Evaluation of the antioxidant activity of aromatic plants from Valsesia

Popular medical traditions that developed during time begin to find solid scientific bases for their right use and application in officinal medicine. The historical isolation of populations living in the Alpine valley and the uniqueness of the organism which developed without particular contaminations by cultivations transferred by humans, allowed to preserve these traditions. The ethnobotanic traditions of Valsesia, an example of uncontaminated habitat and rich autochthonous flora, are well known thanks to doctors and botanics. In this valley, there are a lot of aromatic plants species, some of which were eveluated in the first part of our study (ie, Achillea distans Waldst. et Kit, Achillea moschata Wulf., Artemisia genepì Weber, Cardamine amara L., Gentiana kochiana Perr. et Song., Thymus alpestris Tausch., Thymus froelichianus Opiz, Thymus pulegioides L, an hybrid Thymus species and Valeriana collina Wallroth). Concerning the Thymus genus, we also examined a trade sample (T. vulgaris) with the aim to comparing it with the spontaneous species. As polyphenols are ascribed interesting antioxidant properties, our research focused on the presence of these compounds in the raw extracts and on their in vitro activity. Therefore, our work developed trough the following phases: species finding and determination in loco; drying at room temperature; extractions with increasing polar solvents: n-hexan, chloroform, chloroform-methanol (9:1), and methanol; polyphenols content; scavenging of the stable radical DPPH; antioxidant capacity (Cu++ to Cu+ reduction); LDL oxidation. The abundance of polyphenols in the extracts differed among the species, the richest ones belonging to the Thymus and Achillea geniuses. These differences, however, did not significantly correlate with the results of the antioxidant tests. Indeed, apart from the polyphenolic content, all of the extract showed a strong activity at 10-5 M concentrations, as compared with 10-6 M, in the evaluation of LDL oxidation and Cu++ reduction. Concerning DPPH, most extracts had an EC50 in the order of 10-6 M. We would like to point out the remarkable antioxidant capacity showed by Cardamine amara, the specie with the lowest polyphenolic content among all the examined species. Future development of this work includes an extension of the study to fractions of these extracts and to other species of aromatic plants that characterize Valsesia.