The present study was performed to investigate the enzyme inhibitory and antidiabetic activities of the
constituents isolated from Callistemon lanceolatus. The leaves of C. lanceolatus were extracted with successively with
petroleum ether, dichloromethane and methanol. The dried dichloromethane and methanol extracts were subjected to
fractionation and chromatographic separation, which led to the isolation of seven compounds: 3-epi-betulinic acid (1), 3-
epi-ursolic acid (2), oleanolic acid (3), ursolic acid (4), lup-12, 20(29)-diene-3α-ol-28-oic acid (5), heptacosenone (6)
and kaempferol (7). Their structures were elucidated on the basis of spectroscopic studies as well as by comparison with
the data available in the literature. Among these isolates, compounds 1, 2, 3, 4 and 7 were evaluated for in vitro enzyme
inhibition effect. Compounds 1, 2, 3, 4 and 7 showed 38.34, 52.59, 62.4, 54.95 and 32.43 % α-amylase inhibition
respectively and 49.27, 53.34, 84.2, 67.98 and 52.25 % α-glucosidase inhibition respectively at the concentration of 50
µg/kg. Compounds 3, 4 and 7 were also showed antidiabetic activity in streptozotocin-nicotinamide induced diabetic mice
at the dose of 10 mg/kg.
α-amylase inhibition, antidiabetic, Callistemon lanceolatus, α-glucosidase inhibition, streptozotocin-nicotinamide,
Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra-136119, Haryana, India.