Publications

Publications serve as the concrete art form for the scientist. It is his modus operandi. Authorship is akin to success and achievement. It cannot and should not deteriorate into a bargaining tool or commodity. Dardik
Mncwangi, N.P., Viljoen, A.M., Zhao, J., Vermaak, I., Chen, W., Khan, I. 2014. What the devil is in your phytomedicine? Exploring species substitution in Harpagophytum through chemometric modeling of 1H-NMR and UHPLC-MS datasets. Phytochemistry 106: 104-115.

 

Harpagophytum procumbens (Pedaliaceae) and its close taxonomical ally H. zeyheri, indigenous to southern Africa, are being harvested for exportation to Europe where phytomedicines are developed to treat inflammation-related disorders. The phytochemical variation within and between natural populations of H. procumbens (n=241) and H. zeyheri (n=107) was explored using proton nuclear magnetic resonance (1H-NMR) and ultra high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) in combination with multivariate data analysis methods. The UHPLC-MS results revealed significant variation in the harpagoside content: H. procumbens (0.17 - 4.37%); H. zeyheri (0.00 - 3.07%). Only 41% of the H. procumbens samples and 17% of the H. zeyheri samples met the pharmacopoeial specification of 1.2%. Both principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) indicated separation based on species (UHPLC-MS data OPLS-DA model statistics: R2X = 0.258, R2Y (cum) = 0.957 and Q2 (cum) = 0.934; 1H-NMR data OPLS-DA model statistics: R2X = 0.830, R2Y = 0.865 (cum) and Q2 (cum) = 0.829). It was concluded that the two species are not chemically equivalent and should not be used interchangeably.