Quantitative analysis of neosalacinol and neokotalanol, another two potent α-glucosidase inhibitors from Salacia species, by LC-MS with ion pair chromatography.

A quantitative analytical method for the highly polar sulfonium pseudo-sugar constituents neosalacinol (3) and neokotalanol (4), another two potent α-glucosidase inhibitors isolated from Ayurvedic traditional medicine Salacia species, was developed by employing an ion pair reagent upon chromatographic separation. The optimum conditions for separation and detection of these two constituents were achieved on an ODS column (3-µm particle size, 2.1-mm i.d. × 100 mm) with 5 mM undecafluorohexanoic acid-MeOH (99:1, v/v) as the mobile phase and using MS equipped with an electrospray ionization source. More than ten samples of Salacia from different origins were analyzed, and the results indicated that the assay was reproducible and precise and could be readily utilized for evaluation of α-glucosidase inhibitory activity of Salacia species. By combining this assay with the quantitative analytical method previously developed for salacinol (1) and kotalanol (2), a more precise and strict evaluation of α-glucosidase inhibitory activities of extracts from Salacia species (R = 0.959 for maltase and 0.795 for sucrase) was achieved.