Correction: Eid et al. Interference with TGFß1-Mediated Inflammation and Fibrosis Underlies Reno-Protective Effects of the CB1 Receptor Neutral Antagonists AM6545 and AM4113 in a Rat Model of Metabolic Syndrome. Molecules 2021, 26, 866.

The authors wish to make the following changes to the paper [...].

Rosuvastatin, but not atorvastatin, enhances the antihypertensive effect of cilostazol in an acute model of hypertension.

PURPOSE: Hypertensive emergency, a sudden and severe increase in blood pressure, necessitates immediate intervention to avoid end-organ damage. Cilostazol, a selective phosphodiesterase-III inhibitor, has vasodilator effect. Here, we investigated the effect of two commonly used statins, atorvastatin or rosuvastatin, on cilostazol antihypertensive activity in acute model of hypertension. METHODS: Hypertensive emergency was induced via angiotensin II intravenous infusion (120 ng.kg-1.min-1). Rats were subjected to real-time arterial hemodynamics and electrocardiogram recording while investigated drugs were injected slowly at cumulative doses 0.5, 1, and 2 mg.kg-1, individually or in combination, followed by baroreflex sensitivity (BRS) analysis and serum electrolytes (Na+ and K+) and vasomodulators (norepinephrine (NE), and nitric oxide (NO)) assessment. RESULTS: Cilostazol reduced systolic blood pressure (SBP), while co-injection with rosuvastatin augmented cilostazol SBP-reduction up to 30 mmHg. Compared to atorvastatin, rosuvastatin boosted the cilostazol-associated reduction in peripheral resistance, as evidenced by further decrease in diastolic, pulse, and dicrotic-notch pressures. Rosuvastatin co-injection prevented cilostazol-induced changes of ejection and non-ejection durations. Additionally, rosuvastatin coadministration produced better restoration of BRS, with an observed augmented increase in BRS indexes from spectral analysis. Greater reduction in sympathetic/parasympathetic ratio and serum NE upon rosuvastatin coadministration indicates further shift in sympathovagal balance towards parasympathetic dominance. Additionally, rosuvastatin coinjection caused a greater decrease in serum sodium, while more increase in NO indicating augmented reduction of extracellular volume and endothelial dysfunction. CONCLUSION: Rosuvastatin boosted cilostazol's antihypertensive actions through effects on peripheral resistance, BRS, sympathovagal balance, endothelial dysfunction, and electrolytes balance, while atorvastatin did not demonstrate a comparable impact.

Effects of the CB1 receptor antagonists AM6545 and AM4113 on metabolic syndrome-induced prostatic hyperplasia in rats.

Metabolic syndrome (MetS) is a combination of metabolic disorders that can predispose individuals to benign prostatic hyperplasia (BPH). The inhibition of the cannabinoid 1 (CB1) receptor has been used to treat metabolic disorders in animal models. This study reports the use of a peripherally restricted CB1 antagonist (AM6545) and a neutral CB1 antagonist (AM4113) to improve MetS-related BPH in rats. Animals were divided into three control groups to receive either a normal rodent diet, AM6545, or AM4113. MetS was induced in the fourth, fifth, and sixth groups using a concentrated fructose solution and high-salt diet delivered as food pellets for eight weeks. The fifth and sixth groups were further given AM6545 or AM4113 for additional four weeks. Body and prostate weights were measured and prostate sections were stained with hematoxylin eosin. Cyclin D1, markers of oxidative stress and inflammation, and levels of the endocannabinoids were recorded. BPH in rats with MetS was confirmed through increased prostate weight and index, as well as histopathology. Treatment with either AM6545 or AM4113 significantly decreased prostate weight, improved prostate histology, and reduced cyclin D1 expression compared with the MetS group. Groups treated with CB1 antagonists experienced reduced lipid peroxidation, recovered glutathione depletion, restored catalase activity, and had lower inflammatory markers interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α). MetS rats treated with either AM6545 or AM4113 showed reduced concentrations of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in the prostate compared with the MetS group. In conclusion, the CB1 antagonists AM6545 and AM4113 protect against MetS-induced BPH through their anti-proliferative, antioxidant, and anti-inflammatory effects.

Development of depot PLGA-based in-situ implant of Linagliptin: Sustained release and glycemic control.

