Eight weeks of resistance training in conjunction with glutathione and L-Citrulline supplementation increases lean mass and has no adverse effects on blood clinical safety markers in resistance-trained males

BACKGROUND

Supplementation of combined glutathione (GSH) with L-citrulline in response to a single bout of resistance exercise has been shown to increase plasma nitric oxide metabolites, nitrite and nitrate and cyclic guanosine monophosphate (cGMP), which may play a role in muscle protein synthesis. As a result, in response to resistance training (RT) these responses may establish a role for GSH + L-citrulline to increase muscle mass. This study attempted to determine the effects of an 8-week RT program in conjunction with GSH (Setria®) + L-citrulline, L-citrulline-malate, or placebo supplementation on lean mass and its association with muscle strength. The secondary purpose was to assess the safety of such supplementation protocol by assessing clinical chemistry markers.

METHODS

In a randomized, double-blind, placebo-controlled design, 75 resistance-trained males were randomly assigned to ingest GSH + L-citrulline (GSH + CIT), L-citrulline-malate, or cellulose placebo daily while also participating in 8 weeks of RT. The full dose of each supplement was delivered in capsules that were identical in weight, size, shape, and color. Participants completed testing sessions for body composition and muscle strength before and after 4 and 8 weeks of RT and supplementation. Venous blood samples were obtained before and after 8 weeks.

RESULTS

Leg press was increased with RT but was not significantly different between groups (p > 0.05); however, bench press strength was not increased with RT (p > 0.05). There were no significant changes in total body mass, fat mass, or total body water during 8 weeks of RT and supplementation. Lean mass increased in both GSH + CIT when compared to PLC; however, the increase was significant only after 4 weeks. Lean mass and strength were positively correlated (p < 0.05) in GSH + CIT, but not CIT-malate or PLC. Neither RT nor supplementation had any significant effects on blood clinical chemistry variables (p > 0.05).

CONCLUSION

Compared to PLC, supplementation of GSH + CIT during resistance training increased lean mass after 4 weeks of RT and was positively associated with muscle strength. However, after 8 weeks of RT there were no significant differences in any of the measured variables.

L-citrulline supplementation in the treatment of pulmonary hypertension associated with bronchopulmonary dysplasia in preterm infant: A case report

Introduction:

the aim of this case report is to present that oral L-citrulline supplementation may attenuate chronic pulmonary hypertension and reduce oxygen requirement in infants with severe bronchopulmonary dysplasia.

Important clinical findings:

a boy, with a birth weight of 700 g, born by cesarean section after 25 weeks of pregnancy complicated with preeclampsia, was admitted to the neonatal intensive care unit. He was ventilatory dependent for the next 3 months with significantly increased oxygen requirements. A severe stage of bronchopulmonary dysplasia, complicated with increased pulmonary vascular resistance, was diagnosed. Treatment with inhaled nitric oxide and oral sildenafil was included in the therapy of chronic pulmonary hypertension. The results of screening echocardiograms and increased plasma brain natriuretic peptide concentrations, suggested right ventricle dysfunction.

The main intervention:

at the beginning of the sixth month of hospitalization, oral supplementation of L-citrulline in a single dose of 150 mg/kg/day was introduced and continued for 70 days. During the first 3 weeks after L-citrulline was started, the patient was weaned from mechanical ventilation and he was never intubated again until he was discharged. Plasma brain natriuretic peptide concentrations decreased significantly during the first month of L-citrulline administration and became stable until the termination of L-citrulline supplementation. At discharge, the patient required 22%–25% concentration of oxygen supplemented intermittently, exclusively during feeding.

Conclusion:

these results indicate that L-citrulline supplementation may deserve coverage as an additional, potentially beneficial alternative in the prophylaxis or therapy of chronic pulmonary hypertension in newborns.

