Chemical constituents from Ficus sur Forssk (Moraceae).

Phytochemical investigation of the aerial roots of Ficus sur, a Cameroonian medicinal plant, resulted in a previously undescribed cerebroside, suroside (1), in addition to its aglycon congener suramide (2). Moreover, six known natural products including alpinumisoflavone (3), wighteone metabolite (4), oleanolic acid (5), ß-sitosterol (6), ß-sitosterol-3-O-ß-D-glucopyranoside (7), and epi-ѱ-taraxastanolone (8) were identified. The structures of the previously undescribed compounds were determined by analysis of 1D and 2D-NMR (One and two dimensional nuclear magnetic resonance), mass spectrometry, chemical conversion, and by comparison of these data with those from the literature. Wighteone metabolite (4) exhibited a weak cytotoxic activity against the human HepG2 hepatocellular carcinoma cells with an IC50 value of 51.9 µM.

Bioactive constituents from Manilkara obovata (Sabine & G.Don) J.H.Hemsl.

The phytochemical investigation of the methanolic extracts of roots, stem bark, leaves and twigs of Manilkara obovata has led to the isolation of one new friedelane triterpene, lacefriedelic acid or 3ß,23-dihydroxy D:A-friedooleanan-28-oic acid (1) and one new prenylated xanthone, lacexanthone or 4,7-dihydroxy-2,3,3,9,9-pentamethyl-2,2-dihydrofurano[2,3-a]pyrano[2,3-i]xanthen-13(9H)-one (2) alongside twenty-four known compounds. Compounds 1-11 are reported here for the first time from the genus Manilkara. The structures of all compounds were determined by spectroscopic analyses and X-ray crystallography. The methanolic extracts of twigs and leaves showed anti-oxidant activity of 93.2 and 91.1%, respectively, at 100 µg/mL when measured by DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate), while the twig extract displayed 86.3% at 100 µg/mL against the urease inhibition assay. Some isolated compounds (1-4, 15 and 20) showed significant to moderate anti-oxidant activity and urease inhibition assay. It is estimated that significantly active anti-oxidants and urease inhibitors metabolized by the plant may find future application in food industry.

A rotameric tryptamide alkaloid from the roots of Vepris lecomteana (Pierre) Cheek & T. Heller (Rutaceae).

A rotameric tryptamide alkaloid (1a-1b) was isolated from the methanolic extract of the roots of Vepris lecomteana together with the known compounds anhydroevoxine (2), lecomtequinoline C (3), evoxine (4), N-methylflindersine (5), evoxanthine (6), hesperidin, lupeol, ß-sitosterol and stigmasterol. The previously not reported 7-(3-anilino-2-hydroxyprenyloxy)-8-methoxydictamine (2a) was obtained by opening the epoxide of anhydroevoxine (2). The structures of above compounds were determined by comprehensive spectroscopic analyses of 1D and 2D NMR, EI-/ESI-MS, X-ray crystallography and comparison with the reported data. At room temperature, 1H and 13C NMR spectra show two rotamers (1a and 1b) with integrated intensities of 2/3, whereas at around 60 °C, only the 1b conformer was observed. Furthermore, the crystal structure of 1 was determined by the direct method of single crystal X-ray diffraction. The suggested biosynthesis for the formation of the new rotameric tryptamide alkaloid 1 is presented. Some of the isolated compounds (1, 2 and 2a) were tested in vitro against bacteria, resulting in weak for (1 and 2) to moderate activity for (2a) against Micrococcus luteus and Escherichia coli with MIC values of 15.3 and 15.3 µg/mL, respectively.

Oxidative burst inhibition, cytotoxicity and antibacterial acriquinoline alkaloids from Citrus reticulate (Blanco).

Two novel acridone-quinoline alkaloids, acriquinoline A (1) and acriquinoline B (2), together with twenty-two known compounds were isolated from the methanol extract of the root of Citrus reticulata Blanco. The structures of all compounds were determined by comprehensive analyses of their 1D and 2D NMR and mass spectral (EI and ESI) data. The possible biosynthesis for the formation of above compounds is proposed, based on close examination of their structures. Compounds 1, 2, 6, 10 and 14-17 exhibited strong suppressive effect on phagocytosis response upon activation with serum opsonized zymosan in the range of IC50 0.2-10.5µM, which was tested in vitro for oxidative burst studies of whole blood. However, compounds displayed low cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3, with IC50 between 30.8 and 60.5µM compared to the standard doxorubicin with IC50 0.9µM. These compounds, tested against bacteria, fungi and plant pathogen oomycetes by the paper disk agar diffusion assay, resulting in missing to low activities corresponding with MICs>1mg/mL.

Alkaloids from Oriciopsis glaberrima Engl. (Rutaceae).

Two alkaloid derivatives, oriciacridone A and B, were isolated from the stem bark of Oriciopsis glaberrima (Rutaceae). The structures were elucidated by a detailed spectroscopic analysis. The extract exhibited in vitro significant antimicrobial activity against a range of micro-organisms.