Isolation, Purification And Identification Of Bioactive Compounds From Mangifera Indica L. Fruit And Evaluation Of Their Bioactivities

To have a better understanding of the nutritional quality of Chinese mango (Mangifera indica L.) germplasm, fruits of29mango cultivars harvested from the germplasm collection of Guangxi Subtropical Crops Research Institute were used for investigation of the bioactive compounds and bioactivity. Basic fruit qualities such as fruit weight, total soluble solid (TSS) content, firmness, color as well as carotenoids, total phenolics and antioxidant activity were evaluated in different mango cultivars. The chemical compound profiles in different fruit tissue extracts and their bioactivities including anti-diabetes, anti-cancer, and human umbilical vein endothelial cells (HUVEC) protective activity were investigated for selected mango cultivars. In addition, efficient separation and purification procedures were established for important bioactive compounds such as mangiferin. The main results are as follows:1. There were significant differences in fruit weight, TSS, firmness and color among different cultivars. By using HPLC system coupled with a diode array detector (DAD), six carotenoids were identified in mango peel and pulp.β-Carotene and lutein were the major carotenoids in mango peel while phytoene, luteoxanthin,β-carotene, violaxanthin,9-cis-violaxanthin were the major carotenoids in the pulp. There were significant differences in the total phenolic contents and antioxidant activities among different fruit tissues as well as fruit cultivars, and the total phenolic contents in different fruit extracts were well correlated with their antioxidant activities.2. Identification of major compounds in pulp extract as well as their anti-diabetic activities were carried out for five mango cultivars. Twelve compounds were successfully isolated by solid phase extract (SPE) combined with preparative HPLC, and identified by high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR). Among these compounds,1-[5-(4,8-dihydroxy-1,5-dimethyl-6-oxabicyclo[3.2.1]oct-8-yl)-3-methyl-2,4-pentadienoate]-1-O-β-D-Glucopyranose and (2E,4E)-8-hydroxy-4,9-dimethyl-2.4- decadiene-1,10-dioic acid1-O-β-D-glucopyranosyl ester were two new compounds. In addition,7compounds, i.e. abscisic acid (ABA)-glucoside, dihydrophaseic acid, dihydrophaseic acid glucoside ester,(2E.4E)-8-hydroxy-2,7-dimeethyl-2,4-decadiene-1,10-dioic acid1-O-β-D-glucopyranosyl ester.1-O-β-hydroxyphenyl-β-D-glucose,6-O-β-coumaroyl-D-glucopyranose. and1-O-(E)-feruloyl-β-D-glucopyranose were reported in mango for the first time. The results of glucose consumption analysis of five mango cultivars showed that pulps of ’JHM’LPM’’MQS’ and ’ZHM’ as well as ABA all showed significant induction of glucose consumption in HepG2cells. Pulp of’JHM’exhibited strongest activity while pulp of ’TN-1’ showed lowest activity, indicating the different potentials that mango germplasm may have as far as anti-diabetic activity is concerned.3. Identification of major compounds in kernel and peel extract as well as their anti-proliferative activities were carried out for three mango cultivars. Mango kernel and peel, especially kernel, were rich in gallotannins. By using’TN-1’ kernel as plant material, five gallotannins, i.e. penta-, hexa-, hepta-, octa-. and nona-O-galloyl-glucoside were isolated by SPE and preparative HPLC. Kenerls and peels of’MQS’,’TN-1’, and ’ZHM’all showed significant inhibition effect on the proliferation of MDA-MB-231breast, HepG2liver, and HL-60leukemia cancer cells, in dose-dependent manner. In addition, penta-O-galloyl-glucoside and gallic acid also revealed high anti-proliferative activity, which indicated that gallotannins and their in vivo metabolite may be important bioactive compounds in mango kernel and peel extract. Therefore, the gallotannin-rich extracts of mango kernel and peel may serve as natural sources for anticancer agents and may have important pharmaceutical potential.4. Quantification and purification of mangiferin from different mango cultivars and its protective effect on HUVEC were carried out in the present study. Mango peel contained much higher mangiferin content than did pulp and kernel and ’LPM’ fruit peel contained the highest mangiferin content (7.49mg/g DW). Therefore, efficient purification of mangiferin from’LPM’ peel was then established time by combination of HPD100macroporous resin chromatography with optimized high-speed counter-current chromatography (HSCCC). Purified mangiferin showed strong DPPH radical scavenging capacities and redox ability of FRAP. In addition, it showed significant protective effects on HUVEC under H2O2-induced stress. Therefore, mangiferin from mango fruit provides a promising perspective for the prevention of oxidative stress-associated diseases.Overall, our results showed that different parts of mango fruit are rich in various bioactive compounds. The pulp extracts exhibited significant anti-diabetic potential through increasing the glucose consumption. The gallotannin-rich extracts of kernel and peel exhibited significant anti-proliferation effect on different cancer cell lines. Mangiferin exhibited significant antioxidant activity and protective effect on HUVEC under H2O2-induced stress. Therefore, mango fruit and its by-products are important sources of natural bioactivity compounds and have great health-promoting potential.