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

Abstract 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 1.19 mol/L, temperature 107.9 °C and time 2.79 h) 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.