Enzymatic Formation of Novel Ginsenoside Rg1-α-Glucosides by Rat Intestinal Homogenates

Abstract

The variation of linkage positions in ginsenosides leads to diverse pharmacological efficiencies. The hydrolysis and transglycosylation properties of glycosyl hydrolase family enzymes have a great impact on the synthesis of novel and structurally diversified compounds. In this study, six ginsenoside Rg1-α-glucosides were found to be synthesized from the reaction mixture of maltose as a donor and ginsenoside Rg1 as a sugar acceptor in the presence of rat small intestinal homogenates, which exhibit high α-glucosidase activities. The individual compounds were purified and were identified by spectroscopy (HPLC-MS, (1)H-NMR, and (13)C-NMR) as 6-O-[α-D-glcp-(1→4)-β-D-glcp]-20-O-(β-D-glcp)-20(S)-protopanaxatriol, 6-O-β-D-glcp-20-O-[α-D-glcp-(1→6)-(β-D-glcp)]-20(S)-protopanaxatriol, 6-O-β-D-glcp-20-O-[α-D-glcp-(1→4)-(β-D-glcp)]-20(S)-protopanaxatriol, 6-O-[α-D-glcp-(1→6)-β-D-glcp]-20-O-(β-glcp)-20(S)-protopanaxatriol, 6-O-[α-D-glcp-(1→3)-β-D-glcp]-20-O-(β-D-glcp)-20(S)-protopanaxatriol, and 6-O-β-D-glcp-20-O-[α-D-glcp-(1→3)-(β-D-glcp)]-20(S)-protopanaxatriol. Among these six, 6-O-β-D-glcp-20-O-α-D-glcp-(1→6)-(β-D-glcp)-20(S)-protopanaxatriol and 6-O-α-D-glcp-(1→6)-β-D-glcp-20-O-(β-D-glcp)-20(S)-protopanaxatriol are considered to be novel compounds of alpha-ginsenosidal saponins which pharmacological activities should be further characterized. This is the first report on the enzymatic elaboration of ginsenoside Rg1 derivatives using rat intestinal homogenates. To the best of our knowledge, it is also the first to reveal the sixth and 20th positions of an unusual α-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl sugar chain with 20(S)-protopanaxatriol saponins in Panax ginseng Mayer.

Rare ginsenoside Ia synthesized from F1 by cloning and overexpression of the UDP-glycosyltransferase gene from Bacillus subtilis: synthesis, characterization, and in vitro melanogenesis inhibition activity in BL6B16 cells

“…For large-scale production, final concentrations of 0.5mM ginsenoside F1, 2.5mM UDP-glucose, and 10mM Co 2+ with BSGT1 enzyme (pH 7.0) were combined in 25 mL and reacted for 24 h at 30°C in a shaking incubator. The resulting metabolite 1 was purified by open silica column chromatography with a solvent system of CHCl 3 :CH 3 OH:H 2 O (65:35:10, v/v/v, lower phase); further separation and purification were achieved by repeated prep HPLC using a Nova-pak C 18 column for further characterization [37] . The yield of metabolite 1 was 40.6%.…”

Synthesis of a Novel α-Glucosyl Ginsenoside F1 by Cyclodextrin Glucanotransferase and Its In Vitro Cosmetic Applications

“…Among the major ginsenosides, Rb1, Rc, Re, and Rg1 have already been used as substrates for the synthesis of series of new α-glycosylginsenosides through transglycosylation [13,25,26]. However, after oral administration, the major ginsenosides were converted into minor ginsenosides by intestinal microflora.…”

“…F1 showed significantly greater inhibition of viability than Rh1 in prostate cancer cell lines [30]. The glycosylation and nano formulations of ginseng saponins [13,25,26,31,32,33] and other steroidal saponins [19,27] has recently attracted increased interest.…”

“…Semiqualitative screening of the glycosylated products was carried out by TLC and high-performance liquid chromatography (HPLC) was carried out by Ramya et al, 2015 and Quan et al, 2012 [13,23] with slight modifications. TLC was performed with silica gel plates (60 F254, Merck, Darmstadt, Germany) using the developing solvent CHCl 3 :CH 3 OH:H 2 O (65:35:10, v / v , lower phase).…”

“…Synthesis of novel and diversified compounds is a way to extend the efficacy of natural products. Such diversity can be generated by biosynthetic reactions such as glucosylation [12,13]. Especially, enzymatic glycosylation provides more regioselectiveness than conventional chemical synthesis [14].…”