High percentage of diabetic people are diagnosed as type 2 who require daily dosing of an antidiabetic drug such as Linagliptin (Lina) to manage their blood glucose levels. This study aimed to develop injectable Lina-loaded biodegradable poly (lactic-co-glycolic acid) (PLGA) in-situ implants (ISIs) to deliver a desired burst effect of Lina followed by a sustained release over several days for controlling the blood glucose levels over prolonged time periods. The morphological, pharmacokinetic, and pharmacodynamic assessments of the Lina-loaded ISIs were performed. Scanning electron microscopy (SEM) study revealed the rapid exchange between the water miscible solvent (N-methyl-2-pyrrolidone; NMP) and water during the ISI preparation, hence enhancing the initial burst Lina release. While, triacetin of lower water affinity could lead to formation of more compact and dense ISI structure with slower drug release. By comparing various ISI formulations containing different solvents and different PLGA concentrations, the ISI containing 40 % PLGA and triacetin was selected for its sustained release of Lina (93.06 ± 1.50 %) after 21 days. The pharmacokinetic results showed prolonged half life (t1/2) and higher area under the curve (AUC) values of the selected Lina-loaded ISI when compared to those of oral Lina preparation. The single Lina-ISI injection produced a hypoglycemic control in the diabetic rats very similar to the daily oral administration of Lina after 7 and 14 days. In conclusion, PLGA-based ISIs confirmed their suitability for prolonging Lina release in patients receiving long-term antidiabetic therapy, thereby achieving more enhanced patient compliance and reduced dosing frequency.

Hinokitiol for hypertensive emergencies: effects on peripheral resistance, cardiac load, baroreflex sensitivity, and electrolytes balance.

Hinokitiol, a natural monoterpenoid, has been shown previously to possess a potent vasodilating activity in vitro in both control and hypertensive aortae. Here, the antihypertensive and cardioprotective effects of an intravenous hinokitiol injection were fully investigated in angiotensin II-induced hypertensive emergency in rats. Hinokitiol intravenous injection was prepared in the form of self-nanoemulsifying drug delivery system. Rat's arterial and ventricular hemodynamics were measured in real-time recordings in addition to surface electrocardiogram while slow injection of cumulative doses of hinokitiol or vehicle as well as time control. Hinokitiol at dose 10 mg/kg showed a considerable reduction in the raised systolic blood pressure (30 mmHg) within only 30 min. The decrease in blood pressure seems to be mediated through a reduction in peripheral resistance, as appears from the decreases in diastolic pressure, dicrotic notch pressure, and pulse pressure. In addition, hinokitiol injection reduced heart load due to the decrease in heart rate, increases in cycle duration (particularly the non-ejection duration) and diastolic duration, and decreases in end-diastolic pressure. An effect most likely mediated via prolongation of ventricular repolarization as appears from the increases in PR, QTc, and JT intervals. However, acute intravenous injection of hinokitiol neither affected the baroreflex sensitivity nor sodium/potassium balance. In conclusion, acute hinokitiol intravenous injection markedly reduced severe hypertension in rats. This effect seems to be mediated through decreasing peripheral resistance and decreasing cardiac load, suggesting that it is an effective treatment in hypertensive emergencies after clinical evaluation.

Investigation of Alogliptin-Loaded In Situ Gel Implants by 23 Factorial Design with Glycemic Assessment in Rats.

The aim of the study was to design injectable long-acting poly (lactide-co-glycolide) (PLGA)-based in situ gel implants (ISGI) loaded with the anti-diabetic alogliptin. Providing sustained therapeutic exposures and improving the pharmacological responses of alogliptin were targeted for achieving reduced dosing frequency and enhanced treatment outputs. In the preliminary study, physicochemical characteristics of different solvents utilized in ISGI preparation were studied to select a proper solvent possessing satisfactory solubilization capacity, viscosity, water miscibility, and affinity to PLGA. Further, an optimization technique using a 23 factorial design was followed. The blood glucose levels of diabetic rats after a single injection with the optimized formulation were compared with those who received daily oral alogliptin. N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO), as highly water-miscible and low viscous solvents, demonstrated their effectiveness in successful ISGI preparation and controlling the burst alogliptin release. The impact of increasing lactide concentration and PLGA amount on reducing the burst and cumulative alogliptin release was represented. The optimized formulation comprising 312.5 mg of PLGA (65:35) and DMSO manifested a remarkable decrease in the rats' blood glucose levels throughout the study period in comparison to that of oral alogliptin solution. Meanwhile, long-acting alogliptin-loaded ISGI systems demonstrated their feasibility for treating type 2 diabetes with frequent dosage reduction and patient compliance enhancement.

