Endophytic Fungi of Tropical Forests: A Promising Source of Bioactive Prototype Molecules for the Treatment of Neglected Diseases

Abstract

Endophytic fungi are ubiquitous fungi that reside interor intracellularly in plant parts for at least a portion of their lives without causing apparent symptoms of infection (Petrini, 1991) and represent a large portion of fungal species. Endophytic fungi can be biotrophic mutualists, benign commensals, decomposers or latent pathogens (Promputtha et al., 2007). According to Rodriguez et al. (2009), all plants in the natural environment can shelter endophytic fungi, including algae, mosses, ferns, conifers and angiosperms. This fungal group appears to significantly influence the lifestyle of its host. Taxonomically, most of the endophytic fungi belong to the phylum Ascomycota and its associated anamorphs, while some species belong to the phyla Basidiomycota and Zygomycota (Huang et al., 2001). There have been many studies on the diversity, ecology and biotechnological applications of endophytic fungi in grasses and wood plants in temperate environments. However, there is limited information about the diversity of endophytic fungal communities in tropical forests, which are endowed with a rich biodiversity of flora. Dreyfuss & Chapela (1994) have estimated that approximately 1.3 million species of endophytic fungi remain to be discovered. This diverse fungal group could impact the ecology, fitness and shape of plant communities, conferring resistance to abiotic (temperature, pH, osmotic pressure) and biotic (from bacteria, fungi, nematodes and insects) stresses (Rodriguez et al., 2001). Endophytic fungi are an important source of bioactive molecules. These bioactive metabolites have a broad range of biological activities and could be the starting materials for pharmaceuticals or lead structures for the development of pharmaceutical or agrochemical products. The substances produced by endophytic fungi originate from different biosynthetic pathways, including isoprenoid, polyketide and amino acid and belong to diverse structural groups, such as terpenoids, steroids, xanthones, quinones, phenols, isocoumarins, benzopyranones, tetralones, cytochalasins and enniatins (Schulz et al., 2002). Indeed, these bioactive