Rat Aortic Strips Research Articles

Comparative Study of Different H2S Donors as Vasodilators and Attenuators of Superoxide-Induced Endothelial Damage.

In the last years, research proofs have confirmed that hydrogen sulfide (H2S) plays an important role in various physio-pathological processes, such as oxidation, inflammation, neurophysiology, and cardiovascular protection; in particular, the protective effects of H2S in cardiovascular diseases were demonstrated. The interest in H2S-donating molecules as tools for biological and pharmacological studies has grown, together with the understanding of H2S importance. Here we performed a comparative study of a series of H2S donor molecules with different chemical scaffolds and H2S release mechanisms. The compounds were tested in human serum for their stability and ability to generate H2S. Their vasorelaxant properties were studied on rat aorta strips, and the capacity of the selected compounds to protect NO-dependent endothelium reactivity in an acute oxidative stress model was tested. H2S donors showed different H2S-releasing kinetic and produced amounts and vasodilating profiles; in particular, compound 6 was able to attenuate the dysfunction of relaxation induced by pyrogallol exposure, showing endothelial protective effects. These results may represent a useful basis for the rational development of promising H2S-releasing agents also conjugated with other pharmacophores.

Effects of Sanoshashinto on left ventricular hypertrophy and gut microbiota in spontaneously hypertensive rats.

In our previous study, we found that the methanolic extract of Sanoshashinto () (SHXXTM) exhibited significant vasorelaxant effects in vitro and antihypertensive effects in vivo, and baicalin and berberine were the main antihypertensive constituents in SHXXTM. We also speculated that the baicalin-berberine (BB) combination produced vasorelaxant effects by activating the NO/cGMP pathway, and the BKCa channel and the DAG/PKC/CPI-17 pathway were involved. In this study, we examined the vasorelaxant effects using helical strips of rat aorta pretreated with different activators or inhibitors. The results suggested that the KATP channel and the voltage-dependent Ca2+ channel (VDCC) were also involved in the vasorelaxant effects. Furthermore, we found that SHXXTM and the BB combination reduced left ventricular hypertrophy and altered gut microbiota. Together, the results indicated that Sanoshashinto might have comprehensive effects on ameliorating hypertension.

Effects of ticagrelor, empagliflozin and tamoxifen against experimentally-induced vascular reactivity defects in rats in vivo and in vitro.

In the current investigation, the effects of the P2Y12 blocker ticagrelor, the sodium/glucose transporter-2-inhibitor empagliflozin, and the selective estrogen receptor modulator tamoxifen were examined against rheumatoid arthritis (RA)/diabetes mellitus (DM)-co-morbidity-induced defects in vascular reactivity. After model setting, rats were allocated into a normal control, an RA/DM-co-morbidity, and three treatment groups receiving ticagrelor, empagliflozin and tamoxifen. Aorta tissue was isolated for enzyme-linked immunosorbent assay (ELISA) and western blot estimation of the pro-inflammatory molecules angiotensin-II (Ang-II) and endothelin-1 (ET-1), the adhesion molecules P-selectin and vascular cell adhesion molecule-1 (VCAM-1), the energy preserving molecule adenosine-5'-monophosphate-activated protein kinase (AMPK), and the anti-inflammatory molecule vasoactive intestinal peptide (VIP). Estimations of endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 were performed immunohistochemically, together with histopathological examination using hematoxylin and eosin and Masson trichrome staining. An in vitro study on rat aortic strips was conducted to assess aorta vasorelaxation. Ticagrelor, empagliflozin and tamoxifen significantly increased aorta tissue AMPK and eNOS and decreased Ang-II, ET-1, P-selectin, VCAM-1 and VIP levels compared with RA/DM-co-morbidity, coupled with improved acetylcholine vasorelaxation in vitro. Ticagrelor, empagliflozin and tamoxifen may correct vascular reactivity defects, where modulation of vascular AMPK, eNOS, Ang-II, ET-1, P-selectin, VCAM-1 and MMP-2 underline their protective effects.

Gem-Dinitroalkyl Benzenes: A Novel Class of IOP-Lowering Agents for the Treatment of Ocular Hypertension.

