| In order to investigate the antioxidants in Longan seeds, systematic studies were carried out on the extraction, isolation, purification, identification of phenolic compounds from Longan seeds.1. Based on single factor tests, the optimum extraction conditions of polyphenols from Longan seed were obtained through Box-Behnken Design (BBD) and response surface methodology (RSM). The results showed that the optimum extraction conditions of polyphenols are as follows:alcohol concentration 70%(v/v), extraction temperature 77.4℃, extraction time 4h and. solid-liquid ratio 1:20 (g/mL). The order of factors affecting the content of polyphenols (Y) was temperature, extraction time and alcohol concentration. Under such conditions, the one-time extraction content of polyphenols is up to 21.71 mg/g.2. The rough extraction, and different polarity solvent extractions of Longan seeds own strong antioxidant activity. It shows that they all contain lots of phenolic antioxidants. And it declares the extraction extracting by ethyl-acetate has the strongest antioxidant activity.3. Different fraction constituents of ethyl-acetate extract were obtained by isolating with ethanol solvent, purifying with macro-porous resin column chromatography and recrystallization and so on. It shows that most fraction have stronger antioxidant activity than ascorbic acid. Fraction Fr7 and Fr8 own the strongest antioxidant activity. And fraction Fr7 had been recognized as Gallic acid.4. High-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis revealed eleven compounds (including six phenols) were found in Longan seed, along with some unknown compounds. The six phenols are Gallic acid, ellagic acid, galloyl-Hexahydroxy diphenoyl-glucopyranose, pyrogallol, ellagic acid-pentose conjugate, quercetin-3-O-rhamnoside.
|
PDF Full Text Request