Effect of papaya supplementation on oxidative stress markers in Parkinson’s disease

Objective: In Parkinson’s disease (PD), oxidative processes occur that are probably involved in the progression of neuronal damage. Recent studies suggest that regular consumption of antioxidant-rich foods or supplementation with functional foods like fermented papaya, may reduce cellular oxidative stress and protect against many agerelated diseases by strengthening the physiological antioxidant barrier. Our study aims to assess the antioxidant properties of a commercial fermented papaya preparation (FPP) in PD by evaluation of its effects on a wide panel of oxidative stress markers in blood and urine. Methods: A group of parkinsonian voluntary patients (T, n = 15) were treated 9 months with FPP and compared with a control group (NT, n = 12). The efficacy of FPP in increasing the physiological antioxidant barrier was evaluated at the times 0, 6 and 9 months with the analysis of 23 oxidative markers including total radical oxygen species, homocysteine, biological antioxidant potential, glutathione, superoxide dismutase, uric acid, total bilirubin, iron, ferritin, coenzyme Q10, 3-nitrotyrosine, total lipoperoxide, 4-hydroxy-nonenal, 8-hydroxydeoxyguanosine (8OHdG) and 2-deoxyguanosine (2-dG). Results: Among the considered markers, twenty not showed significant differences at times 0, 6 and 9 months between T and NT patients, demonstrating a consequent non-significant effect of FPP supplementation. Instead, three urinary markers of oxidative stress on nucleic acids, 8-OHdG/2-dG, 2-dG/uric acid and 2-dG/creatinine showed statistical significant interactions between ‘time’ and ‘treatment’, highlighting an effective better response to oxidative attack for T than NT. Conclusions: Papaya supplementation for a medium-long time seems able to affect positively the turnover of oxidized nucleic acids helping to restore the normal nitrogenous bases into nucleotide chains and to replace those altered by radicals’ attack.