A Review of Endothelium-Dependent and -Independent Vasodilation Induced by Phytochemicals in Isolated Rat Aorta

Carob leaves: Phytochemistry, antioxidant properties, vasorelaxant effect and mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

Ceratonia siliqua L., is a species of significant nutritional and industrial interest with extensive traditional uses. This fabaceae is renowned for its medicinal properties, including the treatment of high blood pressure. Due to its chemical composition, carob exhibits several valuable therapeutic functions such as antioxidant, antidiarrheal, antidiabetic, and antibacterial actions.

AIM OF THE REVIEW

This study investigates the chemical composition of Ceratonia siliqua L. leaves aqueous extract (CsAE) and explores the vasorelaxant effect and its underlying mechanisms. Acute toxicity and antioxidant activity of CsAE were also examined.

METHODS

The phytochemical profile was elucidated using TLC and UHPLC-MS. The vasorelaxant effect and mechanisms were studied on thoracic aortic rings from normotensive rats, using various antagonists. Acute toxicity was assessed by orally administering the extract to mice. Antioxidant activity was evaluated using β-carotene bleaching and DPPH.

RESULTS

TLC analysis of CsAE reveals flavonoids and hydrolysable tannins. Gallic acid, myricitrin, quercitrin as well as galloylglucopyranoside derivatives were identified by UHPLC-MS. CsAE relaxed phenylephrine-precontracted aorta in a concentration-dependent manner. This response was reduced when the aorta was denuded or pretreated with L-NAME, hydroxocobalamin, ODQ, 4-AP, TEA, calmidazolium chloride, and thapsigargin. CsAE showed significant antioxidant activity with no observed toxicity in the experimental animals.

CONCLUSION

CsAE has a significant vasodilatory effect, mediated through the CaM/eNOS/sGC pathway, activation of Kca and Kv, and intracellular calcium mobilization into SERCA. It also exhibits strong antioxidant activity, with no observed toxicity in the experimental animals. These findings represent the first evidence of the vasorelaxant effect of Ceratonia siliqua L. leaves from Eastern Morocco.

Effect of Torilis japonica Fruit Extract for Endothelium-Independent Vasorelaxation and Blood Pressure Lowering in Rats

Torilis japonica (TJ) fruit, is a herb that is traditionally used for erectile dysfunction (ED). Given the shared mechanisms of ED and hypertension through vascular smooth muscle, we hypothesized that TJ would be effective in vasodilation and blood pressure reduction. This study confirmed the authenticity of TJ samples via DNA barcoding and quantified the main active compound, torilin, using HPLC. TJ was extracted with distilled water (TJW) and 50% ethanol (TJE), yielding torilin contents of 0.35 ± 0.01% and 2.84 ± 0.02%, respectively. Ex vivo tests on thoracic aortic rings from Sprague-Dawley rats showed that TJE (3-300 µg/mL) induced endothelium-independent, concentration-dependent vasodilation, unlike TJW. Torilin caused concentration-dependent relaxation with an EC50 of 210 ± 1.07 µM. TJE's effects were blocked by a voltage-dependent K+ channel blocker and alleviated contractions induced by CaCl2 and angiotensin II. TJE inhibited vascular contraction induced by phenylephrine or KCl via extracellular CaCl2 and enhanced inhibition with nifedipine, indicating involvement of voltage-dependent and receptor-operated Ca2+ channels. Oral administration of TJE (1000 mg/kg) significantly reduced blood pressure in spontaneously hypertensive rats. These findings suggest TJ extract's potential for hypertension treatment through vasorelaxant mechanisms, though further research is needed to confirm its efficacy and safety.

