In silico and in vitro screening for carcinogenic potential of angiotensin-converting enzyme inhibitors and their degradation impurities.

According to some clinical observations, the use of angiotensin-converting enzyme inhibitors (ACEI) may be associated with an increased risk of cancer. The aim of the present study was to screen for the potential carcinogenicity, mutagenicity and genotoxicity of these drugs using in silico methodology. Delapril, enalapril, imidapril, lisinopril, moexipril, perindopril, ramipril, trandolapril, spirapril were thereby analyzed. In parallel, the corresponding degradation impurities, the diketopiperazine (DKP) derivatives, were also investigated. (Q)SAR computer software (VEGA-GUI and Lazar), available in the public domain, was employed. The obtained predictions suggested that none of the compounds tested (from the group of ACE-Is and DKPs) was mutagenic. Moreover, none of the ACE-Is was carcinogenic. The reliability of these predictions was high to moderate. In contrast, in the DKP group, ramipril-DKP and trandolapril-DKP were found to be potentially carcinogenic, but the reliability of this prediction was low. As for the genotoxicity screening, all compounds tested (ACE-I and DKP) were predicted to be active and genotoxic, with moexipril, ramipril, spirapril, and all DKP derivatives within the highest risk group. They were prioritized for experimental verification studies to confirm or exclude their toxic activity. On the other hand, the lowest risk of carcinogenicity was assigned to imidapril and its DKP. Then, a follow-up in vitro micronucleus assay for ramipril was performed. It showed that this drug was genotoxic via aneugenic activity, but only at concentrations exceeding real-life levels. At concentrations found in human blood after standard dose, ramipril was not genotoxic in vitro. Therefore, ramipril was considered safe for human use with a standard dosing regimen. The other compounds of concern (spirapril, moexipril and all DKP derivatives) should be subjected to analogous in vitro studies. We also concluded that the adopted in silico software was applicable for ACE-I toxicity prediction.

Design, synthesis of novel Triazolones and bis-Triazolones derivatives under ultrasound irradiation and evaluation as potent angiotensin converting enzyme (ACE) inhibitors.

The condensation of several primary amines and diamines with various N1-ethoxycarbonyles N1-tosylhydrazonates (1a-b), triazolones (2) and bis-triazolone (3) resulted in ethanol under ultrasound irradiation. Compared with the conventional methods, the main advantages of the present procedure are milder conditions, shorter reaction time and higher yields. The newly synthesized compounds were evaluated for angiotensin I-converting enzyme (ACE) inhibition. The results were compared to Captopril as a reference drug. Compounds 3b, 2h, 3a, 2d, and 2f showed not only inhibition activity with IC50 values of 0.162, 0.253, 0.253, 0.281 and 0.382 µM, respectively, but also minimal toxicity. The docking of chemical compounds in the ACE active site showed possible inhibitory effect of all compounds on the catalytic activity of the enzyme, which would satisfactorily explain the anti-hypertensive effect of these compounds.

Fetopathies associated with exposure to angiotensin converting enzyme inhibitor from Tropaeolum majus L.

The prevalence of the use of herbal medicines is on the rise across the world, especially amongst pregnant women. A fact that draws attention is that many species commonly used by pregnant women, including the Tropaeolum majus L. (Tropaeolaceae), also present inhibitory activity on the angiotensin-converting enzyme (ACE). Herein, we have investigated the effects of T. majus extract (HETM) on fetal development, evaluating its relationship with possible ACE inhibitory activity. Pregnant Wistar rats were treated with different HETM doses (3, 30 and 300 mg/kg/day) from gestational days 8-20. Rats were sacrificed on the day 20 of pregnancy and the following parameters were evaluated: clinical symptoms of maternal toxicity; maternal body weight; feed and water intake; maternal liver, kidney, and ovary weights, maternal ACE activity and aldosterone levels, live fetuses mean; dead fetuses percentage, fetus weight, and fetal malformation. All pregnant rats treated with high HETM doses showed significant reduction in plasma ACE activity accompanied by a decrease in serum aldosterone levels. Moreover, significant changes in fetal development were observed, including growth retardation and renal damage after 20 days of gestation. Thus, data presented demonstrate the significant effects of the use of HETM on fetal development during pregnancy.