Hinokitiol produces vasodilation in aortae from normal and angiotensin II- induced hypertensive rats via endothelial-dependent and independent pathways.

Hinokitiol is a natural bioactive compound with numerous pharmacological properties. Here, we aimed to examine hinokitiol's effects on vascular relaxation. Cumulative relaxation responses to hinokitiol were assessed in isolated aortae from normotensive and angiotensin II-induced hypertensive rats in the presence and absence of selective inhibitors. Hinokitiol produced vasodilation of phenylephrine preconstricted aortae using both normotensive and hypertensive rats. In normotensive rats, hinokitiol's vasodilation was reduced by endothelial denudation and nitric oxide synthase (NOS), guanylate cyclase, and cyclooxygenase inhibition. Also, hinokitiol vasodilation was attenuated by ß-receptors, adenylate cyclase, Ca2+-activated K+ channels and hyperpolarization inhibition. Moreover, hinokitiol exhibited a blocking activity on Ca2+ mobilization through voltage dependent Ca2+ channels (VDCC). However, its effect was not changed by muscarinic receptor and Sarc-K+ ATP channels blocking but was enhanced by blocking voltage-dependent K+ channels. However, in angiotensin II-induced hypertension, hinokitiol vasodilating activity was attenuated by NOS inhibition and it blocked Ca2+ mobilization through VDCC, while its vasodilation was partially attenuated by Sarc-K+ ATP channels blocking. However, the vasodilating effect of hinokitiol was not attenuated by either cyclooxygenase, ß-receptor, Ca2+-activated K+ channels, or voltage-dependent potassium channels inhibition, but was enhanced by blocking hyperpolarization. Hinokitiol's vasodilating effect in normotensive and hypertensive vessels is mediated through both endothelium-dependent and endothelium-independent mechanisms.

A Nano-Pharmaceutical Formula of Quercetin Protects from Cardiovascular Complications Associated with Metabolic Syndrome.

Metabolic syndrome (MetS) is closely associated with the development of cardiovascular diseases. We recently developed a nano-preparation of the flavonoid quercetin (QU) in a self-nanoemulsifying drug delivery system (SNEDDS). The latter comprised a mixture composed of pumpkin seed oil, D-α-Tocopherol polyethylene glycol 1,000 succinate and polyethylene glycol. The QU SNEDDS preparations exhibited a considerably higher bioavailability compared with the standard quercetin suspension. Here, we investigated whether the quercetin loaded SNEDDS could offer better protection compared with the standard formulation against cardiovascular complications of MetS in rats. MetS was induced by high fructose, high salt and high fat diet for 12 weeks while the nano-preparation or the standard suspension of quercetin was orally administered for the last 6 weeks. Compared to little effect for the standard quercetin suspension (MQ), the treatment of MetS rats with the quercetin loaded SNEDDS (MNQ) virtually abolished the depressant effect of MetS on contractility index (control, 114 ± 4; MetS, 92 ± 3; MQ, 100 ± 2; MNQ, 114 ± 6 1/s) and rate of rise in left ventricular pressure (dP/dtmax) (control, 8,171 ± 274; MetS, 6,664 ± 135; MQ, 6,776 ± 108; MNQ, 7,498 ± 303 mmHg/s). Likewise, the prolongation by MetS of electrocardiographic markers of arrhythmogenesis (QTc, JT, and Tpeak-to-Tend intervals) and concomitant rises in dicrotic notch pressure were preferentially reversed by quercetin nano-preparation. On the other hand, the rises in the isovolumic relaxation constant (Tau, denotes diastolic dysfunction), blood pressure, pulse pressure, and difference between systolic and dicrotic pressure (SDP difference) were equally improved by the two preparations of quercetin. Additionally, no differences were noted in the ability of the two quercetin preparations in abrogating the elevated oxidative (MDA) and inflammatory (TNFα) markers in cardiac tissues of MetS rats. Histopathological, microscopical signs of necrosis, inflammatory cell infiltration, and vascular congestion in MetS hearts were more markedly inhibited by the nano-preparation, compared with the standard preparation of quercetin. In conclusion, the quercetin loaded SNEDDS is evidently more advantageous than the standard preparation of the drug in alleviating functional and histopathological manifestations of cardiac damage incited by MetS.

