Simultaneous determination of free biliverdin and free bilirubin in serum: A comprehensive LC-MS approach.

BACKGROUND: Prognosis, diagnosis, and treatment of several diseases strongly rely on the sensitive, selective, and accurate determination of specific biomarkers in relevant biological samples. Free biliverdin and free bilirubin represent important new biomarkers of oxidative stress, however, the lack of suitable analytical methods for their determination has hindered progress in biomedical and clinical research. RESULTS: Here, we introduce a first comprehensive approach for robust and simultaneous determination of these bilins in serum using liquid chromatography - mass spectrometry (LC-MS). The developed analytical method exhibits linearity for both analytes within the concentration range of 0.5-100 nM, with limits of detection and quantitation determined at 0.1 nM and 0.5 nM, respectively. Moreover, several analytical pitfalls related to the intrinsic molecular structures of free bilirubin and free biliverdin and their trace concentration levels in biological samples are discussed here in detail for the first time. We have shown that the solubility, chemical stability, and affinity of these bilins to various materials strongly depend on the solvent, pH, and addition of stabilizing and chelating agents. Finally, the validated LC-MS method was successfully applied to the analysis of both bilins in fetus bovine serums, yielding higher free bilirubin/biliverdin ratios compared with previously reported values for human serum. SIGNIFICANCE: Failure to recognize and address the challenges presented here often leads to substantial analytical errors and consequently biased interpretation of the obtained results. This pertains not only to LC-MS, but also to many other analytical platforms due to the compound-derived sources of error.

Sarcopenic obesity and hypertension in elderly patients: a narrative review of pathophysiology and management strategies.

INTRODUCTION: Sarcopenic obesity and hypertension are a public health problem that is increasing worldwide due to the progressive aging of the population and the increasing prevalence of obesity and physical inactivity. Sarcopenic obesity is characterized by the simultaneous presence of sarcopenia (loss of muscle mass) and adiposity (increase in fat mass). Because symptoms are not specific, sarcopenic obesity remains largely undiagnosed. This review explores the latest research on sarcopenic obesity and its association with hypertension, with a focus on arterial stiffness. METHODS: A comprehensive narrative review was conducted by systematically searching PubMed and Scopus databases for relevant scientific literature. RESULTS: Sarcopenic obesity and hypertension are closely linked, sharing common factors such as inflammation, insulin resistance, and oxidative stress, with arterial stiffness playing a crucial role. DISCUSSION: Given the lack of specific symptoms for sarcopenic obesity, early diagnosis and management are crucial. Treatment strategies should prioritize weight loss, adequate protein intake, and regular physical activity. Further investigation is warranted for pharmacological interventions. CONCLUSION: Sarcopenic obesity and hypertension present significant challenges to global public health. Addressing arterial stiffness is paramount in managing these conditions effectively. Lifestyle modifications, including weight management and physical activity, remain central to the treatment of sarcopenic obesity, while additional research is needed to explore potential pharmacological options.

NaYF4-based upconverting nanoparticles with optimized phosphonate coatings for chemical stability and viability of human endothelial cells.

