Effect of Aqueous and Alcoholic Extracts of Ashwagandha Roots on the Virulence Factors of Pseudomonas Aeruginosa

Abstract

Background: Since most studies on the Ashwagandha plant include the study of the leaf extract, this study included the roots of this plant and studied their effect on Pseudomonas aeruginosa bacteria.

Methodology: The minimum inhibitory concentration (MIC) of both aqueous and alcoholic extracts of ashwagandha root was determined using the Broth dilution method.⁽³⁾ A series of dilutions of 40, 80, 160, and 320 mg/ml of the extracts were prepared in sterile Mueller-Hinton Broth medium, and a fixed volume of a standard bacterial solution (10⁶ CFU/ml) of an effective isolate of Pseudomonas aeruginosa was added to each tube.⁽⁴⁾ The tubes were incubated at 37°C for 24 hours, and turbidity was observed to determine the lowest concentration that inhibited apparent bacterial growth.⁽⁵⁾ The concentration at which no visible growth occurred was considered the minimum inhibitory concentration (MIC) and was recorded for each extract separately to compare the efficacy of the aqueous and alcoholic extracts.

Results: The results of the minimum inhibitory concentration (MIC) test   of ashwagandha root extract against Pseudomonas aeruginosa showed that both the aqueous and alcoholic extracts exhibited a similar pattern of inhibition. At a concentration of 40 mg/ml, the bacteria continued to grow, indicating that this concentration was insufficient to inhibit bacterial activity. At a concentration of 80 mg/ml, weak or intermittent growth was observed, indicating a partial effect of the extract but insufficient to completely eliminate the bacteria. At the two higher concentrations, 160 and 320 mg/ml, no bacterial growth was observed, indicating that the MIC was 160 mg/ml for both extracts. This effect is explained by the presence of active antibacterial compounds in ashwagandha roots, such as withanolides, which exhibit increased activity with increasing concentration, leading to penetration of the bacterial cell wall or inhibition of essential biosynthetic pathways, thus preventing the growth of P. aeruginosa.

Keywords: aqueous and alcoholic extracts, Ashwagandha roots, virulence factors, Pseudomonas aeruginosa