Codonopsis lanceolata Extract Restores Smooth Muscle Vasorelaxation in Rat Carotid Arteries Even under High Extracellular K+ Concentrations

Recent studies showed that Codonopsis lanceolata (CL) has antihypertensive effects. However, to date, no study has examined the effects of CL on vascular tone under a high extracellular K+ concentration ([K+]o). Thus, the present study examined the effect of an extract of Codonopsis lanceolata (ECL) on the vascular tension of rat carotid arteries exposed to high [K+]o. We used myography to investigate the effect of an ECL on the vascular tension of rat carotid arteries exposed to high [K+]o and the underlying mechanism of action. In arteries with intact endothelia, the ECL (250 μg/mL) had no effect on vascular tension in arteries exposed to normal or high [K+]o. In contrast, the ECL significantly increased vasorelaxation in endothelium-impaired arteries exposed to a physiologically normal or high [K+]o compared with control arteries exposed to the same [K+]o conditions in the absence of ECL. This vasorelaxing action was unaffected by a broad-spectrum K+ channel blocker and an ATP-sensitive K+ channel blocker. The ECL significantly inhibited the vasoconstriction induced by Ca2+ influx through voltage-dependent Ca2+ channels (VDCCs) but not Ca2+ influx induced via receptor-operated Ca2+ channels or the release of Ca2+ from the sarcoplasmic reticulum in the vascular smooth muscle. In summary, our study reveals that the ECL acts through VDCCs in vascular smooth muscle to promote the recovery of vasorelaxation even in arteries exposed to high [K+]o in the context of endothelial dysfunction and provides further evidence of the vascular-protective effects of ECL.

Beyond standard PSE testing: An exploratory study of bioimpedance as a marker for ham defects

During post-mortem conversion from muscle to meat, diverse quality anomalies can emerge. Recent pork defects are often accompanied by deteriorating fibre structure. Here we investigate how bioimpedance response, an indicator of structural disintegration, can help in detecting quality defects. We, first, measured the relationship between standard meat quality variables (pHu, CIELAB, drip loss) and bioimpedance (BI) response. To screen for defect-biomarkers that are linked to aberrant bioimpedance and physicochemical indicators of quality decline, we performed LC-MS/MS proteomic analysis on samples, classified with a multivariate-based separation into good versus poor quality. We found that BI correlated significantly with, e.g., colour and drip loss. Proteomics revealed eleven proteins to be unique for either, good or poor ham quality groups, and maybe linked to structural degradation. In all, our data supports a wider integration of BI testing in pork quality testing to assess structural disintegration, which can render ham unsuitable for, e.g., costly curing.

UV-B filter octylmethoxycinnamate-induced vascular endothelial disruption on rat aorta: In silico and in vitro approach

Throughout human life, an extensive and varied range of emerging environmental contaminants, called endocrine disruptors (EDCs), cause adverse health effects, including in the cardiovascular (CV) system. Cardiovascular diseases (CVD) are worryingly one of the leading causes of all mortality and mobility worldwide. The UV-B filter octylmethoxycinnamate (also designated octinoxate, or ethylhexyl methoxycinnamate (CAS number: 5466-77-3)) is an EDC widely present in all personal care products. However, to date, there are no studies evaluating the OMC-induced effects on vasculature using animal models to improve human cardiovascular health. This work analysed the effects of OMC on rat aorta vasculature and explored the modes of action implicated in these effects. Our results indicated that OMC relaxes the rat aorta by endothelium-dependent mechanisms through the signaling pathways of cyclic nucleotides and by endothelium-independent mechanisms involving inhibition of L-Type voltage-operated Ca²⁺ channels (L-Type VOCC). Overall, OMC toxicity on rat aorta may produce hypotension via vasodilation due to excessive NO release and blockade of L-Type VOCC. Moreover, the OMC-induced endothelial dysfunction may also occur by promoting the endothelial release of endothelin-1. Therefore, our findings demonstrate that exposure to OMC alters the reactivity of the rat aorta and highlight that long-term OMC exposure may increase the risk of human CV diseases.

Vasorelaxant Effects of Syzygium samarangense (Blume) Merr. and L.M.Perry Extract Are Mediated by NO/cGMP Pathway in Isolated Rat Thoracic Aorta