The increasing interest in upconverting nanoparticles (UCNPs) in biodiagnostics and therapy fuels the development of biocompatible UCNPs platforms. UCNPs are typically nanocrystallites of rare-earth fluorides codoped with Yb3+and Er3+or Tm3+. The most studied UCNPs are based on NaYF4but are not chemically stable in water. They dissolve significantly in the presence of phosphates. To prevent any adverse effects on the UCNPs induced by cellular phosphates, the surfaces of UCNPs must be made chemically inert and stable by suitable coatings. We studied the effect of various phosphonate coatings on chemical stability andin vitrocytotoxicity of the Yb3+,Er3+-codoped NaYF4UCNPs in human endothelial cells obtained from cellular line Ea.hy926. Cell viability of endothelial cells was determined using the resazurin-based assay after the short-term (15 min), and long-term (24 h and 48 h) incubations with UCNPs dispersed in cell-culture medium. The coatings were obtained from tertaphosphonic acid (EDTMP), sodium alendronate and poly(ethylene glycol)-neridronate. Regardless of the coating conditions, 1 - 2 nm-thick amorphous surface layers were observed on the UCNPs with transmission electron microscopy. The upconversion fluorescence was measured in the dispersions of all UCNPs. Surafce quenching in aqueous suspensions of the UCNPs was reduced by the coatings. The dissolution degree of the UCNPs was determined from the concentration of dissolved fluoride measured with ion-selective electrode after the ageing of UCNPs in water, physiological buffer (i.e., phosphate-buffered saline-PBS) and cell-culture medium. The phosphonate coatings prepared at 80 °C significantly suppressed the dissolution of UCNPs in PBS while only minor dissolution of bare and coated UCNPs was measured in water and cell-culture medium. The viability of human endothelial cells was significantly reduced when incubated with UCNPs, but it increased with the improved chemical stability of UCNPs by the phosphonate coatings with negligible cytotoxicity when coated with EDTMP at 80 °C.

Serum Bilirubin Levels in Overweight and Obese Individuals: The Importance of Anti-Inflammatory and Antioxidant Responses.

Obesity is a chronic condition involving low-grade inflammation and increased oxidative stress; thus, obese and overweight people have lower values of serum bilirubin. Essentially, bilirubin is a potent endogenous antioxidant molecule with anti-inflammatory, immunomodulatory, antithrombotic, and endocrine properties. This review paper presents the interplay between obesity-related pathological processes and bilirubin, with a focus on adipose tissue and adipokines. We discuss potential strategies to mildly increase serum bilirubin levels in obese patients as an adjunctive therapeutic approach.

Dietary vitamin D equilibrium in serum ameliorates direct bilirubin associated diabetes mellitus.

Diabetes mellitus (DM), a non-communicable endocrine disease that is marked by a differing degree of tolerance to insulin and dysfunction. The connection between diabetes and liver failure important to doctors in general practice diabetologists and hepatologists. DM is linked with an elevated risk of hepatic consequences and mortality of liver cirrhosis patients. DM may facilitate to insult the liver by inducing inflammation and fibrosis by elevating mitochondrial oxidative stress. The conventional liver function indices are bilirubin including Indirect Bilirubin (IBil), Direct Bilirubin (DBil), and Total Bilirubin (TBil). DBil, IBil, and TBil, have diverse clinical implications as the standard index of liver disorder. An elevated level of DBil may suggest damage to the hepatic cell whereas TBil is within the normal range. Thus, increased liver enzymes are correlated with hepatic insulin resistance in healthy subjects. Notably, a significant correlation between DBil levels and Insulin resistance risk could indicate a connection between liver dysfunction and diabetes mellitus risk. Thus, our primary goal via the current review to examine the impact of dietary vitamin D (VitD) in serum mediated risk reduction of insulin resistance and further incidence of DM through inflammatory liver associated high DBil. Therefore, modifying these inflammatory pathways may be a therapeutic alternative approach for diabetes treatment.

SERUM BILIRUBIN CORRELATES WITH SERUM ADIPOKINES IN NORMAL WEIGHT AND OVERWEIGHT ASYMPTOMATIC ADULTS.

Overweight and obesity are considered as chronic low-grade inflammation accompanied by imbalanced production of adipokines. The aim of this study was to elucidate the relationship between serum bilirubin, which is an endogenous antioxidant with anti-inflammatory activity, and pro- and anti-inflammatory serum adipokines in asymptomatic normal weight and overweight individuals. Healthy men and women aged 25-49 participated in this cross-sectional study. All participants underwent fasting serological measurements of adipokines, interleukin-6, tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), total and direct serum bilirubin, and other biochemical parameters. Participants were divided into normal weight and overweight groups. We found a significant negative association between total bilirubin and CRP, TNF-α, visfatin and resistin values, and a significant positive association between total bilirubin and adiponectin values in both normal-weight and overweight groups. Importantly, after adjusting for body mass index, we also found a significant negative association between total serum bilirubin levels and both visfatin and CRP serum levels. Moreover, visfatin, resistin and CRP were predictors of the total serum bilirubin levels.

