Investigation of phenolic acids and some biological activities of Nepeta macrosiphon

Phenolic acids are secondary metabolites which have many biological activates, which are found at different organs of plants and have an important role in human health. In this study, the extraction from different organs of Nepeta macrosiphon was done using ethanol 80% as solvent, and divided into free and esterified phenolic acids. Then, the total phenolic and flavonoid contents, antioxidant activity and inhibition of alpha-glucosidase enzyme of the extracts and their fractions were evaluated by using Folin-Ciocalteu, aluminum chloride, DPPH and spectrophotometric methods, and finally their compounds were analyzed by HPLC. The results indicated that the ethanolic extract of flower had the highest total phenolic and flavonoid, respectively. Also, this extract showed the highest antioxidant activity. Moreover, the flower extract had a greater ability to inhibit the alpha-glucosidase enzyme. The results of phenolic acids analysis showed that among the studied organs, flower had the highest amount of phenolic acids, and rosmarinic acid and para-coumaric acid were the main free phenolic acid, respectively, and caffeic acid was the main compound in the flower extract of esterified phenolic acids. Also, the flower extract containing free phenolic acids had the highest antioxidant activity and inhibition of alpha-glucosidase enzyme in comparison with the extracts containing esterified phenolic acids and other organs. Based on the results, the flower have the highest phenolic compounds, including rosmarinic, para-coumaric, and caffeic acids and due to its high antioxidant potential and inhibition of alpha-glucosidase enzyme, it can be used in the pharmaceutical and food industries.