Essential oils obtained by hydrodistillation of dried fruits of Zanthoxylum xanthoxyloides and Z. leprieurii\ud (Rutaceae), were analysed by gas chromagraphy–flame ionization detection and gas chromatography–mass spectrometry. In the former, the major volatiles resulted citronellol (29.9%) and geraniol (11.5%), followed by citronellyl acetate (5.5%), limonene (5.5%) and citronellal (4.6%), while in the latter the major compounds were (E)-b-ocimene (29.4%), myrcene (28.6%), limonene (13.6%) and a-pinene (8.1%), respectively. The chemical composition supports the traditional use of these plants as spices in local food. The oils were also tested for antiproliferative, antimicrobial and antioxidant activities by MTT assay, agar disc diffusion method, and DPPH, ABTS and b-carotene–linoleic acid assay, respectively. The noteworthy cytotoxic effects of Z. xanthoxyloides are probably related to the presence of geraniol and citronellol, which exhibited strong antiproliferative activity against all the tested human tumor cell lines, and support the local traditional use of this plant for the treatment of various cancers

The chemical composition of the essential oils obtained from the seeds of bush onion (Afrostyrax lepidophyllus) and tropical garlic tree (Scorodophloeus zenkeri), plants used as spices in the traditional African cuisine, was determined by GC-FID and GC/MS analyses. Moreover, in vitro biological properties of the oils, namely, the cytotoxic, antioxidant, and antimicrobial activities, were investigated by the MTT, the DPPH(.) and ABTS(.+) scavenging, and the agar disc-diffusion methods, respectively. Both oils were composed mainly by S-containing compounds, accounting for 91.0-96.1% of the total oil compositions, which provided them the typical garlic- and onion-like odors of spices. The predominant compound in both oils, 2,4,5,7-tetrathiaoctane (1; 51.5-52.9%), was isolated by preparative TLC and structurally elucidated by (1) H- and (13) C-NMR data. The oils exhibited a strong inhibitory effect on the growth of human cancer cells, namely, T98G (human glioblastoma multiforme cell line), MDA-MB 231 (human breast adenocarcinoma cell line), A375 (human malignant melanoma cell line), and HCT116 (human colon carcinoma cell line) cells, and a good DPPH(.) - and ABTS(.+) -scavenging activity, while the antimicrobial effects were negligible. The volatile compositions of A. lepidophyllus and S. zenkeri oils supported their use as odorous spices. The significant inhibition activities detected make these oils worthy of further investigation as promising chemopreventive agents to be exploited in the African pharmaceutical market.

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Wild pepper (Piper capense L.f., Piperaceae) is a spice traditionally used in western Cameroon to make soups called 'Nkui' and 'Nah poh'. In the present work, the essential oil hydrodistilled from fruits was analyzed by GC-FID and GC-MS, and for in vitro biological activities, namely cytotoxic, antioxidant and antimicrobial, by MTT, DPPH, ABTS and agar disc diffusion methods. The oil composition was dominated by monoterpene hydrocarbons (56.5%) responsible for the pepper odor, such as β-pinene (33.2%), sabinene (10.0%) and α-pinene (8.9%). The oil induced a concentration-dependent inhibitory effect on human tumor cells MDA-MB 231 (breast adenocarcinoma), A375 (malignant melanoma) and HCT116 (colon carcinoma), showing IC 50 values of 26.3, 76.0 and 22.7 μg/ml, respectively. The oil showed total antioxidant activity with a Trolox equivalent antioxidant concentration (TEAC) value of 140 µmol/g. The essential oil of P. capense proved to be an effective scavenger of the ABTS + radical, with an activity only about 30 times lower than that of Trolox. Moderate activity was observed against the Gram-positive species Staphylococcos aureus and Enterococcus faecalis, and the yeast Candida albicans. The notable inhibition of some human tumor cells is worthy of further investigation to discover the possible mechanisms of action responsible for the observed cytotoxic effect of this essential oil.

Experiments were conducted in the laboratory to evaluate the bioefficacy of essential and vegetable oils of Zanthoxylum xanthoxyloides (Rutaceae) against Acanthoscelides obtectus (Coleoptera: Bruchidae). The chemical composition of the essential oil and the fatty acid composition of the vegetable oil extracted from the seeds of Z. xanthoxyloides were determined. The insecticidal activities of these oils and the associated aromatized clay powder were evaluated against A. obtectus. Both oils were strongly repellent (100% repellency at 0.501 μl/cm² essential oil and 3.144 μl/cm² vegetable oil) and highly toxic (LC₅₀ = 0.118 μl/cm² for essential oil) to this beetle after contact on filter paper. The vapors of the essential oil were highly toxic to adult insects (LC₅₀ = 0.044 μl/cm³), and the aromatized powder made from clay and essential oil was more toxic (LD₅₀ = 0.137 μl/g) than the essential oil alone (LD₅₀ = 0.193 μl/g) after 2 days of exposure on a common bean. Both oils greatly reduced the F₁ insect production and bean weight loss and did not adversely affect the bean seed viability. In general, the results obtained indicate that these plant oils can be used for control of A. obtectus in stored beans.