Syzygium samarangense (Blume) Merr. and L.M.Perry is utilized widely in traditional medicine. We have reported previously a wide array of pharmacological properties of its leaf extract, among them anti-inflammatory, antioxidant, hepatoprotective, antidiabetic, antiulcer, and antitrypanosomal activities. We also annotated its chemical composition using LC-MS/MS. Here, we continue our investigations and evaluate the vasorelaxant effects of the leaf extract on aortic rings isolated from rats and explore the possible underlying mechanisms. S. samarangense extract induced a concentration dependent relaxation of the phenylephrine-precontracted aorta in the rat model. However, this effect disappeared upon removing the functional endothelium. Pretreating the aortic tissues either with propranolol or NG-nitro-L-arginine methyl ester inhibited the relaxation induced by the extract; however, atropine did not affect the extract-induced vasodilation. Meanwhile, adenylate cyclase inhibitor, MDL; specific guanylate cyclase inhibitor, ODQ; high extracellular KCl; and indomethacin as cyclooxygenase inhibitor inhibited the extract-induced vasodilation. On the other hand, incubation of S. samarangense extract with aortae sections having their intact endothelium pre-constricted using phenylephrine or KCl in media free of Ca²⁺ showed no effect on the constriction of the aortae vessels induced by Ca²⁺. Taken together, the present study suggests that S. samarangense extract dilates isolated aortic rings via endothelium-dependent nitric oxide (NO)/cGMP signaling. The observed biological effects could be attributed to its rich secondary metabolites. The specific mechanisms of the active ingredients of S. samarangense extract await further investigations.

Expatiating the Pharmacological and Nanotechnological Aspects of the Alkaloidal Drug Berberine: Current and Future Trends

Traditionally, herbal compounds have been the focus of scientific interest for the last several centuries, and continuous research into their medicinal potential is underway. Berberine (BBR) is an isoquinoline alkaloid extracted from plants that possess a broad array of medicinal properties, including anti-diarrheal, anti-fibrotic, antidiabetic, anti-inflammatory, anti-obesity, antihyperlipidemic, antihypertensive, antiarrhythmic, antidepressant, and anxiolytic effects, and is frequently utilized as a traditional Chinese medicine. BBR promotes metabolisms of glucose and lipids by activating adenosine monophosphate-activated protein kinase, stimulating glycolysis and inhibiting functions of mitochondria; all of these ameliorate type 2 diabetes mellitus. BBR has also been shown to have benefits in congestive heart failure, hypercholesterolemia, atherosclerosis, non-alcoholic fatty liver disease, Alzheimer’s disease, and polycystic ovary syndrome. BBR has been investigated as an interesting pharmacophore with the potential to contribute significantly to the research and development of novel therapeutic medicines for a variety of disorders. Despite its enormous therapeutic promise, the clinical application of this alkaloid was severely limited because of its unpleasant pharmacokinetic characteristics. Poor bioavailability, limited absorption, and poor water solubility are some of the obstacles that restricted its use. Nanotechnology has been suggested as a possible solution to these problems. The present review aims at recent updates on important therapeutic activities of BBR and different types of nanocarriers used for the delivery of BBR in different diseases.

A Novel Modulator of the Renin–Angiotensin System, Benzoylaconitine, Attenuates Hypertension by Targeting ACE/ACE2 in Enhancing Vasodilation and Alleviating Vascular Inflammation

The monoester alkaloids in Aconitum carmichaelii, including benzoylaconitine (BAC), benzoylmesaconine, and benzoylhypaconitine, were found to have anti-hypertensive effects in spontaneously hypertension rats (SHRs), of which BAC is the strongest. However, its antihypertensive target and underlying molecular mechanisms remain unclear. In this study, first, we screened the antihypertensive targets of BAC by using the CVDPlatform (www.cbligand.org/CVD) and found that ACE/ACE2 are the most possible targets. Then, we verified the effect of BAC on ACE/ACE2 by virtual docking, SPR, enzyme activity assay, and HUVECs cell experiment. We found that BAC could bind with ACE/ACE2, inhibit ACE activity and protein expression, and activate ACE2 enzyme activity. Using vascular function test in vitro, we found that BAC could target ACE/ACE2 to enhance endothelium-dependent vasorelaxation. In BAC-treated SHRs, the levels of ACE and AngII in serum were reduced while Ang (1–7) was increased significantly, and the expression of ACE was reduced, which suggested that BAC can inhibit ACE and activate ACE2 to inhibit AngI to AngII and promote AngII to Ang (1–7) to inhibit vasoconstriction and finally attenuate hypertension. Furthermore, the signaling pathways with regard to vasorelaxation and vascular inflammation were investigated. The results showed that BAC could significantly activate Akt/eNOS, increase NO production, and promote endothelial-related vasodilation; BAC could also reduce inflammatory factors TNF-α and IL6, inhibition of COX-2 expression, and IKB-α phosphorylation to reduce vascular inflammation in SHRs. In brief, BAC targets ACE/ACE2 to enhance endothelium-dependent vasorelaxation and reduce vascular inflammation to attenuate hypertension as a potential modulator of the renin–angiotensin system.