Primary open angle glaucoma is the second most common cause of blindness worldwide. Nitric oxide has recently received particular attention as a potential antiglaucoma agent. In this work, gem-dinitroalkyl benzenes are evaluated for their capability to act as a new class of IOP lowering agents. These derivatives have been endowed with a variety of NO-release capacities and found to relax contracted rat aorta strips in a concentration-dependent manner. They have been studied for their IOP-lowering activity in a transient ocular hypertensive rabbit model at 1% dose. The most effective IOP-lowering products were compounds 9-11 and 13, whose activity was similar to that of Molsidomine 120 min after administration. Compounds 9 and 13 were selected for evaluation using carbomer-induced glaucoma as the chronic model of IOP. They cause a significant reduction in IOP in the first 24 h, and their activity is maintained over 5 days, displaying a Molsidomine-like profile.

Pharmacological basis for the medicinal use of polyherbal formulation and its ingredients in cardiovascular disorders using rodents

BackgroundA compound herbal formulation (POL4) has been used in the indigenous system of medicine to treat cardiometabolic disorders like diabetes and associated hypertension. POL4 and most of its constituents have not been studied widely for its therapeutic use in hypertension. This study is aimed to determine the efficacy and possible insight into mechanism(s) for the medicinal use of POL4 and its ingredients in hypertension.MethodsThe aqueous methanolic extracts of POL4 (POL4.Cr) and its components [Cichorium intybus (Ci.Cr), Gymnema sylvestre (Gs.Cr), Nigella sativa (Ns.Cr) and Trigonella foenum graecum (Tfg.Cr)] were tested for blood pressure lowering activity in anaesthetized Sprague-Dawley rats. To assess the vasomodulatory effect, isolated tissue experiments were performed on rat aortic strips using isometric force transducer coupled with PowerLab data acquisition system.ResultsAdministration of POL4 to rats caused a dose-dependent (1–100 mg/kg) fall in mean arterial pressure (MAP) with maximum effect of 85.33 ± 1.76% at 100 mg/kg, similar to the effect of verapamil. All ingredients of POL4 also decreased blood pressure with varying efficacy in following order Ns.Cr ≅ Ci.Cr > Tfg.Cr > Gs.Cr. In rat aortic preparations, POL4 and its ingredients inhibited K+ (80 mM)-induced contractions, Ci.Cr was the most potent followed by Ns.Cr > Tfg.Cr > Gs.Cr ≅ POL4. Against phenylephrine (P.E) contractions, Ci.Cr and Tfg.Cr exhibited complete relaxation, while POL4.Cr, Gs.Cr and Ns.Cr showed vasomodulatory effect. The Ca++ antagonist activity was confirmed when POL4 and its ingredients shifted Ca++ concentrations-response curves to the right in a manner similar to that of verapamil. On baseline of rat aorta, the parent formulation and its ingredients (except Tfg.Cr) exhibited partially phentolamine (1 μM)-sensitive vasoconstriction.ConclusionThese data show that POL4 and its constituents possess blood pressure lowering activity mediated through inhibition of Ca++ influx via membranous Ca++ channels and receptor (α-adrenergic) operated pathways. Thus, this study provides a rationale to the medicinal use of POL4 and its constituents in hypertension.

Protective effects of MCR-1329, a dual α1 and angII receptor antagonist, in mineralocorticoid-induced hypertension.

With the prototypical structures of losartan and prazosin as the axis of our research, MCR-1329 emerged as a potential designed multiple ligand from a series of compounds designed to possess dual antagonistic activity on the α1 and AT1 receptor. After confirming the activity of MCR-1329 in in vitro and acute in vivo models, the present study was undertaken to determine the efficacy of MCR-1329 in a mammalian test system. A rat model of deoxycorticosterone acetate (DOCA)-salt induced renal hypertension following unilateral nephrectomy was utilized to determine the effect of MCR-1329. For mechanistic evaluations, MCR-1329 was evaluated on rat aortic strips in vitro and on rat aortic smooth muscle cells to determine the role of MCR-1329 on phosphoinositide 3 kinase (PI3K) signaling. Results of the study showed that MCR-1329 prevents development of arterial hypertension. It was also observed that MCR-1329 upheld the intimal structures of major arteries like the thoracic aorta. Acetylcholine (Ach)-mediated relaxation remained intact in arteries from MCR-1329 treated animals. It was observed that MCR-1329 partially prevents Thr-308 phosphorylation of Akt following ligand-mediated receptor stimulation in vascular smooth muscle cells. Addition of LY294002 to the reaction medium caused a near-complete inhibition of Akt-phosphorylation. This suggested that MCR-1329 elicits its antihypertensive role by blocking activation of receptor-mediated PI3K-Akt downstream signaling as well as through preservation of arterial integrity. MCR-1329 has the potential to be evaluated further for clinical development as a potential antihypertensive agent with multiple mechanisms of action.

