Designing drugs against leishmaniasis: is targeting the sterol biosynthesis pathway the answer?

Leishmaniasis is a devastating and complex parasitic disease caused by different species of protozoan members of the genus Leishmania. Unfortunately, available drugs are far from ideal and no vaccines are available. Under these circumstances, new effective antileishmanial drugs with reduced host toxicity and improved dosing protocols are urgently needed. The sterol biosynthesis pathway (SBP) is a promising focus for combating Leishmania infections. Thus, various strategies have been documented, such as drug repurposing, combined therapy, rational drug design, and the use of synergistic effects to develop the metallodrugs that can act on essential parasite targets. This article reviews the critical enzymes participating in the ergostane-based sterol biosynthesis pathway (SBP) of Leishmania species, as well as recent progress in rational drug design, repurposing drugs, combined therapies, and the development of metallodrugs for use as antileishmanial agents. This review is based on literature searchers using SciFinder, Lens.org, Google Scholar, Web of Science, Pub Med, and DrugBank. The limited focus on human leishmaniasis has resulted in a shortfall in effective treatments for this parasitic disease. The post-squalene segment of the sterol biosynthetic pathway is a promising target for treating Leishmania infections, particularly effective drugs or metallodrugs that inhibit the CYP51 or 24-SMT enzymes.