Changes in polyphenols composition and antioxidative properties of hemp (Cannabis sativa L.) inflorescences pretreated by Ganoderma lucidum

Abstract

The purpose of present study was to improve the antioxidative activity and explore the potential biotransformation mechanism in hemp (Cannabis sativa L.) inflorescences pretreated with Ganoderma lucidum. Ganoderma lucidum, Rhizopus oryzae and Aspergillus oryzae were applied to the transformation of bioactive substances in hemp inflorescences, and the results showed that G. lucidum was the most suitable strain for pretreatment of hemp inflorescences.The optimum time and temperature of G. lucidum pretreatment was 28 ℃ and 7 days respectively. Under the optimum conditions, the 1,1-diphenyl-2-picryl-hydrazyl (DPPH·) and hydroxyl radical (-OH) scavenging ratio were increased by 1.73 and 1.46-fold respectively than that of untreated hemp inflorescences. The total polyphenols (TP) and total flavonoids (TF) were significantly decreased. The metabonomic analysis indicated that, after pretreatment, flavonoids were methoxylated to O-methylated flavonoids. In addition, cinnamic acids hydroxylated to hydroxycinnamic acids. Moreover, flavonoid O-glycosides were rapidly metabolized to release aglycones. Our results showed that pretreatment by G. lucidum exerts significant changes on the polyphenols composition of hemp inflorescences, thus modifying their antioxidative properties.