Antimicrobial Evaluations of Juglans Regia Bark Against Oral Pathogenic Microorganisms

Oral pathogenic microorganisms significantly contribute to various diseases, impacting both oral and systemic health, including chronic periodontitis and dental caries. Natural plants, including Juglans regia (walnut tree), have gained momentum for their therapeutic potential due to their antibacterial properties, offering a promising avenue to combat antibiotic resistance. This study fundamentally aimed to validate the traditional use of Juglans regia bark in maintaining oral health; it sought to evaluate the antibacterial and antifungal effects of Juglans regia bark. The methanolic extracts of Juglans regia bark, imported from China, were prepared using the maceration technique, various microorganisms procured from the American Type Culture Collection (ATCC), including Gram-positive bacteria (Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA)), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and the local fungal strain Candida albicans. Antimicrobial activity was assessed using the agar well diffusion assay at concentrations of 250 mg/ml and 125 mg/ml, with chlorhexidine and phenol serving as reference standards. Minimum inhibitory concentrations (MIC) were determined using the microdilution technique, with serial dilutions ranging from 125 mg/ml down to 3.9 mg/ml. At 250 mg/ml, Escherichia coli exhibited the largest zone of inhibition (27mm), followed by Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans (25mm, 23mm, and 25mm, respectively). At 125 mg/ml, Candida albicans showed the best results (22mm). The lowest effective inhibitory concentration (MIC) for C. albicans was 15.6 mg/ml, while S. aureus and P. aeruginosa also showed equal MICs.