Investigation Of Polyphenol Compounds And Their Antioxidant Activity In The Fruits Of Chinese Olive

Chinese olive(Canarium album L.)is a medicinal food with homologous compounds and a unique fruit resource in China that possesses a variety of physiological activities and shows great promise for research and development.At present,systematic studies on phenolic compounds and their antioxidant activities are lacking.In this paper,the main phenolic compounds in olive fruit were isolated and identified using modern chromatography and spectroscopic techniques,and the components responsible for this antioxidant activity were investigated.A quantitative method for the rapid detection of the major phenolic compounds in Chinese olive fruit was established using UPLC-ESI-MS/MS technology.The effects of different cultivars,developmental stages and processing methods on the antioxidant activity and polyphenols of Chinese olive fruit were systematically evaluated.At the same time,the composition of phenolic compounds in different tissues of the Chinese olive and the antioxidant activity of these compounds,as determined using different methods,were analyzed.The purpose of this study is to provide a scientific basis for the comprehensive application of techniques developed for Chinese olive fruit in the extraction of natural products and the development of practical foods.The main results are as follows:1.Extraction techniques using organic solvents and ultrasound-assisted extraction were studied.Compared with solvent extraction,ultrasound-assisted extraction had the advantages of low temperature,high efficiency and high polyphenol content.Under optimal processing conditions,the extraction yield of total phenolics was 85.26 mg GAE/g DW,and the antioxidant activity was 952.27 ?mol TE/g DW using ultrasonic-assisted extraction.2.By using static adsorption experiments and dynamic adsorption experiments,HPD-750 macroporous resin was selected from ten types of macroporous adsorption resins as suitable for the enrichment and purification of phenolic compounds from Chinese olive fruit.The dynamic adsorption/desorption experiments and column chromatography with HPD-750 resin resulted in enrichment of the phenolic compounds and antioxidants in the 30%ethanol fraction.3.An in vivo antioxidant assay showed that treating animals with the polar compound CR30,which targets the liver,significantly increased the levels of SOD,CAT,GSH-Px,and GSH in liver tissue and reduced MDA.At the same time,the results of tissue section staining showed that CR30 treatment can also improve liver tissue necrosis,cell structure and other characteristics.These results suggest that CR30 can prevent the peroxidation of lipids by increasing antioxidant capacity in mice.4.The CR30 group was isolated and identified,and 10 phenolic compounds were found.Of these,3-O-galloylquinic acid,ellagic acid 4-O-?-D-glucopyranoside,ellagic acid 4-O-?-D-xylopyranoside,chebulagic acid,geraniin and geraniin isomers were identified for the first time in Chinese olive.The result of the antioxidant activity assay indicated that 10 phenolic compounds exhibited good antioxidant activity.DPPH and ABTS assays indicated that most compounds had a strong free radical scavenging ability and total FRAP reduction ability.The ellagitannin component exhibited the strongest antioxidant activity:the DPPH and ABTS radical scavenging ability and FRAP reducing power of this component were significantly better than those of ascorbic acid.In the ellagitannin component,geraniin isomers had the strongest free radical scavenging ability.Structure-activity relationship analysis showed that the number of hydroxyl groups was closely related to antioxidant activity.5.A UPLC-ESI-MS/MS method was developed to simultaneously characterize 12 polyphenolic components in Chinese olive.Mass spectrometry using the multiple reaction monitoring mode and negative ion mode scanning was performed.All of the calibration cirves expressed good linearity over a relatively wide concentration range.Twelve types of polyphenolic compounds were clearly separated within 15 min;the linear range of detection,detection limit and quantification limit were below 2.876 ng/mL;and the recovery rate was above 84.03%,with high accuracy and precision.These results indicated that gallic acid derivatives and ellagitannin were the main components of Chinese olive fruit.Among them,3-O-galloylquinic acid and geraniin isomers were main monomeric compounds.6.There were significant differences in fruit weight,size,TSS and TA among different cultivars.Phenolics were detected as the most abundant antioxidants(1174.03-1799.55 mg gallic acid equivalent(GAE)/100 g fresh weight).A significant positive correlation between antioxidant activity and phenolic content was also found.The 'Tantou 23' cultivar exhibited high TP and antioxidant activity,which are important as major sources of natural antioxidants;the 'Maken 22' fruit was characterized by a high total sugar content and low phenolic content,suggesting their potential for fresh consumption.The fruit weight,size,edibility,TSS,and TSS/TA ratio increased significantly,while the water content and TA decreased significantly during fruit development and ripening in the fruit of both 'Tanxiang' and 'Meipu'cultivars.A high total phenolic accumulation and strong antioxidant activity,together with high levels of 3-O-galloylquinic acid and geraniin isomers,were observed during the early fruit growth stage(especially S3).The phenolics present in free,esterified,glycosided,and insoluble-bound groups,the distribution of these compounds in different tissues(pulp,seed,and peel)of Chinese olive fruit and the antioxidant activity of these compounds were studied.The results show that the polyphenol component of Chinese olive fruit mainly exists in the free form,followed by the esterified and glycosided forms,with the insoluble-bound groups representing the smallest fraction.The highest content of total phenols and flavonoids and the strongest antioxidant activity were found in the peel of Chinese olive fruit.7.The total phenolic content and antioxidant capacity of Chinese olive fruits decreased significantly after drying methods.However,relative to other methods,the vacuum freeze drying method showed the lowest total loss of phenolic content and higher antioxidant capacity,indicating that this method is suitable for the production and processing of dried Chinese olive fruit.The effects of different drying treatments on phenolic metabolites in Chinese olive fruits were studied using UPLC-QTof-MS-based metabonomics analysis methods for the first time.Based on the high resolution mass spectrometry results,thirty phenolic compounds were identified,mainly consisting of gallic acid and its derivatives,gallotannins,ellagic acid and its derivatives,ellagitannins and flavonoid components.Using the multivariate data analysis method for pattern recognition,we could clearly distinguish between the fresh samples and the dried samples,indicating that the polyphenol components of Chinese olive fruits changed significantly after drying.Correlation analysis of 6 selected biomarker metabolites and antioxidant activity showed that 3-O-galloylquinic acid,geraniin isomers and isocorilagin might be the main components of the Chinese olive fruit responsible for the antioxidant activity.This study is the first of its kind and not only elucidated the main components responsible for the antioxidant properties of Chinese olive fruit but also provided a scientific basis for the comprehensive utilization of polyphenol resources.