[Production of L-citrulline by a recombinant Corynebacterium crenatum SYPA 5-5 whole-cell biocatalyst]

Arginine deiminase (ADI) was first high-efficient expressed in Corynebacterium crenatum SYPA 5-5. The ADI was purified by Ni-NTA affinity chromatography and SDS-PAGE analysis showed the molecular weight (MW) was 46.8 kDa. The optimal temperature and pH of ADI were 37 ℃ and 6.5 respectively. The Michaelis constant was 12.18 mmol/L and the maximum velocity was 0.36 μmol/(min·mL). Under optimal conditions, 300 g/L of arginine was transformed and the productivity reach 8 g/(L·h). The recombinant strain was cultivated in a 5-L fermentor and used for whole-cell transformation of 300 g/L arginine, under repeated-batch bioconversion, the cumulative production reached 1 900 g/L.

Decreased serum L-arginine and L-citrulline levels in major depression

RATIONALE

It has been suggested that endothelial dysfunction caused by a decreased endothelial production of nitric oxide (NO) may contribute to the consistently observed increased risk of developing cardiovascular disease (CVD) in physically healthy patients suffering from major depression (MD). NO is a gas synthesized from Larginine (a conditionally essential amino acid) and oxygen by endothelial nitric oxide synthase (eNOS). The end products of NO production include both NO and L-citrulline. NO is rapidly reduced to the anions nitrite and nitrate, classically referred to as NO metabolites. Their measurement has been used as a surrogate measurement for endothelial NO production. We and others have shown decreased levels of NO metabolites in the serum of MD patients. The mechanism of this decreased production of NO by the endothelium has not yet been elucidated.

OBJECTIVES

The purpose of this study is to assess serum levels of L-arginine and L-citrulline in patients with MD.

METHODS

Levels of L-arginine and L-citrulline were measured in 35 unmedicated physically healthy MD patients and 36 healthy controls (HCs).

RESULTS

L-arginine and L-citrulline concentrations were significantly lower in MD patients than in healthy controls (L-arginine, 73.54 + 21.53 μmol/L and 84.89 + 25.16, p = 0.04 μmol/L and L-citrulline 31.58 + 6.05 μmol/L and 35.19 + 6.85 μmol/L, p = 0.03, respectively).

CONCLUSIONS

The decrease in L-arginine levels in MD patients is a possible explanation for the decrease in NO metabolites in MD patients and therefore may contribute, through endothelial dysfunction, to the increased CV risk associated with MD.

Treatment with L-citrulline in patients with post-polio syndrome: study protocol for a single-center, randomised, placebo-controlled, double-blind trial

BACKGROUND

Post-polio syndrome (PPS) is a condition that affects polio survivors years after recovery from an initial acute infection by the Poliomyelitis virus. Most often, patients who suffered from polio start to experience gradual new weakening in muscles, a gradual decrease in the size of muscles (muscle atrophy) and fatigue years after the acute illness. L-citrulline is known to change muscular metabolism synthesis by raising nitric oxide (NO) levels and increasing protein synthesis. This investigator-initiated, randomised, placebo-controlled, double-blind, trial aims to demonstrate that L-citrulline positively influences muscle function and increases muscular energy production in patients with PPS.

METHODS/DESIGN

Thirty ambulant PPS patients will be recruited in Switzerland. Patients will be randomly allocated to one of the two arms of the study (placebo:verum 1:1). After a 24-week run-in phase to observe natural disease history and progression, participants will be treated either with L-citrulline or placebo for 24 weeks. The primary endpoint is change in the 6-min Walking Distance Test. Secondary endpoints will include motor function measure, quantitative muscle force, quantitative muscle magnetic resonance imaging and magnetic resonance spectroscopy and serum biomarker laboratory analysis DISCUSSION: The aim of this phase IIa trial is to determine if treatment with L-citrulline shows a positive effect on clinical function and paraclinical biomarkers in PPS. If treatment with L-citrulline shows positive effects, this might represent a cost-efficient symptomatic therapy for PPS patients.

TRIAL REGISTRATION

ClinicalTrial.gov, ID: NCT02801071 . Registered on 6 June 2016.

