Phytochemical Profiles, Antimicrobial and Antioxidant Activity of Knautia integrifolia (L.) Bertol. subsp. integrifolia

The genus Knautia (L.) (Caprifoliaceae) is widely distributed in the Mediterranean region and is represented by 11 species of flora in Turkey. This study conducted a detailed phytochemical investigation of the methanol extract of the whole plant of K. integrifolia using a combination of LC-ESI-FT-MS and NMR analyses. According to the results of this analysis, 25 compounds were identified in the methanol extract of K. integrifolia. The extract is particularly rich in phenolic secondary metabolites, including phenolic acid derivatives, flavonoid glycosides, and flavones, along with the presence of triterpenoid compounds. Additionally, the total phenolic content of the K. integrifolia methanol extract was evaluated. Considering the pharmacological activities reported for Knautia species, the antioxidant potential of the methanol extract was assessed using the DPPH radical scavenging assay, resulting in a value of 77.5% when compared to the ascorbic acid standard. In this study, antimicrobial activity tests were performed on K. integrifolia methanol extract for the first time. The results indicated that the extract demonstrated greater susceptibility to Staphylococcus epidermidis compared to the control group. At the same time, Pseudomonas aeruginosa exhibited a minimum inhibitory concentration value, indicating high sensitivity to the methanol extract.