Bioactive Natural Products from Marine-Derived Fungi

Purification and evaluation of 2, 4-di-tert butylphenol (DTBP) as a biocontrol agent against phyto-pathogenic fungi

A fungal strain, Marasmiellus sp (PUK64), isolated from the mangrove forests in Muthupet, Tamil Nadu, East coast of India, along with others were screened for the search of potent bioactive compounds. A phenolic compound, 2,4-di-tert-butylphenol (DTBP), was isolated from the most promising strain PUK64 and its chemical structure was ascertained. DTBP demonstrated remarkable antifungal activity against the phytopathogenic fungi Aspergillus oryzae, Curvularia lunata and Fusarium verticillioides. In an in-vitro experimental setup, DTBP suppressed the growth of all three fungi, among which F. verticillioides was found to be highly susceptible. This effect relates with the inhibition of spore germination and hyphal growth that we observed. DTBP showed high affinity with the F. verticillioides's β-tubulin protein (determined by ligand-protein docking) as compared to the standard fungicide carbendazim (CBZ). Molecular docking and simulation studies of DTBP with target β-tubulin further confirmed the potential of β-tubulin binding in F. verticillioides. To our knowledge, this is the first report on DTBP-mediated biocontrol of phytopathogenic fungi, produced by Marasmiellus sp. PUK64 that can be potent inhibitor of β-tubulin protein of F. verticillioides.

Biodiversity of Pigmented Fungi Isolated from Marine Environment in La Réunion Island, Indian Ocean: New Resources for Colored Metabolites

Marine ecosystems cover about 70% of the planet surface and are still an underexploited source of useful metabolites. Among microbes, filamentous fungi are captivating organisms used for the production of many chemical classes of secondary metabolites bound to be used in various fields of industrial application. The present study was focused on the collection, isolation, screening and genotyping of pigmented filamentous fungi isolated from tropical marine environments around La Réunion Island, Indian Ocean. About 150 micromycetes were revived and isolated from 14 marine samples (sediments, living corals, coral rubble, sea water and hard substrates) collected in four different locations. Forty-two colored fungal isolates belonging to 16 families, 25 genera and 31 species were further studied depending on their ability to produce pigments and thus subjected to molecular identification. From gene sequence analysis, the most frequently identified colored fungi belong to the widespread Penicillium, Talaromyces and Aspergillus genera in the family Trichocomaceae (11 species), then followed by the family Hypocreaceae (three species). This study demonstrates that marine biotopes in La Réunion Island, Indian Ocean, from coral reefs to underwater slopes of this volcanic island, shelter numerous species of micromycetes, from common or uncommon genera. This unstudied biodiversity comes along with the ability for some fungal marine inhabitants, to produce a range of pigments and hues.

Anthraquinones and Derivatives from Marine-Derived Fungi: Structural Diversity and Selected Biological Activities

Anthraquinones and their derivatives constitute a large group of quinoid compounds with about 700 molecules described. They are widespread in fungi and their chemical diversity and biological activities recently attracted attention of industries in such fields as pharmaceuticals, clothes dyeing, and food colorants. Their positive and/or negative effect(s) due to the 9,10-anthracenedione structure and its substituents are still not clearly understood and their potential roles or effects on human health are today strongly discussed among scientists. As marine microorganisms recently appeared as producers of an astonishing variety of structurally unique secondary metabolites, they may represent a promising resource for identifying new candidates for therapeutic drugs or daily additives. Within this review, we investigate the present knowledge about the anthraquinones and derivatives listed to date from marine-derived filamentous fungi's productions. This overview highlights the molecules which have been identified in microorganisms for the first time. The structures and colors of the anthraquinoid compounds come along with the known roles of some molecules in the life of the organisms. Some specific biological activities are also described. This may help to open doors towards innovative natural substances.