The Effects of Acute and Chronic Selective Phosphodiesterase 1 Inhibition on Smooth Muscle Cell-Associated Aging Features

Age-related cardiovascular diseases (CVDs) remain among the leading global causes of death, and vascular smooth muscle cell (VSMC) remodeling plays an essential role in its pathology. Reduced NO-cGMP pathway signaling is a major feature and pathogenic mechanism underlying vasodilator dysfunction. Recently, we identified phosphodiesterase (PDE) 1, an enzyme that hydrolyzes and inactivates the cyclic nucleotides cAMP and cGMP, and thereby provides a potential treatment target for restoring age-related vascular dysfunction due to aging of VSMC. Based on this hypothesis, we here tested the effects of PDE1 inhibition in a model of SMC-specific accelerated aging mice. SMC-KO and their WT littermates received either vehicle or the PDE1 inhibitor lenrispodun for 8 weeks. Vascular function was measured both in vivo (Laser Doppler technique) and ex vivo (organ bath). Moreover, we deployed UV irradiation in cell culture experiments to model accelerated aging in an in vitro situation. SMC-KO mice display a pronounced loss of vasodilator function in the isolated aorta, the cutaneous microvasculature, and mesenteric arteries. Ex vivo, in isolated vascular tissue, we found that PDE1 inhibition with lenrispodun improves vasodilation, while no improvement was observed in isolated aorta taken from mice after chronic treatment in vivo. However, during lenrispodun treatment in vivo, an enhanced microvascular response in association with upregulated cGMP levels was seen. Further, chronic lenrispodun treatment decreased TNF-α and IL-10 plasma levels while the elevated level of IL-6 in SMC-KO mice remained unchanged after treatment. PDE1 and senescence markers, p16 and p21, were increased in both SMC-KO aorta and cultured human VSMC in which DNA was damaged by ultraviolet irradiation. This increase was lowered by chronic lenrispodun. In contrast, lenrispodun increased the level of PDE1A in both situations. In conclusion, we demonstrated that PDE1 inhibition may be therapeutically useful in reversing aspects of age-related VSMC dysfunction by potentiating NO-cGMP signaling, preserving microvascular function, and decreasing senescence. Yet, after chronic treatment, the effects of PDE1 inhibition might be counteracted by the interplay between differential PDE1A and C expression. These results warrant further pharmacodynamic profiling of PDE enzyme regulation during chronic PDE1 inhibitor treatment.

Cumulative average nut consumption in relation to lower incidence of hypertension: a prospective cohort study of 10,347 adults

PURPOSE

Maintaining optimal blood pressure (BP) levels can be an effective preventive strategy for reducing disease burden. Nut consumption may play a preventive role against hypertension, which is a lifelong condition. We aimed to prospectively examine the association between cumulative average nut consumption and the incidence of hypertension in Korean adults aged 40 years and older.

METHODS

A total of 10,347 participants who were free of hypertension at baseline, were included. Hypertension was defined as having a physician diagnosis and taking antihypertensive medications or having abnormal BP (systolic ≥ 140 mmHg or diastolic ≥ 90 mmHg). As an exposure, cumulative average nut consumption was calculated using repeated food-frequency questionnaires (mean: 2.1). We used a modified Poisson regression model with a robust error estimator to estimate the incidence rate ratios (IRRs) with 95% confidence intervals (CIs) for hypertension.