Nitric-Oxide-Mediated Vasodilation of Bioactive Compounds Isolated from Hypericum revolutum in Rat Aorta.

Vasodilators are an important class in the management of hypertension and related cardiovascular disorders. In this regard, the chloroform fraction of Hypericum revolutum (HR) has been reported to produce vasodilating activity in phenylephrine-precontracted aortae. The current work aims to identify the active metabolites in the chloroform fraction of HR and illustrate the possible mechanism of action. The vasodilation activities were investigated using the isolated artery technique. NO vascular release was assessed by utilizing the NO-sensitive fluorescent probe DAF-FM. Free radical scavenging capacity was assessed utilizing DPPH. Chemical investigation of this fraction yielded two new compounds, revolutin (1) and hyperevolutin C (2), along with three known metabolites, ß-sitosterol (3), euxanthone (4), and 2,3,4-tirmethoxy xanthone (5). Compounds 1, 2, 3, and 5 showed significant vasodilation activities that were blocked by either endothelial denudation or L-NAME (nitric oxide synthase inhibitor), pointing towards a role of endothelial nitric oxide in their activities. In confirmation of this role, compounds 1-3 showed a significant release of NO from isolated vessels, as indicated by DAF-FM. On the other hand, only compound 5 showed free radical scavenging activities, as indicated by DPPH. In conclusion, isolated compounds 1, 2, 3, and 5 produce vasodilation activities that are dependent on endothelial nitric oxide release.

Modulation of preeclampsia by the cholinergic anti-inflammatory pathway: Therapeutic perspectives.

The cholinergic anti-inflammatory pathway (CAP) is vital for the orchestration of the immune and inflammatory responses under normal and challenged conditions. Over the past two decades, peripheral and central circuits of CAP have been shown to be critically involved in dampening the inflammatory reaction in a wide array of inflammatory disorders. Additionally, emerging evidence supports a key role for CAP in the regulation of the female reproductive system during gestation as well as in the advent of serious pregnancy-related inflammatory insults such as preeclampsia (PE). Within this framework, the modulatory action of CAP encompasses the perinatal maternal and fetal adverse consequences that surface due to antenatal PE programming. Albeit, a considerable gap still exists in our knowledge of the precise cellular and molecular underpinnings of PE/CAP interaction, which hampered global efforts in safeguarding effective preventive or therapeutic measures against PE complications. Here, we summarize reports in the literature regarding the roles of peripheral and reflex cholinergic neuroinflammatory pathways of nicotinic acetylcholine receptors (nAChRs) in reprogramming PE complications in mothers and their progenies. The possible contributions of α7-nAChRs, cholinesterases, immune cells, adhesion molecules, angiogenesis, and endothelial dysfunction to the interaction have also been reviewed.

Self-Nanoemulsifying Drug Delivery System Loaded with Psiadia punctulata Major Metabolites for Hypertensive Emergencies: Effect on Hemodynamics and Cardiac Conductance.

Vasodilators are an important class of antihypertensive agents. However, they have limited clinical use due to the reflex tachycardia associated with their use which masks most of its antihypertensive effect and raises cardiac risk. Chemical investigation of Psiadia punctulata afforded five major methoxylated flavonoids (1-5) three of which (1, 4, and 5) showed vasodilator activity. Linoleic acid-based self-nanoemulsifying drug delivery system (SNEDDS) was utilized to develop intravenous (IV) formulations that contain compounds 1, 4, or 5. The antihypertensive effect of the prepared SNEDDS formulations, loaded with each of the vasodilator compounds, was tested in the angiotensin-induced rat model of hypertension. Rats were subjected to real-time recording of blood hemodynamics and surface Electrocardiogram (ECG) while the pharmaceutical formulations were individually slowly injected in cumulative doses. Among the tested formulations, only that contains umuhengerin (1) and 5,3'-dihydroxy-6,7,4',5'-tetramethoxyflavone (5) showed potent antihypertensive effects. Low IV doses, from the prepared SNEDDS, containing either compound 1 or 5 showed a marked reduction in the elevated systolic blood pressure by 10 mmHg at 12 µg/kg and by more than 20 mmHg at 36 µg/kg. The developed SNEDDS formulation containing either compound 1 or 5 significantly reduced the elevated diastolic, pulse pressure, dicrotic notch pressure, and the systolic-dicrotic notch pressure difference. Moreover, both formulations decreased the ejection duration and increased the non-ejection duration while they did not affect the time to peak. Both formulations did not affect the AV conduction as appear from the lack of effect on p duration and PR intervals. Similarly, they did not affect the ventricular repolarization as no effect on QTc or JT interval. Both formulations decreased the R wave amplitude but increased the T wave amplitude. In conclusion, the careful selection of linoleic acid for the development of SNEDDS formulation rescues the vasodilating effect of P. punctulata compounds from being masked by the reflex tachycardia that is commonly associated with the decrease in peripheral resistance by most vasodilators. The prepared SNEDDS formulation could be suggested as an effective medication in the treatment of hypertensive emergencies, after clinical evaluation.

