«The Influence of Supplementation With Artichoke (Cynara scolymus L.) Extract on Selected Redox Parameters in Rowers Anna Skarpañska-Stejnborn, Lucia ...»
International Journal of Sport Nutrition and Exercise Metabolism, 2008, 18, 313-327
© 2008 Human Kinetics, Inc.
The Influence of Supplementation With
Artichoke (Cynara scolymus L.) Extract
on Selected Redox Parameters in Rowers
Anna Skarpañska-Stejnborn, Lucia Pilaczynska-Szczesniak,
Piotr Basta, Ewa Deskur-Smielecka,
and Magorzata Horoszkiewicz-Hassan
High-intensity physical exercise decreases intracellular antioxidant potential. An
enhanced antioxidant defense system is desirable in people subjected to exhaustive exercise. The aim of this study was to investigate the influence of supplementation with artichoke-leaf extract on parameters describing balance between oxidants and antioxidants in competitive rowers. This double-blinded study was carried out in 22 members of the Polish rowing team who were randomly assigned to a supplemented group (n = 12), receiving 1 gelatin capsule containing 400 mg of artichoke-leaf extract 3 times a day for 5 wk, or a placebo group (n = 10). At the beginning and end of the study participants performed a 2,000-m maximal test on a rowing ergometer. Before each exercise test, 1 min after the test completion, and after a 24-hr restitution period blood samples were taken from antecubital vein. The following redox parameters were assessed in red blood cells: superoxide dismutase activity, glutathione peroxidase activity, glutathione reductase activity, reduced glutathione levels, and thiobarbituric-acid-reactive-substances concentrations. Creatine kinase activity and total antioxidant capacity (TAC) were measured in plasma samples, lactate levels were determined in capillary blood samples, and serum lipid profiles were assessed. During restitution, plasma TAC was significantly higher (p.05) in the supplemented group than in the placebo group. Serum total cholesterol levels at the end of the study were significantly (p.05) lower in the supplemented group than in the placebo group. In conclusion, consuming artichoke-leaf extract, a natural vegetable preparation of high antioxidant potential, resulted in higher plasma TAC than placebo but did not limit oxidative damage to erythrocytes in competitive rowers subjected to strenuous training.
Keywords: antioxidants, TBARS, exhaustive exercise, training Skarpañska-Stejnborn and Basta are with the Dept. of Water Sports; Pilaczynska-Szczesniak, the Dept.
of Hygiene; and Deskur-Smielecka, the Dept. of Cardiac Rehabilitation, University School of Physical Education in Poznan, 66-400 Gorzów Wlkp., Poland. Horoszkiewicz-Hassan is with the Research and Development Dept., Europlant PhytoPharm Sp. z.o.o., Kleka, Poland.
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There is growing body of evidence (Aslan, Sekeroglu, Tarakcioglu, Bayýroglu, & Meral, 1998; Franzoni et al., 2005) to indicate that physical training can increase antioxidant potential in athletes. Enhanced antioxidant potential might protect against damages associated with exercise-induced oxidative stress. It should be emphasized, however, that the human organism is capable of maintaining stable balance between oxidants and antioxidants only if intensity and duration of exercise are moderate. Exercise of higher intensity is associated with uncontrolled generation of reactive oxygen species (ROS), which inflicts damage on DNA and proteins and decreases fluidity and permeability of cell membranes as a result of lipid peroxidation (Goto et al., 2003; Marzatico, Pansarasa, Bertorelli, Somenzini, & Della Valle, 1997). Increasing intensity of exercise leads to gradual exhaustion of antioxidant potential, which manifests in decreased activity of intracellular antioxidant enzymes and diminished levels of extracellular nonenzymatic antioxidants (Aslan et al.; Liu et al., 2000). According to Kretzschmar and Klinger (1990) and Venditti, Masullo, and Meo (1999), these changes are sensitive markers of enhanced peroxidation processes in humans.
Although training results in adaptations that increase the defensive potential against ROS, these changes might be insufficient to prevent oxidative damages after maximal-intensity exercise (Bloomer, Goldfarb, & McKenzie, 2006; Margonis et al., 2007). Similarly, varied nutrition might be insufficient to supply enough antioxidants to prevent oxidative stress during exhaustive exercise.
High-intensity oxidative stress induced by maximal exercise indicates a need for an increased supply of antioxidants in the diet of those exposed to strenuous exercise (Bloomer et al., 2006; Pilaczynska-Szczesniak, Skarpañska-Stejnborn, Deskur, Basta, & Horoszkiewicz-Hassan, 2005). There are several arguments for
enriching athletes’ diet in vegetable antioxidants; for example:
• Higher assimilation capacity of natural products than synthetic preparations • Impossibility of overdose • Interactions between various antioxidants to neutralize ROS It has been reported that artichoke has antioxidative and antiatherogenic properties. Artichoke inhibits cholesterol synthesis de novo in the liver, prevents LDL modification, stimulates bile secretion, and has strong antioxidant properties (Gebhardt, 1997a; Wolf, 1996). The antioxidant properties of artichoke result from its high content of chlorogenic acid, cynarine, and flavonoids—derivatives of luteoline (cynaroside, scolimoside, and cynarotriozyd; Brown & Rice-Evans, 1998;
Gebhardt, 1997b; Llorach, Espin, Tomas-Barberan, & Ferreres, 2002). According to Gebhardt (1997a), the antioxidant potential of artichoke depends not only on properties of particular substances but also on the quantitative and qualitative composition of the extract.
The aim of the current study was to investigate the influence of artichoke-leaf extract on lipid profile and intensity of exercise-induced oxidative stress in rowers participating in a training camp.
