An overview of some medicinal plants and isolated active compounds with potential antiprotozoal activity

Abstract

Diarrhoea associated illness presents with mortality and morbidity in rural communities in most low income countries especially in children < 5 years of age. The continuous emergence of several opportunistic infections in immuno-compromised individuals has worsened the burden of diarrhoea in most of these countries. Protozoan infections caused by species of Cryptosporidium, Entamoeba spp. Giardia intestinalis, Blastocystis hominis and Trichomonas vaginalis have received insufficient attention because data on their prevalence and incidence are scanty. The commonly used drugs to treat infections caused by these organisms are becoming less effective due to the development of drug resistance. Evidence from literature has shown that natural products from medicinal plants are likely to be suitable alternatives and complimentary therapeutic drugs to combat most protozoan infections. Natural products and their bioactive compounds could be the solution to treat most protozoan infections that have developed resistance to these drugs. This review provides comprehensive information on the potential and limitations on activity of medicinal plants and their isolated compounds used in the treatment of protozoan diseases. Especially those considered as neglected diseases such as Cryptosporidium and other protozoans that are inadequately funded and possibility of lack of interest in drug developments have made them  receive little attention. Isolation and identification of bioactive natural products could be the ultimate panacea to cases of metronidazole resistance and discovery of effective and novel drug for Cryptosporidium infection which is currently suffering inadequate treatment options. Keywords: Protozoan parasites, Diarrhoea, Neglected diseases, Medicinal plants, Bioactive compounds