Estrogens protect against hydrogen peroxide and arachidonic acid induced DNA damage

The ability of estrogens to protect against DNA damage induced by either hydrogen peroxide or arachidonic acid alone or in combination with Cu2+ was investigated. DNA strand breaks were determined by conversion of double stranded supercoiled OX-174 RFI DNA to double stranded open circular DNA and linear single stranded DNA. Estradiol-17 beta significantly decreased the formation of single and double strand breaks in DNA induced by H2O2 alone or with Cu2+. Equilin (an equine estrogen) was more effective than estradiol-17 beta at the doses tested. Arachidonic acid in the presence of Cu2+ caused the formation of high levels of linear DNA which was protected by estrogen with equilen being more effective. These studies suggest that estrogens through this protective effect on DNA damage might contribute to cardioprotection.