The role of catechins of Camellia sinensis leaves in modulating antioxidant enzymes: A review and case study

Abstract

Free radicals are generated in the body due to pollution and unhealthy lifestyle. Unbalanced levels of free radicals and natural antioxidants in the body may induce oxidative stress (OS). OS is responsible for several illnesses, including diabetes mellitus, cancer, and cardiovascular disease. The antioxidants can potentially increase the defense mechanism against OS and protect human health. The study aimed to analyze the catechins’ role as antioxidants. The catechins can upregulate antioxidant enzymes, scavenge free radicals, protect the DNA by intercalating to the helixes, and create chelation due to numerous hydroxyl moieties attached to the aromatic ring, which protects the structural integrity through electron delocalization. Epigallocatechin gallate (EGCG), a catechin with the greatest antioxidant capacity, has ortho-phenolic hydroxyl groups which potentially in binding free radicals. Moreover, the case study showed that dose-dependent treatment of tea had some benefits for human health. Humans with anemia and menopause cannot consume tea in high doses, which could worsen the condition. Conversely, humans with thalassemia are suggested to take tea to decrease the iron in their bodies. This review is expected to be a further study reference, mainly to clarify the EGCG process in restoring antioxidant enzymes and activating the thioredoxin antioxidant system.