The enzymatic transformation of the sugar moiety of the gypenosides provides a new way to obtain more pharmacologically active components. A gene encoding a family 1 glycosyl hydrolase from Bifidobacterium dentium was cloned and expressed in Escherichia coli. The recombinant enzyme was purified, and its molecular weight was approximately 44 kDa. The recombinant BdbglB exhibited an optimal activity at 35 °C and pH 5.4. The purified recombinant enzyme, exhibiting β-glucosidase activity, was used to produce gypenoside XVII (Gyp XVII) via highly selective and efficient hydrolysis of the outer glucose moiety linked to the C-3 position in ginsenoside Rb1 (G-Rb1). Under the optimal reaction conditions for large scale production of gypenoside XVII, 40 g ginsenoside Rb1 was transformed by using 45 g crude enzyme at pH 5.4 and 35 °C for 10 h with a molar yield of 100%. Furthermore, the anti-inflammatory effects of the product gypenoside XVII and its conversion precursor ginsenoside Rb1 were evaluated by using lipopolysaccharide (LPS)-induced murine RAW 264.7 macrophages and the xylene-induced acute inflammation model of mouse ear edema, respectively. Gypenoside XVII showed improved anti-inflammatory activity, which significantly inhibited the generation of TNF-α and IL-6 more effectively than its precursor ginsenoside Rb1. In addition, the swelling inhibition rate of gypenoside XVII was 80.55%, while the rate of its precursor was 40.47%, the results also indicated that gypenoside XVII had better anti-inflammatory activity than ginsenoside Rb1. Hence, this enzymatic method would be useful in the large-scale production of gypenoside XVII, which may become a new potent anti-inflammatory candidate drug.
Keywords: Gynostemma pentaphyllum (Thunb.) Makino; anti-inflammation; biotransformation; gypenoside XVII; β-glucosidase.