The Influence of Artichoke-Leaf Extract in Rowers Material and Methods Study Population The study population consisted of 22 male members of the Polish rowing team for the Youth World Championships 2006 in Hazelwinkel, Belgium. The study was performed in June and July during a 5-week training camp between the preparation and competition periods. The participants’ characteristics are presented in Table
1. Data concerning training profile, including intensity, volume (in minutes), and type (specific: rowing endurance, technique, speed, etc.; semispecific: rowing ergometer; nonspecific: jogging, strength), were recorded daily. All training data were analyzed for intensities below and above the lactate threshold of 4 mmol/L, as shown in Figure 1 as extensive (below lactate threshold) and intensive (above lactate threshold) workload.
During the entire study period, athletes were residents in one of the Olympic Games training centers and took meals exclusively in the center. Their regular menu consisted of a mixed diet containing the recommended dietary allowance of carbohydrates, proteins, fats, and micronutrients (vitamins and minerals). Daily food and caloric intake, as well as fruit and vegetable intake, of the participants did not change over the study period. The athletes informed the scientific staff that they had not been taking any drugs, medication, or nutritional supplements for 2 weeks before and during the study.
Experimental Procedure Athletes enrolled in the study were randomly assigned to receive artichoke-leaf extract (n = 12), or placebo (n = 10). The rowers in the supplemented group were given an artichoke preparation (Europlant PhytoPharm Kleka SA, Poland) three times a day for 5 weeks. One gelatin capsule contained 400 mg of dry artichoke-leaf extract (Cynarae folii extractum aq. siccum [4–6: 1]), which corresponds to 2 g of raw material. The rest of the preparation was composed of the following inactive
Figure 1 — Training schedule during the week preceding blood-sample collection before (Term I) and after (Term II) the supplementation period (volume in min/day).
ingredients: lactose, talc, magnesium stearate, colloidal silica, and cornstarch. At the same time and with the same dosage regimen, participants in the placebo group received dyed gelatin capsules containing inactive ingredients. All participants were informed of the nature of the investigation and gave their written consent to participate in the study according to the requirements of the local ethical committee.
On the first day (before supplementation) and at the end of the training camp (after supplementation), the athletes performed a controlled 2,000-m rowing exercise test. Each participant had to cover the distance on a rowing ergometer (Concept II, USA) in as short a time as possible. Before the test participants performed 5-min individual warm-ups.
The Influence of Artichoke-Leaf Extract in Rowers Sample Treatment Blood samples for redox parameters were taken from the antecubital vein, with K2EDTA (dipotassium ethylene diamine tetra acetic acid) used as an anticoagulant before each incremental exercise test (in the morning, after an overnight fast), 1 min after test completion, and after a 24-hr recovery period. Samples were centrifuged immediately to separate red blood cells from plasma. Packed erythrocytes were washed three times with saline and lysed with ice-cold, redistilled water. Plasma, serum, and lysed erythrocytes were frozen immediately and stored at –28 °C until use (up to 1 week). In addition, capillary blood samples were taken by finger prick before and after each exercise test to assess lactate levels.
Measurements Total antioxidant capacity (TAC), used as an overall measure of plasma antioxidant capacity, was assessed with a commercially available kit (Randox-TAS, Cat. No. NX 2332, UK). This assay was based on interaction between chromogen (2,2′-azinodi-[3-ethylbenzthiazoline sulphonate], ABTS°) and ferrylmyoglobin, a free radical formed in the reaction of metmyoglobin and hydrogen peroxide. Antioxidants in added plasma scavenge ABTS° and prevent absorbance to a degree related to the overall plasma antioxidant capacity. This radical had a stable green color, measured at 600 nm. Antioxidants contained in the plasma suppress the color development proportionally to the amount of antioxidants in the sample.
Superoxide dismutase (SOD) activity was measured in washed erythrocytes after their lysis by means of a commercially available kit (Randox-Ransod, Cat No. SD 125, UK). SOD catalyzes dismutation of superoxide anion (O2), leading to formation of oxygen and hydrogen peroxide. The determination of SOD activity was based on the production of O2 by the xanthine and xanthine oxidase system. Superoxide anions reacted with the 2-(4-iodophenyl)-3-(4-nitrophenol)-5phenyltetrazolium chloride to form a red formazan dye. The units of SOD activity were calculated on the basis of changes in the absorbance over 3 min, at 505 nm and 37 °C, and from data from the standard curve generated with known amounts of purified SOD, which was obtained from the manufacturer. The SOD activity was expressed in U/g Hb.
Glutathione peroxidase (GPx) activity in the hemolysate samples was measured using a commercially available kit (Randox-Ransel, Cat No. RS 506, UK).
GPx catalyzes the oxidation of reduced glutathione in the presence of cumene hydroperoxide. The rate of glutathione oxidation was measured by monitoring the disappearance of NADPH+H+ in the reaction medium, because NADPH+H+ was consumed to reduce oxidized glutathione by glutathione reductase. The decrease in absorbance was measured at 340 nm and 37 °C. GPx activity was expressed in U/g Hb.
Glutathione reductase (GR) activity in the hemolysate samples was assayed using reagent from Randox Laboratories (Cat. No. GR 2368, UK). GR catalyzes reduction of oxidized glutathione in the presence of NADPH, which is oxidized to NADP+. For the GR assay, the 50% hemolysates were centrifuged to remove stroma, and 100 µl were diluted with 1.9 ml of 0.9% NaCl (total dilution of the 318 Skarpañska-Stejnborn et al.
hemolysates for the GR assay, 1:40). The decrease in absorbance at 340 nm was measured at 37 °C. GR activity was expressed in U/g Hb.