Evaluation of Antimicrobial and Biofilm Inhibitory Activities of Flower, Leaf, Seed, and Pulp Extracts of Mahonia aquifolium (Pursh) Nutt.

Abstract

Mahonia aquifolium (Pursh) Nutt. is a medicinal plant traditionally used for its antimicrobial and anti-inflammatory properties, largely attributed to its phytochemical contents. However, comprehensive evaluations of its antimicrobial and antibiofilm activities across different plant parts remain limited. This study investigated the antimicrobial, and antibiofilm profiles of 70% ethanol and n-hexane extracts obtained from the flowers, leaves, pulp, and seeds of M. aquifolium. Antimicrobial activity was assessed against standard bacterial strains (Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL B-3711, Enterococcus faecalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853) and yeasts (Candida albicans ATCC 90028, Candida krusei ATCC 6258) using agar diffusion and broth microdilution methods. Leaf and flower 70% ethanol extracts exhibited the strongest antimicrobial effects, with MIC values as low as 0.625-1.25 mg/mL for Gram-positive bacteria and 1.25-2.5 mg/mL for P. aeruginosa, whereas antifungal activity remained weak across extracts. Agar diffusion results aligned with MIC data, showing the largest inhibition zones for leaf and flower ethanol extracts. Biofilm assays revealed significant inhibition (60-75%) of S. aureus and P. aeruginosa biofilms, especially by leaf 70% ethanol, flower 70% ethanol, and fruit pulp n-hexane extracts. These findings demonstrate that M. aquifolium possesses notable antibacterial and antibiofilm potential, positioning it as a promising natural source for anti-infective and anti-virulence agents, particularly against biofilm-forming pathogens.