In vitro evaluation of the amebicidal activity of Buddleia cordata (Loganiaceae, HBK) on several strains of Acanthamoeba

Infectious diseases produced by free-living amoebae from the genus Acantham oeba have been recently recognized. The need for antiamebic compounds is ur gent as the occurrence of these diseases is being registered more frequentl y since the late sixties. We screened the aqueous and methanolic extract of a plant used by folk medicine (Buddleia cordata) against eye and skin infl ammation for antiamebic activity. We tested the extracts on 29 strains of f ree-living amoebae, with the result that they were amebostatic for 14 and 1 5 strains: respectively. We obtained linarin and vanillic acid from the ext racts, but only linarin was amebostatic to all the strains and vanillic aci d had no activity. However, acetyl vanillic acid had similar effects on amo ebae to linarin. Threshold values of these two active compounds ranged from 31.25 mu g/ml to 4 mg/ml and from 31.25 mu g/ml to 8 mg/ml for linarin and acetyl vanillic acid, respectively. These differences in threshold values were observed even on several strains belonging to the same species (as in the case of A. castellanii and A. polyphaga) indicating the need of suscept ibility testing for each clinical isolate of free-living amoebae. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.