Culture broth of Ganoderma lucidum exhibited antioxidant, antibacterial and α-amylase inhibitory activities

Culture broth of Ganoderma lucidum was determined for antioxidant, antibacterial and alpha-amylase inhibitory activities. The culture broth contained protein as determined by Bradford method equaled to 0.2 mg/ml and total phenol content as 0.078 mg GAE/mg protein (0.557 mg GAE/g extract). It exhibited radicals scavenging activities against ABTS(+center dot) and DPPH center dot radicals with a half maximal inhibitory concentration (IC50) less than 1.70 +/- 0.02 and 2.28 +/- 0.02 A mu g protein/ml, respectively and reducing power equaled to 4.38 +/- 0.02 A mu mol Trolox/A mu g protein as investigated by ferric ion reducing antioxidant power method. The culture broth experimented into two approached; (1) treated with pronase and (2) filtered through a membrane with 10 kDa molecular weight cut-off (MWCO). The pronase-treated culture broth exhibited insignificant lower antioxidant activities, but the retained culture broth 10 kDa MWCO resulted in significant decrease in antioxidant activities suggesting that the small proteins might play the key role in antioxidant activity. The culture broth could protect DNA damage from hydroxyl radicals ((OH)-O-center dot) generated by Fenton's reaction. This culture broth showed antibacterial activity towards pathogenic strains Staphylococcus epidermidis and Pseudomonas aeruginosa and also had an interesting alpha-amylase inhibitory activity. This study suggested that apart from the fruiting bodies and the mycelial of G. lucidum, its culture broth also had potential applications as a value-added ingredient in the product such as in cosmetics and in nutraceuticals.