Adenosine deaminase (ADA) is involved in purine metabolism and plays a significant role in the immune
system. The focus of this investigation was to examine the effects of low concentrations of organic mercury
on ADA activity in human leukocytes and to investigate the relationship between these effects and
cell death. We have examined the protective potential effects of Allium sativum extract (GaE) against
Methylmercury (MeHg)-induced cytotoxic effects on human leucocytes under in vitro conditions. MeHg
(0.05–10 lM) significantly decreased leukocyte viability (58.97% for MTT (3-[4,5-dimethylthiazol-2-yl]-
2,5-diphenyl tetrazolium bromide) and 51.67% for Alamar Blue (AB) and this decrease was positively correlated
to the MeHg-induced inhibition of ADA activity. N-acetylcysteine (NAC) and GaE prevented both
the MeHg-induced cytotoxic effects on leukocytes according to MTT and AB assays and the effects on the
ADA activity. The present results suggest that the protective effects of GaE against MeHg-induced leukocyte
damage is related to the removal of oxidant species generated in the presence of MeHg due to the
antioxidant efficacy of garlic constituents. It is important to point out that the intense presence of ADA
in Leukocyte suspension (LS) highlights the relevant effects in the immune system and in vitro cytotoxicity
of MeHg exposure.