In this study the in vitro antiplasmodial activities of extracts from Cussonia spicata (Araliaceae), Artemisia afra, Vernonia colorata, V. natalensis (Asteraceae), Parinari curatellifolia (Chrysobalanaceae), Clutia hirsuta, Flueggea virosa, (Euphorbiaceae), Adenia gummifera (Passifloraceae) and Hymenodictyon floribundum, (Rubiaceae) were evaluated. The lipophilic extracts from the aerial parts of Artemisia afra and Vernonia colorata proved to be the most active against the chloroquine-sensitive strain PoW and against the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Bioassay-guided fractionation of the extract of A. afra yielded seven flavonoids, from which acacetin, genkwanin and 7-methoxyacacetin showed in vitro activity; the IC(50) values ranged from 4.3 microgram/mL to 12.6 microgram/mL. In addition, several sesquiterpene lactones could be obtained from the most active fractions. Whereas eudesmaafraglaucolide proved to be inactive, the guaianolides 1-desoxy-1alpha-peroxy-rupicolin A-8-O-acetate, 1alpha,4alpha-dihydroxybishopsolicepolide and rupicolin A-8-O-acetate revealed in vitro antiplasmodial activity. Evaluation of V. colorata gained four sesquiterpenes 11beta,13-dihydrovernodalin, vernodalol, 11beta,13-dihydrovernolide and 11beta,13,17,18-tetrahydrovernolide, from which the first two constituents exhibited the strongest antiplasmodial activity (IC(50) values: 1.1-4.8 microgram/mL).

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The dichloromethane extract of the leaves of Myrica serrata inhibits growth of Cladosporium cucumerinum, Bacillus subtilis, and Escherichia coli on TLC plates. Activity-guided fractionation led the isolation of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (1), 2',4'-dihydroxy-6'-methoxy-5'-methylchalcone (aurentiacin A) (2), 2',6'-dihydroxy-4'-methoxy-3',5'-dimethyldihydrochalcone (3), 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (4), and 2', 6'-dihydroxy-4'-methoxy-3'-methyldihydrochalcone (5). In addition, the flavanones demethoxymatteucinol (6) and cryptostrobin (7) were also identified.

The CH,CI, extract of Monores engleri GILG. (Dipterocarpaceae) showed antifungal activity against the yeast Cundidu u1bicun.s in our bioautographic TLC assays. After a first fractionation of the crude extract, the bioactivity was located in one of the fractions.

Steam-distilled volatile oil from Artemisia ajira Jacq. (family Compositae), indigenous to the mountainous regions in southern Africa and used in popular medicine, was analysed by gas chromatography and tested for antimicrobial and antioxidative properties. The main components of the volatile oil were a-and /I-thujone (52%), 1,8-cineole (13 "/,), camphor (15 %) and a-pinene (2 %). Twenty-five bacterial species and three filamentous fungi were used to assess the antimicrobial properties. Fifteen test bacteria and one fungus showed high degree of inhibition of growth caused by the volatile oil. The most susceptible organisms were Acinetobacter calcoaceficus, Beneckea nafriegens, Breuibacferium linens, Brochothrix fhermosphacta, Citrobacter jiieundii, Klebsiella pneumoniae and Serratia marcescens. The oil exerted considerable antioxidative effect.

Using the standard assay on irritant activity testing (4), the phorbol ester exhibited a highly irritant activity on the mouse ear (ID = 0.05 pg/ear). Since skin irritancy is an indication of possible tumor promotion, the use of this plant as a medicine should be discouraged.

Activity-guided isolation of radical-scavenging compounds from the dichloromethane extract of the root bark of Lannea edulis led to isolation of two known bioactive alkylphenols [cardonol 7 (1) and cardonol 13 (2)], and three new dihydroalkylhexenones were also isolated (3-5). Their structures were elucidated by spectroscopic and chemical methods. The absolute configuration of 4 was determined by the Mosher ester method.

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