First report of compounds from an Ancistrocarpus species: Triterpenoids from A. densispinosus Oliv. (Malvaceae).

The stem bark of Ancistrocarpus densispinosus Oliv. exhibited triterpenoids, including the rare fernane-type, fern-9(11)-ene-2α,3ß-diol (1) a possible chemotaxonomically distinct biomolecule for the genus. Other triterpenoids that were isolated from this plant include the ursane-type ursolic acid (2) and corosolic acid (3), friedelane-type friedelin (4) and canophyllol (5), lupane-type lupeol (6), betulin (7), betulinic acid (8) and hennadiol (9), oleanoic acid (10), maslinic acid (11) and taraxerol (12) and three sterols. This is the first report of the chemistry of a plant of the Ancistrocarpus. The structures of the compounds were elucidated based on their NMR, IR and MS techniques and by comparisons of their experimental data with those reported. The twelve triterpenoids 1-12 were found to be inactive against five bacterial strains Escherichia coli, Bacillus subtilis, Pseudomonas agarici, Micrococcus luteus and Staphylococcus warneri; inactive against KB-3-1 cervix carcinoma cancer cell line and inactive as antioxidants in the DPPH assay.

Characterization of secondary metabolites from the berries of Ziziphus mucronata and their antioxidant properties.

Ziziphus mucronata is a medicinal plant used traditionally for treating various diseases. The antioxidant assay for the crude extracts obtained from the berries of Ziziphus mucronata was carried out using DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Purified antioxidant compounds were obtained by chromatographic methods and were subjected to structure elucidation using nuclear magnetic resonance (NMR). Berries of Ziziphus mucronata were found to have high antioxidant activity since their ethyl acetate extract had an IC50 value of 214.9 µg/mL and methanol extract had an IC50 value of 8.9 µg/mL showing significant antioxidant activity in comparison to that of the standard ascorbic acid, which was found to have an IC50 value of 1.5 µg/mL. Betulin, betulinic acid and ursolic acid were among the compounds isolated from the berries of Ziziphus mucronata and are known to possess significant antioxidant activity. They have not been known to be previously isolated from Ziziphus mucronata.

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.