Isolation and characterization of antioxidant compounds from Aspergillus candidus broth filtrate

The objectives of this study were to isolate the antioxidative components in the broth filtrate of Aspergillus candidus (CCRC 31543), to characterize their antioxidative properties, and to evaluate their safety. Three major compounds were isolated and identified as 3,3' '-dihydroxyterphenyllin, 3-hydroxyterphenyllin, and candidusin B. In the linoleic acid peroxidation system, the inhibition of peroxidation in these three compounds was greater than 95% and was significantly higher than that of alpha-tocopherol but equal to that of BHA at 12.5-200 microg/mL. As measured using the Rancimat method in lard, 3,3' '-di-OH-terphenyllin exhibited a protection factor value of 7.82, which was substantially higher than those of BHA (5.58) and alpha-tocopherol (4.29) at 200 microg/mL. 3,3' '-di-OH-terphenyllin and 3-OH-terphenyllin also exhibited marked scavenging effects on the alpha,alpha-diphenyl-beta-picrylhydrazyl radicals (94.7 and 96.0%, respectively), which were similar to those of BHA and alpha-tocopherol. Safety studies showed that these three compounds were neither cyto- nor geno-toxic toward human intestine 407 (INT 407) cells, nor mutagenic toward Salmonella typhimurium TA98 and TA100.