Physicochemical analysis and anti-bacterial activity of rhizome of tumeric (Curcuma longa L.) vegetable plants

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Curcuma longa L (Tumeric) a rhizomatous perennial herb belonging to the ginger family Zingiberaceae, was studied to evaluate its physicochemical properties and antibacterial activity against gram-positive and gram-negative bacteria. Two solvent extractions (Aqueous and Ethanol) were prepared from the rhizomes obtained from Makurdi, Benue State, Nigeria which were dried and ground into powder of mesh size of 0.2 mm in diameter. The physicochemical analysis showed a pH of 6.95, Iodine Value of 51.39, Refractive Index of 1.44 and Specific Gravity of 1.45 which imply moderate level of unsaturated fatty acids content and high antimicrobial activity. Its antibacterial evaluation against Staphylococcus aureus American Type Culture Collection (ATCC) 25923 (gram +ve) and Pseudomonas aeruginosa ATCC 29953 (Gram -ve) were carried out with the two extracts and Chloramphenicol as the control using agar well diffusion method. The antibiotic showed significantly higher inhibitory effect on the bacterial isolates than the aqueous extract (P<0.05). It also showed higher effect than the ethanol extract on S. aureus (P<0.05) but statistically equal effect on P. aeruginosa (P>0.05). The ethanol extract showed higher activity against the test organisms than the aqueous extract at P<0.05. The zones of inhibition for the aqueous extract ranged from 7.00 mm – 13.67 mm for S. aureus and 7.33 mm – 14.33 mm for P. aeruginosa and the ethanol extract, 13.33 mm – 19.00 mm and 15.00 mm – 13.00 mm for S. aureus and P. aeruginosa respectively. The Minimum Inhibitory Concentration was observed at 12.5 mg/mL in both cases. The antibacterial activity shown by C. longa may be due to the presence of phytochemicals such as Alkaloids, Steroids, Saponins, Flavonoids, Phenols and Tannins which were observed when the extract was analyzed phytochemically. C. longa showed potent activity against bacteria in this study and would make a more active and viable antibiotic.