Arginine or citrulline associated with a statin stimulates nitric oxide production in bovine aortic endothelial cells

A study of lovastatin and L-arginine co-loaded PLGA nanomedicine for enhancing nitric oxide production and eNOS expression

Nitric oxide (NO) is an exceptional endogenous biological gas that mediates and regulates physiological and pathological processes in the human body. However, its synthesis process is impaired during athero-progression and formation. Hence, a strategy to boost NO production and target endothelial nitric oxide synthase (eNOS) is crucial and intriguing in atherosclerosis (AS) management. Herein, we prepare L-arginine (LA) and lovastatin (LV) co-loaded PLGA nanomedicine to achieve sustainable release for enhancing NO production. The utilization of LA reveals that LA has dual contributions, acting as a NO donor and enhancing the solubility of LV by stabilizing PLGA NPs. PLGA-LA/LV demonstrated its potential to boost NO in vitro and in vivo confirmed using DAF-FM DA, augment eNOS and p-eNOS mRNA and protein levels, and suppress the ki67 proliferation marker in VSMCs; in addition, it lowers the total cholesterol level of blood plasma in C57BL/6 mice. Moreover, PLGA can protect the compound delivered and enhance the bioavailability to reach and get released in the blood circulation after oral administration. Collectively, our results endow a safe and efficient nanomedicine outcome, specifically with potential for AS management.

LDL-cholesterol lowering effect of a new dietary supplement: an open label, controlled, randomized, cross-over clinical trial in patients with mild-to-moderate hypercholesterolemia

Background

Hypercholesterolemia is a major risk factor for cardiovascular disorders and requires specific intervention through an adequate lifestyle (diet and physical exercise) and, if necessary, an appropriate drug treatment. Lipid-lowering drugs, although generally efficacious, may sometimes cause adverse events. A growing attention has been devoted to the correction of dyslipidemias through the use of dietary supplements. The aim of this study was to assess the lipid-lowering activity and safety of a dietary supplement containing monacolin K, L-arginine, coenzyme Q10 and ascorbic acid, named Argicolina (A), compared to a commercially available product containing monacolin K and coenzyme Q10, Normolip 5 (N).

Methods

This was a single center, controlled, randomized, open-label, cross-over clinical study enrolling 20 Caucasian outpatients aged 18–75 years with serum LDL-C between 130 and 180 mg/dL. Patients assumed two different dietary supplements (A and N) both containing monacolin K 10 mg for 8 weeks each, separated by a 4-week wash-out period. Evaluated parameters were: Total cholesterol (Tot-C), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides (TG), fasting blood glucose, aspartate aminotransferase, alanine aminotransferase, creatinekinase, gamma-glutamyl-transpeptidase, brachial arterial pressure and heart rate, measured at the start and at the end of each treatment period. Safety was monitored through the study.

Results

LDL-C decreased by 23.3% during treatment with N (p < 0.0001) and by 25.6% during treatment with A (p < 0.0001); the LDL-C mean reduction was 36.4 (95% CI: 45,6–27,1) mg/dL during N treatment and 40.1 (95% CI: 49.2–30,9) mg/dL during A treatment. Tot-C decreased significantly (p < 0.0001) within each treatment period. HDL-C increase was negligible during A whereas it was significant during N. TG diminished markedly during A and not significantly during N. The difference between treatments was not statistically significant for all variables. No serious or severe adverse events occurred during the study.

Conclusions

Our results confirm the clinically meaningful LDL-C lowering properties of monacolin K. At variance with a supplement already in the market (N), the novel association (A) of monacolin K with L-arginine, coenzime Q10 and ascorbic acid also produces a significant reduction of triglycerides without significant effects on HDL.

Trial registration

ClinicalTrials.gov ID: NCT03425630.

Combining citrulline with atorvastatin preserves glucose homeostasis in a murine model of diet-induced obesity

BACKGROUND AND PURPOSE

NO is a crucial regulator of energy and lipid metabolism, whose homeostasis is compromised during obesity. Combination of citrulline and atorvastatin potentiated NO production in vitro. Here we have assessed the effects of this combination in mice with diet-induced obesity (DIO).

