Natural and semisynthetic steroidal alkaloids and their antiinfectious potential

Tropical countries account for approximately 40% of the world's population. Most of these populations live in poverty and precarious conditions therefore, they are exposed to numerous infectious diseases. The burden of these diseases constantly challenged local healthcare systems and directly impacted human capital. These health problems reduce the expectation of socio-economic growth, alphabetization, and productivity. Tropical diseases are caused by viral, bacterial, parasitic, and fungal infections, of which 21 are classified by WHO as neglected. Despite the challenge to tackle adverse effects and drug resistance associated with current treatments of some of these diseases, natural products have always provided new agents with anti-infectious potential, especially against bacteria (Mycobacterium tuberculosis and actinomycetoma), protozoan (Plasmodium sp, Leishmania sp, Trypanosoma sp, Wuchereria bancrofti, etc.), viruses (YVF, DENV, CHIKV, and ZIKV), and fungi (eumycetoma). Steroidal alkaloids (SAs) are nitrogenous substances that possess steroid skeletons. This group of compounds contains important biological active secondary metabolites found in plants and marine organisms. SAs are endowed with anticancer, anti-inflammatory, and antimicrobial activities, especially against tropical infectious pathogens. Thus, this document will report on steroidal alkaloids that show promising activity against some of these infectious illnesses, including malaria, bilharzia, chikungunya, tuberculosis, leishmaniasis, and trypanosomiasis. The chapter will also present the structure-activity relationship based on molecular docking and the observed biological activities. The mechanism of action of some of these anti-infectious agents will be described as well as semisynthetic derivatives and their associated biological activity.