16. Enzymatic and acid hydrolysis of steviol and cucurbitane glycosides

Identification of aglycone and sugar residues in diterpene glycosides isolated from Stevia rebaudiana was achieved by enzymatic and acid hydrolysis. Also, the sugar moieties present in triterpene glycosides from Siraitia grosvenorii were determined using acid hydrolysis experiments. Acid hydrolysis was carried out using 5% H2SO4 whereas enzymatic hydrolysis was performed using pectinase. Utilizing these methods, aglycone moieties of eighteen steviol glycosides and sugar parts of twenty four diterpene and triterpene glycosides were identified. Further, the configuration of sugar moieties in glycosides were confirmed by preparing their corresponding thiocarbamoyl-thiazolidine carboxylate derivative with L-cysteine methyl ester and O-tolyl isothiocyanate in comparison of their retention times with standard sugars.