Apple pomace: Antiradical activity and antiproliferative action in HeLa and HT-29 human tumor cell lines

Purpose: Apple pomace is an easily accessible source of bioactive compounds which can be used for various purposes in the food, pharmaceutical and cosmetic industry. Six types of apple pomace extracts were tested to study their health benefits, free radical scavenging and antiproliferative activities. Methods: The radical scavenging activity was determined by electron spin resonance (ESR) spectroscopy. Antiproliferative action was measured using MTT [3-(4,5-dimethylthiazol- 2-yl)2,5-diphenyl tetrazolium bromide] colorimetric assay in cervix epithelioid carcinoma (HeLa) and colon adenocarcinoma (HT-29) human cancer cell lines. Results: All extracts suppressed the formation of 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and hydroxyl-free radical in a dose-dependent manner. In the presence of 12.5 mg/ ml Pinova, Reinders and Nectar pomace extract, the ESR DPPH• signals vanished. The •OH was completely scavenged in the presence of 45 mg/ml or higher concentration of the investigated extracts. Pinova and Braeburn pomace extracts showed the strongest antiproliferative activity against the investigated human cancer cell lines. Also, HeLa cells were found more sensitive than HT-29 cells to all extracts. Conclusion: Although the relationship between radical scavenging activities and phenolic contents or flavonol glycosides (R2≥0.80) was high, there were no significant correlations between the total phenolic contents or individual phenolic compounds and the antiproliferative activity.