Phenolic Compounds from Coconut Milk Reduce Protein Carbonylation in Escherichia coli and Lactobacilli

Reactive Oxygen Species (ROS), including superoxide and hydroxyl radicals, can oxidize amino acid residues in proteins, leading to the formation of carbonyl groups and potential loss of protein function. ROS are generated intracellularly as a result of exposure to molecular oxygen, and aerobic organisms possess defence mechanisms, including antioxidant enzymes, to neutralize them. In addition, exogenous antioxidant compounds can contribute to cellular defence by scavenging ROS. Previous research has demonstrated that phenolic compounds display antioxidant properties. In this study, Escherichia coli and five Lactobacillus spp. were grown overnight in the presence of phenolic compounds extracted from coconut milk, and subsequently subjected to brief sublethal oxidative stress, after which protein carbonylation was measured. A statistically significant reduction in protein carbonylation was observed in bacteria pre-treated with coconut milk phenolics (p < 0.05). These results indicate that bacterial cells acquired enhanced antioxidant protection against oxidative stress following growth in the presence of coconut milk phenolics.