Naphtho-Gamma-Pyrones Produced by Aspergillus tubingensis G131: New Source of Natural Nontoxic Antioxidants.

Seven naphtho-gamma-pyrones (N gamma Ps), including asperpyrone E, aurasperone A, dianhydroaurasperone C, fonsecin, fonsecinone A, fonsecin B, and ustilaginoidin A, were isolated from Aspergillus tubingensis G131, a non-toxigenic strain. The radical scavenging activity of these N gamma Ps was evaluated using ABTS assay. The Trolox equivalent antioxidant capacity on the seven isolated N gamma Ps ranged from 2.4 to 14.6 mu mol L-1. The toxicity and ability of the N gamma Ps to prevent H2O2-mediated cell death were evaluated using normal/not cancerous cells (CHO cells). This cell-based assay showed that N gamma Ps: (1) Are not toxic or weakly toxic towards cells and (2) are able to protect cells from oxidant injuries with an IC50 on H2O2-mediated cell death ranging from 2.25 to 1800 mu mol mL(-1). Our data show that A. tubingensis G131 strain is able to produce various N gamma Ps possessing strong antioxidant activities and low toxicities, making this strain a good candidate for antioxidant applications in food and cosmetic industries.