Phytochemical analysis of Quercus infectoria galls extracts using FTIR, LC-MS and MS/MS analysis

The present study was carried out to characterise and compare types of phytoconstituents present in crude and aqueous extract of Quercus infectoria (QI) using FTIR, LC-MS followed by confirming using MS/MS analysis. QI gall was purchased from local market and grinded to obtain the crude in powdered form. The aqueous extract produced by refluxing in water bath at 50°C for 24 hours was filtered and concentrated using rotary evaporator followed by freeze-drying. The crude and aqueous extract was scanned at wavelength 400 to 3400 nm using Tensor-II-FTIR spectrometer. LC-MS analysis utilised Agilent-1290-Infinity-system coupled to Agilent-6520-Accurate-Mass-Q-TOF mass-spectrometer with dual ESI. Detected constituents matched with METLIN_AM_PCDL-N-130328.cdb database. Compounds with >95 DB score were selected to be confirmed with MS/MS analysis. The FTIR spectrum confirmed presence of several similar functional groups in both crude and aqueous extract. LC-MS screening results indicated similar phytoconstituents present in both crude and aqueous QI (2.64% and 2.16%) respectively. MS/MS analysis confirmed presence of all targeted constituents in aqueous QI extract. In conclusion, LC-MS and MS/MS results show that all major constituents analysed were from polyphenolic derivatives primarily gallic acid and hydrolysable tannins.