Assessment of Antimicrobial and Antioxidant Activities of Nepeta trachonitica: Analysis of Its Phenolic Compounds Using HPLC-MS/MS

Abstract

Continuing our work on the sources of natural bioactive compounds, we evaluated the antimicrobial and antioxidant activities of <i>Nepeta trachonitica</i> as well as its major phenolic content using the high-performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) technique. For antioxidant activity, ferric reducing antioxidant power (FRAP) and cupric ion reducing antioxidant capacity (CUPRAC) methods were performed to measure the reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was employed to evaluate the radical scavenging activity of the sample. For antimicrobial activity, three Gram-positive and four Gram-negative microbial species as well as three fungi species were tested. <i>N. trachonitica</i> appeared to have reasonable antioxidant activity and decent antimicrobial activity as indicated by the inhibition of the organisms' growth. The most susceptible species were <i>Bacillus subtilis</i> ATCC 6633 and <i>Escherichia coli</i> ATCC 11229 among the organisms tested. Ethanol extract of the plant has the highest effect on <i>Saccharomyces cerevisiae</i> but no effect on <i>Yarrowia lipolytica.</i> The HPLC-MS/MS analysis showed that at least 11 major phenolic compounds of <i>N. trachonitica</i> exist, the major ones being rosmarinic acid, chlorogenic acid and quinic acid. The obtained results suggest that <i>N. trachonitica</i> could be a promising source for food and nutraceutical industries because of its antimicrobial and antioxidant properties and phenolic compounds.