Antimicrobial and Antioxidant Potential of Specialized Metabolites From Rubus ulmifolius Schott: A Combined Experimental and Computational Approach

Abstract

The specialized metabolite profile of Rubus ulmifolius Schott leaves collected in Algeria was investigated, and their biological activities were evaluated using complementary in vitro and in silico approaches. Leaf extracts were obtained by maceration followed by n ‐hexane and dichloromethane fractionation, as well as by Soxhlet extraction using n ‐hexane. Quantitative analyses of polyphenols, flavonoids, and flavonols showed that phytochemical contents varied according to the solvent polarity and extraction method, a pattern further confirmed by GC‐MS analysis of the chemical profiles. In vitro antioxidant assays indicate that HE‐M ( n ‐hexane fraction after maceration) exhibited the strongest activity, particularly in ABTS + (IC 50 = 12.76 ± 0.26 µg/mL) and phenanthroline ( A 0.5 = 19.33 ± 0.95 µg/mL) assays, reflecting higher radical scavenging and metal‐chelating capacities. Antimicrobial assays revealed that all extracts exhibited moderate to notable antibacterial and antifungal effects against certain strains, whereas DM‐M (dichloromethane fraction) displayed particularly strong activity against most tested strains. Molecular docking against bacterial DNA gyrase‐A (GyrA) showed that glycerol monostearate, phytol, and methyl caffeate demonstrated favorable binding energies and interactions, providing a plausible molecular explanation for the observed antibacterial activity. Overall, these findings suggest that specialized metabolites produced by R. ulmifolius possess significant antioxidant and antibacterial potential, highlighting their promise as natural bioactive agents.