Fusarium head blight (FHB) is a major fungal disease caused by an infection with a fungus of the genus Fusarium. FHB affects maize, wheat, and small-grain cereals, including barley, oats, rye, and triticale, in all cereal-growing areas of the world, which results in substantial reductions in crop yield and quality(aborted or shriveled seed and reduced seed size) and economically devastating losses around the world.
Additionally, the contamination of mycotoxins produced by these pathogenic fungi is harmful to human beings and animals. Three species, Fusarium graminearum, F. culmorum, and F. avenaceum, are known to be most frequently involved in FHB. Thus, the demand for potent natural chemicals to inhibit the infection of Fusarium species is growing.
Prof. Luo yinggang’s group of Chengdu Institute of Biology, Chinese Academy of Sciences has long been committed to the isolation and characterization of plant and microorganisms’ intriguing secondary metabolites.In the course of a program collaborate with the researchers from Yunnan University, initiated for the discovery of new actinomycetes, more than 100 halophilic actinomycete strains were isolated from various regions of China.
In this research, preliminary biological activity screening experiments suggested that the fermentation broth of halophilic actinomycete Nocardiopsis gilva YIM 90087 exhibited antifungal and antibacterial activities. Subsequently secondary metabolites investigation leaded to the isolation and structural characterization of one new p-terphenyl, one novel p-terphenyl derivative bearing a benzo[d]thiazole moiety, and 13 known compounds of N. gilva YIM 90087.
However, intriguingly, the p-terphenyl showed antifungal activity against the three pathogenic fungi associated with Fusarium head blight, including F. avenaceum, F. graminearum, and F. culmorum with minimal inhibitory concentrations (MICs) of 8, 16, and 128 μg/mL, respectively. This compound also showed antifungal activity against Candida albicans with a MIC of 32 μg/mL and antibacterial activity against Bacillus subtilis with a MIC of 64 μg/mL. The antioxidant activity of the isolated compounds was evaluated by using the DPPH free radical assay, the ABTS cation radical assay, and the superoxide anion radical assay.
The results of biological activity assays indicated that p-terphenyls are new scaffolds for potent antifungal, antibacterial, and antioxidant agents. And their chemical investigations of the halophilic N.gilva YIM 90087 strain suggested that N. gilva YIM 90087 is a new resource for a known antibiotics novobiocin.
Their achievement entitled “Isolation and Characterization of New p‑Terphenyls with Antifungal, Antibacterial, and Antioxidant Activities from Halophilic Actinomycete Nocardiopsis gilva YIM 90087” was published on J. Agric. Food Chem (2013, 61, 3006−3012).