Secondary Metabolites Produced by Endophytic Fungi from Marine Environments

Abstract

Endophytes are symptomless organisms thriving within the living host tissues. Some endophytic fungi have been shown to be producing the same compounds produced by their hosts, e.g., taxol produced by Pestalotiopsis microspora isolated from Taxus wallichiana. Hence, there has been lot of interest to screen the secondary metabolites of endophytic fungi. In recent times the focus on endophytic fungi and the secondary metabolites they produce has shifted to marine environments. Unlike terrestrial environments where more research has been conducted on secondary metabolites from living plant substrata, the secondary metabolites produced by endophytic fungi isolated from marine environments are equally from macroalgae (seaweeds) and sponges in addition to mangrove and different shoreline plant substrata. Many promising secondary metabolites that have therapeutic potential including in antimicrobial, antiviral, antimalarial, and anticancer applications have been reported from endophytic fungi isolated from seaweeds, sponges, and plants from maritime environments. For example, the compound 3-O-methylfunicone isolated from Talaromyces sp., in mangrove habitat, has shown antifungal, antitumor, and lipid-lowering properties and required beyond academic research wherein pharmaceutical industry needs to take it further. A Cladosporium L037 species from the brown alga Actinotrichia fragilis, collected off Seragaki Beach at Okinawa Island, Japan, produced two 12-membered macrolides, namely, sporiolides A and B. Both these metabolites exhibited potent cytotoxicity against murine lymphoma L1210 cells with IC50 values of 0.37 and 3.1 um, respectively. A cyclic tetrapeptide compound produced by Petriella sp., an endophyte of the sponge Suberites domuncula, showed cytotoxicity against murine L5178Y lymphoma cells at an ED50 value of <0.1 μg/ml. The present chapter updates and consolidates the information available on the secondary metabolites produced by endophytic fungi isolated from marine environments.