IN VITRO AND IN VIVO ANTIAMOEBIC ACTIVITY AND PHYTOCHEMICAL SCREENING OF SENNA DIDYMOBOTRYA (FRESEN) IRWIN CRUDE ROOT EXTRACTS

Abstract

Amoebiasis is a disease of global importance, caused by the eukaryotic parasite Entamoeba histolytica. It is the common worldwide cause of mortality from a protozoon after malaria. It is an important health problem, especially in developing countries and highly endemic throughout poor and socio-economically deprived communities in the tropics and subtropics. The most commonly used drug for treatment is metronidazole. However, this drug has been reported to cause mutagenicity in bacteria and is carcinogenic in rodents, with some side effects including metallic taste, nausea, transient neutropenia, interaction with warfarin and peripheral neuropathy. Interactions with alcohol may reduce the level of patient compliance. In addition, amoebae may develop resistance to metronidazole. There is need to investigate substances of natural origin to find new antiamoebic compounds that are effective, safe and affordable. This study, evaluated the in vitro and in vivo antiamoebic activities and toxicity of crude root extracts of Senna didymobotrya and their phytochemical constituents, a plant that is currently used by traditional healers to treat diarrhoea and dysentery in Kenya. The roots were obtained from Bomet County, Kenya where the “Kipsigis” traditional healers have been using the roots to treat diarrhoea. This study also determined the cytotoxicity of the root extracts in mammalian cells and found that the ethyl acetate crude root extract was less toxic while in experimental BALB/c mice the methanol total and dichloromethane crude root extracts were the most toxic with an LD50 of 1927mg/kg each. In addition, in vitro and in vivo bioassays of crude root extracts of Senna didymobotrya were performed in order to determine their antiamoebic activities in comparison with metronidazole. The methanol total crude root extract compared favourably well with metronidazole (ρ>0.05). There was a significant difference in effectiveness between the different types of crude root extracts with methanol total being the most active crude root extract (p<0.05). There was also a significant difference between the different concentrations with the 1000µg/ml being the most active concentration (ρ <0.05). The bioactive compounds were determined by phytochemical screening using standard procedures and Senna didymobotrya was found to contain steroids, terpenoids, anthraquinones, tannins, saponins, glycosides, alkaloids and phenols. The classes of compounds found to exhibit antiamoebic activity against Entamoeba histolytica trophozoites were terpenoids, tannins, saponins, glycosides, alkaloids and phenols. However, some in vivo studies with regards to their effects on human also need to be investigated