RESULTS

We identified 2047 incident cases of hypertension during 44,614 person-years of follow-up. Among both men and women, an average nut consumption of ≥ 1 serving/week (15 g/week]) was inversely associated with hypertension incidence (IRR = 0.74, 95% CI = 0.58-0.96, p for trend = 0.013 for men; IRR = 0.72, 95% CI = 0.59-0.88, p for trend = 0.002 for women) and these significant associations were consistently observed across the strata of potential confounders.

CONCLUSION

An average consumption of at least one serving (15 g) per week of peanuts, almonds, and/or pine nuts may be inversely associated with the risk of hypertension among Korean adults aged 40 years and older, in a dose-response manner.

Vasodilatory Effect of Guanxinning Tablet on Rabbit Thoracic Aorta is Modulated by Both Endothelium-Dependent and -Independent Mechanism

Vasodilatory therapy plays an important role in the treatment of cardiovascular diseases, especially hypertension and coronary heart disease. Previous research found that Guanxinning tablet (GXNT), a traditional Chinese compound preparation composed of Salvia miltiorrhiza (Danshen) and Ligusticum chuanxiong (Chuanxiong), increase blood flow in the arteries, but whether vasodilation plays a role in this effect remains unclear. Here, we found that GXNT significantly alleviated the vasoconstriction of isolated rabbit thoracic aorta induced by phenylephrine (PE), norepinephrine (NE), and KCl in a dose-dependent manner with or without endothelial cells (ECs). Changes in calcium ion levels in vascular smooth muscle cells (VSMCs) showed that both intracellular calcium release and extracellular calcium influx through receptor-dependent calcium channel (ROC) declined with GXNT treatment. Experiments to examine potassium channels suggested that endothelium-denuded vessels were also regulated by calcium-activated potassium channels (K_ca) and ATP-related potassium channels (K_ATP) but not voltage-gated potassium channels (k_v) and inward rectifying potassium channels (K_IR). For endothelium-intact vessels, the nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) contents in vascular tissue obviously increased after GXNT treatment, and pretreatment with the NO synthase inhibitor Nw-nitro-L-arginine methyl ester (L-NAME) or guanylyl cyclase inhibitor methylthionine chloride (MB) significantly inhibited vasodilation. An assessment of NO-related pathway protein expression revealed that GXNT enhanced the expression of phosphorylated endothelial NO synthase (eNOS) in a dose-dependent manner but had no effect on total eNOS, p-Akt, Akt, or PI3K levels in human umbilical vein ECs (HUVECs). In addition to PI3K/AKT signaling, Ca²⁺/calmodulin (CaM)-Ca²⁺/CaM-dependent protein kinase II (CaMKII) signaling is a major signal transduction pathway involved in eNOS activation in ECs. Further results showed that free calcium ion levels were decreased in HUVECs with GXNT treatment, accompanied by an increase in p-CaMKII expression, implying an increase in the Ca²⁺/CaM-Ca²⁺/CaMKII cascade. Taken together, these findings suggest that the GXNT may have exerted their vasodilative effect by activating the endothelial CaMKII/eNOS signaling pathway in endothelium-intact rings and calcium-related ion channels in endothelium-denuded vessels.

Characterization of Fruit Development, Antioxidant Capacity, and Potential Vasoprotective Action of Peumo (Cryptocarya alba), a Native Fruit of Chile

The peumo (Cryptocarya alba) is a native fruit from central Chile that belongs to the Lauraceae family. To characterize the development and the potential health benefits of this edible fruit, quality and physiological parameters, along with antioxidant capacity, were evaluated during three clearly defined developmental stages of the fruit in two seasons. The most distinguishable attributes of ripe fruit were the change in size and color. Low CO₂ production and no detectable ethylene levels suggested non-climacteric behavior of the peumo fruit. Peumo demonstrate a significant increase in their antioxidant capacity per 1 g of fresh weight (FW) of the sample, from small to ripe fruit. Higher values in ripe fruit (FRAP: 37.1–38.3 µmol FeSO4/gFW, TEAC: 7.9–8.1 mmol TE/gFW, DPPH: 8.4-8.7 IC₅₀ μg/mL, and ORAC: = 0.19–0.20 mmol TE/gFW) were observed than those in blueberry fruit (FRAP: 4.95 µmol FeSO4/gFW, TEAC: 1.25 mmol TE/gFW, DPPH: 11.3 IC₅₀ μg/mL, and ORAC: 0.032 mmol TE/ gFW). The methanol extracts of ripe fruit displayed the presence of polyphenol acids and quercetin, an ORAC value of 0.637 ± 0.061 mmol TE per g dried weight (DW), and a high cellular antioxidant and anti-inflammatory potential, the latter exceeding the effect of quercetin and indomethacin used as standard molecules. Also, the assay of isolated rat aorta with endothelium-dependent relaxation damage demonstrated that the peumo extract induced vascular protection, depending on its concentration under a high glucose condition. These results demonstrate that these endemic fruits have a good chance as ingredients or foods with functional properties.

