Antihyperglycemic activity of polyphenolic components of black/bitter cumin Centratherum anthelminticum (L.) Kuntze seeds

The eVect of black/bitter cumin seeds Centratherum
anthelminticum (L.) Kuntze extract (CA) containing
mixture of polyphenolic compounds was tested on rat
intestinal �-glucosidases, human salivary �-amylase activity
and postprandial hyperglycemia in rats. Polyphenolic
components of C. anthelminticum seeds (CA) dose dependently
inhibited rat intestinal disaccharidases. IC50 values
were found to be 34.1 § 3.8, 62.2 § 4.5 and 500.5 § 11.9 �g of CA for rat intestinal sucrase, maltase and
p-nitrophenyl �-D-glucopyranoside (PNP-glycoside), respectively.
CA also inhibited human salivary �-amylase activity
with IC50 value of 185.5 § 4.9 �g. The inhibitory eVect of
CA was found to be 8–32 fold more potent than DL-catechin
but less eVective than acarbose on rat intestinal disaccharidases
and salivary �-amylase. The enzyme kinetic studies
showed a non-competitive type of inhibition with a low Ki
value of 30.24 �g, 76.67 �g and 341.60 �g of CA for maltase,
sucrase and PNP-glycoside hydrolysis activities,
respectively. The in vitro inhibition of glucosidases was
further conWrmed by in vivo maltose tolerance test in rats.
Feeding of CA at 50–200 mg/kg body weight (b.wt) to
maltose (2.0 g/kg b.wt), loaded rats signiWcantly reduced
the postprandial plasma glucose levels compared with acarbose.
The inhibitory components of CA were identiWed as a
mixture of polyphenolic compounds viz., gallic acid, protocatechuic
acid, caVeic acid, ellagic acid, ferulic acid, quercetin
and kaempferol. This study demonstrated that CA
exerts antihyperglycemic eVect by decreasing postprandial
glucose in rats by modulating �- amylase and glucosidases
(sucrase and maltase) activity and thus may be useful for
the management of diabetes mellitus.