Optimization of the selective preparation of 20(R)-ginsenoside Rg3 catalyzed by d, l-tartaric acid using response surface methodology.

The optimization of the selective preparation of 20(R)-ginsenoside Rg3 converting protopanaxadiol type saponins (PPD saponins) by the commercially available d, l-tartaric acid was carried out using response surface methodology (RSM) based on a three-factor and six-level central composite design. The optimal 20(R)-ginsenoside Rg3 de% was predicted to be 94.52% in the combination of the factors (d, l-tartaric acid concentration 1.19mol/L, temperature 107.9°C and time 2.79h) through the canonical analysis with maximum responses. Under the optimum reaction conditions, the actual 20(R)-ginsenoside Rg3 de% was 96.49%. 20(R)-ginsenoside Rg3 (1) and 20(S)-ginsenoside Rg3 (2) were separated and identified by (1)H-NMR and (13)C-NMR. Therefore, the RSM was effective to optimize the preparation of 20(R)-ginsenoside Rg3 by converting PPD saponins using d, l-tartaric acid.