New proline-rich oligopeptides from the venom of African adders: Insights into the hypotensive effect of the venoms.

BACKGROUND: The snakes from the Bitis genus are some of the most medically important venomous snakes in sub Saharan Africa, however little is known about the composition and effects of these snake venom peptides. Considering that the victims with Bitis genus snakes have exacerbate hypotension and cardiovascular disorders, we investigated here the presence of angiotensin-converting enzyme modulators on four different species of venoms. METHODS: The peptide fractions from Bitis gabonica gabonica, Bitis nasicornis, Bitis gabonica rhinoceros and Bitis arietans which showed inhibitory activity on angiotensin-converting enzyme were subjected to mass spectrometry analysis. Eight proline-rich peptides were synthetized and their potencies were evaluated in vitro and in vivo. RESULTS: The MS analysis resulted in over 150 sequences, out of which 32 are new proline-rich oligopeptides, and eight were selected for syntheses. For some peptides, inhibition assays showed inhibitory potentials of cleavage of angiotensin I ten times greater when compared to bradykinin. In vivo tests showed that all peptides decreased mean arterial pressure, followed by tachycardia in 6 out of 8 of the tests. CONCLUSION: We describe here some new and already known proline-rich peptides, also known as bradykinin-potentiating peptides. Four synthetic peptides indicated a preferential inhibition of angiotensin-converting enzyme C-domain. In vivo studies show that the proline-rich oligopeptides are hypotensive molecules. GENERAL SIGNIFICANCE: Although proline-rich oligopeptides are known molecules, we present here 32 new sequences that are inhibitors of the angiotensin-converting enzyme and consistent with the symptoms of the victims of Bitis spp, who display severe hypotension.

Involvement of the TRPV1 receptor in plasma extravasation in airways of rats treated with an angiotensin-converting enzyme inhibitor.

Angiotensin-converting enzyme inhibitors (ACEIs) are widely used in the treatment of hypertension, congestive heart failure and renal disease, and are considered relatively safe and generally well-tolerated drugs. However, adverse effects of ACEIs have been reported, including non-productive cough and angioedema, which can lead to poor adherence to therapy. The mechanisms by which ACEIs promote adverse effects are not fully elucidated, although increased bradykinin plasma levels following ACEI therapy seem to play an important role. Since bradykinin can sensitise the transient potential vanilloid receptor 1 (TRPV1), we investigated the role of TRPV1 in plasma extravasation in the trachea and bronchi of rats treated with the ACEI captopril. We observed that intravenous (i.v.) administration of captopril did not cause plasma extravasation in the trachea or bronchi of spontaneously breathing rats, but induced plasma extravasation in the trachea and bronchi of artificially ventilated rats. The intratracheal (i.t.) instillation of capsaicin or bradykinin also induced an increase in plasma extravasation in the trachea and bronchi of artificially ventilated rats. As expected, capsaicin-induced plasma extravasation was inhibited by i.t. pretreatment with the TRPV1 selective antagonist capsazepine (CPZ) while bradykinin-induced plasma extravasation was reduced by i.t. pretreatment with the selective B2 receptor antagonist Icatibant, originally known as HOE 140 (HOE). Interestingly, bradykinin-induced plasma extravasation was also inhibited by CPZ. The pretreatment with HOE and CPZ, singly or in combination and at doses which do not cause inhibitory effects per se, significantly inhibited the plasma extravasation induced by captopril treatment in artificially ventilated rats. In addition, treatment with a high dose of capsaicin in newborn rats, which induces degeneration of TRPV1-expressing sensory neurons, abolished both capsaicin and captopril-induced plasma extravasation in artificially ventilated rats. In conclusion, our study identified that captopril treatment promoted sensitisation of TRPV1, via B2 receptor activation, inducing plasma extravasation in the airways of mechanically ventilated rats. The present findings add a new view about the role of TRPV1 in the plasma extravasation induced by captopril and could to contribute to the elucidation of mechanisms by which ACEI induces adverse effects on airways.

