The effect of spinach supplementation on exercise-induced oxidative stress.

AIM: Nutritional supplements have been very popular among athletes and individuals. Spinach is an important dietary vegetable rich in antioxidants which is commonly consumed. This study was conducted to assess the effects of chronic daily spinach supplementation on known markers of oxidative stress and muscle damage following half-marathon in well-trained healthy young men. METHODS: Twenty well-trained men volunteered for this study. Participants were randomized in an open study placebo-controlled fashion into two groups: Spinach (S) (N.=10) and placebo (P) (N.=10). The participants took spinach supplementation or placebo daily for 14 days before running. Participants ran 21.1 km. The spinach supplementation was prepared at 1 g/kg body weight. Total antioxidant capacity (TAC) was determined as marker of plasma antioxidant capacity. Creatine kinase (CK) was measured as marker of muscle damage and malondialdehyde (MDA), protein carbonyl (PC) and uric acid were measured as markers of oxidative stress. RESULTS: TAC significantly elevated after supplementation in S group (P<0.05). Acute exercise led to elevated levels of serum MDA, PC and CK (P<0.05). Spinach supplementation maintained PC, MDA, uric acid and CK at lower levels after exercise than the placebo (P<0.05). CONCLUSION: These results suggest that chronic daily oral supplementation of spinach has alleviating effects on known markers of oxidative stress and muscle damage following a half-marathon in well trained healthy young men.

Effect of methylsulfonylmethane supplementation on exercise - Induced muscle damage and total antioxidant capacity.

AIM: The aim of this study was to evaluate effect of 10-day methylsulfonylmethane (MSM) supplementation on exercise-induced muscle damage. METHODS: Eighteen healthy, non-smoking, active young men were recruited to participate in this study. Participants were randomized in a double-blind placebo-controlled fashion into two groups: MSM (M) (N.=9) and placebo (P) (N.=9). Subjects consumed daily either placebo (200 mL water) or MSM supplement (50 mg/kg MSM in 200 mL water) for 10 days. Afterward, participants ran 14 km. Blood samples were taken before supplementation, before exercise, immediately, 30 min, 2, 24 and 48 h after exercise. RESULTS: CK and bilirubin significantly increased in P group 24 h after exercise compared to M group (P=0.041 and P=0.002, respectively). TAC increased immediately post, 30 min, 2 and 24 h after exercise just in M group (P<0.05). TAC showed significant increase in M group 2 and 24 h after exercise compared to P group (P=0.014 and P=0.033, respectively). CONCLUSION: It seems that 10-day supplementation with MSM has allowed to decrease muscle damage via effect on antioxidant capacity.

The effect of methylsulfonylmethane on the experimental colitis in the rat.

Methylsulfonylmethane (MSM), naturally occurring in green plants, fruits and vegetables, has been shown to exert anti-inflammatory and antioxidant effects. MSM is an organosulfur compound and a normal oxidative metabolite of dimethyl sulfoxide. This study was carried out to investigate the effect of MSM in a rat model of experimental colitis. Colitis was induced by intracolonic instillation of 1 ml of 5% of acetic acid. Rats were treated with MSM (400 mg/kg/day, orally) for 4 days. Animals were euthanized and distal colon evaluated histologically and biochemically. Tissue samples were used to measurement of malondialdehyde (MDA), myeloperoxidase (MPO), catalase (CAT), glutathione (GSH) and proinflammatory cytokine (TNF-α and IL-1ß) levels. Results showed that MSM decreased macroscopic and microscopic colonic damage scores caused by administration of acetic acid. MSM treatment also significantly reduced colonic levels of MDA, MPO and IL-1ß, while increased the levels of GSH and CAT compared with acetic acid-induced colitis group. It seems that MSM as a natural product may have a protective effect in an experimental ulcerative colitis.

Allicin from garlic neutralizes the hemolytic activity of intra- and extra-cellular pneumolysin O in vitro.

Pneumolysin (PLY) is a key virulence factor contributes to the pathogenesis of Streptococcus pneumoniae. In this study we investigated the effect of allicin and aqueous garlic extracts on hemolytic activity of PLY both in prelysed and intact cells. Additionally the antimicrobial activity of allicin was tested against the bacteria. All tested materials potently inhibited the PLY hemolytic activity. Allicin neutralizes PLY in a concentration- and time-dependent manner. Twenty five minute incubation of PLY (2 HU/mL) with 0.61 µM/mL concentration of allicin, totally inhibited hemolytic activity of PLY (IC50 = 0.28 µM/mL). The inhibitory activity of old extract of garlic was similar to pure allicin (IC50 = 50.46 µL/mL; 0.31 µM/mL; P < 0.05). In contrast fresh extract of garlic inhibits the PLY hemolytic activity at lower concentrations (IC50 = 13.96 µL/mL; 0.08 µM/mL allicin). Exposure of intact cells to allicin (1.8 µM) completely inhibited hemolytic activity of PLY inside bacterial cells. The inhibitory effect of the allicin was restored by addition of reducing agent DTT at 5 mM, proposing that allicin likely inhibits the PLY by binding to cysteinyl residue in the binding site. The MIC value of allicin was determined to be 512 µg/mL (3.15 µM/mL). These results indicate that PLY is a novel target for allicin and may provide a new line of investigation on pneumococcal diseases in the future.

