Antioxidant, anti-inflammatory, acetylcholinesterase and thioredoxin reductase inhibitory activities of nine selected Turkish medicinal plants

Abstract

Ethyl acetate, methanol, dichloromethane, petroleum ether and water extracts of nine selected plant species, which are commonly used as herbal medicines for anticancer and anti-inflammatory purposes in Turkey, were evaluated for their total phenolic and flavonoid contents and <em>in vitro</em> antioxidant potency with a thiobarbituric acid assay using the lipid peroxidation of phosphatidylcholine liposomes, DPPH&middot; and ferric ion reducing antioxidant power assays. Inhibitory activity against cyclooxygenase (COX) was used to evaluate the anti-inflammatory activities of the extracts. As thioredoxin reductase (TrxR) has emerged as a new target for anticancer drug development, the extracts were investigated for their inhibitory activities on TrxR. The ability of the extracts to inhibit acetylcholinesterase (AChE), which is a target for cholinesterase inhibitors, used for the symptomatic treatment of Alzheimer&rsquo;s disease, was also examined. The results showed that the extracts of <em>C. coggygria</em> and <em>M. officinalis</em> subsp. <em>officinalis</em> are the most effective hydrogen and electron donors and contained the highest amounts of phenolic compounds; thus, they can be considered the best antioxidants among the nine plants selected for the study. All the plants showed inhibitory effects against AChE, COX-1 and COX-2, therefore may be of potential therapeutic interest for the treatment of neurodegenerative and inflammatory disorders. It was found that <em>M. officinalis</em> subsp. <em>officinalis, C. coggyria</em>, <em>S. aucuparia</em> and <em>P. major</em> subsp. <em>major</em> have a strong inhibitory effect on TrxR by up to 99 %, highlighting their potential as preventive therapeutics for cancer. This study confirmed the use of these plants in folk medicine as anti-inflammatory and anticancer agents.