Occupational airborne contact dermatitis from benzodiazepines and other drugs.

BACKGROUND: Healthcare workers (or relatives) crushing drug tablets for patients with difficulties in swallowing are at risk of developing sensitization via airborne exposure. Tetrazepam, in particular, is increasingly being described as an important occupational allergen in this regard, although other drugs are also involved. OBJECTIVES: To identify the allergenic culprits in 4 patients, namely 2 nurses, 1 pharmacy assistant, and 1 spouse, who all regularly crushed tablets of systemic drugs and presented with severe airborne dermatitis. METHODS: The patients were patch tested with all of the drugs that they handled, as well as with potential cross-sensitizing molecules. RESULTS: All 4 patients reacted to tetrazepam and other benzodiazepines, some of which they had not previously come into contact with, which favours cross-reactivity rather than concomitant sensitization. These patients also had positive reactions to several other non-structurally related drugs for which, in some cases, there was no history of exposure. CONCLUSIONS: Subjects having to crush drugs, in either an occupational or a non-occupational context, and who present with dermatitis suspected of being airborne-induced, should be patch tested with all contacted medicaments, as well as with possible cross-reacting molecules. Prevention by the use of crushing devices and protective measures (gloves and masks) when medications are handled should be advised.

Inhibitors of endopeptidase and angiotensin-converting enzyme lead to an amplification of the morphological changes and an upregulation of the substance P system in a muscle overuse model.

BACKGROUND: We have previously observed, in studies on an experimental overuse model, that the tachykinin system may be involved in the processes of muscle inflammation (myositis) and other muscle tissue alterations. To further evaluate the significance of tachykinins in these processes, we have used inhibitors of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE), substances which are known to terminate the activity of various endogenously produced substances, including tachykinins. METHODS: Injections of inhibitors of NEP and ACE, as well as the tachykinin substance P (SP), were given locally outside the tendon of the triceps surae muscle of rabbits subjected to marked overuse of this muscle. A control group was given NaCl injections. Evaluations were made at 1 week, a timepoint of overuse when only mild inflammation and limited changes in the muscle structure are noted in animals not treated with inhibitors. Both the soleus and gastrocnemius muscles were examined morphologically and with immunohistochemistry and enzyme immunoassay (EIA). RESULTS: A pronounced inflammation (myositis) and changes in the muscle fiber morphology, including muscle fiber necrosis, occurred in the overused muscles of animals given NEP and ACE inhibitors. The morphological changes were clearly more prominent than for animals subjected to overuse and NaCl injections (NaCl group). A marked SP-like expression, as well as a marked expression of the neurokinin-1 receptor (NK-1R) was found in the affected muscle tissue in response to injections of NEP and ACE inhibitors. The concentration of SP in the muscles was also higher than that for the NaCl group. CONCLUSIONS: The observations show that the local injections of NEP and ACE inhibitors led to marked SP-like and NK-1R immunoreactions, increased SP concentrations, and an amplification of the morphological changes in the tissue. The injections of the inhibitors thus led to a more marked myositis process and an upregulation of the SP system. Endogenously produced substances, out of which the tachykinins conform to one substance family, may play a role in mediating effects in the tissue in a muscle that is subjected to pronounced overuse.

The effects of ACE inhibitor Enalapril on Mytilus galloprovincialis: Insights into morphological and functional responses.

