The Use of <sup>1</sup>H-NMR Spectroscopy Coupled with Chemometrics for Authentication of <i>Curcuma xanthorrhiza</i> Adulterated with <i>Curcuma aeruginosa</i>

Abstract

Curcuma xanthorrhiza rhizome is known to have several pharmacological activities and it is potential to be adulterated with other species having lower price such as Curcuma aeruginosa to gain more economic benefit. The objective of this study was to develop 1H-NMR spectroscopy combined with chemometrics of principal component analysis (PCA), partial least square-discriminant analysis (PLS-DA), and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) for authentication of C. xanthorrhiza. PCA could be used for differentiation between pure and adulterated C. xanthorrhiza. Chemometrics of PLS-DA showed clear and better separation between authentic and adulterated samples. The obtained R2X was 0.975, R2Y was 0.993, and Q2(cum) was 0.986. OPLS-DA using two principal components and one orthogonal variabel provided complete separation between authentic and adulterated samples better than using PCA and PLS-DA. The model has a good fit indicated by high value of R2X (0.939) and R2Y (0.932) and a good predictivity indicated by its Q2 value (0.925). It can be concluded that combination of 1H-NMR spectroscopy and chemometrics of PCA, PLS-DA, and OPLS-DA could be used for authentication of C. xanthorrhiza adulterated with C. aeruginosa with OPLS-DA showed the best classification.