Phenolic Constituents of Sugarcane Bagasse and Juice Extracts

Abstract

　The phenolic constituents in three sugarcane extracts—bagasse extract (BE), bagasse hydrothermal extract (BHE), and sugarcane juice extract (SJE)—were studied for antioxidant properties using LC coupled to a photodiode array detector and an electrospray ionization mass spectrometer (ESI-MS). The LC-UV/MS chromatogram of the BE showed a signal similar to that of the BHE. Syringic acid (1), 4-hydroxybenzaldehyde (2), p-coumaric acid (3), vanillin (4), syringaldehyde (5), and ferulic acid (6) were detected in the BE and BHE, while the profile of SJE was different; only compounds 4 and 5 were detected in the SJE. In this work, we attempted to elucidate the chemical structure of an unknown peak in the spectrum of the BE. Subsequently, (4E) -3,5-bis (4-hydroxyphenyl) pent-4-enoic acid (7) was identified by a spectral investigation. These seven phenolic compounds were quantified by selective ion mass chromatography (SIM) using LC-MS, and the accumulated contents were 130.3, 105.2 and 1.4mg/g of dry weight in the BE, BHE, and SJE, respectively. Furthermore, each of the seven phenolics and three extracts was examined for antioxidative activity by measurement of the H-ORAC value. These values for the BE, BHE, and SJE were estimated to be 9319, 9417 and 9276 μmol Trolox equivalent/g D.W., respectively. Therefore, the contributions of these seven phenolics to the H-ORAC values were 23.9% for BE, 24.5% for BHE and 0.3% for SJE of the total H-ORAC value.