Application of H-NMR metabolite fingerprinting and chemometrics for the authentication of Curcuma longa adulterated with Curcuma manga

Curcuma longa or turmeric is known to have many functions in the field of foodstuff, cosmetics, and traditional medicines. The rhizome contains curcuminoid, especially curcumin which is believed to be the active compound responsible for pharmacological activities. The authenticity of C. longa is very important to avoid adulteration practices. The objective of this study was to develop thin layer chromatography (TLC) for curcumin analysis combined with H-NMR metabolite fingerprinting and multivariate analysis for the authentication of C. longa powder. Determination of curcumin in pure and adulterated powder of C. longa with Curcuma manga was performed using validated TLC method with the composition of the mobile phase of toluene: glacial acetic acid (82:18 v/v) and silica gel 60 F254 as a stationary phase with elution length 9 cm. The contents of curcumin in pure powder from several regions were in the range of 4.28-5.62%, while those in adulterated were of 5.25-1.35%. H-NMR metabolite fingerprinting combined with chemometrics of principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) using variables of the chemical shift was successfully used to classify the pure and adulterated powder of C. longa.