NO-Donor Dihydroartemisinin Derivatives as Multitarget Agents for the Treatment of Cerebral Malaria.

Hybrid products in which the dihydroartemisinin scaffold is combined with NO-donor furoxan and NONOate moieties have been synthesized and studied as potential tools for the treatment of cerebral malaria (CM). The designed products were able to dilate rat aorta strips precontracted with phenylephrine with a NO-dependent mechanism. All hybrid compounds showed preserved antiplasmodial activity in vitro and in vivo against Plasmodium berghei ANKA, comparable to artesunate and artemether. Hybrid 10, selected for additional studies, was capable of increasing survival of mice with late-stage CM from 27.5% to 51.6% compared with artemether. Artemisinin-NO-donor hybrid compounds show promise as potential new drugs for treating cerebral malaria.

New organic nitrate-containing benzyloxy isonipecotanilide derivatives with vasodilatory and anti-platelet activity

A number of new nitric oxide (NO)-precursors were synthesized by grafting nitrate-containing moieties on the structures of the benzyloxy isonipecotanilide derivatives 1 and 2 already reported as moderately potent antiplatelet agents. Various nitrooxy (ONO2)-alkyl side chains were covalently linked to the piperidine nitrogen of the parent compounds through carbamate and amide linkage, and the synthesis of a benzyl nitrate analog (15) of compound 1 was also achieved. The in vitro vasodilatory activities, as well as platelet anti-aggregatory effects, of the newly synthesized organic nitrates were assessed. The (ONO2)methyl carbamate-based derivative 5a and the benzyl nitrate analog 15, which on the other hand retain activity as inhibitors of ADP-induced platelet aggregation, exhibited strong NO-mediated vasodilatory effects on pre-contracted rat aorta strips, with EC50 values in the low nanomolar range (13 and 29nM, respectively). Experiments carried out with the selectively inhibited soluble guanylate cyclase (sGC), which is the key enzyme of the NO-mediated pathway leading to vascular smooth muscle relaxation, confirmed the involvement of NO in the observed vasodilation. The nitrate derivatives proved to be stable in acidic aqueous solution and at pH 7.4. In human serum, unlike 5a, which showed not to undergo enzyme-catalyzed decomposition, the other tested (ONO2)-alkyl carbamate-based compounds (5b and 5e) and benzyl nitrate 15 underwent a faster degradation. However, their decomposition rates in serum were quite slow (t½>2.6h), which suggests that nitrate moiety is poorly metabolized in blood plasma and that much of the in vitro anti-platelet activity has to be attributed to the intact (ONO2)-containing molecules.

Design, synthesis and pharmacological evaluation of novel NO-releasing benzimidazole hybrids as potential antihypertensive candidate.

Two series of novel NO-releasing benzimidazole derivatives (8a-e, 9a-g) were designed and synthesized by coupling nitro ester and furoxan NO-donor moieties with benzimidazole biphenyl skeleton. The NO-releasing assay indicated that all the target compounds had different level of NO-releasing ability. Furthermore, the isolated organ assay (rat aortic strips) was used to evaluate the antagonism of Ang II-induced vasoconstriction ability. It was observed that the pA2 values of compounds 8e and 9e were better than that of lead compound 6. Moreover, the pharmacological investigation showed that the antagonism of Ang II-induced pressure response by oral administration of compound 8e was obviously superior to that of lead compound 6, and comparable to that of the positive control losartan. These results suggested that NO-releasing hybrids may provide a promising approach for the discovery of novel antihypertensive agents.