Rp-HPLC Determination of Quercetin in a Novel D-α-Tocopherol Polyethylene Glycol 1000 Succinate Based SNEDDS Formulation: Pharmacokinetics in Rat Plasma.

Despite its proven efficacy in diverse metabolic disorders, quercetin (QU) for clinical use is still limited because of its low bioavailability. D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) is approved as a safe pharmaceutical adjuvant with marked antioxidant and anti-inflammatory activities. In the current study, several QU-loaded self-nanoemulsifying drug delivery systems (SNEDDS) were investigated to improve QU bioavailability. A reversed phase high performance liquid chromatography (RP-HPLC) method was developed, for the first time, as a simple and sensitive technique for pharmacokinetic studies of QU in the presence of TPGS SNEDDS formula in rat plasma. The analyses were performed on a Xterra C18 column (4.6 × 100 mm, 5 µm) and UV detection at 280 nm. The analytes were separated by a gradient system of methanol and phosphate buffer of pH 3. The developed RP-HPLC method showed low limit of detection (LODs) of 7.65 and 22.09 ng/mL and LOQs of 23.19 and 66.96 ng/mL for QU and TPGS, respectively, which allowed their determination in real rat plasma samples. The method was linear over a wide range, (30-10,000) and (100-10,000) ng/mL for QU and TPGS, respectively. The selected SNEDDS formula, containing 50% w/w TPGS, 30% polyethylene glycol 200 (PEG 200), and 20% w/w pumpkin seed oil (PSO), showed a globule size of 320 nm and -28.6 mV zeta potential. Results of the pharmacokinetic studies showed 149.8% improvement in bioavailability of QU in SNEDDS relative to its suspension. The developed HPLC method proved to be simple and sensitive for QU and TPGS simultaneous determination in rat plasma after oral administration of the new SNEDDS formula.

Interference with TGFß1-Mediated Inflammation and Fibrosis Underlies Reno-Protective Effects of the CB1 Receptor Neutral Antagonists AM6545 and AM4113 in a Rat Model of Metabolic Syndrome.

The role of cannabinoid receptors in nephropathy is gaining much attention. This study investigated the effects of two neutral CB1 receptor antagonists, AM6545 and AM4113, on nephropathy associated with metabolic syndrome (MetS). MetS was induced in rats by high-fructose high-salt feeding for 12 weeks. AM6545, the peripheral silent antagonist and AM4113, the central neutral antagonist were administered in the last 4 weeks. At the end of study, blood and urine samples were collected for biochemical analyses while the kidneys were excised for histopathological investigation and transforming growth factor beta 1 (TGFß1) measurement. MetS was associated with deteriorated kidney function as indicated by the elevated proteinuria and albumin excretion rate. Both compounds equally inhibited the elevated proteinuria and albumin excretion rate while having no effect on creatinine clearance and blood pressure. In addition, AM6545 and AM4113 alleviated the observed swelling and inflammatory cells infiltration in different kidney structures. Moreover, AM6545 and AM4113 alleviated the observed histopathological alterations in kidney structure of MetS rats. MetS was associated with a ten-fold increase in urine uric acid while both compounds blocked this increase. Furthermore, AM6545 and AM4113 completely prevented the collagen deposition and the elevated expression of the TGFß1 seen in MetS animals. In conclusion, AM6545 and AM4113, possess reno-protective effects by interfering with TGFß1-mediated renal inflammation and fibrosis, via peripheral action.