Berberine in Cardiovascular and Metabolic Diseases: From Mechanisms to Therapeutics.

Cardiovascular and metabolic diseases (CVMD) are the leading causes of death worldwide, underscoring the urgent necessity to develop new pharmacotherapies. Berberine (BBR) is an eminent component of traditional Chinese and Ayurvedic medicine for more than 2000 years. Recently, BBR has attracted much interest for its pharmacological actions in treating and/or managing CVMD. Recent discoveries of basic, translational and clinical studies have identified many novel molecular targets of BBR (such as AMPK, SIRT1, LDLR, PCSK9, and PTP1B) and provided novel evidences supporting the promising therapeutic potential of BBR to combat CVMD. Thus, this review provides a timely overview of the pharmacological properties and therapeutic application of BBR in CVMD, and underlines recent pharmacological advances which validate BBR as a promising lead drug against CVMD.

Indirect clinical markers for the detection of anabolic steroid abuse beyond the conventional doping control in athletes.

Growing analytical challenges have arisen for the detection of misuse of androgenic anabolic steroids (AAS) in athletes the last years. Therefore, consideration of additional indirect markers can substantially aid the efforts to detect AAS abuse in athletes. Moreover, this approach can also help physicians to suspect AAS abuse when treating athletes. Laboratory markers highly indicative of AAS abuse in athletes include the considerable downregulation of high density lipoprotein-cholesterol, elevation of haematocrit or serum γ-glutamyl transpeptidase levels and for males reduced serum levels of both luteinizing hormone and follicle-stimulating hormone. Moreover, physical signs suggestive of current AAS abuse are hypertension, apparent changes in behaviour making the athlete more irritable and aggressive and the sudden appearance of acne vulgaris in an adult athlete with no recent history of acne, while testicular atrophy and gynecomastia raise suspicion of current or past AAS abuse in male athletes.

Oleanolic Acid Alters Multiple Cell Signaling Pathways: Implication in Cancer Prevention and Therapy.

Nowadays, much attention has been paid to diet and dietary supplements as a cost-effective therapeutic strategy for prevention and treatment of a myriad of chronic and degenerative diseases. Rapidly accumulating scientific evidence achieved through high-throughput technologies has greatly expanded the understanding about the multifaceted nature of cancer. Increasingly, it is being realized that deregulation of spatio-temporally controlled intracellular signaling cascades plays a contributory role in the onset and progression of cancer. Therefore, targeting regulators of oncogenic signaling cascades is essential to prevent and treat cancer. A plethora of preclinical and epidemiological evidences showed promising role of phytochemicals against several types of cancer. Oleanolic acid, a common pentacyclic triterpenoid, is mainly found in olive oil, as well as several plant species. It is a potent inhibitor of cellular inflammatory process and a well-known inducer of phase 2 xenobiotic biotransformation enzymes. Main molecular mechanisms underlying anticancer effects of oleanolic acid are mediated by caspases, 5' adenosine monophosphate-activated protein kinase, extracellular signal-regulated kinase 1/2, matrix metalloproteinases, pro-apoptotic Bax and bid, phosphatidylinositide 3-kinase/Akt1/mechanistic target of rapamycin, reactive oxygen species/apoptosis signal-regulating kinase 1/p38 mitogen-activated protein kinase, nuclear factor-κB, cluster of differentiation 1, CKD4, s6k, signal transducer and activator of transcription 3, as well as aforementioned signaling pathways . In this work, we critically review the scientific literature on the molecular targets of oleanolic acid implicated in the prevention and treatment of several types of cancer. We also discuss chemical aspects, natural sources, bioavailability, and safety of this bioactive phytochemical.