Design, Synthesis and Calcium Channel Blocking Activity of Diltiazem- Verapamil Hybrid Molecules

The current manuscript describes the design, synthesis, and in vitro testing of four thioacetanilides with diltiazemverapamil hybrid structural features as potential calcium channel blockers. The current hybrid strategy of drug design aimed to generate compounds that could span, with a single compound, the trans-membrane locales where the two drugs bind, with the ultimate goal of increasing the blocking activity. The latter, was assessed by measuring the inhibitory effects, expressed as IC50, on calcium-induced contractions of potassium depolarized isolated rat aorta strips. The assessment of the binding locales was determined by incubating the test compound with aortic strips for two different periods, 10-minutes and 2-hours, before adding the contractile calcium ions to the assay medium. Diltiazem IC50 values were 0.26 and 0.14 μM, after 10-minutes and 2-hours, respectively, reflecting less than two fold increase in activity and confirming previous reports that its locale of binding in mostly on the exterior side of the membrane. On the other hand, verapamil IC50 values were 0.47 and 0.14 μM after 10-minutes and 2-hour incubation respectively, reflecting approximately a 3-4 fold increase in activity and confirming previous reports that it binds mainly to the interior domains of the membrane. The four designed hybrid compounds showed, after 10-minute incubation, an IC50 value range of 3.7-12.0 μM, and after 2-hour incubation an IC50 range of 0.78-2.12 μM, reflecting approximately a 5-fold increase in activity suggesting more similarity to the verapamil binding profile. The data indicate that the designed compounds are with moderate activities, but generally less active as calcium channel blockers than either of the two parent drugs.

An NO donor approach to neuroprotective and procognitive estrogen therapy overcomes loss of NO synthase function and potentially thrombotic risk.

Selective estrogen receptor modulators (SERMs) are effective therapeutics that preserve favorable actions of estrogens on bone and act as antiestrogens in breast tissue, decreasing the risk of vertebral fractures and breast cancer, but their potential in neuroprotective and procognitive therapy is limited by: 1) an increased lifetime risk of thrombotic events; and 2) an attenuated response to estrogens with age, sometimes linked to endothelial nitric oxide synthase (eNOS) dysfunction. Herein, three 3rd generation SERMs with similar high affinity for estrogen receptors (ERα, ERβ) were studied: desmethylarzoxifene (DMA), FDMA, and a novel NO-donating SERM (NO-DMA). Neuroprotection was studied in primary rat neurons exposed to oxygen glucose deprivation; reversal of cholinergic cognitive deficit was studied in mice in a behavioral model of memory; long term potentiation (LTP), underlying cognition, was measured in hippocampal slices from older 3×Tg Alzheimer's transgenic mice; vasodilation was measured in rat aortic strips; and anticoagulant activity was compared. Pharmacologic blockade of GPR30 and NOS; denudation of endothelium; measurement of NO; and genetic knockout of eNOS were used to probe mechanism. Comparison of the three chemical probes indicates key roles for GPR30 and eNOS in mediating therapeutic activity. Procognitive, vasodilator and anticoagulant activities of DMA were found to be eNOS dependent, while neuroprotection and restoration of LTP were both shown to be dependent upon GPR30, a G-protein coupled receptor mediating estrogenic function. Finally, the observation that an NO-SERM shows enhanced vasodilation and anticoagulant activity, while retaining the positive attributes of SERMs even in the presence of NOS dysfunction, indicates a potential therapeutic approach without the increased risk of thrombotic events.

Design and synthesis of 6,7-dimethoxyquinazoline analogs as multi-targeted ligands for α1- and AII-receptors antagonism

Multiple-targeted ligands can have certain advantages for the management of hypertension which has multiple controls. Molecules with dual bioactivities are available in literature for treating metabolic disorders like diabetes, hypertension and hypercholesterolemia. After scrutinizing the SAR of prazosin-type α1-blockers and AII-antagonists it was planned to develop dual α1- and AII-antagonists. Five series of quinazoline derivatives were synthesized and evaluated as dual α1- and AII-antagonists on rat aortic strips for the blockade of known α1- and AII-agonist mediated contractions. Many compounds showed balanced activity on both the receptors but compound (22) was found to be the most active derivative having higher antagonistic activity on both the receptors. In the in vivo experiments the chosen compound (22) was slightly less active than prazosin but was found to be equipotent to losartan. These findings shed a new light on the structural requirements for both α1- as well as AII-receptor antagonists.