Effects of the CB1 Receptor Antagonists AM6545 and AM4113 on Insulin Resistance in a High-Fructose High-Salt Rat Model of Metabolic Syndrome.

Background and Objectives: Insulin resistance (IR) is a serious condition leading to development of diabetes and cardiovascular complications. Hyper-activation of cannabinoid receptors-1 (CB1) has been linked to the development of metabolic disorders such as IR. Therefore, the effect of blocking CB1 on the development of IR was investigated in the present study. Materials and Methods: A 12-week high-fructose/high-salt feeding model of metabolic syndrome was used to induce IR in male Wistar rats. For this purpose, two different CB1-antagonists were synthesized and administered to the rats during the final four weeks of the study, AM6545, the peripheral neutral antagonist and AM4113, the central neutral antagonist. Results: High-fructose/salt feeding for 12 weeks led to development of IR while both AM6545 and AM4113, administered in the last 4 weeks, significantly inhibited IR. This was correlated with increased animal body weight wherein both AM6545 and AM4113 decreased body weight in IR animals but with loss of IR/body weight correlation. While IR animals showed significant elevations in serum cholesterol and triglycerides with no direct correlation with IR, both AM6545 and AM4113 inhibited these elevations, with direct IR/cholesterol correlation in case of AM6545. IR animals had elevated serum uric acid, which was reduced by both AM6545 and AM4113. In addition, IR animals had decreased adiponectin levels and elevated liver TNFα content with strong IR/adiponectin and IR/TNFα correlations. AM6545 inhibited the decreased adiponectin and the increased TNFα levels and retained the strong IR/adiponectin correlation. However, AM4113 inhibited the decreased adiponectin and the increased TNFα levels, but with loss of IR/adiponectin and IR/TNFα correlations. Conclusions: Both CB1 neutral antagonists alleviated IR peripherally, and exerted similar effects on rats with metabolic syndrome. They also displayed anti-dyslipidemic, anti-hyperurecemic and anti-inflammatory effects. Overall, these results should assist in the development of CB1 neutral antagonists with improved safety profiles for managing metabolic disorders.

Antiglycation Activities and Common Mechanisms Mediating Vasculoprotective Effect of Quercetin and Chrysin in Metabolic Syndrome.

Multiple risk factors combine to increase the risk of vascular dysfunction in patients suffering from metabolic syndrome (MetS). The current study investigates the extent to which quercetin (Q) and chrysin (CH) protect against vascular dysfunction in MetS rats. MetS was induced by feeding rats a high-salt diet (3%) and fructose-enriched water (10%) for 12 weeks. Thoracic aorta was isolated from MetS rats and from control rats, with the latter being injured by methylglyoxal (MG). Aortae were incubated with CH and Q, and vascular reactivity was evaluated through the analysis of aortic contraction and relaxation in response to PE and ACh, respectively. The formation of advanced glycation end products (AGEs) and the free radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) were also evaluated following the introduction of CH and Q. The increased vasoconstriction and impaired vasodilation in MetS aortae were significantly ameliorated by Q and CH. Similarly, they ameliorated glycation-associated exaggerated vasoconstriction and impaired vasodilation produced by MG in control aortae. In addition, both Q and CH were effective in reducing the formation of AGEs and inhibition of glycosylation in response to MG or fructose treatment. Finally, Q successfully scavenged DPPH free radicals while CH showed significant vasodilation of precontracted aorta that was inhibited by L-NAME. In conclusion, Q and CH provide protection against vascular dysfunction in MetS by interfering with AGEs formations and AGEs-associated vascular deterioration, with CH being largely dependent on NO-mediated mechanisms of vasodilation.

Major flavonoids from Psiadia punctulata produce vasodilation via activation of endothelial dependent NO signaling.

