α-Glucosidase Inhibitors from Fruits of Rosa canina L.

As part of ongoing project on screening plants used in Iranian folk medicine to treatment of diabetes, α-glucosidase inhibition activities of Rosa canina extracts have been tested. The acetone extract of the plant exhibited significant inhibition with IC 50 value of 0.3 µg/ml. The enzyme based assay guided fractionation of the acetone extract led to the isolation of daucosterol (1) and D-glucono-1,4-lactone (2), as highly active α-glucosidase inhibitors. Their structures were determined by 1H- and 13C-NMR spectroscopic evidences. The IC 50 values of daucosterol and D-glucono-1,4-lactone on yeast α-glucosidase were 13.3 and 6.5 µM, respectively, while IC 50 of acarbose was 16.1 µM, as a positive control. The Lineweaver-Burk plots analysis elucidated that both of the compounds inhibited the enzyme competitively. The study suggests that isolated compounds can be good candidates as α-glucosidase inhibitors and provide strong rationale for more in vivo studies.