Enzyme inhibitory, antioxidant activities and phytochemical studies on Juniperus macrocarpa & Juniperus excels

Diabetes mellitus and obesity are metabolic disorders that are spreading day by day. Some species belonging to Juniperus are used ethnopharmacologically for the treatment of diabetes mellitus [1]. The main aim of this study is to determine the inhibitory activity of branches, fruits, and leaves of J. macrocarpa Sibt. & Sm. and J. excelsa Bieb. (Cupressaceae) against α-glucosidase, α-amylase, and pancreatic lipase in vitro. For the determination of the activities, ethyl acetate, methanol, and aqueous extracts were prepared for each part of the plants. The antioxidant activities of the extracts were also examined with different assays. Additionally, the amounts of amentoflavone, agathisflavone and umbelliferone were analyzed with HPLC-UV.

All extracts showed high and dose-dependent inhibitory effect on α-glucosidase enzyme. J. macrocarpa branch methanol extract (99.78 ± 0.03%), was more effective than acarbose at 1 mg/ml. When the α-amylase inhibitor effects of the extracts were examined, the highest effect was observed in J. excelsa leaf methanol extract at a concentration of 1 mg/ml (65.27 ± 1.90%). At 3 mg/ml dose of J. macrocarpa branch ethyl acetate extract (77.37 ± 7.75%) displayed potent pancreatic lipase enzyme inhibitor activity. As a result of the HPLC study, the amounts of amentoflavone were found to be higher than the other compounds in the extracts. The highest amount of amentoflavone was calculated as 0.77 ± 0.00% in J. macrocarpa leaf ethyl acetate extract. Consequently, J. macrocarpa and J. excelsa may be considered as a source of isolation of novel compounds having antidiabetic and antioxidant activity. The in-vivo studies would be performed in further studies.

• References

• 1 Honda G, Yeşilada E, Tabata M, Sezik E, Fujita T, Takeda Y. et al. J Ethnopharmacol 1996; 53: 75-87