Polyphenolic Content and Antioxidant Capacity of Cranberry Stem and Leaf Extracts

Abstract

Cranberry fruits are rich in phenolics, however little is known about phenolic content and antioxidant activity in cranberry leafs or stems. Tissues were harvested from three cranberry cultivars, grown at four locations, in three states. Phenolic content was determined by gallic acid equivalents (GAE) and antioxidant capacity was measured for runner leaf (RL), upright leaf (UL), runner stem (RS), and upright stem (US) tissue extracts. LDL oxidation in the presence/absence of extracts was induced with 10uM Cu++ and quantified (A234nm lag‐time) at extract concentrations of 100μg/L, 10μg/L, and 1μg/L to determine antioxidant activity. There was a complex plant‐tissue relationship between UL, US, RL, and RS, cultivar, harvest location, and extract concentration (four‐way‐interaction). All leaf extracts had a significantly higher GAE than all stem extracts, but no similar trends were seen between runner and upright orientations. RL, UL and US extracts from Mullica Queen (MQ) demonstrated superior antioxidant activity relative to Early Black and Demoranville stem extracts. With the exception of MQ, all other leaf extracts (R/U) demonstrated better antioxidant capacity than the remaining stem extracts. Understanding the complexities of cranberry plant phenolics and antioxidant activity may be important for the development of future cranberry‐derived health products.