Identification Of Polyphenol Extract From Durian Husks And Its Antioxidant And Anti-inflammatory Activities

Durian(Durio zibethinus Murr.)is a popular tropical fruit,with high nutritive value and unique flavor.Recent years,massive amounts of the durian husks(as waste products)are disposed due to the high consumption of durians.Researches showed that durian husks exhibited various bioactivities such as antioxidant,anti-inflammatory,antibacterial and anti-diabetic effects.Presently,most researches about durian shells focus on durian shell polysaccharides and durian shell adsorbents,as for the chemical composition,antioxidant and anti-inflammatory effects of Durian husks have not been reported.Durian husks were divided into white durian peel and yellow durian shell.The extraction process of bioactivity compounds from durian shell was optimized by orthogonal experiment.The analysis of the chemical composition of durian husks extracts by UPLC-LTQ-Orbitrap-MS/MS.In addition,H2O2 induced HepG2 cells oxidative damage model and LPS induced RAW264.7 cell inflammation model were used to study the antioxidant and anti-inflammatory effects of durian husk extract.The research results are as follows:1.Single-factor and orthogonal experiment are used to optimize the extraction process of durian shell polyphenols.Ultrasonic temperature,methanol concentration,ultrasonic power and ultrasonic time all have a greater effect on the extraction rate of durian husks polyphenols.Within a certain range,ultrasonic temperature and ultrasonic time significant influence the extraction rate of polyphenols.The best extraction condition is:material-liquid ratio(g/mL)1:30,methanol concentration 80%,ultrasonic temperature 40℃,ultrasonic power 320W,ultrasonic time 30min.Under these conditions,the yield of durian peel polyphenols was 3.77 mg/g,and the yield of durian shell polyphenols was 1.86 mg/g.2.UPLC-LTQ-Orbitrap-MS/MS was used to identify the composition of durian extracts,totally 20 main bioactive components in DPE and DSE were identified,most of which were phenolic compounds,including caffeic acid,anthocyanin,quercetin and its derivatives,catechin and its derivatives;quercetin and catechins had the highest content..Among them,DPE contains TPC 135.522±4.25 mg GAE/g DW,TFC 56.79±0.73 mg CAE/g DW,DSE contains 101.06±3.36 mg GAE/g DW,TFC 12.91±0.03 mg CAE/g DW.3.DPE and DSE showed strong DPPH free radical scavenging ability,Fe3+reducing ability and ABTS free radical scavenging capacity.The cellular antioxidant effects of DPE and DSE were studied by an oxidative damage model of HepG2 cells,stimulated by hydrogen peroxide.DPE and DSE significantly inhibited the content of ROS、MDA、SOD、LDH、AST and ALT;significantly reduced apoptosis caused by oxidative stress.DPE and DSE inhibit the apoptosis by regulating the expression of mitochondrial pathway apoptosis-related genes,significantly increased the expression of BCL-2 and inhibited the expression of BAX,Caspase-3 and Caspase-9.DPE and DSE exhibited great antioxidant activity in HepG2 cells stimulated by hydrogen peroxide,and can reduce cell damage and apoptosis caused by oxidative stress.4.1 μg/mL LPS was used to stimulate RAW264.7 cells to establish inflammation cell model.DPE and DSE significantly inhibited the secretion of inflammatory mediator(NO)and the expression of iNOS,COX-2 mRNA and protein in RAW264.7 cells induced by LPS;significantly inhibited the secretion of inflammatory factors TNF-α,IL-6,IL-1β and its mRNA expression;significantly down-regulated the phosphorylation of MAPK and NF-κB pathway related proteins(JNK,ERK,p38,IκBα,p65);Attenuated the nuclear transfer of NF-κB p65.DPE and DSE exhibited siginificant anti-inflammatory activity in LPS-stimulated RAW264.7 cells,through blocking the phosphorylation of MAPK,NF-κB inflammation signal pathway related proteins(JNK,ERK,p38,IκBα,p65).