Potential of South African medicinal plants used as anthelmintics – Their efficacy, safety concerns and reappraisal of current screening methods

Abstract

Studies on anthelmintic activity of medicinal plants have received insufficient interest and attention from researchers despite the high incidence of helminth infections in the poorer communities of South Africa. There are only a few anthelmintic remedies available which are inadequate in terms of accessibility, affordability and probably efficacy. In this review, we reappraised the various anthelmintic studies on South African medicinal plants to highlight how much and/or how little is known. The rich botanical and medicinal plant knowledge in South Africa is an indication of the potential of discovering potent treatments against helminth diseases in both humans and livestock. A total of 115 plant species encompassing 43 families screened for their anthelmintic potential (mainly nematodes) are listed in the current review. Combretaceae and Fabaceae were the most commonly used families. Tetradenia riparia, Hypoxis colchicifolia, Apodytes dimiata and Leucosidea sericea are a few examples of the South African species that have demonstrated promising anthelmintic activity. Even though other species such as Dicerocaryum eriocarpum, Berchemia zeyheri and Acorus calamus are potent anthelmintics, caution must be exercised in administering these plant extracts because of their potential toxic effects. Besides the benefit of validating the efficacy of traditional medicines, compounds from South African medicinal plants could also provide a template for novel synthetic anthelmintics. However, the major bottleneck in exploring more South African medicinal plants for anthelmintic properties is probably the lack of a robust, rapid and reliable screening technique as well as adequate funding schemes. Perhaps, there could be more success stories via increased research outputs with the development and availability of high throughput screening methods for assessing the activity of these medicinal plants as well as their resultant bioactive compounds. In addition, accessibility of funds to acquire latest technology and motivate researchers will inevitably stimulate more studies geared toward alleviating the problems posed by helminth infections.