isolated natural products in an estrogen receptor (ERα) competitive-binding assay was for 3, which exhibited an IC50 value of 80 µM, compared with 18 nM for the natural steroid 17ß-estradiol. Results were interpreted via virtual docking of isolated compounds to an ERα crystal structure.

C-Glucoside xanthone from the stem bark extract of Bersama engleriana.

BACKGROUND: The genus Bersama belongs to the Melianthaceae family and comprises of four species (B. swinnyi, B. yangambiensis, B. abyssinica, and B. engleriana) all of which are very high trees; the latter two detected species are found in Cameroon. Previous phytochemical investigation on B. yangambiensis, B. swinnyi, and B. abyssinica led to the isolation of triterpenes, saponins, flavonoids, and xanthones. METHOD: The stem bark of B. engleriana were collected in the village, Baham near Bafoussam city, Cameroon in August 2003 and identifi ed by Dr. Onana National Herbaruim, Yaoundι, Cameroon. The air dried and powdered stem bark of B. engleriana (1 kg) was extracted at room temperature with CH2Cl2-MeOH (1:1) 5 L for 48 hours. The mixture of the solvent was removed by evaporation to yield 200 g of crude extract. The latter was then dissolved in CH2Cl2 to give the CH2Cl2 soluble fraction of 5 g and a remaining gum of 195 g. Part of the remaining gum (22 g) was dissolved in water and extracted four times with butanol to give 12 g of red oil; which was then separated by paper chromatography, with butanol-acetic acid-water (4:1:5), to give 3 g of orange gum; purification was carried out on HPLC with MeOH (100%) to yield 2 g of mangiferin (1) as red oil. The CH2Cl2 soluble extract was eluted on silica gel n-hexane-CH2Cl2 gradient ratio and Sephadex LH-20 (n-hexane -CH2Cl2 -MeOH, (7:4:0.5) to afford compounds swinniol (2), Δ4-stigmaster-3ß-ol (3), 4-methylstigmaster-5,23-dien-3ß-ol(4). RESULTS: Herein, we carried out a phytochemical study of the stem bark of B. engleriana, and we report herein the isolation and structural elucidation of mangiferin, in addition to three triterpenes, previously reported from other species of the genus.[35] The assignment of the signals of mangiferin was determined using 1H, 13C-NMR, and 2D-NMR spectral data (HMQC, COSY, HMBC). The terpenoids were identifi ed by comparison of their 1H and 13C-NMR spectra with the literature data. Fractionation of the CH2Cl2-MeOH (1:1) extract of the stem bark of B. engleriana Guike gave mangiferin (1), in addition to three previously reported triterpenes, swinniol (2), Δ4-stigmaster-3ß-ol (3), and 4-methylstigmaster-5,23-dien-3-ß-ol (4). CONCLUSIONS: A chemical investigation of the CH2Cl2-MeOH extract of the stem bark of Bersama engleriana afforded a xanthone C-glucoside (mangiferin) and fi rst isolation of three terpenoids from this species: swinniol (2), Δ4-stigmaster-3ß-ol (3), and 4-methylstigmaster-5,23-dien-3-ß-ol (4). The complete 1H and 13C chemical shift assignments of mangiferin were determined using 1D and 2D NMR spectroscopic data (COSY, HMQC, HMBC, DEPT). The structures of the terpenoids were determined from their 1H and 13C NMR data and compared with the literature data.

Turrealabdane, turreanone and an antisalmonellal agent from Turraeanthus africanus.

Phytochemical investigation of the seeds of Turraeanthus africanus (Meliaceae), a Cameroonian plant species traditionally used in the treatment of typhoid fever, afforded eight compounds, including two labdanes, a C-arabinoside derivative, a sesquiterpene, and several triterpenes, two of which are new: 15',16'-dihydroxy-15(12'),15'(16')-diolidebislabd-8(17),8'(17'),12-trien-16-al ( 1), trivially named turrealabdane and a C-arabinoside derivative ( 2), trivially named turreanone. The other compounds are 12,15-epoxylabda-8(17),12,14-trien-16-acetate ( 3), (+)-eudesmanol- O-L-arabinoside, cyclolaudenol, stigmasterol, sitosterol glucoside and lupeol. Acetylation and oxidation of turrealabdane yielded 15',16'-diacetoxyturrealabdane and 15,12'-dioxoturrealabdane-15',16'-dial, respectively. Their structures were determined by means of spectroscopic data including 1D and 2D NMR in combination with MS. The compounds were evaluated for antibacterial activities, chloramphenicol and amoxicillin being used as standard. Compound 3 was the only active principle, possessing the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of respectively 25 microg/mL and 100 microg/mL against Salmonella typhi, S. paratyphi a and S. paratyphi B.This compound did not show any activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus.

Anti-cancer and immunostimulatory activity of chromones and other constituents from Cassia petersiana.

Phytochemical investigation of Cassia petersiana Bolle leaves afforded four new compounds, including two chromone derivatives, 7-acetonyl-5-hydroxy-2-methylchromone (petersinone 1, 1) and 7-(propan-2'-ol-l'-yl)-5-hydroxy-2-methylchromone (petersinone 2, 2), two benzoic acid derivatives, 5-methyl-3-(propan-2'-on-1'-yl) benzoic acid (petersinone 3, 3) and 5-(methoxymethyl)-3-(propan-2'-ol-1'-yl) benzoic acid (petersinone 4, 4), and glyceryl-1-tetracosanoate (6), in addition to the known compound sistosterol-3-beta-D-glycoside (5). The structures of these compounds were determined by comprehensive NMR studies, including DEPT, COSY, HMQC, HMBC, MS and IR. Compounds 1, 2, 5 and 6 were tested for antioxidant, anti-cancer and immunostimulatory properties. The biological investigations indicated that compound 6, among others, possessed the highest anti-cancer activity against hepatocellular carcinoma, immunoproliferative activity via induction of T-lymphocytes and macrophage proliferation, anti-inflammatory activity as indicated by NO inhibition, and antioxidant activity against DPPH radicals. Moreover, compound 5 was the most effective cytotoxic compound against breast carcinoma and stimulated a consistent immunoproliferative effect on lymphocytes and macrophages combined with strong NO inhibitory activity, while compound 1 was promising as immunoproliferative agent and may act as anti-inflammatory agent as a consequence of its NO inhibitory activity.