Optimisation extraction procedure and identification of phenolic compounds from fractional extract of corn silk (Zea mays hair) using LC-TOF/MS system

Abstract

Presently, there is an increased interest in the production and purification of vegetable extracts by both pharmacological and medicinal sectors. This study aimed to optimise the phenolic extraction of corn silk and to identify phenolic compounds of the fractional extract of corn silk. Single factor experiment was used to optimise the extraction parameters. The liquid chromatography-quadrupole time-of-flight-mass spectrometer (LC-TOF/MS) system was used to identify different types of phenolic compounds in the selected fractions. The optimum conditions (i.e. extraction time of 30 min, extraction temperature of 50 °C, the solid-to-solvent ratio of 1:10 and 40% ethanol) were obtained. The corn silk was extracted using the optimum conditions and the extracted was further fractionated with hexane and ethyl acetate, subsequently. The ethyl acetate fraction exhibited the most significant free radical-scavenging activity and the highest amount of total phenolic compounds. Therefore, ethyl acetate fraction was subjected to further analysis using LC-TOF/MS. A total of 26 compounds were identified. The fractional extract was found to be rich in flavonoid compounds such as flavones, flavonols, flavanols, flavone C-glycosides, flavonols, flavonol O-glycosides, and isoflavonoids. Flavanols were the major group of flavonoids found in this fractional extract. In summary, ethyl acetate fraction of corn silk can be a good source of phenolic compounds that can be useful for application in both nutraceutical and pharmaceutical sectors.