In the last decades, pharmaceuticals have emerged as a new class of environmental contaminants. Antihypertensives, including angiotensin-converting enzyme (ACE) inhibitors, are of special concern due to their increased consumption over the past years. However, the available data on their putative effects on the health of aquatic animals, as well as the possible interaction with biological systems are still poorly understood. This study analysed whether and to which extent the exposure to Enalapril, an ACE inhibitor commonly used for treating hypertension and heart failure, may induce morpho-functional alterations in the mussel Mytilus galloprovincialis, a sentinel organism of water pollution. By mainly focusing on the digestive gland (DG), a target tissue used for analysing the effects of xenobiotics in mussels, the effects of 10-days exposure to 0.6 ng/L (E1) and 600 ng/L (E2) of Enalapril were investigated in terms of cell viability and volume regulation, morphology, oxidative stress, and stress protein expression and localization. Results indicated that exposure to Enalapril compromised the capacity of DG cells from the E2 group to regulate volume by limiting the ability to return to the original volume after hypoosmotic stress. This occurred without significant effects on DG cell viability. Enalapril unaffected also haemocytes viability, although an increased infiltration of haemocytes was histologically observed in DG from both groups, suggestive of an immune response. No changes were observed in the two experimental groups on expression and tissue localization of heat shock proteins 70 (HSPs70) and HSP90, and on the levels of oxidative biomarkers. Our results showed that, in M. galloprovincialis the exposure to Enalapril did not influence the oxidative status, as well as the expression and localization of stress-related proteins, while it activated an immune response and compromised the cell ability to face osmotic changes, with potential consequences on animal performance.

Captopril's influence on Danio rerio embryonic development: Unveiling significant toxic outcomes at environmentally relevant concentrations.

Anticipating a global increase in cardiovascular diseases, there is an expected surge in the use of angiotensin-converting enzyme inhibitors, notably captopril (CAP). This heightened usage raises significant environmental apprehensions, mainly due to limited knowledge regarding CAP's toxic effects on aquatic species. In response to these concerns, the current study aimed to tackle this knowledge gap by evaluating the potential influence of nominal concentrations of CAP (0.2-2000 µg/L) on the embryonic development of Danio rerio. The findings revealed that CAP at all concentrations, even at concentrations considered environmentally significant (0.2 and 2 µg/L), induced various malformations in the embryos, ultimately leading to their mortality. Main malformations included pericardial edema, craniofacial malformation, scoliosis, tail deformation, and yolk sac deformation. In addition, CAP significantly altered the antioxidant activity of superoxide dismutase and catalase across all concentrations. Simultaneously, it elevated lipid peroxidation levels, hydroperoxides, and carbonylic proteins in the embryos, eliciting a substantial oxidative stress response. Likewise, CAP, at all concentrations, exerted significant modulatory effects on the expression of genes associated with apoptosis (bax, bcl2, p53, and casp3), organogenesis (tbx2a, tbx2b, and irx3b), and ion exchange (slc12a1 and kcnj1) in Danio rerio embryos. Both augmentation and reduction in the expression levels of these genes characterized this modulation. The Pearson correlation analysis indicated a close association between oxidative damage biomarkers and the expression patterns of all examined genes with the elevated incidence of malformations and mortality in the embryos. In summary, it can be deduced that CAP poses a threat to aquatic species. Nevertheless, further research is imperative to enhance our understanding of the environmental implications of this pharmaceutical compound.

Renal toxicity of lisinopril and rosuvastatin, alone and in combination, in Wistar rats.

