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Phytochemical investigation of an ethyl-acetate extract of the stem bark of Markhamia tomentosa (Bignoniaceae), which had good antimalarial activity in vitro, resulted in the isolation of eight known compounds: 2-acetylnaphtho[2,3-b]furan-4,9-dione (1), 2-acetyl-6-methoxynaphtho[2,3-b]furan-4,9-dione (2), oleanolic acid (3), pomolic acid (4), 3-acetylpomolic acid (5), tormentic acid (6), beta-sitosterol (7) and beta-sitosterol-3-O-beta-D-glucopyranoside (8). The structures of these compounds were established by spectroscopic methods. Each of compounds 1, 2, 4 and 5 was evaluated in vitro for its antiprotozoal activities against the ring stages of two chloroquine-resistant strains of Plasmodium falciparum (K1 and W2), the amastigotes of Leishmania donovani, and the bloodstream trypomastigotes of Trypanosoma brucei rhodesiense (the species responsible for human malaria, visceral leishmaniasis and African trypanosomiasis, respectively). Although compounds 1 and 2 exhibited potent antiprotozoal activities, they also showed high toxicity against a mammalian (L-6) cell line.

The chemical composition of the essential oils obtained by hydrodistillation of fresh leaves from Hyptis lanceolata, H. pectinata, H. spicigera and H. suaveolens growing in Cameroon were analysed by GC and GC–MS. The oil of H. suaveolens was rich in sabinene (20.6%), β‐caryophyllene (17.5%) and bergamotol (10.9%), while the oil of H. pectinata contained germacrene D (28.0%) and β‐caryophyllene (22.1%) as the major constituents. H. spicigera oil contained α‐pinene (28.3%), β‐caryophyllene (19.1%), limonene (13.4%) and ß‐pinene (10.3%) as the main components. The most abundant constituents identified in the oil of H. lanceolata were β‐pinene (40.7%) and germacrene D (19.9%). These chemical profiles were compared with literature results; relative similarities were found in chemical compositions of each species, but some quantitative and qualitative variations were noted. Copyright © 2005 John Wiley & Sons, Ltd.

Phytochemical studies on the stem bark of Canthium subcordatum afforded eight known compounds: βsitosterol (1), ursolic acid (2), cerbinal (3), quinovic acid (4), Cerberinic acid (5), 3-O-β-Dglucopyranosylquinovic acid (6), 3-O-β-D-glucopyranosyloleanolic acid ( 7) and Clemahexapetoside B (8). Interestingly, 3, 5 and 8 were isolated and characterized for the first time from the genus Canthium. Their structures were elucidated using their physical and spectroscopic data. Furthermore, antiplasmodial potency of Canthium subcordatum and antimicrobial activities of 6, 5 and 8 has not yet been investigated. Fractions and isolates were tested for their antiplasmodial potency. Only the methanol fraction inhibited the growth of P. falciparum with an IC50 value of 3.044 µg/mL. The isolates were also tested against eight bacteria and fungi strains. 4 and 5 were the most active with inhibition diameter zones equal or above 12 mm and MIC equal or lower than 39 µg/mL.

The essential oils obtained from the leaves and stem bark of Uvariastrum pierreanum Engl. (Engl. & Diels) (Annonaceae), collected in Cameroon, were analysed by GC and GC-MS. The leaf oil was found to contain a majority of monoterpenes, with α-and β-pinenes (43.8%) as the major constituents, while the stem bark extract comprised sesquiterpenoids only. In this class of compounds, the leaf and stem bark oils were found to be qualitatively similar, with a predominance of bisabolane (35.9%) and bergamotane (23.9%)-type structures. None of these two samples revealed interesting antiradical activity.

The essential oils obtained from stem and root barks of Pseudocedrela kotschyi (Schweinf.) Harms (Meliaceae) collected in Cameroon were analysed by GC and GC-MS. The two samples were found to be composed exclusively of sesquiterpenoids. The hydrocarbons were found to be most abundant in the stem bark extract, with δ-cadinene (31.3%) as the main constituent, while the root bark oil contained a majority of oxygenated sesquiterpenoids, with cubebols representing almost one-third of the extract. The antioxidant and antiradical activities of both samples were found to be very low compared with those of the reference compounds. Experimental Plant Material and Extraction ProcedureThe stem and root barks of P. kotschyi were collected in Ngouantet II (80 km from Yaounde to the South, Cameroon) in October 1999. The plant samples were identified and a voucher specimen deposited at the National Herbarium, Yaounde.Air-dried barks were ground using a blender. Batches of 500 g of plant material were submitted to hydrodistillation for 3 h using a Clevenger-type apparatus. The resulting essential oils were dried after decantation over anhydrous sodium sulphate. Analysis Gas ChromatographyThe oils were analysed on a Varian CP-3380 GC with flame ionization detectors fitted with a fused silica capillary column (30 m × 0.25 mm i.d. coated with DB1, film thickness 0.25 µm); temperature programme 50-200°C at 5°C/min, injector temperature 220°C, detector temperature 250°C, carrier gas N 2 at 0.8 ml/min. The linear retention indices of the components were determined relative to the retention times of a series of

Nine essential oils were isolated from five Annonaceae species growing in Cameroon. The samples were analysed by GC and GC-MS. The volatile oils obtained from seeds of Monodora myrisfica (Gaertn.) Dunal and Monodora brevipes Benth., those from leaves and fruits of Annona senegalensis. Pers. var. senegalensis and that from fruits of Cunangu odorata (Lam.) Hook. Fil. et Thorns. were mainly monoterpenic, the major components being a-phellandrene or sabinene and mycrene. The leaf essential oil of M. brevipes contained approximately equal amounts of monoterpenes and sesquiterpenes, with two major components with an acyclic structure: (Z)-pocimene and (E),(E) a-famesene. Finally, the oils from leaves of M. myristica, Annona muricafa L. and C. odorata contained mostly sesquiterpenes, the major constituent being p-caryophyllene.

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