野生チンパンジーの薬用的植物利用に関する化学生態学的研究: Vernonia amygdalina を例に

抄録

Vernonia amygdalina (Compositae) has been suggested to be a medicinal plant used by wild chimpanzee in the Mahale Moutains National Park, Tanzania. From this plant, the bitter and related constituents were isolated. There were four known sesquiterpene lactones, and seven new steroid glucosides and two aglycones of these glucosides. The sesquiterpene lactones showed high cytotoxic activity against P-388 and L-1210 cells, and antibacterial activities against Bacillus subtilis and Micrococcus lutea. They also showed significant in vitro antischistosomal, plasmodicidal and leishmanicidal activities. Antischistosomal activity was also found in the major steroid glucoside, vernonioside B₁. A trend in the glucosides was observed for significant antischistosomal, plasmodicidal and amoebicidal activities when the sugar moiety was removed. Vernodalin, the most significant antiparasitic constituent in vitro, was tested for in vivo antischistosomal effect. However, vernodalin is highly toxic to the cercaria-infected mouse, and no effect was observed when orally administrated at below the lethal dose (2.5mg/mouse). Chimpanzees have been only rarely observed to ingest anything but the pith of the young stem. The occurrence of vernonioside B₁ and its aglycone vernoniol B₁, the major constituents among the steroid- related constituents, were detected at significant levels in the pith. However, vernodalin was abundant only in the leaves and bark. Thus, chimpanzees at Mahale were hypothesized to control parasite-related diseases by ingesting the young pith of this tree containing steroid-related constituents.