A phytochemical investigation of the acetone extract from the immature fruits of Garcinia cowa led to the isolation of two novel tetraoxygenated xanthones, garcicowanones A (1) and B (2), together with eight known tetraoxygeanted xanthones. Their structures were determined by spectroscopic analysis. All isolated compounds were evaluated for their antibacterial activity against Bacillus cereus TISTR 688, Bacillus subtilis TISTR 008, Micrococcus luteus TISTR 884, Staphylococcus aureus TISTR 1466, Escherichia coli TISTR 780, Pseudomonas aeruginosa TISTR 781, Salmonella typhimurium TISTR 292 and Staphylococcus epidermidis ATCC 12228. α-Mangostin showed potent activity (MIC 0.25-1 μg/mL) against three Gram-positive strains and garcicowanone A and β-mangostin exhibited strong antibacterial activity against B. cereus with the same MIC values of 0.25 μg/mL.

The chemical study of leaf extracts from Uvaria cherrevensis resulted in the identification of 11 new polyoxygenated cyclohexenes, cherrevenols A–K (1–11), and a new seco-cyclohexene derivative, cherrevenol L (12). Nine known compounds (13–21) were also isolated. Three of the isolated compounds are chlorinated polyoxygenated cyclohexenes. The structures of these compounds were determined using spectroscopic methods and, in some cases (compounds 2, 6, 8, and 10), single-crystal X-ray crystallographic structural analysis or chemical correlation (compounds 6 and 7). Compounds 6 and 7 were both isolated as scalemic mixtures (ee 23–24%).

Three new 2-phenylnaphthalene derivatives, cherrevenaphthalenes A-C (1-3), and a new polyoxygenated cyclohexene derivative, (-)-uvaribonol F (4) together with six known compounds, 5-10, were isolated from the stem and root extracts of Uvaria cherrevensis (Annonaceae). The structures of all isolated compounds were elucidated by spectroscopic analysis. The structures of 3 and 4 were further confirmed by single crystal X-ray diffraction methods. Compound 2 exhibited modest antiplasmodial activity against the P. falciparum stains TM4/8.2 and K1CB1 with IC values of 18.8±3.63 and 23.4±4.08μM, respectively, and weak cytotoxicity to a Vero cell line. Furthermore, compound 4 displayed cytotoxic activity against a KB cell line with an IC value of 22.1±0.42μM but was non-cytotoxic to the Vero cell line. Compound 5 revealed stronger cytotoxicity towards the KB cell line, with an IC value of 5.05±0.86μM and was nearly equally cytotoxic to the Vero cell line.

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The phytochemical investigation of the fruit extracts of Uvaria cherrevensis led to the isolation and characterization of four new C-benzyl flavonoids; cherrevenones A-D (1-4) together with 11 known compounds. The isolated compounds were characterized using spectroscopic techniques. Compounds 1, 3, 5 and 11 showed moderate inhibitory activities against the P. falciparum strains TM4/8.2 and K1CB1 with IC values ranging from 21.0 ± 3.10 - 33.7 ± 7.69 and 21.0 ± 5.44 - 43.5 ± 11.9 μM, respectively. Compounds 1, 2, 5, 10 and 11 exhibited strong cytotoxic activities against KB cells with IC values ranging from 0.60 ± 0.17 - 4.91 ± 2.69 μM which were similar to their cytotoxic activities found against Vero cells, except for compound 5, which was non-toxic to Vero cells.

The phytochemical investigation of the flower and twig extracts of Garcinia mckeaniana yielded a new xanthone, mckeanianone F (1) and a new biphenyl, mckeaniabiphenyl (2) together with 15 known compounds. The isolated compounds were characterized using spectroscopic techniques and mass spectrometry. Some of the isolated compounds from the twigs exhibited antimalarial and cytotoxic activities.

Two novel carbazole alkaloids, guillauminines A and B (1 and 2), and sixteen known compounds were isolated and identified from the acetone extract of Clausena guillauminii roots. Their structures were elucidated by spectroscopic methods. The cytotoxic, antimalarial and antimycobacterial activities of the isolated compounds were evaluated.

The reactions of α,β-unsaturated N-acyliminium ions, generated in situ from 4(S)-O-substitutedhydroxy-5-hydroxy-5-vinyl-N-alkylpyrrolidin-2-ones, with allylsilanes and indoles leading to the formation of spirocyclic heterocycles, are reported.