Multi-target neuroprotective effects of herbal medicines for Alzheimer's disease

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 5mg 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 beta-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.

Background Natural antioxidant products are increasingly being used to treat various pathological liver conditions considering the role of oxidative stress in their pathogenesis. Rosemary essential oil has already being used as a preservative in food industry due to its antioxidant and antimicrobial activities, but it was shown to possess additional health benefits. The aim of our study was to evaluate the protective effect of rosemary essential oil on carbon tetrachloride - induced liver injury in rats and to explore whether its mechanism of action is associated with modulation of hepatic oxidative status. Methods Chemical composition of isolated rosemary essential oil was determined by gas chromatography and mass spectrometry. Antioxidant activity was determined in vitro using DPPH assay. Activities of enzyme markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured using the kinetic spectrophotometric methods. Results In this research, we identified 29 chemical compounds of the studied rosemary essential oil, and the main constituents were 1,8-cineole (43.77%), camphor (12.53%), and α-pinene (11.51%). Investigated essential oil was found to exert hepatoprotective effects in the doses of 5 mg/kg and 10 mg/kg by diminishing AST and ALT activities up to 2-fold in serum of rats with carbon tetrachloride - induced acute liver damage. Rosemary essential oil prevented carbon tetrachloride - induced increase of lipid peroxidation in liver homogenates. Furthermore, pre-treatment with studied essential oil during 7 days significantly reversed the activities of antioxidant enzymes catalase, peroxidase, glutathione peroxidase and glutathione reductase in liver homogenates, especially in the dose of 10 mg/kg. Conclusions Our results demonstrate that rosemary essential oil, beside exhibiting free radical scavenging activity determined by DPPH assay, mediates its hepatoprotective effects also through activation of physiological defense mechanisms.