Antimicrobial and antioxidant activities and phenolic contents of extracts from Verbascum insulare and Inula helenium subsp. pseudohelenium plants

The aim of this study was to investigate the antimicrobial, antioxidant activities and phenolic contents of extracts from two different plants, namely, Verbascum insulare and Inula helenium subsp. Pseudohelenium collected from Muş province in Turkey. For this purpose, the ethanol and pure water extracts were obtained from the leaf and root parts of such plants and investigated using HPLC. The test results showed that none of gallic acid, salicylic acid and vanillin was found in the leaf ethanol extract of I. helenium, gallic acid was not present in the root ethanol extract only. While the leaf pure water extract did not contain gallic acid, vanillin and curcumin, the root pure water extract did not comprise gallic acid, kaempferol, vanilin, salicylic acid and curcumin. Gallic acid was not identified in any of the extracts. Curcumin and salicylic acid were not found in the leaf pure water extract of V. insulare plant, whereas vanillin was not present in its root pure water extract. Similarly, gallic acid was not detected in any of the extracts. The ethanol extracts of I. helenium leaves and roots showed antimicrobial activity against all microorganisms in this study, whereas pure water extracts displayed antifungal activity against fungi only. Although all V. insulare extracts were found to show antifungal activity against fungi, none of them showed antimicrobial activity. It was also observed that V. insulare ethanol extract showed better antifungal activity in comparison with the pure water extract. Another important finding of this study was that I. helenium extracts possessed strong antioxidant features. Particularly, in the removal of DPPH radicals and inhibition of lipid peroxidation, they showed similar or higher activity than BHA and BHT standard antioxidants. In terms of the antioxidant properties of the V. insulare extracts, ethanol extract was seen to show better activity than pure water extract. In general, particularly V. insulare ethanol extract showed higher activity than standard antioxidants (BHA and BHT).