Potential Nutrients for Preventing or Treating Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a frequent complication occurring in extremely preterm infants. Despite recent advances in newborn medicine, the incidence of BPD does not appear to have changed markedly, and specific treatments and prevention strategies are still lacking. Nutrition plays an important role in normal lung development and maturation. Malnutrition may delay somatic growth and new alveoli development, thus aggravating pulmonary injury involved in the pathogenesis of BPD. However, few nutrients have been investigated for their potential to mitigate the pathogenesis of BPD. In this article, we reviewed the recent progress in research on potential nutrients useful for the prevention or treatment of BPD, including glutamine, cysteine and N-acetylcysteine, L-arginine and L-citrulline, long chain polyunsaturated fatty acids (LCPUFAs), inositol, selenium, and some antioxidant vitamins including vitamin A. Current evidence shows that vitamin A and LCPUFA can prevent BPD, and that L-citrulline might provide a new method to treat chronic pulmonary hypertension associated with BPD in premature infants. The effects of other nutrients on BPD prevention need to be further studied.

Treatment with L-citrulline and metformin in Duchenne muscular dystrophy: study protocol for a single-centre, randomised, placebo-controlled trial

Background

Duchenne muscular dystrophy (DMD) is an X-linked recessive disease that affects 1 in 3500–6000 male births. Despite broad research aiming to improve muscle function as well as heart and brain function, sufficient therapeutic efficacy has not yet been achieved and current therapeutic management is still supportive. In a recent pilot trial, oral treatment with l-arginine and metformin showed consistent changes of muscular metabolism both in vitro and in vivo by raising NO levels and expression of mitochondrial proteins in the skeletal muscle tissue of patients with DMD. This randomised, double-blind, placebo-controlled trial aims to demonstrate the superiority of l-citrulline and metformin therapy over placebo in DMD patients with regard to the Motor Function Measure (MFM) D1 subscore (primary endpoint) as well as additional clinical and subclinical tests.

Methods/Design

A total of 40–50 ambulant patients with DMD will be recruited at the outpatient department of the University of Basel Children’s Hospital (Switzerland), as well as from the DMD patient registries of Switzerland, Germany and Austria. Patients will be randomly allocated to one of the two arms of the study and will receive either a combination of l-citrulline and metformin or placebo for 26 weeks. Co-medication with glucocorticoids is allowed. The primary endpoint is the change of the MFM D1 subscore from baseline to week 26 under l-citrulline and metformin therapy. Secondary endpoints will include the motor function measure (MFM) and its items and subscores, the 6-minute walking test, timed function tests and quantitative muscle testing. Furthermore, quantitative muscle MRI assessment to evaluate the muscle fat fraction as well as safety and biomarker laboratory analyses from blood will be included. For comparison, muscle metabolism and mitochondrial function will be analysed in 10–20 healthy age-matched male children.

Discussion

The aim of this study is to test if a 6-month treatment of a combination of l-citrulline and metformin is more effective than placebo in preventing loss of motor function and muscle degeneration in DMD. The MFM D1 subscore is used as a clinical outcome measure and a quantitative muscle MRI assessment as the surrogate outcome measure of fatty muscle degeneration.

Trial registration

ClinicalTrials.gov: NCT01995032. Registered on 20 November 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1503-1) contains supplementary material, which is available to authorized users.

