Evaluation of resveratrol content of some Polygonum L.species growing in Turkey

Resveratrol is a phytoalexin with a phenolic structure occurs against pathogens in plants and medicinal plants such as grape skin (Vitis vinifera L.) and Japanese knotweed (Polygonum cuspidatum Sieb. et Zucc.) are its main source, as well as peanuts (Arachis hypogea L.) and wine. Resveratrol is sold as a food supplement due to its different pharmacological properties such as anti- inflammatory, cardioprotective, anticancer, antioxidant, and anti-aging effects and is frequently used in cosmetic products. The genus Polygonum L., which is in the Polygonaceae family, is represented by 43 taxa, 8 of which are endemic in Turkey. The biological activity studies like wound healing, anti-inflammatory, antibacterial, antiviral, antioxidant, immunomodulator, anti-aging, and estrogenic effects on different Polygonum species were conducted with in vitro / in vivo / in silico methods, and it was concluded that resveratrol was responsible for some of these activities. For this reason, Polygonum species attract attention because of being a source of resveratrol as well as being used as food and for medicinal effects in traditional medicine. Polygonum species grown in our country have not been evaluated in terms of resveratrol content before and have been evaluated for the first time within the scope of this thesis. The plant material of P. aviculare L., P. cognatum Meissn., P. patulum Bieb. subsp. patulum and P. setosum Jacq. subsp. setosum was collected from Konya in May 2020. Resveratrol was not detected by LC-MS QTOF in ethanolic extracts prepared from different parts of the plant species. However, based on the literature survey on recent studies, the P. cuspidatum species, which is used as a source of resveratrol in Japan and China, was distinguished from the Polygonum genus and passed into the Reynoutria genus; hence, now the accepted plant name is Reynoutria japonica. The ethanol prepared from the aerial parts and roots of Polygonum species were tested for cosmetic-related elastase, collagenase and tyrosinase (TYR) enzyme inhibitory activities at different concentrations using an ELISA microplate reader, considering the similar studies in the literature. Root extracts of Polygonum species were found to have moderate TYR inhibitory activity, and P. cognatum root extract showed potent inhibition against collagenase. Our results indicated that P. aviculare root extract had the highest anti-elastase activity at a concentration of 333 µg/mL. Based on our results it was concluded that the Polygonum species studied have inhibitory activity against cosmetics-related TYR, elastase, collagenase enzymes, and the activities were higher in extracts prepared from the roots of the plants. With the LC-MS QTOF analysis performed on the extracts, we concluded that catechin and quercetin glucosides might be the compounds responsible for the activities.