Bilirubin is an Endogenous Antioxidant in Human Vascular Endothelial Cells.

Bilirubin is a standard serum biomarker of liver function. Inexplicably, it is inversely correlated with cardiovascular disease risk. Given the role of endothelial dysfunction in originating cardiovascular diseases, direct analysis of bilirubin in the vascular endothelium would shed light on these relationships. Hence, we used high-performance liquid chromatography coupled with thermal lens spectrometric detection and diode array detection for the determination of endogenous cellular IXα-bilirubin. To confirm the isomer IXα-bilirubin, we used ultra-performance liquid chromatography coupled with a high-resolution mass spectrometer using an electrospray ionization source, as well as tandem mass spectrometric detection. We measured bilirubin in both arterial and venous rat endothelium (0.9-1.5 pmol mg(-1) protein). In the human endothelial Ea.hy926 cell line, we demonstrated that intracellular bilirubin (3-5 pmol mg(-1) protein) could be modulated by either extracellular bilirubin uptake, or by up-regulation of heme oxygenase-1, a cellular enzyme related to endogenous bilirubin synthesis. Moreover, we determined intracellular antioxidant activity by bilirubin, with EC50 = 11.4 ± 0.2 nM, in the range of reported values of free serum bilirubin (8.5-13.1 nM). Biliverdin showed similar antioxidant properties as bilirubin. We infer from these observations that intra-endothelial bilirubin oscillates, and may thus be a dynamic factor of the endothelial function.

Using Literature-Based Discovery to Explain Adverse Drug Effects.

We report on our research in using literature-based discovery (LBD) to provide pharmacological and/or pharmacogenomic explanations for reported adverse drug effects. The goal of LBD is to generate novel and potentially useful hypotheses by analyzing the scientific literature and optionally some additional resources. Our assumption is that drugs have effects on some genes or proteins and that these genes or proteins are associated with the observed adverse effects. Therefore, by using LBD we try to find genes or proteins that link the drugs with the reported adverse effects. These genes or proteins can be used to provide insight into the processes causing the adverse effects. Initial results show that our method has the potential to assist in explaining reported adverse drug effects.

Application of high-performance liquid chromatography combined with ultra-sensitive thermal lens spectrometric detection for simultaneous biliverdin and bilirubin assessment at trace levels in human serum.

We present the applicability of a new ultra-sensitive analytical method for the simultaneous determination of biliverdin and bilirubin in human serum. The method comprises isocratic reversed-phase (RP) C18 high-performance liquid chromatography (HPLC) and thermal lens spectrometric detection (TLS) based on excitation by a krypton laser emission line at 407nm. This method enables the separation of IX-α biliverdin and IX-α bilirubin in 11min with limit of detection (LOD) and limit of quantitation (LOQ) for biliverdin of 1.2nM and 3nM, and 1nM and 2.8nM for bilirubin, respectively. In addition, a step-gradient elution was set up, by changing the mobile phase composition, in order to further enhance the sensitivity for bilirubin determination with LOD and LOQ of 0.5nM and 1.5nM, respectively. In parallel, an isocratic HPLC-DAD method was developed for benchmarking against HPLC-TLS methods. The LOD and LOQ for biliverdin were 6nM and 18nM, and 2.5nM and 8nM for bilirubin, respectively. Additionally, both isocratic methods were applied for measuring biliverdin and free bilirubin in human serum samples (from 2 male and 2 female healthy donors). Combining isocratic HPLC method with TLS detector was crucial for first ever biliverdin determination in serum together with simultaneous free bilirubin determination. We showed for the first time the concentration ratio of free bilirubin versus unbound biliverdin in human serum samples.

Determination of cyanidin 3-glucoside in rat brain, liver and kidneys by UPLC/MS-MS and its application to a short-term pharmacokinetic study.

