Antifilarial efficacy of Hibiscus sabdariffa on lymphatic filarial parasite Brugia malayi

Human lymphatic filariasis, a vector borne debilitating disease is widely prevalent in tropical and subtropical regions of the world and imposes a significant public health and economic burden. Despite global efforts towards elimination of the disease by treatment with existing drugs, diethylcarbamazine (DEC), ivermectin and albendazole and their combinations, the disease is continuing. There is therefore a need for more effective therapeutic alternatives. In the present study, we evaluated antifilarial activity of ethanolic extract of leaves of plant Hibiscus sabdariffa by studying in vitro motility and MTT reduction assays employing microfilariae (mf) and adult worms of human lymphatic filarial parasite, Brugia malayi in B. malayi-jird and B. malayi-Mastomys coucha models. The leaf-extract affected both adult worms and microfilariae in vitro. Out of four fractions, n-butanol insoluble fraction killed mf at 250 mu g/ml conc in vitro. Extract and its n-butanol insoluble fraction showed reasonably high selectivity index with respect to motility of mf (10 to > 20). In B. malayi-jird model the leaf-extract at 500 mg/kg, p.o. x 5 days produced about 30% macrofilaricidal efficacy and 42% sterilization of female worms. In B. malayi/M. coucha the extract (1 g/kg, p.o. x 5 days) exerted 57.0% macrofilaricidal with 64% sterilizing effect on female worms. HPLC profile showed nine components in the n-butanol insoluble fraction. The components eluting at 26.7 and 28.4 min seemed to be the major components present in the fraction. NMR spectra (DQF-COSY, gHSQC, and gHMBC) of the fraction also displayed characteristic peaks of anthocyanin-glycosides. Thus, it is concluded that the plant may provide valuable leads for developing potent macro- and or microfilaricidal agent(s). This is the first ever report on the antifilarial efficacy of H. sabdariffa.