Phenolic compounds of cranberry genotypes and their antioxidant capacities and bioactivities

Abeywickrama, Gihan (2015) Phenolic compounds of cranberry genotypes and their antioxidant capacities and bioactivities. Masters thesis, Memorial University of Newfoundland.

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Abstract

Cranberry species are a rich source of natural antioxidants with potential health benefits linked to the prevention of certain chronic and degenerative diseases. This study compared the antioxidant activity of phenolic constituents of five different cranberry genotypes (pilgrim, wild clone NL2, wild clone NL3, wild clone PEI, wild clone NL1) and market samples. Phenolic constituents were separated into free, esterified and bound fractions, the content of each fraction as well as that of their flavonoid counterparts and antioxidative efficacy were evaluated. The latter was assessed using trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (DRSC), hydroxyl radical scavenging capacity and reducing power (RP) as well as metal chelation assays. Among cranberry varieties, pilgrim genotype showed the highest phenolic content (30.02 mg of gallic acid equivalents (GAE)/g dried fruit weight). Similarly, pilgrim had the highest flavonoid content (19.94 mg of catechin equivalents (CE)/g of dried fruit weight). The phenolic compounds in cranberry were predominantly present in the esterified and free forms in the pilgrim and wild clone NL2. In addition, results showed that contribution of esterified phenolics to the antioxidant activity, metal chelating and reducing power was higher than the free and bound phenolics for all tested cranberry genotypes. HPLC-MS analysis was performed for two of the rich sources of phenolics and antioxidant activity. For these, the results showed that caffeic acid, p-coumaric acid, epicatechin, proanthocyanin trimer A-type, proanthocyanin dimer B-type and quercertin 3-O-glucoside predominated in wild clone NL2, while chlorogenic, caffeic acid, epicatechin, proanthocyanidin dimer B-type, proanthocyanin trimer A-type and myricertin 3-O-arabinoside were predominant in pilgrim.

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