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Background & objectives: Curcumin has antioxidant properties. The aim of this study was to determine the effect of curcumin on bax, bcl-2, antioxidant enzymes and lipid peroxidation of sperm after freezing procedure.
Methods: In this experimental study, semen samples were collected from four mature Holstein bulls, twice a week in eight innings. Semen samples were divided into four groups. Zero (control), 10 (Experimental group one), 20 (Experimental group two) and 30 (Experimental group three) mg/ml of curcumin with diluents were added to the semen samples. After thawing, Bax, Bcl-2 and malondialdehyde levels as well as superoxide dismutase, glutathione peroxidase and catalase enzymes were measured in sperm samples using ELISA.
Results: According to the results, Bcl-2, superoxide dismutase, glutathione peroxidase and catalase levels  in sperm samples treated with 20 and 30 mg/ml curcumin significantly increased and Bax and malondialdehyde levels significantly decreased compared to control groups (p<0.05). This difference was not significant for sperm samples treated with 10 mg/ml curcumin.
Conclusion: Dose-dependent administration of curcumin decreased oxidative stress and lipid peroxidation and increased anti-apoptosis proteins in freeze-thawing sperms.