The effects of glycine and L-arginine on heat stability of ginsenoside Rb1

Abstract

To identify the effects of amino acids on the heat stability of ginsenoside Rb1 (Rb1), Rb1 was heat-processed at 120 °C with or without glycine or L-arginine. Rb1 was changed into 20(S)-Rg3, 20(R)-Rg3, Rk1, and Rg5 by heat-processing through glycosyl elimination and epimerization of carbon-20 by SN1 reaction. Similarly, Rb1 was changed into 20(S)-Rg 3, 20(R)-Rg3, Rk1, and Rg5 when it was heat-processed with the same amount of glycine, but the generated amount of 20(S)-Rg3 was higher than when Rb1 was heat-processed without amino acids, and a significant increase in Maillard reaction products (MRPs) was noted. On the other hand, there were no structural changes in Rb 1 and the generation of MRPs when Rb1 was heat-processed with the same amount of L-arginine. The improved heat stability of Rb1 brought about by the addition of L-arginine was thought to be closely related to its characteristics of interfering with nonenzymatic glycation and forming hydrogen bonds with Rb1. © 2007 Pharmaceutical Society of Japan.