A Potential Source of Medicines from Fungi: An Overview of Biologically Active Secondary Metabolites

Fungi are the second largest group of living organisms that exist as distinct achlorophyllous, filamentous hyphae growing in diverse habitats depending upon their nutrition source(s). The nutrition sources may alter the growth and fungal secondary metabolite (SM) production. Fungi are an outstanding source of bioactive metabolites used in food and agriculture industry and therapeutics. The innumerable SMs produced from fungi play a vital role as anticancer, antibacterial, antifungal, antioxidant, anti-inflammatory and antidiabetic agents. For instance, the food and drug administration (FDA) has approved fungal drugs like penicillin, cephalosporin, cyclosporine A and lovastatin for commercial use. In addition, fungi have the potential to produce plant-derived SMs such as taxol, vinblastine, vincristine, podophyllotoxin and camptothecin. All the fungal SMs are characterized by techniques like fungal cultivation, extraction, purification and structural characterization using chromatographic and spectroscopic analysis. Exploring the SMs of fungi from rare or specific niches may result in the discovery of novel compounds. Each new fungus has the capacity for producing as yet unexplored compounds with bioactivities that can be altered for therapeutic uses. Such potential fungal SMs can be developed to address existing challenges in the medical field. This chapter focuses on different types of fungi used as medicines for the treatment of various human diseases.