Metabolism of phenolic compounds during loquat fruit development

Phenolic compounds in loquat fruit were identified as 5-caffeoylquinic acid (chlorogenic acid), neochlorogenic acid, hydroxybenzoic acid, 5-p-feruloyl quinic acid, protocatechuic acid, 4-caffeoylquinic acid, epicatechin, o-cou maric acid, ferulic acid, and p-coumaric acid. Neochlorogenic acid was foun d to be dominant in the early stages of loquat fruit development. Both the concentrations and types of phenolic compounds were high in young fruit but then decreased steadily during growth. However, the concentration of chlor ogenic acid increased during ripening and became Predominant in ripe fruit. The large rise in chlorogenic acid concentration appears to be a character istic of loquat fruit ripening. In all of the cultivars tested, the types o f phenolic compounds were similar but the total phenolic content varied fro m 81.8 to 173.8 mg/100 g of fresh pulp. In the biosynthetic pathway of chlo rogenic acid, the enzyme activities of phenylalanine ammonia-lyase (PAL), 4 -coumarate:CoA ligase (CL), and hydroxycinnamoyl CoA:quinate hydroxycinnamo yl transferase (CQT) were high at the early stage of growth, diminished to low levels similar to3 weeks prior to harvest, but then rose to a peak at 1 week before harvest, The changes of these enzyme activities seemed to be a ssociated with variations in chlorogenic acid concentration during developm ent, maturation, and ripening of loquat fruit.