Antimicrobial Effectiveness on Selected Bacterial Species and Alkaloid and Saponin Content of Rosa nutkana C. Presl (Nootka Rose) and Urtica dioica L. (Stinging Nettle) Extracts

Abstract

Nootka rose (Rosa nutkana C. Presl) and stinging nettle (Urtica dioica L.) have been traditionally used in the treatment of skin infection by Indigenous peoples of Vancouver Island, British Columbia, Canada. The main objective of this study was to examine the antibacterial efficacy of extracts of Nootka rose and stinging nettle against the common pathogenic skin bacteria Staphylococcus aureus, Micrococcus luteus, and Pseudomonas aeruginosa using Indigenous science and standard methods of analysis. The Indigenous science method of plant extraction by steeping as advised by the Traditional Knowledge keeper was performed to examine minimum inhibitory concentration (MIC) values and minimum bactericidal concentrations (MBC) by serial dilution and bacterial population counts. Soxhlet extractions and Kirby Bauer disc sensitivity testing showed that Nootka rose extracts possessed antibacterial effectiveness against all three bacterial species while stinging nettle extracts were effective against M. luteus. Results for MIC and MBC indicated antibacterial activity against M. luteus and S. aureus for the Nootka rose when using full-strength solutions; all three bacterial species exhibited growth when undiluted stinging nettle treatments were used. When considering bacterial population counts for S. aureus, results indicated that only the Nootka rose treatment offered effective inhibition. Chemical analysis showed that alkaloid percentage was greater in the stinging nettle (0.17%) than Nootka rose (0.07%), while saponin percentage was greater in the Nootka rose (0.87%) than stinging nettle (0.17%). Overall, Nootka rose showed a greater level of antibacterial effectiveness than stinging nettle by Indigenous and Western scientific methods of plant extract preparation.