All isolated lignans, except for sesaminol monoglucoside (4),
inhibited a-glucosidase from baker’s yeast11 with IC50 values in
range of 200–492 lM (Table 1), indicating that lignan aglycone is
a core bioactive motif, whereas increased hydrophilicity by a sugar
moiety in 4 revealed no improved inhibition. Interestingly, (+)-
pinoresinol (1) is the only lignan inhibiting rat intestinal maltase12
with IC50 value of 34.3 lM. Since a-glucosidases in human brush
border and rat intestine are categorized into the same group (aglucosidase
I),13 we thus conclude that (+)-pinoresinol is possibly
responsible for hypoglycemic effect found in defatted sesame
seeds.