Bioactive phytochemicals from African savanna woodland

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Tropical African forest is the one of the most interesting spots in the world from the atandpoint of bioactive natural product research. It is rich in plant species which are adaptive in a coevolution with regard not only to climatic factors but also to complex biological interactions. For such adaptation, a chemical defense system may be one pssible strategy. Thus, we have surveyed useful plants of the savanna woodland of Tanzania, and chemically studied their bioactive constituents as well as the biological or physiological significance. The main survey was conducted on Oct.27th - Oct.22nd at the Mahale Moutains National Park located along Lake Tanganyika in Tanzania, where Dr.Nishida (Kyoto Univ.) and his colleagues have carried out the chimpanzee socioecological study for a long time. We had already listed up some plants of biological and physiological significance, on the basis of the results from the previous survey conducted here in 1991. Also we could well select chimpanzee med … More icinal plants in kind cooperation with Dr.Nishida. Furthermore, we tried to collect informations of tradirional plant-use from native people.We have collected a total of 19 plant species including 12 species of chimpanzee medicinal plant, 3 species of medicinal plant locally used. Among the plants collected, 16 species have thus far identified.Each extract has been tested for several biological activities, e.g.antiparasitic activities including antischistosomal, antimalarial, and antimoebic activities, several enzyme inhibition activities, cyte toxic activities, antibiotic activities against insects and microbials, and active oxygene generation inhibition or scavenging activities. Antiparasitic activities were found in 10 species of plant, and 9 out of these 10 were those collected as chimpanzee medicila plant. Thus, chimpanzee in the wild may often use some plants as antiparasitic medicine. In particular, strong antischistosomal activities were found in Erythrina abyssinica, Trema orientalis, Stephania abyssinica, Combretum molle and Vernonia amygdalina. In E.abyssinica and Aspilia mossambicensis, antimalarial activity was clearly detected, and antiamoebic activity was also in E.abyssinica. From V.amygdalina which we have hitherto extensively studied the antiparasitic agents, new steroids were isolated. The antiparasitic activities of these steroids are now in progress. E.abyssinica and Senna spectabilis showed inhibitory activity of aromatase, Senna spectabilis and S.abyssinica inhibited superoxide anion genaration, and T.orientalis showed insect antifeedant activity. Less