The aim of study was to evaluate the effect of commonly used lisinopril, rosuvastatin and their combined action on site-specific nephrotoxicity in rats using clusterin and microalbumin nephrotoxic biomarkers and other related parameters using oral gavage. Rosuvastatin at 2 different doses showed increase in urinary microalbumin levels whereas lisinopril and its combination with rosuvastatin at 2 different doses did not show urinary microalbumin excretion indicating beneficial effects of lisinopril in terms of reducing microalbumin. Urinary clusterin levels significantly increased in high-dose treated animals of lisinopril and rosuvastatin. The use of lisinopril plus rosuvastatin at low dose also led to worsened renal function by raising urinary clusterin levels (217 ± 4.6 ng/ml) when compared with the control (143 ± 3.3 ng/ml). Renal histopathology showed multifocal regeneration of tubules indicating proximal tubule damaged. These results indicate that lisinopril (50 mg/kg), rosuvastatin (100 mg/kg), lisinopril+rosuvastatin (20+40 mg/kg) and lisinopril+rosuvastatin (50+100 mg/kg) showed toxicity only on proximal tubules.

Antioxidant and ACE enhancing potential of Pankajakasthuri in fluoride toxicity: an in vitro study on mammalian lungs.

Fluoride toxicity occurs due to high concentrations of fluoride in water sources or anthropogenic causes. The aim of the present study was to investigate the effects of an Ayurvedic drug--Pankajakasthuri (PK)--in relation to fluoride-induced toxicity in mammalian lungs. The results indicated that sodium fluoride increased lipid peroxidation and decreased enzymatic and non-enzymatic antioxidants in a concentration-dependent manner in lungs. The antioxidant potential of the lungs was suppressed maximally at 10 ppm fluoride concentration and PK at all three dose levels (i.e., 100, 200 and 300 µl) decreased fluoride induced lipid peroxidation (p < 0.05) and increased the levels of total ascorbic acid, superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase and FRAP values significantly (p < 0.05) in a dose-dependent manner. When PK was examined for its effects on angiotensin-converting enzyme (ACE) activity, in fluoride-induced toxicity, the ACE activity was found to increase (p < 0.0001) in lung homogenates with all three doses. This study indicates that PK, an Ayurvedic drug, improves mammalian lung function by increasing antioxidant potential and ACE activity under the conditions of fluoride toxicity.

Inhibition of angiotensin converting enzyme induces mechanical allodynia through increasing substance P expression in mice.

Although emerging evidence shows that angiotensin converting enzyme (ACE) is associated with pain, it is not clear whether inhibition of ACE could affect to nociceptive transmission and which mediators are involved in this process. Here we investigated whether administration of the ACE inhibitors, captopril and enalapril increases the expression of substance P (SP) and whether this increase contributes to the induction of mechanical allodynia in mice. ACE was expressed in the lumbar dorsal root ganglion (DRG) and the superficial dorsal horn (SDH) region of the spinal cord in mice. Either intraperitoneal or intrathecal administration of the ACE inhibitors, captopril and enalapril for 10 days significantly increased the paw withdrawal frequency to innocuous mechanical stimuli and the levels of SP in both the lumbar DRG and the SDH region of the spinal cord dorsal horn. In addition, intraperitoneal administration of the SP receptor (neurokinin-1 receptor) antagonist, L-733,060 suppressed mechanical allodynia that was induced by pretreatment of captopril and enalapril. Intraplantar administration of SP for 3 days induces mechanical allodynia, and this effect was reduced by exogenous ACE administration. These findings demonstrate that inhibition of ACE increases the levels of SP in both the lumbar DRG and spinal cord dorsal horn, ultimately contributing to the induction of mechanical allodynia in mice.

Inhibitors of angiotensin I converting enzyme potentiate fibromyalgia-like pain symptoms via kinin receptors in mice.

