LC–MS/MS Phenolic Profiling and Antioxidant, Antimicrobial, and Antidiabetic Activities of Caucasian Propolis

Propolis is a natural bee product rich in phenolic and flavonoid compounds and is well known for its remarkable biological properties. In this study, the phenolic compositions of propolis samples collected from various localities in the Caucasus region of Türkiye were characterized using LC–MS/MS, and their antioxidant, antidiabetic, and antibacterial activities were also evaluated. LC–MS/MS analyses identified caffeic acid, ferulic acid, and p-coumaric acid as the major phenolic acid compounds, while pinocembrin, chrysin, and galangin were determined as the major flavonoid constituents. Overall, these findings indicate that the antioxidant capacity of propolis samples obtained from different regions may be particularly associated with these key phenolic and flavonoid compounds. Consistent with this composition, total phenolic and flavonoid contents ranged from 34.72 to 120.54 mg GAE/g and 6.88 to 47.19 mg QE/g, respectively. The extracts exhibited a relatively high antioxidant capacity, with FRAP values between 60.47 and 311.87 mg TE/g and DPPH IC50 values ranging from 215.80 to 37.96 µg/mL. Regarding antidiabetic activity, the IC50 values for α-amylase and α-glucosidase inhibition were determined as 5.86–3.47 and 12.22–5.02 mg/mL, respectively, indicating a pronounced antidiabetic potential. Antimicrobial analyses revealed activity against E. faecalis, B. cereus, E. coli, K. pneumoniae, and C. albicans. Overall, this study provides a comprehensive LC–MS/MS-based phenolic profile of Caucasian propolis and demonstrates its antioxidant properties together with its antidiabetic potential.