Similarity and differential NMR spectroscopy in metabolomics: application to the analysis of vegetable oils with 1H and 13C NMR.

INTRODUCTION: In NMR based metabolomics there is a need for tools to easily compare spectra and to extract the maximum of information from the data. OBJECTIVES: The calculation of similarity and performing differential NMR spectroscopy provides important additional information for classification and validation in metabolomics experiments. METHODS: From 13 different vegetable oils samples were analysed by 1H and 13C NMR. The similarity between spectra was calculated and differential NMR spectroscopy was used to discover marker compounds. RESULTS: The similarity between the individual spectra was calculated for the spectra of all samples. The similarity was used to verify and improve the alignment. For vegetable oils which showed a high similarity, e.g. chia seed oil and linseed oil, differential NMR spectroscopy was used to discover marker compounds. CONCLUSIONS: The calculation of similarity is an important tool to reveal variability between samples and spectra and can be used to verify data sets and improve alignment or binning procedures. With differential spectroscopy marker compounds are easily discovered. The methods can be seen as an important addition to the routine procedures of metabolomics experiments.

Validated high performance thin layer chromatography method for the quantification of bioactive marker compounds in Draksharishta, an ayurvedic polyherbal formulation

ABSTRACT Draksharishta is an ayurvedic polyherbal formulation with Draksha (Vitis vinifera L., Vitaceae) as chief ingredient prescribed for digestive impairment, respiratory disorders and weakness. These herbal medicines containing biologically active compounds play a significant role. Therefore it is necessary to carry out the chemical standardization of bioactive marker compounds present in the polyherbal ayurvedic formulation like Draksharishta. The aim of the present work was to develop and validate a HPTLC method for determination of gallic acid, catechin and resveratrol in commercially available marketed and in-house prepared formulations of Draksharishta. This is the first report of quantification of bioactive marker compound resveratrol using HPTLC in Draksharishta. The method employed silica gel precoated thin layer chromatography plates with F254 as the stationary phase. The respective mobile phases were used to develop the plates which separated bands according to the marker compound. Camag scanner V was used for densitometric scanning. Further, the method was validated according to International Conference of Harmonization (ICH) guidelines. The Rƒ values of the three marker compounds were measured. Correlation coefficients were calculated from the standard graph of linearity. Accuracy, precision and recovery were all within the required limits. The developed HPTLC methods for bioactive marker compounds present in in-house and marketed formulations were found to be simple, accurate, precise and robust.