Isolation And Structural Identification Of Antioxidant And Immunoregulatory Compounds From Cherries (Prunus Spp.) Pulp

Cherry (Prunus spp.) is one of the popular fruits with long plantation history and rich germplasm resources in China. Among them, Prunus avium, Prunus cerasus, Prunus pseudocerasus and Prunus tomentosa are the four commonly consumed edible species. In present study, the physiochemical characteristics of four cherry species were evaluated. Then, antioxidant and immunoregulatory activity-based isolation and structural identification of the bioactive compounds were carried out. The main results were as follows:1. In the 8 tested cultivars, there was sighnificant intra-species variability of physiochemical characteristics. A total of 25 phenolics compounds were identified combining HPLC and MS technologies, including 5 hydrocinnamic acids,2 flavan-3-ols,7 anthocyanins and 11 flavonols. The two P. avium cultivars and two P. cerasus cultivars were rich in anthocyanins, which were mainly cyanidin glycosides. The P. pseudocerasus had rich flavonols varieties. The P. tomentosa was characterized by high proportion of flavonols content, which was mainly quercetin-3-rhamnoside and kaempferol-3-rhamnoside.2. The phenolics rich extracts (PRE), lipid soluble fraction (LSF) and water soluble polysaccharides (PPS) were isolated from the pulp of four cherries cultivars. Phenolics were found to be the main antioxidant compounds. Water soluble polysaccharides were active in inducing NO release from RAW264.7 cell, with the bioactivity of that from P. avium ’Black pearl’ being the highest.3. The phenolics from P. avium ’Black pearl’ were further fractionated into anthocyanins rich fraction, hydrocinnamic acids rich fraction and flavonols rich fraction. The bioactivity of each fraction and the main compounds were evaluated. Cyanidin-3-rutinoside was the main antioxidant component. Hydrocinnamic acids rich fraction was active in inhibiting polysaccharides induced NO release of RAW264.7 cell. Cyanidin-3-glucoside, chlorogenic acid and kaempferol-3-rutinoside significantly suppressed polysaccharides induced NO release from RAW 264.7 cell, with the activity of kaempferol-3-rutinoside the highest among them.4. The water soluble polysaccharides from P. avium ’Black pearl’ was further fractionated, and two components PAPS-1 and PAPS-2 with homogeneous distributed molecular weight were obtained. The monosaccharides composition, infrared spectrum, mathylation esterification, acetylation, and glycosidic bond configuration were analyzed. PAPS-1 and PAPS-2 were deduced to be type Ⅰ rhamnogalacturonan (RG-I) pectic polysaccharide, with arabinogalactans as side chains. PAPS-2 possessed higher proportion of galacturonic acid than PAPS-1. Both PAPS-1 and PAPS-2 significantly induced the gene express of TNFα, IL6, IL10, GCSF, iNOS and COX-2, and induced the release of cytokines TNFα, IL6 and IL10 from RAW264.7 cell.The results of present study could potentially help the general development and utilization of cherries resources.