Abstract

In tropical Africa, protozoan parasites cause several diseases of social and economic importance. Trypanosomiasis, an infection caused by trypanosomes, has affected agricultural development on over a third of the African continent by causing livestock production losses due to weight loss, stunted growth, poor milk production, reproductive failure and death. The efficacy of quercetin and its modified products (quercetin-5-sulphonic acid and quercetin-8-sulphonic acid) were screened for in vitro and in vivo antitrypanosomal activity in mice. In the in vitro studies, blood (20 μl) containing about 20-25 parasites per field after dilution with Phosphate Buffer Saline Glucose solution, was mixed with 5 μl of all the sample solutions at test concentrations of 20, 10 and 5 mg/ml, respectively, while in the in vivo studies, quercetin and its modified compounds were administered to Trypanosoma brucei brucei infected mice after the establishment of parasitemia. The animals grouped into 9 of 3 mice each were treated orally at different dose levels for 7 consecutive days. Groups A and B (Quercetin-8-sulphonic acid 10 and 20 mg/kg bodyweight respectively), Groups C and D (Quercetin-5-sulphonic acid 10 and 20 mg/kg bodyweight respectively), Groups E and F (Quercetin 10 and 20 mg/kg bodyweight respectively), Group G (Standard control, Infected and treated with Diminazine aceturate), Group H (Negative control, infected untreated), Group I (Normal control; uninfected, untreated). Result showed that in in vitro analysis, quercetin-8-sulphonic acid exhibited complete cessation of motility of Trypanosoma brucei brucei within 120 minutes at both concentrations of 10 and 20 mg/ml with the infectivity test at 10 mg/ml bodyweight having the highest survival days after 35 days, when compared to that of Berenil control at both concentration 20 mg/ml bodyweight for 15 days. Similarly, the in vivo analysis showed that quercetin-8-sulphonic acid gave the highest prolongation of life by 9 days when compared to quercetin-5-sulphonic acid of 5 days at 10 mg/kg bodyweight (p < 0.05). Consequently, these studies therefore provide scientific evidence that the modified quercetin compound could be beneficial in the management of trypanosomiasis.

Key words: Trypanosomiasis, Quercetin-5-sulphonic acid, Quercetin-8-sulphonic acid, Parasitemia, Quercetin