Determination of phenolic content and antioxidant activity of Inula viscosa L. Aiton

Abstract

The phenolic profile of three distinct extracts (petroleum ether (IVPE), acetone (IVA) and methanol (IVM)) derived from the aerial parts of the medicinal species Inula viscosa L. Aiton was determined using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). In this study, the analysis of phenolic compounds in petroleum ether and acetone extracts and the total phenolic content (TPC) for I. viscosaspecies were reported for the first time. Based on the results, IVA extract was found to be the richest in phenolic content (3189.14 mg/kg) followed by IVM (2509.39 mg/kg) and IVPE (184.37 mg/kg). Rhamnocitrin, dihydrokaempferol, isosakuranetin, nepetin, nepetin-7-glucoside, acacetin, quercetin, verbascoside, and taxifolin were the most prevalent phenolic compounds; the IVA extract contained the highest concentrations of these. In summary, I. viscosa extracts demonstrate significant phenolic content and considerable antioxidant activity. Furthermore, the TPC of these extracts was quantified using the FolinCiocalteu reagent, with IVA showing the highest phenolic content value (440.4 ± 0.001mg GAE/g), followed by IVM (273.7 ± 0.001mg GAE/g), and the lowest value was determined in IVPE (51.8 ± 0.001 mg GAE/g). The antioxidant capacities of the extracts were assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and the cupric ion (Cu²⁺) reducing capacity (CUPRAC) method. According to the DPPH results, IVA exhibited moderate-to-high radical scavenging activity at all concentrations and had the highest CUPRAC value (0.62±0.04), consistent with its elevated phenolic content. The results showed that I. viscosa extracts are rich in phenolic compounds and exhibit strong antioxidant properties.