Phytochemical profiling and in vitro antioxidant, enzyme-inhibitory, antibacterial, and photoprotective activities of Coronilla minima L. fractions

Abstract

Coronilla minima L. is a Mediterranean Fabaceae species whose phytochemical composition and biological properties remain incompletely characterized. This study profiled the phenolic constituents of methanolic, ethyl acetate, and n-hexane fractions and evaluated their in vitro antioxidant, enzyme-inhibitory, antibacterial, and photoprotective activities. Preliminary phytochemical screening and spectrophotometric determination of total phenolic and flavonoid contents were followed by LC–ESI–MS/MS analysis. Antioxidant activity was assessed using DPPH, reducing-power, silver-nanoparticle, and phenanthroline assays; α-amylase and acetylcholinesterase (AChE) inhibition, agar-disc antibacterial activity, and spectrophotometric sun protection factor (SPF) were also determined. LC–ESI–MS/MS detected 19 compounds among 44 authenticated standards, with chlorogenic acid showing the highest concentration in the methanolic fraction (122.79 µg/g). Rutin (29.46 µg/g), hesperidin (28.67 µg/g), and isoquercitrin (28.50 µg/g) were the most abundant flavonoids. The ethyl acetate fraction generally showed the strongest in vitro activity, including DPPH scavenging (IC50 41.87 ± 0.48 µg/mL), α-amylase inhibition (IC50 113.98 ± 4.65 µg/mL), and AChE inhibition (IC50 11.75 ± 1.84 µg/mL). Antibacterial effects were confined mainly to Gram-positive strains, whereas no tested fraction inhibited Escherichia coli. The three fractions showed similar in vitro SPF values (43.56–44.85). These findings identify C. minima as a source of phenolic constituents with multiple in vitro bioactivities, while further mechanistic, toxicological, and in vivo studies are required before therapeutic or cosmetic applications can be considered.