Vasodilators are important pharmacologic agents for managing and/or treating hypertension. Medicinal plants are considered as valuable source of bioactive compounds. We used a bioguided approach to isolate, identify, and investigate the possible vasodilation activities and mechanism(s) of the prepared methanol extract from aerial parts of Psiadia punctulata (MAPP), its bioactive fraction and active compounds. Vascular effects of MAPP were studied using isolated artery technique in the presence or absence of specific candidate pathways inhibitors, and found to produce a significant vasodilation of phenylephrine preconstricted rat aortae. The bioactive chloroform fraction yielded five methoxylated flavonoids: umuhengerin (1), gardenin A (2), gardenin B (3), luteolin-3',4' -dimethyl ether (4), and 5,3'-dihydroxy-6,7,4',5'-tetramethoxyflavone (5). Metabolites 1, 4, and 5 produced a significant vasodilation. Removal of the endothelium significantly inhibited MAPP vasodilation. Nitric oxide synthase inhibition and not prostacycline inhibition or K+ channel blocking, was found to cause the observed vasodilation inhibition. Both guanylate cyclase and adenylate cyclase inhibitions markedly inhibited MAPP vasodilation. In conclusion MAPP possesses vasodilation activities that is mediated through endothelial nitric oxide pathway, calcium dependent endothelial nitric oxide synthase activation, and interference with the depolarization process through calcium channel blocking activity.

Interference with AGEs formation and AGEs-induced vascular injury mediates curcumin vascular protection in metabolic syndrome.

Vascular dysfunction predisposes to cardiovascular complications of metabolic syndrome (MetS). The current study investigated the mechanism(s) of curcumin's (CUR) protective effect against vascular reactivity irregularities in MetS. MetS was induced by feeding rats on high fructose high salt diet. Tension studies were undertaken in aortic rings to assess the influence of CUR on vasoconstrictor or vasorelaxant responses. The effect on advanced glycation endproducts (AGEs) was studied by incubating aortic tissues with methylglyoxal, the AGEs precursor, in the absence and presence of CUR. In addition, CUR effects on in-vitro generation of AGEs and diphenyl-2-picrylhydrazyl (DPPH) free radicals were studied. The incubation with CUR for 1 hr produced significant and concentration-dependent alleviation of the exaggerated vasoconstriction observed in aortas isolated from MetS, however failed to improve the concomitant attenuation of vasodilatory responses to ACh in PE-precontracted aortas. By contrast, CUR caused direct concentration-dependent vasodilations of precontracted aortas, effects that were blunted after nitric oxide synthase inhibition by L-NAME. Similar to its effects in MetS aortas, CUR alleviated exaggerated PE vasoconstriction but did not affect impaired ACh vasodilations in AGEs-exposed aortas. In addition, CUR showed significant dose-dependent DPPH free radicals scavenging activity and inhibited both MG and fructose induced AGEs formation at the level of protein oxidation step as evident from the effect on dityrosine and N-formylkyramine. CUR alleviates exaggerated vasoconstriction in MetS through interfering with AGEs formation and AGEs-induced vascular injury. Free radical scavenging and direct vasodilatory activities could also participate in the advantageous vascular actions of CUR.

Despite Blocking Doxorubicin-Induced Vascular Damage, Quercetin Ameliorates Its Antibreast Cancer Activity.

Quercetin is a naturally occurring flavonol present in many foods. Doxorubicin is an effective anticancer agent despite its dose-limiting cardiovascular toxicity. Herein, we investigated the potential protective effects of quercetin against doxorubicin-induced vascular toxicity and its effect on the therapeutic cytotoxic profile of doxorubicin in breast cancer cell lines. The incubation of isolated aortic rings with doxorubicin produced concentration-dependent exaggeration of vasoconstriction responses to phenylephrine but impaired vasodilation responses to acetylcholine. Coincubation with quercetin completely blocked the exaggerated vasoconstriction responses and the impaired vasodilation. In addition, doxorubicin incubation increased reactive oxygen species generation from the isolated aorta, while coincubation with quercetin inhibited ROS generation back to normal values. On the other hand, quercetin in combination with doxorubicin, doubled the IC50 of doxorubicin alone in MCF-7 cells from 0.4 ± 0.03 to 0.8 ± 0.06 µM. To a lesser extent, the IC50 of doxorubicin did not change after combination with quercetin in MDA-MB-231 cells. These findings indicate a significant antagonistic interaction between quercetin and doxorubicin in the aforementioned cell lines. Only in T47D cells, quercetin combination with doxorubicin was an additive interaction (CI - value = 1.17). Yet, quercetin significantly impaired the immediate phase of intracellular ROS generation by doxorubicin within breast cancer cells from 125.2 ± 3.6% to 102.5 ± 3.9% of control cells. Using annexin-V/FITC staining technique, the quercetin/doxorubicin combination showed a significantly lower percent of apoptotic cells compared to doxorubicin alone treated cells. Cell cycle distribution in breast cancer cells was performed using DNA content flowcytometry after propidium iodide staining. Quercetin induced significant accumulation of cells in the S phase as well as in the G2/M phase within both MCF-7 and MDA-MB-231 cell lines and interfered with doxorubicin-induced cell cycle effects. Interestingly, quercetin was found to inhibit the P-glycoprotein ATPase subunit with a consequent enhanced intracellular concentration of doxorubicin in MDA-MB-231 and T47D cells. In conclusion, quercetin, despite its potent vascular protective activity against doxorubicin, was found to influence doxorubicin-induced antibreast cancer effects via pharmacodynamic as well as cellular pharmacokinetic aspects.

