Correlation among phenolic, toxic metals and antioxidant activity of the extracts of plant species from Southeast Serbia

The content of metals, total phenols, flavonoids and antioxidant activities of different plant extracts, used in Serbian traditional medicine, were determined. Phenol content determined using UV-Vis spectrophotometer measurements at 765 nm in the tested plant extracts obtained by standard extraction procedure decreases in the order Origanum vulgare L. < Delphinum consolida L. < Cichorium intybus L. < Calendula officinalis L. The tested extracts, examined by DPPH (di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium) method, showed high antioxidant activity that correlates significantly with the content of phenols and flavonoids. The contents of metals (Zn, Fe, Cu, Mn, Cd, Cr, Pb) were determined by flame atomic absorption spectrometer. Toxic metals, such as Cd, Cr, Pb, were not detected in the investigated plants. Content of other metals in plants and their extracts were low, except content of Fe. We examined the correlation of metals (Zn, Fe, Cu, Mn) and phenolic compounds content in the extracts using PCA (principal component analysis). The investigated plants from Southeastern Serbia are suitable for the preparation of teas and herbal extracts, due to the low content of toxic metals (Zn, Fe, Cu, Mn), the high content of phenolic compounds and high antioxidant activity. KEY WORDS: Toxic metals, Phenols, Flavonoids, Antioxidant activity, Correlation analysis