alpha-Glucosidase and alpha-amylase inhibitory potential of main compounds and drug candidates from Elaeagnus rhamnoides (L.) A. Nelson

Elaeagnus rhamnoides (L.) A. Nelson (synonym: Hippophae rhamnoides) (Elaeagnaceae) is an important plant with multiple usages. The current study was laid on discovering the phytochemical profiling of E. rhamnoides leaves through antihyperglycemic and antioxidant effects. The ethyl acetate (IC50 = 46.89 +/- 2.18 mu g/mL) and n-butanol extracts (IC50 = 51.33 +/- 2.53 mu g/mL) possessed potent inhibitory activity against alpha-glucosidase enzyme as compared with standard compound, acarbose (IC50 = 4212.62 +/- 130.00 mu g/mL). Seven compounds were isolated, and their structure was determined by 1D- and 2D-NMR. Isorhamnetin-3-O-beta-d-glucopyranosyl-7-O-alpha-l-rhamnopyranoside (1), isorhamnetin-7-O-alpha-l-rhamnopyranoside (2), isoquercitrin (3), narcissin (4), isorhamnetin-3-O-beta-d-glucopyranoside (5), arjunglucoside I (6), and casuarinin (7) were isolated from n-butanol extract. All isolated compounds, especially arjunglucoside I (IC50 = 1074 +/- 32 mu M) and casuarinin (IC50 = 21 +/- 2 mu M), showed higher alpha-glucosidase inhibitory activity than acarbose (IC50 = 6561 +/- 207 mu M). Casuarinin displayed powerful scavenging activity against to both ABTS radical with 2 +/- 1 mu M IC50 value and DPPH radical with 14 +/- 1 mu M IC50 value while IC50 values of trolox and alpha-tocopherol were 31 +/- 1 and 50 +/- 1 mu M against ABTS radical, and 67 +/- 2 and 95 +/- 3 mu M against DPPH radical, respectively. Arjunglucoside I was isolated for first time from this species and Elaeagnaceae family. Preparations prepared from E. rhamnoides leaf extracts standardized via casuarinin and arjunglucoside I could be potential phytotherapeutics for diabetes mellitus.