Ethyl Acetate Fraction from Leandra dasytricha (A. Gray) Cong. Leaves Promotes Vasodilatation and Reduces Blood Pressure in Normotensive and Hypertensive Rats

Leandra dasytricha (A. Gray) Cong. is widely distributed in the south of Brazil and is commonly used for cardiovascular and kidney ailments. For this study, we used male Wistar normotensive rats (NTRs) and spontaneously hypertensive rats (SHRs) to verify the effects of the ethyl acetate fraction (EAF) obtained from L. dasytricha leaves on isolated aorta relaxation and in the arterial blood pressure. The EAF was analyzed by LC-DAD-MS, and several components were annotated, including hydrolysable tannins, triterpenes, and O- and C-glycosylated dihydrochalcones, such as the most intense ion peak relative to C-hexosyl phloretin (nothofagin; compound number 13). The EAF caused a concentration and endothelium-dependent relaxation of the aorta in both NTRs and SHRs. This effect was abolished in the endothelium-denuded aorta. L-NAME, a nonselective nitric oxide synthase inhibitor, and ODQ, a soluble guanylate cyclase inhibitor, entirely blocked the EAF-induced relaxation. The presence of a muscarinic receptor antagonist or a cyclooxygenase inhibitor did not alter the EAF's effectiveness in relaxing the aorta. The preincubation with tetraethylammonium, a Ca²⁺-activated K⁺ channel blocker, and with 4-aminopyridine, a voltage-dependent K⁺ channel blocker, significantly interfered with the EAF's relaxation. However, the incubation with glibenclamide, an ATP-sensitive K⁺ channel blocker, and barium chloride, an inward-rectifier K⁺ channel blocker, did not interfere with the EAF-induced relaxation. The EAF treatment also caused a dose-dependent decrease in the mean arterial pressure, systolic arterial pressure, and diastolic arterial pressure of both NTRs and SHRs, without significantly interfering with heart rate values. In conclusion, this study demonstrated the EAF-induced vasorelaxant and hypotensive actions, primarily dependent on the endothelium function and mainly with the participation of the nitric oxide and Ca²⁺-activated and voltage-dependent K⁺ channels.

Key Characteristics of Cardiovascular Toxicants

BACKGROUND

The concept of chemical agents having properties that confer potential hazard called key characteristics (KCs) was first developed to identify carcinogenic hazards. Identification of KCs of cardiovascular (CV) toxicants could facilitate the systematic assessment of CV hazards and understanding of assay and data gaps associated with current approaches.

OBJECTIVES

We sought to develop a consensus-based synthesis of scientific evidence on the KCs of chemical and nonchemical agents known to cause CV toxicity along with methods to measure them.

METHODS

An expert working group was convened to discuss mechanisms associated with CV toxicity.

RESULTS

The group identified 12 KCs of CV toxicants, defined as exogenous agents that adversely interfere with function of the CV system. The KCs were organized into those primarily affecting cardiac tissue (numbers 1-4 below), the vascular system (5-7), or both (8-12), as follows: 1) impairs regulation of cardiac excitability, 2) impairs cardiac contractility and relaxation, 3) induces cardiomyocyte injury and death, 4) induces proliferation of valve stroma, 5) impacts endothelial and vascular function, 6) alters hemostasis, 7) causes dyslipidemia, 8) impairs mitochondrial function, 9) modifies autonomic nervous system activity, 10) induces oxidative stress, 11) causes inflammation, and 12) alters hormone signaling.

