Effects of pomegranate juice in circulating parameters, cytokines, and oxidative stress markers in endurance-based athletes: A randomized controlled trial

OBJECTIVE

The aim of the present study was to assess the effects of pomegranate juice on the level of oxidative stress in the blood of endurance-based athletes. Pomegranate juice is rich in polyphenols, conferring it a higher antioxidant capacity than other beverages with polyphenolic antioxidants.

METHODS

A randomized double-blind, multicenter trial was performed in athletes from three different sport clubs located in southeastern of Spain. Plasma oxidative stress markers (protein carbonyls and malondialdehyde [MDA]) as well as C-reactive protein and sE-selectin were measured. Thirty-one athletes participated in the study. Participants were divided into three groups. The first group was supplemented with 200 mL/d pomegranate juice (PJ; n = 10) over a 21-d period, the second with 200 mL/d pomegranate juice diluted 1:1 with water (PJD; n = 11), and a control group that did not consume pomegranate juice (C; n = 10). Nine athletes were excluded due to protocol violations (n = 4 in the PJ group and n = 5 in the PJD group) because they did not observe the 24 h of rest before the last blood test.

RESULTS

The control group increased levels of carbonyls (+0.7 ± 0.3 nmols/mg protein) and MDA (+3.2 ± 1.0 nmols/g protein), whereas the PJ and PJD groups maintained or decreased their levels, respectively. On the other hand, lactate levels increased in the PJ group (from 10.3 at day 0 to 21.2 mg/dL at day 22). A nonsignificant decrease was detected in sE-selectin and C-reactive protein in the groups consuming pomegranate juice.

CONCLUSION

Consumption of pomegranate juice over a 21-d period improved MDA levels and carbonyls, and thus decreased the oxidative damage caused by exercise.

Phenylpropanoids and their metabolites are the major compounds responsible for blood-cell protection against oxidative stress after administration of Lippia citriodora in rats

Lippia citriodora (lemon verbena) has been widely used in folk medicine for its pharmacological properties. Verbascoside, the most abundant compound in this plant, has protective effects associated mostly with its strong antioxidant activity. The purpose of this study was to test the effect of L. citriodora extract intake on the antioxidant response of blood cells and to correlate this response with the phenolic metabolites found in plasma. For this purpose, firstly the L. citriodora extract was characterized and its radical scavenging activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Then, catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GRed) activities were determined in lymphocytes, erythrocytes, and neutrophils isolated from rats after acute intake of L. citriodora. Phenolic metabolites were analyzed in the same plasma samples by HPLC-ESI-TOF-MS. Myeloperoxidase (MPO) activity in neutrophils, which has been proposed as a marker for inflammatory vascular damage, was also determined. After L. citriodora administration, the antioxidant enzymes activities significantly accelerated (p<0.05) while MPO activity subsided, indicating that the extract protects blood cells against oxidative damage and shows potential anti-inflammatory and antiatherogenic activities. The main compounds found in plasma were verbascoside and isoverbascoside at a concentration of 80±10 and 57±4 ng/ml, respectively. Five other metabolites derived from verbascoside and isoverbascoside were also found in plasma, namely hydroxytyrosol, caffeic acid, ferulic acid, ferulic acid glucuronide, and homoprotocatechuic acid, together with another eight phenolic compounds. Therefore, the phenylpropanoids verbascoside and isoverbascoside, as well as their metabolites, seem to be the responsible for the above-mentioned effects, although the post-transcriptional activation mechanism of blood-cell antioxidant enzymes by these compounds needs further investigation.