Characterization of natural monatin isomers, a high intensity sweetener from the plant Sclerochiton ilicifolius from South Africa

Abstract The objective was to establish the natural occurrence of the various isomers of monatin in extracts of Sclerochiton ilicifolius plant material harvested from different growing regions in South Africa. The natural occurrence of the 2 S ,4 S isomer has been reported as well as the synthesis of the 2 R ,4 R isomer. The 2 R ,4 R is reported as the most intense sweetness however its natural occurrence has not been fully reported, as a result it was not possible to establish whether these isomers are indeed already present in the plant or come from racemisation during the processing of the plant. The presence of the monatin isomers 2 S ,4 S ; 2 R ,4 R in aqueous extracts of S. ilicifolius root bark was demonstrated in each sample harvested at two different time points. The 2 R ,4 R , 2 S ,4 S , 2 R ,4 S , and 2 S ,4 R monatin isomers were absent in the aqueous extracts of S. ilicifolius stem and leaf samples, however was shown to be present in the root bark, and root core samples. This report confirms previous findings which suggested that the 2 S ,4 S and 2 R ,4 R monatin isomers occur naturally in S. ilicifolius .