Phenolic compound characterisation and antiproliferative activity of Annurca apple, a southern Italian cultivar

In Annurca apples, a southern Italian variety, polyphenols were studied. The phenolic composition of Annurca apple peel was determined by HPLC coupled with electrospray negative ionisation multistage ion trap mass spectrometry (HPLC/ESI-ITMSⁿ). In addition, the antiproliferative and pro-apoptotic activities of peel extracts enriched in polyphenols and prepared from Annurca (APE), Red Delicious (RDPE) and Golden Delicious (GPE) varieties were evaluated on an HL-60 cell line. APE exhibited the highest total phenol content among the three apple cultivars tested, as determined by Folin-Ciocalteau's procedure and HPLC-UV analysis. APE also showed higher amounts of chlorogenic acid, procyanidins, flavonols, dihydrochalcones and cyanidin-3-O-galactoside than GPE or RDPE. All three apple extracts were able to significantly decrease cell viability, from 50% to 80%, with APE appearing the most effective, while GPE was the least cytotoxic among the three samples. Similarly, APE and RDPE induced a significant increase of caspase-3 activity, whose activation represents a hallmark of apoptosis.