Nitric oxide synthesis capacity, ambulatory blood pressure and end organ damage in a black and white population: the SABPA study

Nitric oxide (NO) synthesis capacity is determined by the availability of substrate(s) such as L-arginine and the influence of nitric oxide synthase (NOS) inhibitors, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). These factors may be important in black South Africans with a very high prevalence of hypertension. We compared ambulatory blood pressure (BP), markers of end organ damage and NO synthesis capacity markers [L-arginine, L-homoarginine, L-citrulline, L-arginine:ADMA, ADMA, SDMA and dimethylarginine (DMA)], between black and white teachers (n = 390). Associations of nighttime BP and markers of end organ damage with NO synthesis capacity markers were also investigated. Although black men and women had higher BP and albumin-to-creatinine ratio (ACR) (all p < 0.001), they also had higher L-arginine, L-homoarginine, L-arginine:ADMA and lower SDMA and DMA levels (all p < 0.05). Only in white men ADMA concentrations associated positively with nighttime systolic blood pressure (R (2) = 0.20, β = 0.26, p = 0.009), nighttime diastolic blood pressure (R (2) = 0.23, β = 0.27, p = 0.007), carotid intima media thickness (cIMT) (R (2) = 0.36, β = 0.22, p = 0.008) and ACR (R (2) = 0.14, β = 0.32, p = 0.001). Our findings suggest that despite an adverse cardiovascular profile in blacks, their NO synthesis capacity profile seems favourable, and that other factors, such as NO inactivation, may prove to be more important.

Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis

Background

Nitric oxide (NO) is endogenously synthesized from L-arginine and L-citrulline. Due to its effects on nitric oxide synthase (NOS), reduced glutathione (GSH) may protect against the oxidative reduction of NO. The present study determined the effectiveness of L-citrulline and/or GSH on markers indicative of NO synthesis in in vivo conditions with rodents and humans and also in an in vitro condition.

Methods

In phase one, human umbilical vein endothelial cells (HUVECs) were treated with either 0.3 mM L-citrulline, 1 mM GSH (Setria®) or a combination of each at 0.3 mM. In phase two, Sprague–Dawley rats (8 weeks old) were randomly assigned to 3 groups and received either purified water, L-citrulline (500 mg/kg/day), or a combination of L-citrulline (500 mg/kg/day) and GSH (50 mg/kg/day) by oral gavage for 3 days. Blood samples were collected and plasma NOx (nitrite + nitrate) assessed. In phase three, resistance-trained males were randomly assigned to orally ingest either cellulose placebo (2.52 g/day), L-citrulline (2 g/day), GSH (1 g/day), or L-citrulline (2 g/day) + GSH (200 mg/day) for 7 days, and then perform a resistance exercise session involving 3 sets of 10-RM involving the elbow flexors. Venous blood was obtained and used to assess plasma cGMP, nitrite, and NOx.

Results

In phase one, nitrite levels in cells treated with L-citrulline and GSH were significantly greater than control (p < 0.05). In phase two, plasma NOx with L-citrulline + GSH was significantly greater than control and L-citrulline (p < 0.05). In phase three, plasma cGMP was increased, but not significantly (p > 0.05). However, nitrite and NOx for L-citrulline + GSH were significantly greater at 30 min post-exercise when compared to placebo (p < 0.05).

Conclusions

Combining L-citrulline with GSH augments increases in nitrite and NOx levels during in vitro and in vivo conditions.

Analysis of L-citrulline and L-arginine in Ficus deltoidea leaf extracts by reverse phase high performance liquid chromatography

Background:

Ficus deltoidea (FD) is one of the native plants widely distributed in several countries in Southeast Asia. Previous studies have shown that FD leaf possess antinociceptive, wound healing and antioxidant properties. These beneficial effects have been attributed to the presence of primary and secondary metabolites such as polyphenols, amino acids and flavonoids.

Objective:

The aim was to develop a reverse phase high-performance liquid chromatography method with ultraviolet detection that involves precolumn derivatisation with O-phthaladehyde for simultaneous analysis of two amino acids L-citrulline and L-arginine in FD leaf extracts.

Materials and Methods:

An isocratic elution program consisting of methanol: acetonitrile: Water at 45:45:10 v/v (solvent A) and 0.1 M phosphate buffer pH 7.5 (solvent B) at A: B v/v ratio of 80:20 on Zorbax Eclipse C18 SB-Aq column (250 × 4.6 mm, 5 μm) were used. The flow rate was set at 1 ml/min and detection was carried out at 338 nm with 30 min separation time.

