A Brief Insight into Peptide and Non-Peptide Drugs of Fungal Origin

Microorganisms are valuable resources for obtaining bioactive compounds, which have proven to be very useful in various domains, e.g., agriculture, food and pharmaceutical industries. The kingdom of fungi constitutes unicellular and multicellular eukaryotic microorganisms. Various types of molecules identified from fungi have shown very fruitful medicinal and biological functions. Consequently, fungi have been recognized to be a vital resource for isolating compounds that have achieved success for treating infectious as well as non-infectious diseases. In this chapter, we are highlighting certain important characteristics, mainly molecular structural properties and key pharmacological activities of secondary metabolites discovered from different species and genera of fungi. The secondary metabolites that we have chosen are also commercially known drug compounds with very important therapeutic activities. We have classified these metabolites into two categories: peptide drugs and non-peptide drugs. Five non-ribosomal cyclic peptides: caspofungin, micafungin, anidulafungin, rezafungin and cyclosporine constitute the peptide drugs category (1000–1500 Daltons). While all these five peptides are anti-fungal agents, cyclosporine is also a popular immunosuppressant drug. Caspofungin, micafungin and anidulafungin are approved drugs that are available in market, whereas rezafungin is currently under clinical trials. In the non-peptide drugs category, we have selected small molecule secondary metabolites (intact molecular mass: 200–600 Daltons), which are griseofulvin, fusidic acid, mycophenolic acid, fingolimod and irofulven. Griseofulvin and fusidic acid are anti-fungal and anti-bacterial drugs, respectively. Mycophenolic acid and fingolimod are immunosuppressant drugs. Irofulven is an anticancer agent, which is currently under clinical trials.