Chemical composition of turmeric (Curcuma longa L.) ethanol extract and its antimicrobial activities and free radical scavenging capacities

Authors: WU, HUAN - Anhui University Of Chinese Medicine; LIU, ZHIHAO - University Of Maryland; ZHANG, YAQIONG - Shanghai Jiaotong University; GAO, BOYAN - Shanghai Jiaotong University; LI, YANFANG - University Of Maryland; He, Xiaohua; Sun, Jianghao; CHOE, UYORY - University Of Maryland; Chen, Pei; BLAUSTEIN, RYAN - University Of Maryland; YU, LIANGLI - University Of Maryland

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2024
Publication Date: 5/16/2024
Citation: Wu, H., Liu, Z., Zhang, Y., Gao, B., Li, Y., He, X., Sun, J., Choe, U., Chen, P., Blaustein, R., Yu, L. 2024. Chemical composition of turmeric (Curcuma longa L.) ethanol extract and its antimicrobial activities and free radical scavenging capacities. Foods. 13(10). Article 1550. https://doi.org/10.3390/foods13101550.
DOI: https://doi.org/10.3390/foods13101550

Interpretive Summary: Turmeric is widely used in foods, such as curries, fried rice, soup, salad and grilled chicken etc. Previous analysis has shown that it mainly contains terpenoids, curcuminoids and other phenolic compounds. One of the main component of turmeric, curcumin is also an important food colorant. Besides its applications for enhancing flavor and color in food products, turmeric has played an important role in supporting human health such as potential anti-inflammatory, anti-cancer, and antimicrobial effects. Although understanding the antimicrobial properties of spices is critical for developing novel applications for functional foods, little is known for turmeric in this aspect. In this study, the ethanol extract of turmeric and its antimicrobial and free radical scavenging properties were investigated. It was found that the ethanol extract of turmeric has concentration-dependent inhibitory effects against Gram-negative bacteria including E. coli and Pseudomonas sp., as well as Gram-positive bacteria such as E. faecalis, L. innocua, and S. aureus. It also contained higher total phenolic content and showed scavenging activities against HO', ABTS'+, and DPPH'. The results suggest that turmeric extract could be used to prevent microbial infection and reduce the risk of foodborne illnesses. At the same time, the use of turmeric in home cooking dishes may provide potential health benefits by quenching excessive free radical.

Technical Abstract: Turmeric (Curcuma longa L.) is a perennial tuberous plant from the genus Curcuma (Zingiberaceae) and has been widely used in foods for thousands of years. The present study examined the ethanol extract of turmeric for its chemical composition, antimicrobial activity, and free radical scavenging properties. UHPLC-MS/MS analysis tentatively identified 9 compounds in the turmeric extract. Potential antimicrobial effects of 0.1, 1.0, and 10 mg turmeric equivalents (TE)/mL were evaluated in vitro against a variety of Gram-negative bacteria (i.e., Escherichia coli, Klebsiella pneumoniae and Pseudomonas sp.) and Gram-positive bacteria (i.e., Enterococcus faecalis, Listeria innocua and Staphylococcus aureus). The concentrations of 0.1 and 1.0 mg mL-1 inhibited growth of S. aureus and significantly suppressed that of Pseudomonas sp., E. faecalis, and L. innocua. Growth of all strains was inhibited by turmeric extract at 10 mg TE/mL, including E. coli, which had appeared tolerant to lower concentrations of the extract. Moreover, free radical scavenging capacities were determined using HO', ABTS'+, and DPPH' (HOSC, ABTS, and RDSC, respectively) radicals. The turmeric ethanol extract had a TPC value of 27.12 mg GAE/g, together with HOSC, RDSC and ABTS values of 1524.59, 56.38 and 1.70 µmol TE/g, respectively. Our results suggest that turmeric extract has potential applications for use in functional foods to reduce microbial burdens and oxidative stress related health problems.