科研之友
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摘要
An aqueous extract from the aerial parts of Brickellia cavanillesii attenuated postprandial hyperglycemia in diabetic mice during oral glucose and sucrose tolerance tests. Experimental type-II DM was achieved by treating mice with streptozotocin (100 mg/kg) and beta-nicotinamide adenine dinucleotide (40 mg/kg). These pharmacological results demonstrated that B. cavanillesii is effective for controlling fasting and postprandial blood glucose levels in animal models. The same aqueous extract also showed potent inhibitory activity (IC50 = 0.169 vs 1.12 mg/mL for acarbose) against yeast a-glucosidase. Bioassay-guided fractionation of the active extract using the a-glucosidase inhibitory assay led to the isolation of several compounds including two chromenes [6-acetyl-5-hydroxy-2,2-dimethyl-2H-chromene (1) and 6-hydroxyacetyl-5-hydroxy-2,2-dimethyl-2H-chromene (2)1 two sesquiterpene lactones [caleins B (3) and C (4)1 several flavonoids [acacetin (5), genkwanin (6), isorhamnetin (7), kaempferol (8), and quercetin (9)1 and 3,5-di-O-caffeoylquinic acid (10). Chromene 2 is a new chemical entity. Compounds 2, 4, 7, and 9 inhibited the activity of yeast alpha-glucosidase with IC50 0.42, 0.28, 0.16, and 0.53 mM, respectively, vs 1.7 mM for acarbose. Kinetic analysis revealed that compounds 4 and 7 behaved as mixed-type inhibitors with K-i values of 1.91 and 0.41 mM, respectively, while 2 was noncompetititive, with a K-i of 0.13 mM. Docking analysis predicted that these compounds, except 2, bind to the enzyme at the catalytic site.
- 出版日期2012-5
