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Georgia Journal of Science

Article Title

INVESTIGATION OF ANTIBACTERIAL EFFECTS OF SOUTHERN APPALACHIAN PLANTS: PHYTOLACCA AMERICANA AND JUGLANS NIGRA ON SELECTED BACTERIA **

Abstract

Juglans nigra L. (Black Walnut) and Phytolacca americana L. (American Pokeweed) have both been used in folk medicine traditions as treatments for disorders ranging from shingles to rheumatism. Many plants used in folk medicines, like Xanthorhiza simplicissima Marshall (Yellowroot) and Sanguinaria canadensis L. (Bloodroot) have been found previously to have antibacterial properties. In this study, the antibacterial properties of J. nigra and P. americana were investigated against Escherichia coli, Salmonella enteritidis, and Enterococcus faecalis. A Disc Diffusion Assay Method was employed to identify any potential antibacterial properties of both plants. For this experiment, 6.25 g of dehydrated plant material (either J. nigra nut husks or P. americana berries) was combined with 50 mL of 75% ethanol creating their respective tinctures. The antibacterial activity of the tinctures were tested against a 75% ethanol control. Sterile filter paper discs were soaked in the tinctures or ethanol. These discs were placed in petri dishes of Mueller-Hinton agar that were inoculated individually with the above bacterial species (bacterial concentrations were standardized using the 0.5 McFarland Standard). After 24 hours of incubation at 37° the zones of inhibition were measured for each bacteria/tincture combination. For J. nigra tinctures: E. coli 7.7±2.4 mm vs. control 5.1±2.8 mm; E. faecalis 3.1±1.1 mm vs. control 0.5±0.9 mm; and S. enteritidis 8.2±2.8 mm vs. control 4.3±1.4 mm (n=20 for each). Mean zones of inhibition for P. americana tinctures were: E. coli 0.4±1.2 mm vs. control 0.2±0.6 mm; E. faecalis 1.0±1.3 mm vs. control 0.5±0.9 mm; and S. enteritidis 0.0±0.0 mm vs. control 0.0±0.0 mm (n=20 for each). J. nigra tincture showed significantly greater inhibition of all bacterial species tested (t-test, p<0.05) while P. americana tincture showed no significant inhibition of bacteria. A Minimum Inhibitory Concentration (MIC) test for J. nigra tincture is now in progress.

Acknowledgements

YHC Biology Dept.

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