Analysis Of Phenolic Compounds In Loquat[Eriobotrya Japonica (Thunb.) Lindl.] Fruit And Their Bioactivity Evaluation

Phenolic profile of loquat [Eriobotrya japonica (Thunb.) Lindl] fruit were investigated in the peel and pulp of seven cultivars. Their antioxidant were evaluated by DPPH, ABTS and FRAP assays, respectively. In addition, anti-cancer, anti-diabetic activity, as well as the protective effects on human endothelial cell of loquat fruit extracts were evaluated using different cell models. The main results are as follows:Eleven phenolic compounds, including five hydroxycinnamic acids (i.e.3-p-coumaroylquinincacid,3-caffeoylquinic acid,4-caffeoylquinic acid,5-caffeoylquinic acid and5-feruloylquinic acid) and six flavonols (i.e. quercetin-3-O-galactoside, quercetin-3-O-glucoside, quercetin-3-O-rhamnoside, kaempferol-3-O-galactoside, kaempferol-3-O-rhamnoside, and kaempferol-3-O-glucoside) were identified from loquat fruit. All the five hydroxycinnamic acids were found both in the peel and pulp of loquat fruit, while the flavonols can only be found in the peel. Among these phenolic compounds,3-caffeoylquinic acid showed the highest content followed by5-caffeoylquinic acid. In addition, fruit peel showed higher phenolic contents than pulp, and the total phenolic content in the peel was about3times that of the pulp. Significant difference in the phenolic content was observed among different loquat cultivars, where ’DHP’ and ’LYQ’ showed relatively higher total phenolics than other cultivars tested.The antioxidant capacity of’DHP’and’LYQ’were higher than the other cultivars, which was also reflected by their higher APC, and it showed high correlation with their higher phenolic contents. In addition,’BZ’pulp and ’RTBS’ peel exhibited significant inhibitory effect on the growth of HepG2liver cancer cells;’DHP’ pulp and peel of’BZ’,’DHP’, and ’LYQ’ exhibited significant inhibitory effect on the growth of MDA-MB-231breast cancer cells; peel of ’BZ’ and ’DHP’ exhibited significant inhibitory effect on the growth of HL-60leukemia cancer cells. Both fruit peel and pulp of ’BZ’ and’DHP’ showed increased glucose consumption in HepG2cells. Pulp of ’DHP’ and ’RTBS’ showed protective effect on HUVEC under H2O2-induced stress.Overall, loquat fruit is rich in phenolic compounds, and significant differences were found in various bioactivities among loquat cultivars and fruit tissues. The present study may provide foundation for further investigation of the health-promoting effects of loquat fruit, which is important for better utilization of the loquat resources.