In vitro anti-diabetic, anti-obesity and antioxidant proprieties of Juniperus phoenicea L. leaves from Tunisia

To examine chemical composition and antioxidant activity as well as the in vitro α-amylase and pancreatic lipase inhibitory activities of the essential oil and various extracts of Juniperus phoenicea (J. phoenicea). Essential oil obtained by steam distillation were analyzed by gas chromatography-mass spectrometry technique. The antioxidant activity of the essential oil and various extracts of J. phoenicea were determined by DPPH and β-carotene bleaching methods. Gas chromatography-mass spectrometry analysis of the J. phoenicea essential oil resulted in the identification of 37 compounds, representing 96.98% of the oil; α-Pinene (24.02%), limonene (7.94%), D-3-Carene (16.9%), Germacrene D (11.98%), Germacrene B (5.40%) and δ-cadinene (6.52%) were the major compounds. The IC50 values of essential oil, hexane and methanol extracts against α-amylase were 35.44, 30.15 and 53.76 μg/mL respectively, and those against pancreatic lipase were 66.15, 68.47 and 60.22 μg/mL respectively, suggesting powerful anti-diabetic and anti-obesity effects. Antioxidant activity (IC50=2 μg/mL) and total phenolics content (265 mg as gallic acid equivalent/g extract) of the methanol extract were found to be the highest compared to the other extracts. The findings showed that the extents of α-amylase and pancreatic lipase inhibitory activities of the J. phoenicea extracts as well as their antioxidant activity are in accordance with total phenolics contents. Leaves of J. phoenicea being rich in phenolics may provide a good source of natural products with interesting medicinal properties.