Phytochemical Composition, Antioxidant and Antimicrobial Activity of the Balkan Endemic <i>Micromeria frivaldszkyana</i> (Degen) Velen. (Lamiaceae)

Abstract

The current study investigates the content of sugars, organic acids, phenolic acids and flavonoids, as well as antioxidant and antimicrobial activity of Balkan-endemic Micromeria frivaldszkyana. Glucose was the most abundant sugar in the plant (2.77%), followed by fructose (1.18%) and galactose (0.82%). Eight organic acids were detected with quinic acid being in the highest content—556.3 mg/100 g DW. From the individual phenolic acids, rosmarinic acid was found in the most significant amounts (2040.1 ± 1.97 mg/100 g) and hesperidin was the major representative of flavonoids with content 131.2 ± 5.6 mg/100 g DW. The antioxidant activity of the plant was studied by six methods: 2,2′-diphenylpicrylhydrazyl (DPPH)—286.4 ± 10.43 mM TE/g, 2,2′azinobis (3)-ethylbenzthiazoline-6-sulfonic acid (ABTS)—358.4 ± 10.4 mM TE/g, ferric reducing antioxidant power (FRAP)—388.0 ± 32.4 mM TE/g, cupric reducing antioxidant capacity (CUPRAC)—905.6 ± 19.2 mM TE/g, Oxygen Radical Absorbance Capacity (ORAC)—3250.5 ± 208.1 µmol TE/g and Hydroxyl Radical Averting Capacity (HORAC)—306.1 ± 23.5 µmol GAE/g. In vitro antimicrobial activity against nine microorganism was evaluated but the extract displayed antimicrobial activity only against Listeria monocytogenes ATCC 19111 with inhibition zone diameter 9 mm and minimal inhibitory concentration (MIC) 10 mg/mL.

Keywords

• <i>Micromeria frivaldszkyana</i>
• polyphenols
• antioxidant activity
• antimicrobial activity