Antioxidant and Antiproliferative Activities of Common Fruits

TLDR

Fruits and vegetables contain phenolic phytochemicals linked to reduced chronic disease risk, yet their antioxidant potential has been underestimated because bound phenolics are often omitted. This study profiled total phenolics (free and bound) in common fruits using extraction and digestion methods and proposed a bioactivity index for dietary cancer prevention. Phenolics were extracted, digested, and total antioxidant activity quantified with the TOSC assay. Cranberry showed the highest total phenolic content, antioxidant activity, and antiproliferative effect, with apple, red grape, and strawberry following in descending order.

Abstract

Consumption of fruits and vegetables has been associated with reduced risk of chronic diseases such as cardiovascular disease and cancer. Phytochemicals, especially phenolics, in fruits and vegetables are suggested to be the major bioactive compounds for the health benefits. However, the phenolic contents and their antioxidant activities in fruits and vegetables were underestimated in the literature, because bound phenolics were not included. This study was designed to investigate the profiles of total phenolics, including both soluble free and bound forms in common fruits, by applying solvent extraction, base digestion, and solid-phase extraction methods. Cranberry had the highest total phenolic content, followed by apple, red grape, strawberry, pineapple, banana, peach, lemon, orange, pear, and grapefruit. Total antioxidant activity was measured using the TOSC assay. Cranberry had the highest total antioxidant activity (177.0 +/- 4.3 micromol of vitamin C equiv/g of fruit), followed by apple, red grape, strawberry, peach, lemon, pear, banana, orange, grapefruit, and pineapple. Antiproliferation activities were also studied in vitro using HepG(2) human liver-cancer cells, and cranberry showed the highest inhibitory effect with an EC(50) of 14.5 +/- 0.5 mg/mL, followed by lemon, apple, strawberry, red grape, banana, grapefruit, and peach. A bioactivity index (BI) for dietary cancer prevention is proposed to provide a new alternative biomarker for future epidemiological studies in dietary cancer prevention and health promotion.