In vivo and in vitro effects of extracts from Cassia aubrevillei in onchocerciasis.

A traditional herbal drug, called "Ganna Ganna", is used in rural areas of Liberia to treat onchocerciasis. It is prepared from the bark of the "Ganna Ganna" tree, which was identified as Cassia aubrevillei. An aqueous extract was prepared from the bark according to informations from local people and its effects on microfilaria (mf) density and pruritus were studied in eleven patients with onchocerciasis. In four patients a 1.8-4.8 fold increase in mf density was observed after three weeks and in two patients mf counts dropped to almost zero. Histology and embryogram of adult worms, isolated after treatment, revealed no significant changes. All patients reported a rapid decline of pruritus and this effect lasted for up to three months. The in vitro effect of different extracts on mf viability was tested. The alcoholic extract gave the best results, killing mf within 24 h at concentrations of 50 micrograms/ml. Chrysophanic acid, an anthraquinone identified in the drug, also showed good in vitro microfilaricidal activity. It is concluded, that "Ganna Ganna" could be a useful adjuvant in the therapy of onchocerciasis and that further evaluation of the drug seems promising.