Association between bone mineral density and VDR and IGF-1 gene polymorphisms in patients with congenital adrenal hyperplasia treated with glucocorticoids

Association between bone mineral density and VDR and IGF-1 gene polymorphisms in patients with congenital adrenal hyperplasia treated with glucocorticoids

Androgen regulations of cellular events involve in bone perfusion

Androgen regulations of cellular events involve in bone perfusion

203 INFLUENCE OF SELF-FERMENTED PINE NEEDLE FRACTIONS ON CATECHOLAMINE RELEASE FROM THE RAT ADRENAL MEDULLA

Previously, we have found that self-fermented pine needle (Pinus densiflora) extract inhibits secretion of catecholamines (CA) from the perfused rat adrenal medulla (Shin & Lim, 2010), and also the contractile responses of isolated rat aortic strips induced by phenylephrine and high K+ (Yu et al., 2009). Therefore, the aim of the present study was to investigate the effects of several fractions obtained from methylene chloride (CH2Cl2) extract of self-fermented pine needle on the acetylcholine (ACh)-evoked CA release from the isolated perfused model of the rat adrenal medulla and to establish the mechanism of the most active fraction (Fr.)-induced inhibitory action on the CA release. We obtained 6 fractions from CH2Cl2 extract of self-fermented pine needle. For the ACh (5.32 mM)-evoked CA release, the following rank order of inhibitory potency was obtained: Fr.4>Fr.8-11>>Fr.3>Fr.6=Fr.7>Fr.1.2. Fr.4 (60 μg/mL) perfused into an adrenal vein for 90 min produced relatively time-dependent inhibition of the CA secretory responses to ACh (5.32 mM), high K+ (56 mM), DMPP (100 μM) and McN-A-343 (100 μM). Fr.4 itself did not affect basal CA secretion (data not shown). Also, in the presence of Fr.4 (60 μg/mL), the CA secretory responses to angiotensin II (AngII, 0.1 μM), veratridine (a selective Na+ channel activator, 10 μM), Bay-K-8644 (a L-type dihydropyridine Ca2+ channel activator, 10 μM), and cyclopiazonic acid (a cytoplasmic Ca2+-ATPase inhibitor, 10 μM) were significantly reduced, respectively. In the simultaneous presence of Fr.4 (60 μg/mL) and L-NAME (an inhibitor of NO synthase, 30 μM), the inhibitory responses of Fr.4 on the CA secretion evoked by ACh, high K+, DMPP, McN-A-343, Bay-K-8644, cyclopiazonic acid, AngII and veratridine were considerably recovered to the extent of the corresponding control secretion compared with that of Fr.4-treatment alone. The level of NO released from adrenal medulla after the treatment of Fr.4 (60 μg/mL) was greatly elevated compared with the basal level. Taken together, these results demonstrate that Fr.4 inhibits the CA secretion from the isolated perfused rat adrenal medulla evoked by stimulation of cholinergic receptors as well as by direct membrane-depolarization. It seems that this inhibitory effect of Fr.4 is mediated by blocking the influx of Ca2+ and Na+ into the adrenomedullary chromaffin cells as well as by inhibition of Ca2+ release from the cytoplasmic calcium store, which is evoked at least partly through the increased NO production due to the activation of NO synthase. Based on these results, it is also thought that Fr. 4 isolated from CH2Cl2 extract of pine needle may contain beneficial antihypertensive components to prevent or treat hypertension.

Carnosine analogues containing NO-donor substructures: Synthesis, physico-chemical characterization and preliminary pharmacological profile

The synthesis, physico-chemical, and biological characterisation of a short series of carnosine amides bearing NO-donor nitrooxy functionalities are described. The NO-donor carnosine analogues and their des-NO derivatives display carnosine-like properties, differing from the lead for their high serum stability. The newly-synthesised compounds are able to complex Cu2+ ions at physiological pH, displaying significant copper ion sequestering ability, and protect LDL from oxidation catalysed by Cu2+ ions. All products show moderately-potent HNE quenching activity. The NO-donor compounds 7c–f relaxed rat aorta strips via an NO-dependent mechanism. In vivo evaluation of organ protection in a model of cerebral ischaemia/reperfusion injury, using the selected NO-donor 7e and its des-NO analogue 7a, showed that both derivatives protect from hypoxia-induced brain damage, at lower concentrations than carnosine; 7e also decreased serum TNF-α levels. This class of NO-donor carnosine amides is worthy of further study as potential tools for treating a wide range of chronic vascular and neurodegenerative diseases in which NO-bioavailability is reduced.

