Phytochemical content and activity of organic and aqueous extracts of turmeric (Curcuma longa) was studied to determine their potential for use as natural antioxidants and antimicrobials for therapeutic and food applications. Turmeric rhizomes were extracted with acetone, ethanol, methanol, water and analysed using standard procedures. Organic extracts exhibited significantly higher total phenolic and flavonoid content compared to aqueous extract; 1379.94, 515.60, 561.16, 307.45 mg /100g Gallic acid equivalence and 382.66, 411.88, 339.01, 158.11mg /100g quercetin equivalent in acetone, ethanol, methanol and water aqueous respectively (p˂0.05). Tannins were highest in acetone and lowest in ethanol extracts (175.86 and 20.45 mg /100g Catechin equivalent respectively); while vitamin C levels varied significantly, being highest in water and lowest in acetone extract; 62.78 and 11.77 mg /100g ascorbic acid equivalent respectively (p˂0.05). Free radical scavenging activity of the extracts was in decreasing order of acetone, ethanol, water, and methanol. Antioxidant activity of acetone extracts compared favourably with vitamin C (standard). Antimicrobial activity (Diameter of growth inhibition zones) varied significantly among the extracts. Antifungal activity of aqueous extracts (29.33 millimeters) was significantly higher than organic solvent (19-25.33 millimeters) extract (p˂0.05). Ethanolic extract was the most effective against Escherichia coli (18.33 millimeters); while the efficacy against Staphylococcus aureus was not significantly different among the extracts (p>0.05) and Candida albicans was the most susceptible microorganism to all extracts. The study concluded that both organic and aqueous turmeric extracts exhibited varied antioxidant and antimicrobial activities owing to the level of major phytochemical groups in the extracts.
Citation: Akullo JO Kiage-Mokua B, Nakimbugwe D, Ng’ang’a J, Kinyuru J. 2022. Potential Sources of Natural Antioxidants and Antimicrobials: Comparative Analysis of Turmeric (Curcuma longa) Extracts from Different Solvent Extraction Systems. J Food Chem Nanotechnol 8(4): 138-146.