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Since the leaves of some Pistacia species are used in traditional folk medicine for diabetes, this study investigated the in vitro antidiabetic effect (α-glucosidase and α-amylase) of Pistacia vera leaves. Additionally, the current study investigated the antihypercholesterolemic (cholesterol esterase), antiobesity (pancreatic lipase), and antioxidant activities (i.e., total antioxidant capacity, DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity, metal chelating activity, and ferric-reducing antioxidant power) of P. vera leaves. The aqueous-alcoholic leaf extract inhibited α-amylase, α-glucosidase, and pancreatic lipase with the half-maximal inhibitory concentration values of 7.74 ± 0.72, 11.08 ± 3.96, and 168.43 ± 26.10 µg/mL, respectively. It was determined that the crude extract had high DPPH radical scavenging activity, ferric-reducing power, and moderate metal chelating activity. The ethyl acetate (EtOAc) subextract obtained by the liquid-liquid fractionation of the crude extract showed potent α-amylase and α-glucosidase inhibitory activities. The EtOAc subextract (5.794 ± 0.027 g/100 g subextract) was standardized by reversed-phase high-performance liquid chromatography based on β-pentagalloyl glucose, which showed inhibitory effects on both amylase and glucosidase enzymes. Fifteen compounds, seven of which are organic acid derivatives and eight of which are flavonoids, were identified by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) analysis in the crude extract of P. vera leaves. Seven of the fifteen phenolic compounds detected in the crude extract by LC-QTOF-MS have both glucosidase and amylase inhibitory effects. As a result, P. vera leaves can be a potential source for compounds with high antioxidant effects that show inhibitory effects on enzymes involved in carbohydrate digestion in the prevention and treatment of diabetes or can be evaluated as a standardized extract.

Juniperus speciesgrowing in Turkey are used for various medicinal purposes in traditional folk medicine. We aimed to evaluate in-vitro antidiabetic (α-glucosidase and α-amylase inhibition assays), antiobesity (pancreatic lipase inhibition assay), and antioxidant (ABTS and DPPH radical scavenging activities, ferric reducing activity, metal chelating activity, and phosphomolybdenum assay) activities of the extracts obtained from branches, leaves, and fruits of Juniperus macrocarpa and Juniperus excelsa. The branch (IC50 =  67.1 ± 1.7 µg/mL) and leaf ethyl acetate extracts (IC50 =  83.4 ± 0.8 µg/mL) of J. macrocarpa exhibited the strongest activity on the α-glucosidase enzyme. Besides that, J. excelsa leaf methanol extract exerted remarkable α-amylase inhibitory activity (IC50 = 950.1 ± 3.5 µg/mL). Only J. macrocarpa branch and J. excelsa leaf ethyl acetate extract slightly inhibited pancreatic lipase enzyme with 2963.3 ± 736.4 and 2343 ± 557.8 µg/mL IC50 values, respectively. The RP-HPLC-DAD analysis results demonstrated that the more active J. macrocarpa extracts are richer in agathisflavone, amentoflavone, and umbelliferone than J. excelsa extracts. With this study, it is concluded that J. macrocarpa branch and leaf ethyl acetate extracts may be a new source of α-glucosidase enzyme inhibitory activity and agathisflavone, amentoflavone can be used in the standardization of the extracts.