PHYSICOCHEMICAL PROPERTIES, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF TURMERIC (Curcuma longa L.) RHIZOME OIL

Abstract

Turmeric (Curcuma longa) rhizomes, has been widely used for centuries as indigenous medicine for the treatment of a variety of anti-inflammatory conditions and other diseases. Turmeric and its active components (volatile oil and curcuminoids) have unique antioxidant, antitumorigenic, anticarcinogenic, antiinflammatory, antimutagenic, antiarthritic and antimicrobial properties. This study was aimed to determine the physicochemical properties, antioxidant and antimicrobial activities of turmeric (Curcuma longa ) rhizome oil extract. The oil extraction was done in Soxhelt apparatus using petroleum ether as a solvent. The physicochemical properties of the oil extract was carried based on determination of oil content, specific gravity, acid value, percent free fatty acid and peroxide value. The antioxidant activity was investigated based on free radical scavenging activities of DPPH and hydrogen peroxide. The antimicrobial experiment was arranged as 1x1x6 completely randomized factorial design in three replications. The antimicrobial activity was tested using disc diffusion method and broth dilution method. The result of physicochemical properties and antioxidant activities of Curcuma longa rhizome oil presented oil yield (8.25%), specific gravity (0.89), acid value (2.67%), free fatty acid (1.34%), peroxide value (3.90). The antioxidant activities of C. longa rhizome oil extract was recorded high ascorbic acid content ( 54.0), DPPH (21.10), and hydrogen peroxide free radical scavenging activity (5.95). The strongest antibacterial activity with maximum zone of inhibition (16.15mm) at highest concentration (3µl/ml) of the oil was recorded against Staphylococcus aureus. Stronger antifungal activity with maximum zone of inhibition (16.80mm) was recorded against C. albican. The effectiveness of C. longa rhizome oil against pathogenic microbes was further assessed using MIC, MBC and MFC exhibited strongest bactericidal activity with MIC (0.12µl/ml) and the corresponding MBC (0.25 µl/ml) against S. aureus while the weakest bactericidal activity with MIC (1.00µl/ml, the largest value) and MBC (2.00µl/ml) was recorded against E. coli indicating that S.aureus was the most susceptible while E. coli was the least susceptible to the C. longa rhizome oil extract. C. longa oil has presented stronger antifungal activity with MIC (0.06µl/ml, the least value) and MFC (0.12µl/ml) against C. albicans whereas weaker antifungal activity with MIC (0.50µl/ml) and MFC (1.00µl/ml) was recorded against A. niger showing C. albicans was the more susceptible to the oil extract while A. niger was more susceptible to the C. longa oil.