Phenolic Profiling of Laurus nobilis by LC-ESI-MS/MS: In Vitro Bioactivities and In Silico Enzyme Docking

This study evaluated the branch, leaf, and fruit extracts of Laurus nobilis collected from Artvin in terms of phenolic composition, antioxidant, antimicrobial, and antidiabetic activities and additionally investigated the binding of selected phenolics to α-amylase/α-glucosidase targets through molecular docking. Using LC-ESI-MS/MS analysis, 31 phenolic compounds were quantitatively identified, with epicatechin, luteolin-7-O-glucoside, and rutin predominating particularly in the branches and leaves. Antioxidant capacity was higher in branches and leaves (total phenolic content [TPC]/FRAP/DPPH IC₅₀: branches and leaves, respectively, 95.27-60.84 mg gallic acid equivalent [GAE]/g, 206.16-162.05 mg Trolox equivalent [TE]/g, and 46.95-113.49 µg/mL). Antimicrobial activity was observed within a minimum inhibitory concentration (MIC) range of 1.25-10 mg/mL; leaves exhibited the strongest effect against Bacillus cereus (1.25 mg/mL), whereas fruits were most effective against Candida albicans (1.25 mg/mL). In antidiabetic evaluation, fruits yielded the lowest IC₅₀ values against α-amylase and α-glucosidase (4.31 and 8.97 mg/mL, respectively), suggesting a "composition-over-quantity" effect despite low total phenolic content. Docking results supported high binding affinities of rutin (α-glucosidase -9.3 kcal/mol; α-amylase -8.1 kcal/mol) and luteolin (-8.6 kcal/mol for both enzymes). Overall, although branches and leaves exhibited strong antioxidant profiles, fruits showed more pronounced inhibitory effects on digestive enzymes; therefore, fractionation studies and in vivo/kinetic validations are recommended.