Effect of vitamin C supplementation on lipid peroxidation, muscle damage and inflammation after 30-min exercise at 75% VO2max.

AIM: Hypothetically, supplementation with the antioxidant vitamins C could alleviate exercise-induced lipid peroxidation. The purpose of this study was to evaluate the effect of vitamin C supplementation on exercise-induced lipid peroxidation, muscle damage and inflammation. METHODS: Sixteen healthy untrained male volunteers participated in a 30-min exercise at 75% Vo2max. Subjects were randomly assigned to one of two groups: 1) placebo and 2) vitamin C (VC: 1 000 mg vitamin C). Blood samples were obtained prior to supplementation (baseline), 2 h after supplementation (immediately pre-exercise), post-exercise, 2 and 24 h after exercise. Plasma levels of VC, total antioxidant capacity (TAC), creatine kinase (CK), malondealdehyde (MDA), total leukocytes, neutrophils, lymphocytes, interleukin-6 (IL-6) and cortisol were measured. RESULTS: Plasma vitamin C concentrations increased significantly in the VC in response to supplementation and exercise (P<0.05). TAC decreased significantly in Placebo group 24 h after exercise compared to pre-exercise (P<0.05). Although MDA levels were similar between groups at baseline, it increased significantly 2 h after exercise only in the Placebo group (P<0.05). CK increased immediately and 2 h after exercise in both groups and 24 h after exercise only in placebo group compared to pre-exercise (P<0.05). Markers of inflammation (total leukocyte counts, neutrophil counts and IL-6) were increased significantly in response to the exercise (P<0.05). In VC group, there was significant increase in lymphocyte counts immediately after exercise compared with pre-exercise (P<0.05). Serum cortisol concentrations significantly declined after supplementation compared with baseline (P<0.05) as well as declined 2 and 24 h after exercise compared with immediately after exercise in VC group (P<0.05). CONCLUSION: VC supplementation prevented endurance exercise-induced lipid peroxidation and muscle damage but had no effect on inflammatory markers.

Metabolism of the dihydropyridine calcium channel blockers mebudipine and dibudipine by isolated rat hepatocytes.

The prototype 1,4-dihydropyridine (1,4-DHP) nifedipine, indicated for the management of hypertension and angina pectoris, has drawbacks of rapid onset of vasodilating action and a short half-life. Several newer analogues have been designed to offset these problems and these include mebudipine and dibudipine. These analogues contain t-butyl substituents that have been selected to alter the fast metabolism without altering pharmacological activity. In this study, the metabolism of mebudipine and dibudipine by isolated rat hepatocytes has been investigated. These compounds were extensively metabolized in 2 h by oxidative pathways, analogous to those known for nifedipine, and by O-glucuronidation after hydroxylation of the t-butyl substituents. The in-vitro half-lives of mebudipine (22 +/- 7.1 min) and dibudipine (40 +/- 9.8 min) were significantly longer than that of nifedipine (5.5 +/- 1.1 min), which was investigated in parallel in this study. These newer 1,4-DHPs address the problem of the short half-life of nifedipine and have potential for further development in view of their comparable potency to nifedipine.

High performance liquid chromatography of mebudipine: application to pharmacokinetic study.

PURPOSE: To develop a high performance liquid chromatography system for the determination of a new 1,4-dihydropyridine, mebudipine, in rabbit plasma. METHODS: To 1 ml of rabbit plasma was added internal standard (dibudipine) and 0.5 ml of 1 M NaOH. Mebudipine and internal standard were extracted to 5 ml ethyl acetate, evaporated under slow stream of nitrogen. The residue was reconstituted in 200 microl mobile phase and 20 microl of aliquots were injected into a HPLC system equipped with 4.6 x 250 mm i.d. C18 analytical column. Mobile phase consisted of methanol (70%), water (25%) and acetonitril (5%) and its flow rate was 1 ml/min. RESULTS: There were no interfering peaks from endogenous components in blank plasma chromatograms. Standard curves were linear (r(2)>0.99) over 10 to 500 ng/ml. The extraction efficiency was >90% and the minimum quantifiable concentration was 10 ng/ml (CV<10%). CONCLUSION: A suitable, convenient and simple HPLC assay for pharmacokinetic study of mebudipine in rabbits was developed.