Isolation, structural determination and anti-hyperglycemic effect of dietthyl terephthalate extracted from the leaves of Dalium guineense (Caesalpiniaceae)

Abstract

Previous work had demonstrated the lack of hypoglycemic effect of the butanol-ethyl acetate fraction (BEAF) of the leaves of Dialium Guineense (Caesalpiniaceae). However, this same fraction is anti-hyperglycemic in glucose tolerance test in type 2 diabetic rats. The purpose of that study was to evaluate the effect on blood glucose of dietyl terephthalate (DT) isolated from BEAF of D. guineense leaves. Diethyl terephthalate (DT) was tested in normoglycemic rats, glucose tolerance test and type 2 diabetic rats. Per os administration of DT in normoglycemic rats is not associated with a significant change in basic blood glucose. At 30 mg/kg per os, blood glucose ranges from 0.76±0.02 to 0.84±0.02 g/L (ns, n=5). Under the same conditions, similar results were observed at 100 mg/kg per os (0.91±0.04 vs 0.95±0.03 g/L) (ns, n=5). In glucose tolerance test, prior administration of DT (30 mg/kg, 100 mg/kg, per os) significantly prevents the appearance of frank hyperglycemia. The blood glucose was 1.10±0.04 g/L and 1.29±0.08 g/L, respectively at 30 mg/kg and 100 mg/kg per os, after DT administration vs 2.04±0.13 g/L in control group (p<0.05, n=5). The daily administration of DT (30 mg/kg, per os) in type 2 diabetic rats significantly prevents the hyperglycemia previously observed in the control group. The effect profile on blood glucose of DT is identical to that butanol-ethyl acetate fraction (BEAF) of the leaves of D. guineense and is reminiscent that of antihyperglycemic agents of thiazolidine-dione group. The anti-hyperglycemic action of DT would involve the body peripheral tissues.