DISCUSSION

These 12 KCs can be used to help identify pharmaceuticals and environmental pollutants as CV toxicants, as well as to better understand the mechanistic underpinnings of their toxicity. For example, evidence exists that fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5)] air pollution, arsenic, anthracycline drugs, and other exogenous chemicals possess one or more of the described KCs. In conclusion, the KCs could be used to identify potential CV toxicants and to define a set of test methods to evaluate CV toxicity in a more comprehensive and standardized manner than current approaches. https://doi.org/10.1289/EHP9321.

Cardioprotective, hypotensive and toxicological studies of Populus ciliata (Wall. ex Royle)

Populus ciliata Wall ex. Royle has folkloric repute to treat various cardiovascular ailments and related disorders. The current study was designed to evaluate the toxic profile, cardioprotective and hypotensive effects of Populus ciliata (Wall. ex Royle). Populus ciliata crude ethanolic extract (Pc. Cr) and its aqueous (Pc. Aq) & organic (Pc. Dcm) fractions were tested on isolated aorta of rat and rabbit having intact and non-intact endothelium respectively. Pc. Cr & Pc. Aq relaxed the contractions induced by PE (1 µM)-induced and K⁺ (80 mM)-induced on aorta, possibly by mediating endothelium derived relaxing factor (EDRF) in intact endothelium and voltage dependent L-type calcium channels blocking (CCB) mechanism in non-intact endothelium. Pc. Cr showed anti-hypertensive & cardioprotective activity by decreasing force of contraction & heart rate on isolated rabbit paired atria and reduced blood pressure in anesthetized rat. Cardioprotective effect of Pc. Cr was assessed in isoproterenol induced acute myocardial infarction (AMI) and left ventricular hypertrophy (LVH) in Sprague Dawley rats. In LVH, Pc. Cr exerted positive effects by decreasing angiotensin II & renin and increasing cGMP & nitric oxide (NO) with reduced cardiac fibrosis, necrosis and cardiac cell size. In AMI, Pc. Cr responded effectively by decreasing cardiac markers creatinine kinase (CK), creatinine kinase myocardial band (CK-MB) and lactate dehydrogenase (LD) in blood associated with less edema and necrosis. Presence of catechin, vinallic acid, P-coumeric acid and quercitin identified through HPLC support the effectiveness of Pc. Cr in hypertension, AMI and LVH. Pc. Cr showed no significant adverse effects in Sprague Dawley albino rats after acute & sub-acute treatment in histopathological investigation. Extract of Populus ciliata showed vasorelaxant, hypotensive and cardioprotective effect in Sprague Dawley albino rats and white albino rabbit by mediating EDRF and voltage dependent L-type CCB mechanism respectively.

Study on the Effects of Kuanxiong Aerosol on the Isolated Artery and Rabbits Acute Myocardial Ischemia Model

BACKGROUND

Kuan xiong aerosol (KXA) is a kind of Chinese herbal compound used to regulating qi-flowing for relieving pain and improving angina. However, little pharmacological study of this traditional Chinese medicine preparation has been reported to confirm these activities.

OBJECTIVE

This article aims to observe the effect of resisting acute myocardial ischemia (AMI) in vivo and dilating vessel in vitro of KXA.

MATERIALS

The AMI model involves intravenously injecting pituitary (2 U.kg-1) into the ear of rabbits. Electrocardiograph (ECG) T waves were then recorded after administration and the falling range was calculated. Following this, the level of serum Cardiac troponin T (cTn-T) and the histopathology of the cardiac muscle tissue was evaluated. In vitro, the effect of KXA on vasodilation of isolated aortic rings that had been pre-contracted with KCl (30 mM) was observed.

RESULTS

It was found KXA reduced ECG ST-T waves and serum cTn-T in the rabbit AMI model, protected myocardial tissue from fracturing and loss of myocardial fibers, and inhibited inflammatory cell infiltration, cavitation degeneration and karyopyknosis of the myocardial matrix. Furthermore, the administration of 0.215, 1.075 and 2.150 mg.mL-1 KXA resulted in significant relaxation of the aortic rings at a rate of 69.63 %, 90.14 % and 118.72 % (p < 0.01) of the untreated ones, and a second shrinkage ratio of 20.17 %, 4.29 %, and 4.54 % (p < 0.01) of the untreated ones, respectively.

