Antimicrobial and Antioxidant Activities of Phenolic Compound Extracted from New Verbascum Species Growing in Turkey

Abstract

The aim of this study was to evaluate the antimicrobial and antioxidant potential of the aerial parts of four new Verbascum L. (Scrophulariaceae) species namely, Verbascum bellum Hub.-Mor., Verbascum detersile Boiss. & Heldr., Verbascum myriocarpum Boiss. & Heldr. and Verbascum pestalozzae Boiss., growing in Turkey. Plant materials were extracted with chloroform, ethylacetate and methanol for antimicrobial tests. These extracts were assayed against both gram-positive and gram-negative bacteria by the microdilution method. The minimum inhibitory concentrations of the Verbascum species varied between 150-0.59 mg/ml. In general, ethylacetate extract was effective for E.coli (ATCC 25922, 1.88 mg/ml). Ethyl acetate extract of V. pestalozzae exhibited the highest effect on P. aeroginosa (ATCC 29853, 0.59 mg/ml). The antioxidant capacity of the studied species was only tested with methanol extracts. Their antioxidant action was tested by DPPH and β-carotene-linoleic acid methods. While V. pestalozzae (IC₅₀=15 µg/ml) exhibited the strongest activity in DPPH assay, V. detersile and V. pestalozzae provided an excellent inhibition effect (100% RAA) in the β-caroten- linoleic acid system. HPLC analysis of methanol extracts was also carried out to determine the composition of the phenolic compounds responsible for the activity. Methanol extracts were also subjected to HPLC analysis to determine their phenolic compound profile.