Unexpected effect of dry olive leaf extract on the level of DNA damage in lymphocytes of lead intoxicated workers, before and after CaNa2EDTA chelation therapy

The CaNa2EDTA chelation therapy is often practiced with antioxidant supplementation. Dry olive leaf extract (DOLE) is natural product with antioxidant and DNA protective properties. The effects of DOLE on the levels of DNA damage were investigated ex vivo in peripheral blood lymphocytes (PBLs) of 19 workers occupationally exposed to lead (Pb), before and after CaNa2EDTA chelation therapy. DOLE demonstrated pronounced radical scavenging activity in concentrations ≥1 mg/mL, and showed no genotoxicity per se, in concentrations 0.125-1 mg/mL. The level of DNA damage in PBLs of workers before chelation therapy was elevated (24.21 ± 14.26) compared to controls (6.0 ± 3.37). The incubation of PBLs before chelation therapy with selected concentration of DOLE lead to a severe increase of DNA damage (64.03 ± 20.96), exhibiting prooxidant rather than antioxidant effect. After the five-day CaNa2EDTA chelation regimen, DNA damage in PBLs of workers decreased (8.26 ± 4.62) significantly compared to baseline. Treatment of PBLs with DOLE after chelation, again produced high level of damage (41.82 ± 23.17) and the acute prooxidant effects of DOLE remained, but, DNA damage was less severe than before chelation. The DOLE exhibits prooxidant effect in presence of Pb in lymphocytes of exposed workers, and its effect is less pronounced following the removal of Pb after standard chelation therapy.