Free radicals produced by metabolism and various other factors in the human body can cause oxidative stress to the cell, which can develop into many diseases (e.g. cancer and cardiovascular and neurodegenerative diseases). Antioxidants are known to protect cells by neutralizing free radicals. However, many antioxidants in the presence of transition metal ions such as Cu2+ and Fe3+ produce more radicals through pro-oxidant effects and cause oxidative damage to cellular molecules like DNA, proteins, and fatty acids. To solve this contradictory antioxidant problem, we designed antioxidants in dendritic forms to have multiple hindered phenols on the surface and metal chelating groups within internal cavities to trap the metal ions, thus preventing pro-oxidant effects. We successfully synthesized over 20 star-shaped dendrimers (MW= 800~6,000 g/mol). These dendritic antioxidants displayed far superior free radical scavenging activities than naturally occurring popular antioxidants like vitamin C and quercetin. More importantly, they did not show pro-oxidant effects in the presence of physiological amounts of transition metals and cytotoxicity on CHO (Chinese Hamster Ovary) cells. These antioxidants were able to separate antioxidant properties from pro-oxidant effects but unfortunately, they lacked aqueous-solubility. Therefore, our recent studies focused on developing water-soluble antioxidants. This presentation will summarize synthesis and characterization of star-shaped dendritic antioxidants as well as water-soluble antioxidants and their protective effects on human low-density lipoproteins and DNA.

Star-shaped dendrimers with antioxidant properties

256th National Meeting (2018)

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