Background and purpose: Alpha-glucosidase inhibitors are used in treatment of type 2 diabetes because they decrease postprandial hyperglycemia. Consistent use of these drugs has undesirable side effects such as liver toxicity and gastrointestinal symptoms. The purpose of this study was to investigate the inhibitory effect of Ziziphus jujuba and Heracleum persicum on the activity of partial purified rat intestinal alpha-glucosidase enzyme.

Materials and methods: Alpha-glucosidase enzyme was partially purified by gel filtration chromatography Sephadex G-200 from the rat intestine. The methanol extract of plants was prepared and IC₅₀ value of extracts on alpha-glucosidase enzyme was obtained and compared with acarbose IC₅₀. The polyphenolic content and antioxidant capacity of extracts were determined by Folin-Ciocalteu test and DPPH test, respectively.

Results: The specific activity of the enzyme was 59.1 U/mg. The IC₅₀ values of Z. jujuba, H. persicum and acarbose for alpha-glucosidase inhibition were 815, 258 and 104 μg/ml, respectively. For inhibition of DPPH radical, IC₅₀ values of extracts were calculated as 721 and 243 μg/ml, respectively. Total phenolic content of methanol extracts were 36.06±2.1 and 68.2±2.6 μg tannic acid equivalent/mg extract, respectively.

Conclusion: Z. jujuba is used in traditional medicine to treat gastrointestinal disorders, liver pain, diabetes and H. persicum is used as anti-flatulence. Antioxidant properties, polyphenolic content, saponin and remarkable inhibition of the alpha-glucosidase make them appropriate candidates in treatment of diabetic patients.