β-glucan contents and antioxidant capacities of water and ethanol extracts from Ganoderma lucidum depending on pH value

Fruiting bodies of Ganoderma lucidum cultivated in Korea were reflux extracted at 90°C using water and ethanol under different pH conditions. β-Glucan contents, extraction yield, and antioxidant capacities of extracts were investigated. Antioxidant activities of water and ethanol extracts were measured by DPPH radical scavenging test and the FRAP method, along with their total phenolic contents and total flavonoid contents. Extraction time for the experiment was determined to be 6 h, and β-glucan contents were the highest. Overall, β-glucan contents of extracts increased with higher pH values, except those of 90% ethanol extracts (P<0.05). The yields and β-glucan contents of ethanol extracts were lower than those of water extracts, and highest in water extract at pH 10 (8.53±0.17%, 6.20±0.12 g/100 g, respectively). Ethanol extracts of fruiting bodies of G. lucidum showed stronger antioxidant capacities than water extracts (P<0.05). Especially, total phenolic contents of 30% ethanol extract at pH 10 was highest (35.06 GAE mg/g). Total phenolic contents of water and ethanol extracts showed good correlations with DPPH radical scavenging activities (r=0.969).