Potential of endophytic fungi as therapeutics: Antibiotics, Antiviral and Anticancer properties

Antibiotic resistance, an emerging threat to human health, is the world's major challenge today. Endophytic microbes found in medicinal plants aid in the resolution of these issues. It is critical to select the plant that will be used to investigate endophytes for bioactive metabolites. As a result, medicinal plants which have been used as a traditional source of medicine for centuries, are a valuable source for bioprospecting endophytes. Fungi are the most commonly reported organisms among endophytes. Endophytic fungi are a diverse group of microbes that invade plant interior tissues without creating any symptoms. Endophytic fungi represent an abundant source of novel bioactive secondary metabolites with diversified structures that can be exploited for various applications in the field of therapeutics. Endophytic fungi produce secondary metabolites such as alkaloids, enzymes, steroids, terpenoids, phenols, quinones, peptides, polyketides etc. which have a higher therapeutic value. They produce a wide range of bioactive molecules with various biological activities such as antibacterial, antiviral, antifungal, antioxidants, cytotoxic and antimalarial compounds. The chemical diversity of endophytic fungi also serves to protect host plants from pathogens by hindering their growth and stimulating the host immune system, thereby enhancing plant defense mechanisms. Endophytic fungi synthesize metabolites that are identical to their host medicinal plant (azadirachtin, taxol, ginkgolide, jasmonic acid, camptothecin etc.) due to their specific capacity to form a symbiotic association with the host. Endophytic fungi can serve as substitutes for secondary metabolite production, aiding in biodiversity conservation. This review discusses numerous bioactive metabolites produced by endophytic fungi that have diverse biological activities. The majority of these metabolites have the potential to be utilized as drugs to treat a wide range of diseases.