Anthocyanins exert neuroprotection in various in vitro and in vivo experimental models. However, no details regarding their brain-related pharmacokinetics are so far available to support claims about their direct neuronal bioactivity as well as to design proper formulations of anthocyanin-based products. To gather this missing piece of knowledge, we intravenously administered a bolus of 668 nmol cyanidin 3-glucoside (C3G) in anaesthetized Wistar rats and shortly after (15 s to 20 min) we collected blood, brain, liver, kidneys and urine samples. Extracts thereof were analysed for C3G and its expected metabolites using UPLC/MS-MS. The data enabled to calculate a set of pharmacokinetics parameters. The main finding was the distinctive, rapid distribution of C3G in the brain, with an apparently constant plasma/brain ratio in the physiologically relevant plasma concentration range (19-355 nM). This is the first report that accurately determines the distribution pattern of C3G in the brain, paving the way to the rational design of future tests of neuroprotection by C3G in animal models and humans.

Inhibition of metalloproteinase and proteasome activities in colon cancer cells by citrus peel extracts.

BACKGROUND: Citrus peels are consumed in the form of infusions, candy or wine, based on their well-documented nutritional and medicinal properties. This study sought to investigate the effect of some citrus peels' [grapefruit (Citrus paradisii), orange (Citrus sinensis) and shaddock (Citrus maxima)] extracts on matrix metalloproteinase (MMP) and proteasome activities in primary human colonic tumor (Caco-2) and the metastatic cell lines (LoVo and LoVo/ADR) in a bid to explain the possible mechanism by which the peels could manage/prevent colon cancer. METHODS: The inhibition of MMP and proteasome activities in the cells by the peel extracts, as well as the identification of phenolic compounds using high-performance liquid chromatography with diode-array detection (HPLC-DAD), was determined. RESULTS: Orange peel extracts had the strongest inhibition of MMP in Caco-2 and LoVo cells, while shaddock had the least. Shaddock peel extracts also had the least MMP inhibition in LoVo/ADR lysates. Grapefruit had the least proteasome inhibition in Caco-2 and LoVo lysates, while there was no significant (p>0.05) difference in the proteasome inhibition of the peel extracts in LoVo/ADR lysates. The extracts inhibited proteasome activity in extract-treated cells, and HPLC fingerprinting of the extracts revealed the presence of some phenolic compounds such as quercetin, caffeic acid, kaempferol, catechin and naringin. CONCLUSIONS: The inhibition of MMP and proteasome activities in colon cancer cell lines suggests the potential use of citrus peels as functional food in the management and/or prevention of colon cancer.

Direct determination of free bilirubin in serum at sub-nanomolar levels.

Direct analysis of free bilirubin in human and animal blood serum samples is reported for the first time. A state-of-the-art system comprised of newly developed high-performance liquid chromatography (HPLC) on reverse-phase (RP) C18 support coupled with thermal lens spectrometric detection (TLS), based on excitation at λ=457.9 nm by an argon laser was used for this purpose. This HPLC-TLS method enabled a baseline separation of all three structural isomers of bilirubin (XIII-α, IX-α and III-α) and the respective degradation products in isocratic mode in fewer than 7 min. The method excels in ultra-high sensitivity with limit of detection (LOD) and limit of quantitation (LOQ) of 90 pM and 250 pM, respectively. Moreover, this method also affords high precision and accuracy, with correlation coefficients R(2)>0.997 over a broad linear range (0.250-150 nM) and R(2)=0.9998 in a concentration range of clinical interest (0.500-25 nM). The method's boosted sensitivity enabled to streamline sample preparation to just one serum ultrafiltration step, which made qualitative evaluation of sample preparation possible for the first time. The performance of the HPLC-TLS method was assessed to have 20-fold enhanced sensitivity when compared to a comparable method incorporating HPLC coupled with diode array detector (DAD), which is also a novel method by itself, and could be applied for free bilirubin determination in patients with elevated bilirubin levels.

Role of endothelial cell membrane transport in red wine polyphenols-induced coronary vasorelaxation: involvement of bilitranslocase.

