Chemical analysis and giardicidal effectiveness of the aqueous extract of Cymbopogon citratus Stapf.

Abstract

CcAE (25, 50, 100, 200, 400, and 500μg/ml) was in vitro incubated with G. lamblia trophozoites in comparison with metronidazole (MTZ 10 and 25μg/ml). Growth inhibition was evaluated after 3, 24, and 48h of drug exposure. Infected groups of mice were orally treated for 7days with CcAE at 125, 250, and 500mg/kg/day/mouse, in comparison with a group treated with 15mg/kg/day/mouse MTZ for the same period. The total phenolic components (TPC), the total flavonoid components (TFC), the 2,2,diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, and the high-performance liquid chromatography (HPLC) for quantitative and qualitative phenolic content were chemically estimated. After 24 and 48h of in vitro incubation, the estimated minimal inhibitory concentrations (MIC) were 500 and 400μg/ml, respectively, and the concentrations that induced 50% growth inhibition (IC50) were 93.8 and 60.4μg/ml, respectively (P < 0.001). Mice given 500mg/kg CcAE showed 100% stool clearance of G. lamblia stages, similar to MTZ-treated control group (P < 0.001). The TPC was 10.7 ± 0.2mg GAE/g and the TFC was 23.9 ± 0.3mg quercetin/g, and the estimated IC50 for DPPH free radical scavenging was 16.4 ± 0.1mg/ml. HPLC revealed the major phenolic components of CcAE to be carnosic acid, p-coumaric acid, cinnamiac acid, quercetin, rutin, and chlorogenic acid. In conclusion, CcAE is significantly effective against G. lamblia in vitro and in vivo, and has considerable phenolic and antioxidant properties.