Plant-part specific in vitro antibacterial activity of crude ethanolic extracts of Mangifera indica against Salmonella typhi: an exploratory laboratory study

Background Medicinal plants remain widely used in the management of infectious diseases in low- and middle-income countries, yet experimental evidence supporting the antibacterial activity of specific plant parts remains inconsistent. This study evaluated the plant-part–specific antibacterial activity of crude ethanolic extracts of Mangifera indica against Salmonella typhi under controlled laboratory conditions. Methods An exploratory in vitro study was conducted using crude ethanolic extracts prepared from the seed kernel, stem bark, and root of Mangifera indica , as well as a combined extract. Antibacterial activity was assessed using the agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using broth microdilution and sub-culture techniques. A standardized bacterial inoculum (0.5 McFarland) of Salmonella typhi was used. Experiments were conducted in triplicate (n = 3). Tetracycline (6.667 µg/mL) served as the positive control, while dimethyl sulfoxide (DMSO) was used as the negative control. All assays were incubated at 37°C for 24 hours. Results The seed kernel extract demonstrated measurable antibacterial activity, producing a mean zone of inhibition of 18.0 ± 0.7 mm. The combined extract showed lower activity (11.5 ± 0.7 mm), while stem bark and root extracts showed no detectable activity. One-way ANOVA demonstrated a statistically significant difference among treatments, p < 0.0001. Both active extracts exhibited an MIC of 16.67 mg/mL and an MBC of 33.34 mg/mL. The MBC/MIC ratio was 2 for both extracts, which is consistent with bactericidal activity under the in vitro conditions employed. Conclusions Crude ethanolic extract of Mangifera indica seed kernel exhibited in vitro antibacterial activity against Salmonella typhi , with evidence of plant-part specificity and reduced activity in combined extracts. These findings are limited to preliminary laboratory observations and do not imply clinical effectiveness.