Development of a novel micro-assay for evaluation of peroxyl radical scavenger capacity: Application to carotenoids and structure-activity relationship

A micro-assay was developed and validated, using a microplate reader in 96-well format, C-11-BODIPY581/591 as fluorescent probe and AIBN as ROO generator. The structure-activity relationship was established for 15 carotenoid standards, indicating that the opening of the beta-ionone ring and the increase of chromophore extension in the carotenoid structure were the major factors leading to the increase of ROO scavenging capacity. The values for ROO- scavenging capacity were calculated using alpha-tocopherol as reference compound. Among the studied carotenoids, all-trans-lycopene was the most efficient ROO- scavenger (8.67 +/- 0.74) followed by all-trans-astaxanthin (6.50 +/- 0.62). All the carotenoids showed to be more effective Roa scavengers than alpha-tocopherol and some hydrophilic compounds. Finally, the method was successfully applied to assay the ROO scavenging capacity of carotenoid extracts from two Amazonian fruits, peach palm (7.83 +/- 0.21) and mamey (6.90 +/- 0.44). (C) 2012 Elsevier Ltd. All rights reserved.