The Antioxidant Potential of Black Tea Polyphenols in Heavy Metal Toxicity: An In Vitro Perspective

Black tea is one of the most widely consumed beverages in the world, second only to water. Its properties are primarily due to the presence of polyphenols, which are associated with various effects, including antioxidant, anticancer, antiviral, and anti-inflammatory activities. These compounds include, among others, theaflavins (TFs) and thearubigins (TRs). The available literature provides numerous reports confirming the positive properties of these compounds. However, it is important to highlight their potential protective effects against oxidative stress induced by heavy metals. This is an important topic, given the ongoing exposure to such pollutants—resulting mainly from industrial development, among other factors. This manuscript provides a summary of the current knowledge on the properties of TFs and TRs and their effect against oxidative stress caused by heavy metals in in vitro studies. The limited amount of research in this area shows that this is still a poorly researched topic. Comparing the results obtained for epigallocatechin gallate (EGCG) from green tea, which has a similar structure to TFs and TRs suggests that they may exhibit similar or even enhanced antioxidant properties. Considering that black tea is consumed much more frequently than green tea worldwide, it is understandable that the antioxidant potential of these two compounds on cells needs to be investigated.