Fibromyalgia is a potentially disabling chronic disease, characterized by widespread pain and a range of comorbidities such as hypertension. Among the mechanisms involved in fibromyalgia-like pain symptoms are kinins and their B1 and B2 receptors. Moreover, angiotensin I converting enzyme (ACE) inhibitors, commonly used as antihypertensive drugs, can enhance pain by blocking the degradation of peptides such as substance P and bradykinin, besides enhancing kinin receptors signalling. We investigated the effect of ACE inhibitors on reserpine-induced fibromyalgia-like pain symptoms and the involvement of kinins in this effect in mice. Nociceptive parameters (mechanical and cold allodynia and overt nociception) were evaluated after ACE inhibitors administration in mice previously treated with reserpine. The role of kinin B1 and B2 receptors was investigated using pharmacological antagonism. Additionally, bradykinin levels, as well as the activity of ACE and kininase I, were measured in the sciatic nerve, spinal cord and cerebral cortex of the mice. The ACE inhibitors enalapril and captopril enhanced reserpine-induced mechanical allodynia, and this increase was prevented by kinin B1 and B2 receptor antagonists. Substance P and bradykinin caused overt nociception and increased mechanical allodynia in animals treated with reserpine. Reserpine plus ACE inhibitors increased bradykinin-related peptide levels and inhibited ACE activity in pain modulation structures. Since hypertension is a frequent comorbidity affecting fibromyalgia patients, hypertension treatment with ACE inhibitors in these patients should be reviewed once this could enhance fibromyalgia-like pain symptoms. Thus, the treatment of hypertensive patients with fibromyalgia could include other classes of antihypertensive drugs, different from ACE inhibitors.

Design, synthesis and biological evaluation of novel pyxinol derivatives with anti-heart failure activity.

Heart failure (HF) is an important and leading cause of substantial morbidity and mortality globally. The angiotensin-converting enzymatic (ACE) is the causative source for congestive heart failure. Natural products and its derivatives play a vital role in drug discovery and development owing to their efficacy and low toxicity. Pyxinol is a potent natural agent for cardiovascular disease. Thus we investigated the effect on ACE and HF of pyxinol derivatives. We designed and synthesized 32 novel fatty acid ester derivatives of pyxinol via esterification. Among them, compounds 2e (IC50=105 nM) and 3b (IC50=114 nM) displayed excellent ACE inhibitory activity in vitro, and exhibited non-toxic to H9c2 cells. The interactions between ACE and compounds were predicted by molecular docking respectively. In verapamil-induced zebrafish HF model, the activity assay showed that these two derivatives could improve cardiovascular physiological indexes including heart beats, venous congestion, heart dilation, cardiac output, ejection fraction and fractional shortening in a dose-dependent manner. A UPLC-QTOF-MS-based serum metabolomics approach was applied to explore the latent mechanism. A total of 25 differentiated metabolites and 8 perturbed metabolic pathways were identified. These results indicated that pyxinol fatty acid ester derivatives 2e and 3b might be considered as potent drug candidates against heart failure and deserved further research and development.

Podocyte repopulation contributes to regression of glomerular injury induced by ACE inhibition.

Angiotensin-converting enzyme (ACE) inhibition induces glomerular repair in the Munich Wistar Frömter (MWF) rat, a model of spontaneous glomerular injury. In this study, we investigated whether this effect is related to changes in glomerular cell number, particularly of podocytes, which are progressively lost with age. MWF rats with advanced nephropathy were studied at both 40 weeks and after 20 weeks of observation either with or without treatment with the ACE inhibitor lisinopril. Forty-week-old Wistar rats were used as controls. In untreated MWF rats, proteinuria, hypertension, glomerulosclerosis, and renal function worsened, while lisinopril induced regression of both functional and structural changes. Despite glomerular hypercellularity in untreated MWF rats, the number of endothelial cells per glomerulus did not change, and podocyte number even decreased. ACE inhibition halted the progressive increase in glomerular cell number and enhanced endothelial cell volume density. Surprisingly, lisinopril not only halted age-related podocyte loss but also increased the number of glomerular podocytes above baseline, which was associated with an increased number of proliferating Wilms tumor 1-positive cells, loss of cyclin-dependent kinase inhibitor p27 expression, and increased number of parietal podocytes. These data indicate that ACE inhibition restructures glomerular capillary, primarily by restoring the podocyte population in this model of glomerular injury. Increased parietal podocyte number in lisinopril-treated MWF rats suggests that the remodeling of Bowman's capsule epithelial cells contributes to this effect.