CONCLUSIONS

these results suggest KXA protects against AMI, contributes to dilation of blood vessels and has long-acting effectiveness.

Vasorelaxant property of Plectranthus vettiveroides root essential oil and its possible mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Plectranthus vettiveroides (Jacob) N.P. Singh & B.D. Sharma is a traditional medicinal plant used in Siddha System of Medicine and its aromatic root is used to reduce the elevated blood pressure.

AIM

The aim of the present study was to study vasorelaxant property of the root essential oil nanoemulsion (EON) of P. vettiveroides.

METHODS

The EON was formulated to enhance the solubility and bioavailability and characterized. The preliminary screening was performed by treating the EON with aortic rings pre-contracted with phenylephrine (1 μM) and potassium chloride (80 mM). The role of K⁺ channels in EON induced vasorelaxation was investigated by pre-incubating the aortic rings with different K⁺ channel inhibitors namely, glibenclamide (a non-specific ATP sensitive K⁺ channel blocker, 10 μM), TEA (a Ca2⁺ activated non-selective K⁺ channel blocker, 10-2 M), 4-AP (a voltage-activated K⁺ channel blocker, 10-3 M) and barium chloride (inward rectifier K⁺ channel blocker, 1 mM). The involvement of extracellular Ca2+ was performed by adding cumulative dose of extracellular calcium in the presence and absence of EON and the concentration-response curve (CRC) obtained is compared. Similarly, the role of nitric oxide synthase, muscarinic and prostacyclin receptors on EON induced vasorelaxation were evaluated by pre-incubating the aortic rings with their inhibitors and the CRC obtained in the presence and absence of inhibitor were compared.

RESULTS

The GC-MS and GC-FID analyses of the root essential oil revealed the presence of 62 volatile compounds. The EON exhibited significant vasorelaxant effect through nitric oxide-mediated pathway, G-protein coupled muscarinic (M3) receptor pathway, involvement of K+ channels (KATP, KIR, KCa), and blocking of the calcium influx by receptor-operated calcium channel.

CONCLUSION

It is concluded that the root essential oil of P. vettiveroides is possessing marked vasorelaxant property. The multiple mechanisms of action of the essential oil of P. vettiveroides make it a potential source of antihypertensive drug.

Synthesis and vasorelaxant evaluation of novel 7-methoxyl-2,3-disubstituted-quinoxaline derivatives

An array of novel 7-methoxyl-2,3-disubstituted quinoxaline derivatives was designed, synthesized and their potential antihypertensive activities were examined, in an attempt to discover potent small molecules with vasorelaxant effects. The vasoactivities of these compounds on vascular tone, as well as underlying mechanisms were hereby explored. Results showed that five compounds (7s, 7t, 7v, 7w, 7γ) could induce endothelium-independent relaxation in high extracellular K⁺- and phenylephrine-precontracted C57 mice aortic rings. These five compounds, unlike other commonly used vasodilators, could slowly but effectively inhibit vasoconstriction.

Secondary Metabolites of Plants as Modulators of Endothelium Functions

According to the World Health Organization, cardiovascular diseases are the main cause of death worldwide. They may be caused by various factors or combinations of factors. Frequently, endothelial dysfunction is involved in either development of the disorder or results from it. On the other hand, the endothelium may be disordered for other reasons, e.g., due to infection, such as COVID-19. The understanding of the role and significance of the endothelium in the body has changed significantly over time—from a simple physical barrier to a complex system encompassing local and systemic regulation of numerous processes in the body. Endothelium disorders may arise from impairment of one or more signaling pathways affecting dilator or constrictor activity, including nitric oxide–cyclic guanosine monophosphate activation, prostacyclin–cyclic adenosine monophosphate activation, phosphodiesterase inhibition, and potassium channel activation or intracellular calcium level inhibition. In this review, plants are summarized as sources of biologically active substances affecting the endothelium. This paper compares individual substances and mechanisms that are known to affect the endothelium, and which subsequently may cause the development of cardiovascular disorders.