A validated HPTLC method for the simultaneous quantifications of three phenolic acids and three withanolides from Withania somnifera plants and its herbal products.

A simple, rapid and selective high-performance thin-layer chromatographic (HPTLC) method has been developed and validated for simultaneous determination of three withanolides (withaferin A, withanone and withanolide A) and three phenolic acids (caffeic acid, ferulic acid and benzoic acid) from different parts (root, stem and leaf) of Withania somnifera and its two commercially available polyherbal formulations. The extraction efficiency of withanolides and phenolic acids were tested using two solvents, chloroform and methanol, respectively. HPTLC separation was performed on silica coated aluminium plates Si 60F ₂₅₄ ; using toluene, ethyl acetate and acetic acid (60:40:4). The samples were quantitated at 231 nm. The purity and identity of peaks of all the six analytes were confirmed by matching Rf values and UV-spectrum with authentic standards. The identity of three withanolides was further confirmed by positive ion electrospray ionization mass spectrometry (ESI-MS/MS) analyses. The developed method was validated for sensitivity, linearity, reproducibility, accuracy, the limit of detection (LOD) and limit of quantification (LOQ) following the guidelines of the International Conference on Harmonization (ICH). The method was found to be linear (r > 0.99) in the range of 50-2000 ng/band for benzoic acid and 50-1000 ng/band for the other five studied metabolites. This simple and accurate HPTLC method provided enhanced resolution of studied analytes as compared to other phytoconstituents present in W. somnifera extracts. It has also been successfully applied in the analysis and quantification of two polyherbal formulations containing W. somnifera plant parts.
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