Identifying of Phenolic Content, Antimicrobial and Antioxidant Activities of Lonicera caucasica Pallas subsp. Orientalis Leaves

Abstract

: The extracts' antioxidant and antimicrobial properties are linked to phenolic compounds, one of the most abundant classes of secondary metabolites. In order to add new information to the scientific literature, it is crucial to investigate the phenolic content and bioactivity of previously unstudied or unknown plant parts. Lonicera caucasica Pallas subsp. orientalis is an endemic species that grows in a few cities in Turkey. In this study, methanolic extraction of Lonicera caucasica leaves was performed, and the obtained fraction was analyzed by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) to determine the phenolic content of the extract. The amounts of 22 of the 56 identified phenolic compounds were determined. The three highest of these are chlorogenic acid (2.223 ± 0.065 mg g-1), quinic acid (2.163 ± 0.057 mg g-1) and syringic acid (1.192 ± 0,036 mg g-1). At the same time, the antioxidant activities of the extracts were examined and ABTS•+ and DPPH• (SC50, mg/mL) values were determined as 0.0135 ± 0.0001 and 0.0136 ± 0.0001, respectively. In addition, the obtained extract was tested against three gram-negative (P. aeruginosa, E. aerogenes and E. coli) and three gram-positive (E. fecalis, B. megaterium and S. pyogenes) bacteria and the results were recorded. The best antimicrobial activity was observed at 19.33 mm against P. aeruginosa at a dose of 3.9 mg mL-1. These results show that Lonicera caucasica leaves have rich phenolic content, high antioxidant activity, and a strong antimicrobial effect.