Antioxidant and antidiabetic activities of 11 herbal plants from Hyrcania region, Iran

In the present study, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, α-amylase and α-glucosidase inhibition activities, and total phenolic contents of n-hexane, ethyl acetate, and methanol extracts of various parts of Allium paradoxum, Buxus hyrcana, Convolvulus persicus, Eryngium caucasicum, Heracleum persicum, Pimpinella affinis, Parrotia persica, Primula heterochroma, Pyrus boissieriana, Ruscus hyrcanus, and Smilax excelsa were investigated. These plants, which mostly serve as food flavoring, were collected from Hyrcania region, Sari, Iran. Some extracts of H. persicum, S. excels, P. boissieriana, P. persica, and P. heterochroma exhibited significant antidiabetic activities in α-amylase and α-glucosidase assays, more effective than acarbose (concentrations that cause 50% inhibition = 75.7 μg/mL and 6.1 μg/mL against α-amylase and α-glucosidase, respectively). Also, C. persicus, P. boissieriana, and P. heterochroma showed strong antioxidant activities, compared with butylated hydroxytoluene (concentration that causes 50% inhibition = 16.7 μg/mL). In conclusion, this study can recommend these plants as good candidates for further investigations to find potent antidiabetic natural products or probable lead compounds. Statistical analysis showed significant correlation between the 2,2-diphenyl-1-picrylhydrazyl scavenging activity and total phenolic contents (r = 0.711, p < 0.001).