Testosterone modulates platelet aggregation and endothelial cell growth through nitric oxide pathway

The aim of the present study was to investigate the effect of testosterone on the modulation of cellular events associated with vascular homeostasis. In rat aortic strips, 5-20 min treatment with physiological concentrations of testosterone significantly increased nitric oxide (NO) production. The rapid action of the steroid was suppressed by the presence of an androgen receptor antagonist (flutamide). We obtained evidence that the enhancement in NO synthesis was dependent on the influx of calcium from extracellular medium, because in the presence of a calcium channel blocker (verapamil) the effect of testosterone was reduced. Using endothelial cell (EC) cultures, we demonstrated that androgen directly acts at the endothelial level. Chelerythrine or PD98059 compound completely suppressed the increase in NO production, suggesting that the mechanism of action of the steroid involves protein kinase C and mitogen-activated protein kinase pathways. It is known that endothelial NO released into the vascular lumen serves as an inhibitor of platelet activation and aggregation. We showed that testosterone inhibited platelet aggregation and this effect was dependent on endothelial NO synthesis. Indeed, the enhancement of NO production elicited by androgen was associated with EC growth. The steroid significantly increased DNA synthesis after 24 h of treatment, and this mitogenic action was blunted in the presence of NO synthase inhibitor N-nitro-l-arginine methyl ester. In summary, testosterone modulates vascular EC growth and platelet aggregation through its direct action on endothelial NO production.

Revelation on the potency of α1 -blockers – parallel blockade of angiotensin II receptor: A new finding

Context: The problem of hypertension has gained enormous proportions in the past decade. Multifactorial etiology and complex pathophysiology of the disease has rendered the treatment of the disease a hard task. Sympathetic nervous system and the renin–angiotensin–aldosterone system are primary contributors of blood pressure homeostasis.Objective: Structural similarities were identified among AT1 and α1-antagonists, initiating a speculation that α1-antagonists could possibly block the AT1 receptor and vice-versa.Methods: To corroborate this speculation, we screened prototypical α1-antagonists such as prazosin, doxazosin, and terazosin for antagonism of angiotensin II on rat aortic strips. We also examined the AT1 antagonists losartan, valsartan, and olmesartan for their possible antagonistic effect, on contractions of rat aortic strips induced by phenylephrine.Results: To our astonishment, we found that prazosin and its analogs which have been reported to have α1-antagonistic activity only, were able to shift concentration response curves of angiotensin II.Conclusion: Our findings suggest that the potent antihypertensive effect of prazosin-type α1-antagonists is not purely due to α1-receptor blocking activity of these compounds but also due to blockade of AT1 receptors. This finding may lead to the development of more potent dual inhibitors which would prove to be of immense value in the control of the scourge of hypertension.

Searching for new NO-donor aspirin-like molecules: Furoxanylacyl derivatives of salicylic acid and related furazans

A new group of derivatives of salicylic acid containing NO-donor furoxans, and the related des-NO-furazans, were synthesized and evaluated as new aspirin-like molecules. Their stability was assessed in acid (pH 1) and physiological solutions (pH 7.4), and in human serum. No compound exhibited COX-inhibitory activity against COX-1 and COX-2 isoforms, when tested up to 100 μM, respectively, on isolated platelets and on monocytes. Phenylsulfonyl- and cyano-substituted furoxans inhibited platelet aggregation induced by collagen in human platelet-rich plasma, through a cGMP dependent mechanism. Furoxan derivatives displayed cGMP-dependent vasodilator activities, tested on rat aorta strips precontracted with phenylephrine. All products showed anti-inflammatory activity similar to that of ASA, tested on rats by the carrageenan-induced paw edema assay. Unlike ASA, all products showed markedly reduced gastrotoxicity in a rat lesion model.

New Nitric Oxide or Hydrogen Sulfide Releasing Aspirins

A new series of (((R-oxy)carbonyl)oxy)methyl esters of aspirin (ASA), bearing nitric oxide (NO) or hydrogen sulfide (H(2)S) releasing groups, was synthesized, and the compounds were evaluated as new ASA co-drugs. All the products were quite stable in buffered solution at pH 1 and 7.4. Conversely, they were all rapidly metabolized, producing ASA and the NO/H(2)S releasing moiety used for their preparation. Consequent on ASA release, the compounds were capable of inhibiting collagen-induced platelet aggregation of human platelet-rich plasma (PRP). The simple NO/H(2)S donor substructures were able to relax contracted rat aorta strips, with a NO- and H(2)S-dependent mechanism, respectively, but they either did not trigger antiaggregatory activity or displayed antiplatelet potency markedly below that of the related co-drug. The new products might provide a safer and improved alternative to the use of ASA principally in its anti-inflammatory and antithrombotic applications.