Chemical composition and antioxidant and radical-scavenging activities of Periploca laevigata root bark extracts

BACKGROUND: The root powder of Periploca laevigata is used for preparing soft drinks and as an aromatic in Tunisia. The infusion or decoction of its root bark has widespread use in folk medicine. The plant is used to treat digestive disorders and hypertensive effects as well as other health problems.RESULTS: The antioxidant activities of extracts of P. laevigata root bark obtained with solvents of different polarity were investigated using assays of 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity, ferric-reducing capacity, β-carotene-bleaching ability, hydroxyl radical-scavenging activity and lipid peroxidation inhibition. The methanol extract, with the highest amount of total phenolics and flavonoids, showed the highest antioxidant activities in all assays, followed by the water extract. Gas chromatography/mass spectrometry was used to determine the composition of the water and methanol extracts. Thirty-four compounds were identified in the methanol extract, with proflavine (516.2 g kg⁻¹ dry matter (DM)) and 4-methoxysalicylaldehyde (198.3 g kg⁻¹ DM) being the most abundant. Sixteen compounds were identified in the water extract, of which 4-hydroxy-3-methoxyphenethylene glycol (351.2 g kg⁻¹ DM) was the main component.CONCLUSION: As far as is known, this is the first report on the chemical composition and biological activities of phenolic extracts from P. laevigata. The results of the study indicate that the root bark of this plant might be a good candidate for further investigation in developing new antioxidants.