The in vitro screening for acetylcholinesterase inhibition and antioxidant activity of medicinal plants from Portugal

Essential oil, ethanolic extract and decoction of 10 plant species from interior Portugal were analyzed for their activity towards acetylcholinesterase (AChE) enzyme and their antioxidant activity. Of these, Melissa officinalis, Paronychia argentea, Sanguisorba minor, Hypericum undulatum and Malva silvestris are used in herbal medicine, Laurus nobilis and Mentha suaveolens as condiments, and Salvia officinalis, Lavandula angustifolia and Lavandula pedunculata also as aromatics. Melissa officinalis and Mentha suaveolens showed AChE inhibitory capacity higher then 50% in the essential oil fraction. Laurus nobilis, Hypericum undulatum, and Sanguisorba minor showed a high inhibition value of AChE in the ethanolic fraction, 64% (1 mg ml−1) 68% (0.5 mg ml−1), and 78% (1 mg ml−1), respectively. Higher values of AChE inhibitory activity were found using decoctions of Lavandula pedunculata, Mentha suaveolens and Hypericum undulatum, 68, 69 and 82% (at a concentration of 5 mg dry plant ml−1 of assay), respectively. The free radical scavenger activity was higher for the polar extracts. In the water extracts most of the plants showed values around 90%. When antioxidant activity was measured with the β-carotene-linoleic acid assay high activity (65–95%) was also found in the water extracts. Hypericum undulatum, Melissa officinalis and Laurus nobilis showed both high AChE inhibitory capacity and antioxidant activity.