Bioconversion of quercetin glucosides from Dendrophthoe pentandra leaf using Aspergillus acueletus LS04-3 Available to Purchase

Mistletoe (Dendrophthoe pentandra Miq.) leaves serve as a herbal medicine, particularly used in Indonesian folk medicine, for treating various immunological disorders and cancers. One major active compound of mistletoe plant was flavonoid that occured in the form of glycosides (quercetin-3-O-rhamnoside) instead of aglycone (quercetin). Quercetin from the flavonoid group had high bioactivities than that in glycosidic form. The fermentation of flavonoid glycoside with filamentous fungi resulted in the conversion of bioactive compounds. The objectives of this study were to explore the derivatives of quercetin-3-O-rhamnoside during fungal fermentation of water-extracted mistletoe (D. pentandra Miq.) leaves (B) by A. acueletus LS04-3 and investigate the influence of glucose (B+G), yeast (B+Y), and both glucose and yeast (B+G+Y) in the medium on the metabolism of quercetin-3-O-rhamnosidebased on HPLC and LCMS-MS analysis. Based on HPLC analysis, the addition of yeast to the medium (B+Y) increased the conversion of glucoside to quercetin almost twice as much as that on the control medium (B), during the first day of incubation period (D-1). The 10% increase of quercetin peak was only seen on the third day of incubation in B+G medium, when compared to the control sample (B). Moreover, LCMS-MS analysis revealed that quercetin-3-O-rhamnoside and quercetin were detected as the major components in fermented mistletoe leaves. Furthermore, quercetin-3-galactoside-7-glucoside and robinetin were found in the medium that had been added with glucose. The study suggest that glycosilation could also occur in processes other than hydrolisis of glycoside because external glucose would affect the energy metabolism and sugar activation of the microbe. Our finding expanded the understanding of the mistletoe leaf fermentation process and provided further guidance for the biotransformation of quercetin-3-O-rhamnoside in scale up production.