Comparative Evaluation of Antioxidant and Antibacterial Activities of Methanolic and Ethanolic Leave and Rhizome Extracts of Curcuma Caesia Roxb. And Curcuma Longa L.

The increasing prevalence of antimicrobial resistance and oxidative stress-related disorders has stimulated the search for effective natural bioactive compounds from medicinal plants. The present study aimed to comparatively evaluate the antibacterial and antioxidant potential of methanolic and ethanolic extracts of leaves and rhizomes of Curcuma caesia roxb. and Curcuma longa L. Fresh plant materials were shade-dried, powdered, and extracted using methanol and ethanol through maceration. Antibacterial activity was assessed against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae using the agar well diffusion method, while antioxidant activity was determined by the DPPH free radical scavenging assay.All extracts exhibited varying degrees of antibacterial and antioxidant activities. Among the tested samples, the methanolic rhizome extract of Curcuma caesia roxb. demonstrated the strongest antibacterial activity, producing inhibition zones of 18.53 ± 0.20 mm against E. coli, 21.27 ± 0.32 mm against S. aureus, 15.87 ± 0.18 mm against P. aeruginosa, and 19.43 ± 0.20 mm against K. pneumoniae. Methanolic extracts generally exhibited higher antibacterial activity than ethanolic extracts, while rhizome extracts were more effective than leaf extracts. The DPPH assay revealed concentration-dependent antioxidant activity for all extracts. The methanolic rhizome extract of Curcuma caesia roxb. exhibited the strongest antioxidant activity among the plant samples, with 86.27 ± 0.58% inhibition at 300 µg/ml and an IC₅₀ value of 104.5 ± 3.5 µg/ml. Antioxidant activity followed the order: Ascorbic Acid > CCR(M) > CCR(E) > CLR(M) > CCL(M) > CLR(E) > CCL(E) > CLL(M) > CLL(E). Overall, Curcuma caesia roxb. exhibited superior antibacterial and antioxidant activities compared with Curcuma longa L., and methanolic extracts were consistently more potent than ethanolic extracts. The findings support the traditional medicinal use of these species and highlight the rhizomes of Curcuma caesia roxb. as promising sources of natural antibacterial and antioxidant compounds for future pharmaceutical and nutraceutical applications.