A review of natural products as a source of next-generation drugs against apicomplexan parasites

Abstract

Despite the substantial global health and economic burden of apicomplexan parasites in humans and livestock, treatment options remain limited. Natural products have long played an important role in combating these diseases, offering diverse chemical structures and bioactive compounds. This review summarises past and present natural-product-based therapies for six economically significant apicomplexans and explores the potential of revisiting natural products as a source of next-generation treatments.

Fig. 1. Phylogenetic tree of six prevalent and pathogenic genera of apicomplexan parasites that cause disease in humans and livestock.

The Apicomplexa phylum comprises over 6000 species, capable of infecting a broad range of hosts. These six genera and species are the focus for this review as they have a disproportionately large health and economic impact on the represented hosts compared with other apicomplexans and/or have a more developed history of clinical drug use in humans and livestock.

Fig. 2. Most widely used drugs in human and veterinary medicine for the treatment of apicomplexan infections.

Around 39% are natural products or chemically modified derivatives (semi-synthetic), and a further 22% are synthetic compounds inspired by natural pharmacophores. Clinical resistance has emerged to the majority of these drugs, leaving few alternatives with strong therapeutic potential available.