Antioxidant capacity and phenolic contents of some Mediterranean medicinal plants and their potential role in the inhibition of cyclooxygenase-1 and acetylcholinesterase activities

Abstract

Extracts of nine medicinal plants were screened for their anti-inflammatory activity using the cyclooxygenase-1 assay and their acetylcholinesterase inhibitory effect. The antioxidant activity was assessed by four methods: free radicals DPPH (1,1-diphenyl-2-picrilhydrazyl), nitric oxide assay, β-carotene bleaching test and metal chelating power. The amounts of different phenolic compounds were also determined. Myrtus communis (leaves), Pistacia lentiscus (leaves) and Globularia alypum (flowers) presented the highest amounts of total phenolic compounds while the concentrations of total flavonoids, flavonols, proanthocyanidins and total tannins varied with plant species. Marrubium vulgare (leaves) gave the best inhibitory activity of the enzyme Cox-1 with an IC50 of 0.082mg/ml which was statistically not different from the standard indomethacin (0.061mg/ml). The best anti-acetylcholinesterase activity was exhibited by the leaf extracts of M. communis, P. lentiscus and Eryngium maritimum, 92.38, 73.84 and 65.34%, respectively. In the DPPH assay, P. lentiscus and M. communis presented the best activity and their inhibitions were not different from each other (*p<0.05) but were significantly different from the pure standards rutin and BHA. Among the tested plants, Scilla maritima presented the best nitric oxide scavenging activity. In the β-carotene assay, extracts of M. communis leaves and fruits and P. lentiscus leaves were the most potent with 63.60, 47.61 and 43.02%, respectively. Metal chelating activity assay showed that E. maritimum leaves and stem and M. communis leaves had the best chelating power, 49.78, 32.32 and 35.98%, respectively.