A Preliminary Study of Molecular Structure of Sweet Substances from "Enqiyetian" Variety of Gynostemma pentaphyllum
ZHENG Xiao-jiang1,2,LIU Jin-long1,2,MAO Xian-fa2 (1. Hubei Key Laboratory of Biological Resource Conservation and Utilization, Enshi 445000, China; 2. School of Biological Science and Technology, Hubei Institute for Nationalities, Enshi 445000, China)
Sweet substances, which give a pleasant, cool, sweet taste when eaten, were extracted from "Enqiyetian", a new variety of Gynostenma Pentaphyllurn with a yield up to 9.3%. Due to non-carbohydrate and low heat, they have wide medical applications in prevention of obesity, diabetes, cardiovascular diseases and dental caries. Apart from this, they also can be used as a new natural sweetener. The optimal procedure for extraction and purification of sweet substances developed in this study was based on the following steps: defatting of dried powder of "Enqiyetian" leaves as the raw material with ether, ultrasonic cell disruption in 95% ethanol, hot water extraction, centrifugation, impurity removal using ZTC+1, centrifugation, concentration, dissolution in methanol and then precipitation with acetone, redissolution in deionized and then extraction with water-saturated n-butanol, rotary evaporation of the aqueous phase, separation of sweet substances using silica gel column, purification of sweet substances using Sephadex G-10 column, freeze-drying, and LC-MS analysis. The final product was showed to consist of two compounds sharing with the same molecular formula of C11H10N2 and the molecular weight of one was 274 and another of 170. Our findings suggested the potential of these sweet substances as a novel sweet material.