Psiadia punctulata major flavonoids alleviate exaggerated vasoconstriction produced by advanced glycation end products.

Exaggerated vasoconstriction plays important roles in vascular complication in aging and many diseases like diabetes. Here, we investigated the protective effect of Psiadia punctulata (PP) on advanced glycation end products (AGEs)-induced aggravated vasoconstriction. The effect of total methanol extract of PP leaves (PPT) on AGE-induced vascular injury was studied through bioassay-guided fractionation procedures in order to find the bioactive fraction and isolate the bioactive compounds. Vascular reactivity was studied using the isolated artery technique by adding cumulative concentrations of phenylephrine (PE) or acetyl choline (ACh). In addition, the antiglycating effect, as well as the effect on AGEs intermediates dityrosine and N`-formylkynurenine and their radical scavenging activity were measured. The results showed that PPT alleviated the AGEs-induced aggravated vasoconstriction in a concentration-dependent manner. The bioassay guided fractionation procedures suggested the chloroform fraction (Fr I) to be responsible for the activity. Chemical investigation of this fraction resulted in isolation of four major bioactive compounds that were identified as: umuhengerin (1), gardenin (2), luteolin-3`,4`-dimethyl ether (3), and 5,3`-dihydroxy-6,7,4`,5`-tetramethoxyflavone (4). The four compounds alleviated the exaggerated vasoconstriction in a dose dependent manner. In search for their mechanism of action, we observed that PPT, Fr. I and the isolated compounds did not improve the impaired vasodilation associated with AGEs exposure. PPT, Fr. I and the isolated compounds 1-4 inhibited AGEs formation and their protein oxidation intermediates. Furthermore, PPT, Fr. I and the isolated compounds 1-4 showed weak radical scavenging activity with compound 4 as the most potent. In conclusion, PPT appears to protect against AGEs-induced exaggerated vasoconstriction through antiglycation and radical scavenging activities.

Mentha longifolia alleviates experimentally induced angina via decreasing cardiac load.

Angina occurs due to imbalance between heart oxygen demand and supply and is associated with serious morbidity and mortality. Here, the possible antianginal effect of Mentha longifolia extract was studied in experimental model of angina. Aerial parts of M. longifolia were extracted, standardized, and given to rats three days before angina. Heart hemodynamics and conductivity were recorded by microtip catheter and surface electrodes. M. longifolia extract significantly alleviated the sustained decline in cardiac contractility after vasopressin exposure. However, M. longifolia did not affect the impaired cardiac dilation after vasopressin. Heart rate was significantly decreased after vasopressin exposure in rats treated with M. longifolia compared with untreated animals. In addition, M. longifolia produced more increase in systolic and diastolic durations after vasopressin exposure compared with untreated animals. Moreover, the plant extract alleviated the ST height changes during vasopressin injection. M. longifolia extract alleviates impaired cardiac function associated with angina through decreasing heart work. PRACTICAL APPLICATIONS: The present study is the first to study the effect of M. longifolia in an experimental model of angina. M. longifolia alleviated the impaired cardiac contractility associated with angina exposure. The antianginal effect of M. longifolia could be through reducing cardiac load. This can be concluded from the decrease in heart rate and the systolic and diastolic cycles elongation after exposure to vasopressin in animals pretreated with M. longifolia. This helps in reducing the associated cardiac ischemia upon exposure to vasopressin as indicated by ST change. This could provide new directions in the management of the serious angina disease.