EXPERIMENTAL APPROACH

C57BL/6J male mice were given a standard diet (control) or a high fat-high sucrose diet (DIO) for 8 weeks. DIO mice were then treated with DIO alone, DIO with citrulline, DIO with atorvastatin or DIO with citrulline and atorvastatin (DIOcit-stat) for 3 weeks. Thereafter, body composition, glucose tolerance, insulin sensitivity and liver fat metabolism were measured.

KEY RESULTS

DIOcit-stat mice showed lower body weight, fat mass and epididymal fat depots compared with other DIO groups. Unlike other DIO groups, glucose tolerance and insulin sensitivity of DIOcit-stat, along with blood glucose and insulin concentrations in response to feeding, were restored to control values. Refeeding-induced changes in liver lipogenic activity were also reduced in DIOcit-stat mice compared with those of DIO animals. This was associated with decreased gene expression of the transcription factor SREBP-1, liver X receptor α, ChREBP and of target lipogenic enzymes in the liver of DIOcit-stat mice compared with those of other DIO groups.

CONCLUSIONS AND IMPLICATIONS

The citrulline-atorvastatin combination prevented fat mass accumulation and maintained glucose homeostasis in DIO mice. Furthermore, it potentiated inhibition of hepatic de novo lipogenesis activity. This combination has potential for preservation of glucose homeostasis in patients receiving statin therapy.

Erythrocyte nitric oxide synthase as a surrogate marker for mercury-induced vascular damage: the modulatory effects of naringin

In this study, endothelial nitric oxide synthase activity and nitric oxide (NO) production by human erythrocytes in the presence and absence of mercuric chloride (HgCl2 ), L-arginine (L-ARG), N ω- nitro-L-arginine methyl ester (L-NAME), and naringin (NAR) were investigated. In addition, the levels of reduced glutathione (GSH) and related enzymes were estimated in erythrocytes hemolysate. The protein carbonyl content (PCC) and thiobarbituric acid-reactive substances (TBARS) levels were also determined. The results of this study revealed that the treatment of erythrocytes with either HgCl2 or L-NAME induced a significant decrease in NOS activity and nitrite levels compared with control cells. Furthermore, mercury exposure significantly increased the levels of PCC and TBARS but reduced the GSH level. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, and glutathione-S-transferase (GST) were inhibited. The exposure of erythrocytes to HgCl2 in combination with L-ARG, NAR, or both ameliorated the investigated parameters compared with erythrocytes incubated with HgCl2 alone. These results indicate that mercury exposure decreased both erythrocyte NOS activity and nitrite production, and that these parameters might be indicative of mercury exposure. The data also suggest that concomitant treatment with NAR can restore NO bioavailability through either its metal-chelating properties or its antioxidant activity.

Contribution of SLC7A1 genetic variant to hypertension, the TAMRISK study

BACKGROUND

The rs41318021 polymorphism in the SLC7A1 gene affects endothelial NO production through changes in L-arginine transport. This variation could thus hypothetically cause dysfunction of endothelium and lead to hypertension. The association of rs41318021 with hypertension was therefore studied in a Finnish cohort.

METHODS

A total of 412 hypertensive cases and 771 non-hypertensive controls from a Finnish 50-year-old cohort were included in this study. The data was collected from the Tampere adult population cardiovascular risk study (TAMRISK). DNA was extracted from buccal swabs and amplified using PCR. A subpopulation of men and women who had available follow-up data of blood pressure measurements at the age of 35-, 40-, 45- and 50 years was also analyzed.

RESULTS

There was no difference between the variant frequencies of the hypertension group and normotensive group at the age of 50 years (p = 0.209). However, repeated measures analysis from the 15-year follow-up showed that subjects having gene variants CT or TT had slightly higher diastolic blood pressure than subjects having genotype CC (p = 0.047). By post-hoc analysis, this was most pronounced at the age of 35 years (p = 0.044).

CONCLUSION

The rs41318021 polymorphism in the SLC7A1 gene was not associated with essential hypertension in 50-year-old subjects. However, a borderline effect of this variation upon diastolic blood pressure was seen in these same subjects in a 15-year follow-up from a 35-year-old cohort to 50 years of age.