Inhibition of Angiotensin Converting Enzyme Impairs Anti-staphylococcal Immune Function in a Preclinical Model of Implant Infection.

Background: Evidence suggests the renin-angiotensin system (RAS) plays key immunomodulatory roles. In particular, angiotensin-converting enzyme (ACE) has been shown to play a role in antimicrobial host defense. ACE inhibitors (ACEi) and angiotensin receptor blockers (ARB) are some of the most commonly prescribed medications, especially in patients undergoing invasive surgery. Thus, the current study assessed the immunomodulatory effect of RAS-modulation in a preclinical model of implant infection. Methods:In vitro antimicrobial effects of ACEi and ARBs were first assessed. C57BL/6J mice subsequently received either an ACEi (lisinopril; 16 mg/kg/day), an ARB (losartan; 30 mg/kg/day), or no treatment. Conditioned mice blood was then utilized to quantify respiratory burst function as well as Staphylococcus aureus Xen36 burden ex vivo in each treatment group. S. aureus infectious burden for each treatment group was then assessed in vivo using a validated mouse model of implant infection. Real-time quantitation of infectious burden via bioluminescent imaging over the course of 28 days post-procedure was assessed. Host response via monocyte and neutrophil infiltration within paraspinal and spleen tissue was quantified by immunohistochemistry for F4/80 and myeloperoxidase, respectively. Results: Blood from mice treated with an ACEi demonstrated a decreased ability to eradicate bacteria when mixed with Xen36 as significantly higher levels of colony forming units (CFU) and biofilm formation was appreciated ex vivo (p < 0.05). Mice treated with an ACEi showed a higher infection burden in vivo at all times (p < 0.05) and significantly higher CFUs of bacteria on both implant and paraspinal tissue at the time of sacrifice (p < 0.05 for each comparison). There was also significantly decreased infiltration and respiratory burst function of immune effector cells in the ACEi group (p < 0.05). Conclusion: ACEi, but not ARB, treatment resulted in increased S. aureus burden and impaired immune response in a preclinical model of implant infection. These results suggest that perioperative ACEi use may represent a previously unappreciated risk factor for surgical site infection. Given the relative interchangeability of ACEi and ARB from a cardiovascular standpoint, this risk factor may be modifiable.

Yak milk casein as potential precursor of angiotensin I-converting enzyme inhibitory peptides based on in silico proteolysis.

Yak milk casein was selected as a potential precursor of bioactive peptides based on in silico analysis. Most notable among these are the angiotensin I-converting enzyme (ACE) inhibitory peptides. First, yak milk casein has high homology with cow milk casein by homologous analysis. The potential of yak milk casein for the releasing bioactive peptides was evaluated by determining the frequency of occurrence of fragments with a given activity. Through the BIOPEP database analysis, there are many bioactive peptides in yak milk casein sequences. Then, an in silico proteolysis using single or combined enzymes to obtained ACE inhibitory peptides was investigated. Cytotoxicity analysis using the online toxic prediction tool ToxinPred revealed that all in silico proteolysis derived ACE inhibitory peptides are non-cytotoxic. Overall, the present study highlights a in silico proteolysis approach to assist the yak milk casein releasing ACE inhibitory peptides and provides a guidance for the actual hydrolysis of proteins for the production of bioactive peptides.

A 90-day subchronic toxicity study and reproductive toxicity studies on ACE-inhibiting lactotripeptide.

