Complete conversion of all typical glycosylated protopanaxatriol ginsenosides to aglycon protopanaxatriol by combined bacterial β-glycosidases

Eun-Joo Yang, Tae-Hun Kim, Kyung-Chul Shin, Deok-Kun Oh

Aglycon protopanaxatriol (APPT) has valuable pharmacological effects such as anti-inflammatory and anti-stress activities. However, the complete conversion of all typical glycosylated protopanaxatriol ginsenosides to APPT has not been achieved to date. β-Glycosidase from the hyperthermophilic bacterium Dictyoglomus turgidum (DT-bgl) hydrolyzes the glucose residues at C-6 and the inner glucose at C-20 in protopanaxatriol (PPT), but not the outer rhamnose residues at C-6. In contrast, β-glycosidase from the hyperthermophilic bacterium Pyrococcus furiosus (PF-bgl) hydrolyzes the outer rhamnose residue at C-6 but not the inner glucose residues at C-6 and C-20 in PPT. Thus, the combined use of DT-bgl and PF-bgl resulted in the complete the conversion of all typical glycosylated PPT ginsenosides, including R1, R2, Re, Rg1, Rg2, Rh1, Rf, F1, F3, and F5, to APPT. DT-bgl combined with PF-bgl completely hydrolyzed 1.0 mg ml-1 R1 and 1.0 mg ml-1 total PPT-type ginsenosides in Panax notoginseng root extract to 0.5 and 0.63 mg ml-1 APPT for 4 and 3 h, with molar conversions of 100% and productivities of 125 and 210 mg l-1 h-1, respectively. To the best of our knowledge, this is the first report of the complete conversion of all typical glycosylated PPT ginsenosides to APPT and the highest productivity of APPT obtained from ginseng extract achieved to date.