Evaluation of phytochemical constituents and antibacterial properties of crude ethanolic extract from turmeric (Curcuma longa L.) rhizomes against Escherichia coli

Antimicrobial resistance (AMR) is a critical global health concern that necessitates the discovery of novel therapeutic agents, including plant-derived compounds. Turmeric (Curcuma longa L.), widely recognized in traditional medicine, contains bioactive constituents with reported antimicrobial potential. This study evaluated the antibacterial activity of crude ethanolic extract from C. longa rhizomes against Escherichia coli, a Gram-negative pathogen prioritized by the World Health Organization due to its rising multidrug resistance. Fresh turmeric rhizomes were collected, shade-dried, pulverized, and subjected to Soxhlet extraction using 80% ethanol. The crude extract yield was 8.78%. Phytochemical screening revealed the presence of flavonoids, saponins, and tannins, compounds known for their diverse pharmacological activities. Antibacterial activity was assessed using the disk diffusion method at concentrations of 25, 50, and 100 mg/mL. Ciprofloxacin (5 mcg/disc) served as the positive control, while 1% dimethyl sulfoxide (DMSO) acted as the negative control. Results indicated that the crude ethanolic extract did not produce measurable zones of inhibition against E. coli at any tested concentration, while ciprofloxacin exhibited significant inhibition (25.67 ± 12.70 mm). Statistical analysis (ANOVA, p = 0.073) confirmed the absence of significant antibacterial activity. The findings suggest that crude ethanolic extracts of turmeric may have limited efficacy against Gram-negative bacteria under standard laboratory conditions. Nonetheless, the presence of bioactive phytochemicals highlights turmeric’s potential as a natural antimicrobial source. Further research employing optimized extraction methods, advanced formulations, or synergistic approaches is recommended to unlock its therapeutic potential in addressing AMR