Red wine polyphenols (RWP) induce nitric oxide (NO) and endothelium-derived hyperpolarization (EDH)-mediated coronary vasodilatation involving the redox-sensitive PI3-kinase/Akt-dependent pathway in the endothelium. However, there is a gap of knowledge in explaining how bioactive polyphenols initialize their signalling pathway in endothelial cells. Here, we investigated the hypothesis that flavonoids act subsequently to their entry into the endothelium via the flavonoid membrane transporter bilitranslocase (TC 2.A.65.1.1). Thus, vascular reactivity studies were performed using isolated porcine coronary artery rings. We separately determined the NO- and EDH-mediated components of the relaxation in the presence of specific inhibitors. In either case, bilitranslocase antibodies significantly reduced the relaxations of coronary artery rings induced by RWP. Furthermore, bilitranslocase antibodies significantly reduced RWP-induced phosphorylation levels of Akt and eNOS, assessed in cultured endothelial cells from porcine coronary arteries by Western blot analysis. The present findings indicate that bilitranslocase-mediated membrane transport substantially contributes to the initial step of RWP-induced coronary vasodilatation.

Serum bilirubin levels are lower in overweight asymptomatic middle-aged adults: an early indicator of metabolic syndrome?

OBJECTIVE: Low levels of bilirubin have recently been associated with obesity, diabetes mellitus, and metabolic syndrome. Here, we hypothesized that serum bilirubin levels might be already altered in overweight asymptomatic middle-aged individuals before full development of the metabolic syndrome. METHODS: Healthy nonsmoking adults aged 25-49 (64 women and 32 men) participated in this cross-sectional study. All participants who reported stable weight within the last three months underwent standard anthropomorphological measurements of body composition, blood pressure measurements, aerobic and anaerobic capabilities assessment, dietary intake evaluation, and fasting serological measurements of total and direct bilirubin, glucose, insulin, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and C-reactive protein. Participants were divided into normal-weight and overweight groups. Linear correlation and multiple regression analyses were used to examine the association of serum bilirubin levels with all metabolic syndrome risk factor changes. RESULTS: Serum bilirubin levels were lower in overweight healthy individuals of both sexes, and were negatively associated with abdominal obesity, insulin resistance, fasting glucose, fasting insulin, fasting triglycerides, total cholesterol, low-density lipoprotein cholesterol, and C-reactive protein levels but positively associated with aerobic body capabilities. CONCLUSION: Our findings suggest that serum bilirubin levels have the potential to be employed as an early biomarker for indicating asymptomatic individuals at increased risk of developing metabolic syndrome.

Low-dose atorvastatin, losartan, and particularly their combination, provide cardiovascular protection in isolated rat heart and aorta.

Statins and angiotensin receptor blockers at therapeutic doses have beneficial cardiovascular effects, which can be applied for cardiovascular protection. We explored whether low doses of atorvastatin, losartan, and particularly their combination, possess important pleiotropic vasodilatory effects. Wistar rats were treated daily with low-dose atorvastatin (2 mg/kg, n = 15), low-dose losartan (5 mg/kg, n = 15), their combination (n = 15), or saline (n = 15). After 4, 6, or 8 weeks the animals were anesthetized, blood samples taken, and their hearts and thoracic aortas isolated. Two kinds of experiments were performed: the measurement of coronary flow rate after ischemia/reperfusion myocardial injury and endothelium-dependent relaxation of thoracic aorta. In both models, maximal vasodilation activity was obtained in rats treated for 6 weeks. In the ischemia/reperfusion myocardial injury model, coronary flow increased (atorvastatin or losartan 1.9-fold, P < 0.01; combination 2.4-fold, P < 0.001) compared with controls. In the thoracic aorta model, endothelium-dependent relaxation significantly increased only in the combination group compared with the control group (up to 1.4-fold; P < 0.01). Simultaneously, we detected increased anti-inflammatory activity and increased nitric oxide concentration, but no changes in lipids and blood pressure. In a rat model we showed important vasodilatory activity of low-dose atorvastatin, losartan, and particularly their combination. The effects of the low-dose combination were accompanied by, and probably at least partly achieved by, anti-inflammatory and nitric oxide pathways. Overall, these results could be valuable for the development of new vascular protective strategies focusing on a low-dose regimen of statins and sartans, and particularly their combination.

