Investigation of phytochemical composition and potential antioxidant activity of Campanula cymbalaria (Campanulaceae) species

In the present thesis study, the antioxidant properties and phenolic compound contents of methanol (MetOH) extracts obtained from the leaf and flower tissues of Campanula cymbalaria var. papillosa were comprehensively evaluated. The total phenolic content (TPC) in the leaf and flower MeOH extracts was determined as 54.39 mg GAE/g and 40.80 mg GAE/g, respectively. The total flavonoid content (TFC) was found to be 58.89 mg QE/g in the leaf extract and 33.54 mg QE/g in the flower extract. In terms of total antioxidant capacity, the leaf extract exhibited an ascorbic acid equivalent of 150.98 mg AE/g, while the flower extract showed 122.83 mg AE/g. The copper ion reducing capacity, measured by the CUPRAC method, was found to be 128.73 mg TE/g in leaves and 99.18 mg TE/g in flowers. The iron ion reducing capacity, determined by the FRAP method, was 63.24 mg TE/g in leaves and 61.79 mg TE/g in flowers. Additionally, the ABTS⁺ and DPPH radical scavenging activities of the leaf and flower MeOH extracts were evaluated. The ABTS⁺ activity of the leaf extract was 74.39 mg TE/g and the DPPH activity was 69.39 mg TE/g, whereas the flower extract showed an ABTS⁺ activity of 50.03 mg TE/g and a DPPH activity of 54.99 mg TE/g. LC-MS/MS analysis using 53 standards identified 25 phenolic acids. Among the phenolic compounds, quinic acid was found in higher amounts in the flower tissue (54.418 mg analyte/extract) compared to the leaf tissue (38.253 mg analyte/extract). On the other hand, syringic acid was more abundant in the leaf tissue (19.615 mg analyte/extract) than in the flower tissue (11.868 mg analyte/extract). Tannic acid, astragalin, quercetin, naringenin, hesperidin, and kaempferol were detected only in the flower tissue. These data indicate that C. cymbalaria var. papillosa, particularly its leaf tissue, possesses a high phenolic content and strong antioxidant capacity.