Chemiluminescent screening of quenching effects of natural colorants against reactive oxygen species: Evaluation of grape seed, monascus, gardenia and red radish extracts as multi-functional food additives

The quenching effects of commercial available natural colorants against reactive oxygen species (ROS) were investigated. The effectiveness was evaluated by measuring the quenching ratio of chemiluminescence (CL) intensity with each colorant on luminol or methyl-6-(p-methoxyphenyl)-3,7-dihydroimidaz[1,2-a]pyrazin-3-one CL induced by ROS. As a result, the grape seed extracts and polyphenolics dose-dependently quenched CL. The quenching effects of grape seed extract A at 1 mg/ml for superoxide, singlet oxygen, hydroxyl radical, hypochlorite ion and linolenic acid peroxide were 81.1 ± 0.5%, 95.7 ± 0.4%, 99.3 ± 0.3%, 27.7 ± 4.2% and 88.3 ± 1.0%, respectively (n = 3). Except for chalcone, the polyphenolics, such as pelargonidin, cyanidin, delphinidin and trans-resveratrol, also showed the high quenching effects against ROS. These results suggested that the grape seed extract might be useful as a multi-functional food additive.Moreover, the quenching effects of several natural colorants were measured to screen new multi-functional food additives which can effectively quench ROS. Among the extracts from monascus red, gardenia yellow, blue and red radish, the red radish extract showed high quenching effects against hydroxyl radical and linolenic acid peroxide.