Results:

Good linearity for L-citrulline and L-arginine was obtained in the range 0.1-1000 μg/ml at R² ≥ 0.998. The limit of detection and limit of quantification values for both L-citrulline and L-arginine were 1 and 5 μg/ml, respectively. The average of recoveries was in the range 94.94-101.95%, with relative standard deviation (%RSD) less than 3%. Intra- and inter-day precision was in the range 96.36-102.43% with RSD less than 2%.

Conclusion:

All validation parameters of the developed method indicate the method is reliable and efficient for simultaneous determination of L-citrulline and L-arginine for routine analysis of FD.

Pretreatment With L-Citrulline Positively Affects the Mucosal Architecture and Permeability of the Small Intestine in a Murine Mucositis Model

BACKGROUND

Mucositis is a common complication in patients undergoing radiotherapy and chemotherapy. It is associated with pain, poor quality of life, and malnutrition, leading to an increased number of hospital admissions and prolonged hospitalization. The use of immunonutrients may be an alternative treatment option, which may help to improve patient outcome.

OBJECTIVE

Here we assessed the impact of L-citrulline (CIT) on a murine model of 5-fluorouracil (5FU)-induced mucositis.

METHODS

Swiss male mice were randomized into 4 groups: control, CIT, 5FU, and 5FU+CIT. Mice were fed with commercial chow and supplemented with an oral solution of alanine (control and 5FU groups) or CIT (CIT and 5FU+CIT groups). On the seventh day, mice received intraperitoneal phosphate-buffered saline or 5FU (200 mg/kg, single dose) to induce mucositis. On the 10th day, mice were euthanized, and the blood and small intestines were harvested. Body weight, morphology, histopathology score (hematoxylin and eosin) of the small intestine (from 0-12), myeloperoxidase activity, oxidative stress level, and intestinal permeability were assessed.

RESULTS

We observed significant weight loss after the administration of 5FU in both treated and control animals. CIT administration contributed to a partial recovery of the mucosal architecture as well as an intermediate reduction of the histopathologic score, and functional intestinal permeability was partially rescued.

CONCLUSIONS

CIT administration attenuated 5FU-mediated damage to the mucosal architecture of the small intestine, decreasing the size of the injured areas and promoting decreased intestinal permeability.

Effects of L-citrulline diet on stress-induced cold hypersensitivity in mice

BACKGROUND

L-citrulline is an amino acid discovered in watermelon (Citrullus lanatus, Cucurbitaceae) and is a known component of the nitric oxide (NO) cycle that plays an important role in adjusting blood circulation and supplying NO and a key component of the endothelium-derived relaxing factor.

OBJECTIVE

The objective of this study is to evaluate the effect of L-citrulline on a newly established stress-induced cold hypersensitivity mouse model.

MATERIALS AND METHODS

When normal mice were forced to swim in water at 25°C for 15 min, their core body temperature dropped to 28.9°C, and then quickly recovered to normal temperature after the mice were transferred to a dry cage at room temperature (25°C). A 1-h immobilization before swimming caused the core body temperature to drop to ca. 24.1°C (4.8°C lower than normal mice), and the speed of core body temperature recovery dropped to 57% of the normal control. We considered this delay in recovery from hypothermia to be a sign of stress-induced cold hypersensitivity. Similar cold hypersensitivity was induced by administration of 50 mM L-NG-nitroarginine methyl ester, a NO synthesis inhibitor.

RESULTS

In this study, we showed that recovery speed from the stress-induced hypothermia remarkably improved in mice fed a 1% L-citrulline-containing diet for 20 days. Furthermore, the nonfasting blood level of L-arginine and L-citrulline increased significantly in the L-citrulline diet group, and higher serum nitrogen oxide levels were observed during recovery from the cold.

CONCLUSIONS

These results suggested that oral L-citrulline supplementation strengthens vascular endothelium function and attenuates stress-induced cold hypersensitivity by improving blood circulation.