A low-dose atorvastatin and losartan combination directly improves aortic ring relaxation and diminishes ischaemic-reperfusion injury in isolated rat hearts.

BACKGROUND: The cardiovascular pleiotropic effects of statins and angiotensin receptor blockers (ARBs) could be of interest for innovative preventive approaches. We aimed to investigate whether low-dose atorvastatin and losartan, separately not possessing protective cardiovascular pleiotropic effects, express them when combined. MATERIAL/METHODS: Forty-five adult male Wistar rats were anaesthetized and their thoracic aortas and hearts were isolated. Relaxation of aortic rings, coronary flow rate and the extent of myocardial ischaemic-reperfusion injury were measured. Different concentrations (0.01, 0.1, 1.0 µM) of atorvastatin and losartan added to a perfusion medium were first tested. The separate drugs, which were ineffective, were then combined at the same concentrations and the concentration was tested in the same model. RESULTS: Low concentrations of atorvastatin or losartan (0.1 and 1 µM, respectively) produced no effects in isolated aorta. However, surprisingly, when these drug concentrations were combined, a significantly improved endothelium-dependent relaxation of the thoracic aorta was observed. Similarly, when combining individually ineffective concentrations of atorvastatin or losartan (0.01 and 0.1 µM, respectively), significantly increased coronary flow and a decreased extent of myocardial injury were observed. By using a nitric oxide-synthase inhibitor, we demonstrated that the vasodilatory effects obtained were nitric oxide-dependent. The degree of effectiveness by the combination was comparable to that obtained by 10-fold (atorvastatin) or 100-fold (losartan) higher concentrations of the separate drugs. CONCLUSIONS: Our results revealed that remarkable additive/synergistic effects exist between low-doses of a statin (atorvastatin) and an ARB (losartan), resulting in important cardiovascular protection. This new concept could be valuable in cardiovascular prevention.

Cardiovascular effects induced by polymeric 3-alkylpyridinium salts from the marine sponge Reniera sarai.

Water-soluble polymeric 3-alkylpyridinum salts (poly-APS), isolated from the marine sponge Reniera sarai, are natural products with promising biomedical applications. However, their ability to form non-specific cell membrane pores raises safety issues. Therefore, the aim of the present study was to investigate the direct toxic effects of poly-APS on the cardiovascular system. To study the impact of poly-APS toxicodynamics on vascular function, the relaxation and contraction responses of isolated rat thoracic aortas incubated in poly-APS solutions (0.01-10 µM) were tested. In addition, cardiac toxicity was studied by measuring coronary flow, lactate dehydrogenase release rate, left ventricular pressure, heart rate, and the duration of arrhythmias in isolated rat hearts perfused with poly-APS (0.001-1 µM). Poly-APS diminished endothelium-dependent relaxation and contraction in a concentration- and time-dependent manner. Endothelial function was affected earlier and to a greater extent than contractile responses. Likewise, in isolated hearts the most evident cardiotoxic effects were observed after perfusion with the highest concentration (1 µM) of poly-APS: compared to the control group the coronary flow and heart rate were diminished by 2.2- and 1.8-fold, while lactate dehydrogenase release rate and left ventricular pressure were increased by 7.8- and 2.2-fold (all P < 0.001). Further, poly-APS had evident proarrhythmogenic activity in a concentration-dependent manner. However, in the low concentration range (1-10 nM) poly-APS showed only minor toxicity. Our results confirmed the direct toxic effects of poly-APS on the rat cardiovascular system. Therefore, it seems reasonable to conclude that the use of poly-APS as therapeutic adjuvants has limited safety margins.