In recent years there has been an increasing body of literature describing the antihypertensive effects of peptides produced from milk protein. The tripeptides isoleucine-proline-proline (IPP) and valine-proline-proline (VPP), isolated from hydrolysed casein have been shown to lower blood pressure by inhibiting angiotensin I-converting enzyme (ACE). This has led to the use of these tripeptides, collectively referred to as lactotripeptide (LTP) as ingredients of functional foods intended to help control blood pressure. A programme of studies including a 90-day repeat-dose oral gavage toxicity study in the rat and an embryo-fetal (pre-natal) development study in the rabbit was conducted to ensure the safety of this ACE-inhibiting ingredient. In addition, a non-standard pre- and post-natal development study in the rat was performed. This study included direct dosing of the neonates, and was designed specifically to investigate renal development and to ensure that the bioactive peptides were not associated with the same type of fetopathy exhibited by ACE inhibiting drugs. These studies showed that there were no adverse effects of treatment at the highest doses tested.

Potentiation of Paclitaxel-Induced Pain Syndrome in Mice by Angiotensin I Converting Enzyme Inhibition and Involvement of Kinins.

Paclitaxel is a chemotherapeutic agent used to treat solid tumours. However, it causes an acute and neuropathic pain syndrome that limits its use. Among the mechanisms involved in neuropathic pain caused by paclitaxel is activation of kinin receptors. Angiotensin converting enzyme (ACE) inhibitors can enhance kinin receptor signalling. The goal of this study was to evaluate the role of kinins on paclitaxel-associated acute pain syndromes (P-APS) and the effect of ACE inhibition on P-APS and paclitaxel-associated chronic peripheral neuropathy (P-CPN) in mice. Herein, we show that paclitaxel caused mechanical allodynia and spontaneous nociceptive behaviour that was reduced by antagonists of kinin receptors B1 (DALBk and SSR240612) and B2 (Hoe140 and FR173657). Moreover, enalapril (an ACE inhibitor) enhanced the mechanical allodynia induced by a low dose of paclitaxel. Likewise, paclitaxel injection inhibited ACE activity and increased the expressions of B1 and B2 receptors and bradykinin-related peptides levels in peripheral tissue. Together, our data support the involvement of kinin receptors in the P-APS and suggest kinin receptor antagonists to treat this syndrome. Because hypertension is the most frequent comorbidity affecting cancer patients, treatment of hypertension with ACE inhibitors in patients undergoing paclitaxel chemotherapy should be reviewed, since this could enhance the P-APS and P-CPN.

Mitigation of radiation nephropathy after internal alpha-particle irradiation of kidneys.

PURPOSE: Internal irradiation of kidneys as a consequence of radioimmunotherapy, radiation accidents, or nuclear terrorism can result in radiation nephropathy. We attempted to modify pharmacologically, the functional and morphologic changes in mouse kidneys after injection with the actinium ((225)Ac) nanogenerator, an in vivo generator of alpha- and beta-particle emitting elements. METHODS AND MATERIALS: The animals were injected with 0.35 muCi of the (225)Ac nanogenerator, which delivers a dose of 27.6 Gy to the kidneys. Then, they were randomized to receive captopril (angiotensin-converting enzyme inhibitor), L-158,809 (angiotensin II receptor-1 blocker), spironolactone (aldosterone receptor antagonist), or a placebo. RESULTS: Forty weeks after the (225)Ac injection, the placebo-control mice showed a significant increase in blood urea nitrogen (BUN) (87.6 +/- 6.9 mg/dL), dilated Bowman spaces, and tubulolysis with basement membrane thickening. Captopril treatment accentuated the functional (BUN 119.0 +/- 4.0 mg/dL; p <0.01 vs. placebo controls) and histopathologic damage. In contrast, L-158,809 offered moderate protection (BUN 66.6 +/- 3.9 mg/dL; p = 0.02 vs. placebo controls). Spironolactone treatment, however, significantly prevented the development of histopathologic and functional changes (BUN 31.2 +/- 2.5 mg/dL; p <0.001 vs. placebo controls). CONCLUSIONS: Low-dose spironolactone and, to a lesser extent, angiotensin receptor-1 blockade can offer renal protection in a mouse model of internal alpha-particle irradiation.