New triterpene sulfates from Vietnamese red alga Tricleocarpa fragilis and their α-glucosidase inhibitory activity

Three new compounds (methyl-3β,25-dihydroxycycloart-23-en-29-oate 3-sulfate (1), methyl-3β-hydroxy-25-methoxycycloart-23-en-29-oate 3-sulfate (2) and 3β-hydroxy-25-methoxycycloart-23-ene 3-sulfate (3)) and a known one (3β-hydroxycycloart-24-en-23-one 3-sulfate (4)) were isolated from Vietnamese red alga Tricleocarpa fragilis. All isolated compounds 1-4 showed potent inhibitory activity against yeast α-glucosidase with IC50 values of 16.62 ±...