Enhancement of Antioxidant and Antibacterial Activities of Salvia miltiorrhiza Roots Fermented with Aspergillus oryzae

Abstract

The roots of Salvia miltiorrhiza are known to exhibit antioxidant and antibacterial activities. To improve the antioxidant and antibacterial activities of S. miltiorrhiza roots, the roots were fermented with Aspergillus oryzae at 25 °C for 3 weeks. The non-fermented (SME) and fermented (SMBE) roots of S. miltiorrhiza were extracted with 70% ethanol, respectively, and then fractionated with organic solvents. By fermentation, total phenolic and flavonoid contents, as well as antioxidant activity of SMBE, were increased by about 1.2 to 1.3 times compared with those of SME. The antibacterial activity of SMBE was also twice as high as that of SME. The antibacterial activity of SMBE against Bacillus cereus was lower in the n-hexane and chloroform fractions, but higher in the ethyl acetate and n-butanol fractions, compared with those of SME. These results indicate that the bioactive components of S. miltiorrhiza roots exhibiting antibacterial activity were converted to more polar compounds by fermentation of A. oryzae. Gas chromatography and mass spectrometry (GC-MS) and LC-MS analyses of SME and SMBE demonstrate that these changes are due to the acylation of dihydrofuran-2(3H)-one, dealkylation of 4-methylbenzene-1,2-diol and 4-ethylbenzene-1,2-diol, and esterification of hexadecanoic acid and (9Z, 12Z)-octadec-9,12-dienoic acid during fermentation.