Quantitative NMR Estimation of Primary Metabolites in Turmeric Spice

Collins, Kyle, Williamson, David, Marin, Maria J., Jones, Adam and Kemsley, E. Kate (2025) Quantitative NMR Estimation of Primary Metabolites in Turmeric Spice. In: Experimental Nuclear Magnetic Resonance Conference 2025, 2025-04-06 - 2025-04-10, Asilomar Conference Center, Pacific Grove, California.

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Abstract

Turmeric (Curcuma longa) is a rhizomatous plant, of which the dried and ground roots are widely used as a spice and in traditional medicine. The roots contain curcuminoids, a group of polyphenolic compounds that include curcumin, demethoxycurcumin, and bisdemethoxycurcumin. These compounds are responsible for turmeric’s bright yellow colour and are associated with various bioactive properties, including antioxidant, anti-inflammatory and potentially anti-cancer effects. However, the natural variation in curcuminoid content between different turmeric varieties can be significant, with some containing up to ten times more curcuminoids than others. Accurate quantification is therefore essential, not only for quality control in dietary supplement production, but also for detecting adulteration with synthetic dyes or fillers, which can compromise product authenticity and safety. This study compares two analytical methods for quantifying curcuminoids in turmeric extracts: ultraviolet-visible (UV-Vis) spectroscopy and quantitative nuclear magnetic resonance (qNMR). The UV-Vis method is widely used due to its simplicity, affordability, and speed. It relies on the strong absorbance of curcuminoids at wavelengths between 420 - 430 nm. However, while effective for bulk quantification, this method is somewhat lacking in specificity, and the presence of other absorbing compounds in turmeric extracts can lead to interference, reducing its reliability for regulatory applications. 500 MHz ¹H qNMR offers an alternative, more precise method for curcuminoid quantification. The characteristic chemical shifts of curcuminoids appear in the 6 - 8 ppm range, and allow clear differentiation between curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Unlike UV-Vis, qNMR does not require external reference standards and instead enables absolute concentration determination using an internal reference compound. This makes qNMR a robust and accurate technique for quality control and authentication of turmeric-based products, particularly in regulatory and research settings where precise and accurate quantification is desirable.

Item Type:	Conference or Workshop Item (Poster)
Uncontrolled Keywords:	sdg 3 - good health and well-being ,/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being
Faculty \ School:	Faculty of Science > School of Chemistry, Pharmacy and Pharmacology
Depositing User:	LivePure Connector
Date Deposited:	04 Apr 2025 15:30
Last Modified:	07 Apr 2025 00:21
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98968
DOI:

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