Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.

Estrogen is known to induce rapid vasodilatory response in isolated arteries. Because estrogen is a nonselective receptor agonist, the involvement of estrogen receptor (ER) subtypes in acute estrogenic responses has remained elusive. Acute administration of the selective ER␣ agonist 4,4Ј,4Љ-(4-propyl-[ 1 H]pyrazole-1,3,5-triyl) tris-phenol (PPT) to precontracted aortic rings from intact female rats dose-dependently induced an ER-dependent vascular relaxation fully overlapping to that induced by 17␤-estradiol. By contrast, the selective ER␤ agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) had no acute effect on vasomotion. This short-term vasorelaxant action of PPT was abolished by the NO synthase inhibitor N -nitro-L-arginine methyl ester and by endothelium removal. In aortic tissues from ovariectomized (OVX) rats, however, neither 17␤-estradiol nor PPT induced acute vascular relaxation. The effect of PPT was restored in preparations from estrogen-replaced OVX rats, whereas DPN remained ineffective even after estrogen replacement. PPT acted through an ER-dependent mechanism, as shown by impaired response in the presence of the anti-estrogen ICI 182,780 (7␣,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol). Accordingly, isolated rat aortic endothelial cells expressed both ER␣ and ER␤. These data show that selective ER␣ but not ER␤ agonists reproduced the acute vasodilation of estrogen via a receptor-mediated pathway in the aorta from intact as well as 17␤-estradiolreplaced OVX rats. This beneficial effect was undetectable in tissues from OVX rats. Selective pharmacological targeting of ER subtypes may thus represent a novel and promising approach in the treatment of vascular disease.The vascular wall is clearly one of the target organs of estrogens. A number of studies have shown that estrogens modulate vasomotor responses after both acute application and in vivo short-or long-term treatment (for review, see Mendelsohn and Karas, 1999;Cignarella et al., 2001). Although different mechanisms have been reported (Shaw et al., 2001), such effects seem to be mediated by specific estrogen receptors (ERs) that are located on the plasma membrane as well as intracellularly. So far, two ER subtypes have been described: ER␣ and ER␤. Both subtypes are found in vascular smooth muscle (Register and Adams, 1998;Hodges et al., 2000;Maggi et al., 2003) and human endothelial cells (Caulin-Glaser et al., 1996). Although similar, the two ER isoforms are distinct gene products with nonoverlapping functions. They are coexpressed in most tissues but increasing evidence suggests that ER␣ and ER␤ mediate opposite effects in a kind of yin-yang manner (Gustafsson, 2003).The relative contribution of each ER subtype to vascular responses has been difficult to investigate because the physiological ER ligand 17␤-estradiol (E 2 ) has no binding affinity preference for ER␣ and ER␤. Selective ER agonists have now become available, the most widely used being 4,4Ј,4Љ-(4-propyl-[1 H]pyrazole-1,3,5-triyl) tris-phen...

Olvanil (N-9-Z-octadecenoyl-vanillamide) is an agonist of transient receptor potential vanilloid type 1 (TRPV1) channels that lack the pungency of capsaicin and was developed as an oral analgesic. Vanillamides are unmatched in terms of structural simplicity, straightforward synthesis, and safety compared with the more powerful TRPV1 agonists, like the structurally complex phorboid compound resiniferatoxin. We have modified the fatty acyl chain of olvanil to obtain ultra-potent analogs. The insertion of a hydroxyl group at C-12 yielded a compound named rinvanil, after ricinoleic acid, significantly less potent than olvanil (EC 50 ϭ 6 versus 0.7 nM), but more versatile in terms of structural modifications because of the presence of an additional functional group. Acetylation and phenylacetylation of rinvanil re-established and dramatically enhanced, respectively, its potency at hTRPV1. With a two-digit picomolar EC 50 (90 pM), phenylacetylrinvanil (PhAR, IDN5890) is the most potent vanillamide ever described with potency comparable with that of resiniferatoxin (EC 50 , 11 pM). Benzoyl-and phenylpropionylrinvanil were as potent and less potent than PhAR, respectively, whereas configurational inversion to ent-PhAR and cyclopropanation (but not hydrogenation or epoxidation) of the double bond were tolerated. Finally, iodination of the aromatic hydroxyl caused a dramatic switch in functional activity, generating compounds that behaved as TRPV1 antagonists rather than agonists. Since the potency of PhAR was maintained in rat dorsal root ganglion neurons and, particularly, in the rat urinary bladder, this compound was investigated in an in vivo rat model of urinary incontinence and proved as effective as resiniferatoxin at reducing bladder detrusor overactivity.The "transient receptor potential" (TRP) channels are characterized by six trans-membrane domains and by permeability to several cations, including Ca 2ϩ . Several members of this large family of plasma membrane channels function as sensors for physical stimuli such as temperature higher or lower than physiological, changes in osmotic pressure, and stretching. Of the vanilloid-type (TRPV) subfamily of TRP receptors (Gunthorpe et al., 2002), TRPV1 and TRPV4 respond to stimulation with natural products, with capsaicin and resiniferatoxin being the best known and most thoroughly studied natural TRPV1 agonists (Sterner and Szallasi, 1999) and 4␣-phorbols being capable of activating TRPV4 (Nilius et al., 2004). Another common feature of TRPV1 and TRPV4 is their capability of being gated by endogenous ligands, which are distinct arachidonate derivatives in both cases (Di Marzo et al., 2002a;Nilius et al., 2004). It is now recognized that TRPV1 functions as a molecular Article, publication date, and citation information can be found at

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Adenosine‐5′‐triphosphate (ATP) is known to exert a variety of biological effects via the activation of either ionotropic P2X‐ or G‐protein coupled P2Y‐purinoceptor subtypes. In this study the effects induced by ATP and ATP analogues on rat bladder strips were characterized at resting tone and in carbachol‐prestimulated tissues. ATP exerted a clear concentration‐dependent biphasic response, which was maximal at 1 mM concentration and was characterized by an immediate and transient contraction, followed by a slower sustained relaxation. The receptor mediating contraction was susceptible to desensitization by ATP and by the ATP analogue, α,β‐methyleneATP (α,β‐meATP) showing the typical features of the P2X‐purinoceptor; conversely, ATP‐evoked relaxation did not undergo tachyphylaxis following either ATP or α,β‐meATP. The slower and sustained relaxant phase seemed to be due to activation of P2Y‐purinoceptors, based on responses obtained with the P2Y agonist, 2‐methyl‐thioATP (2‐meSATP) and, more importantly, based on the clear involvement of the G‐proteins. In fact, the G‐protein activator, guanosine 5′‐O‐(3‐thiotriphosphate) (GTPγS) significantly potentiated and the G‐protein blocking agent, guanosine 5′‐O‐(2‐thio‐diphosphate) (GDPβS) completely abolished the ATP‐induced relaxation. No effects were exerted by these two G‐protein modulators on the ATP‐induced contraction. The relaxant component of the ATP response of bladder tissue was not significantly influenced by nitro‐benzyl‐thioinosine (NBTI) or by 8‐phenyltheophylline (8‐PT), suggesting that the contribution of the ATP metabolite adenosine to this response was negligible. Moreover, relaxation evoked by ATP and by the adenosine analogue, 5′‐N‐ethylcarboxamidoadenosine (NECA) was additive. Suramin was unable to modify either the relaxant or the contractile responses of bladder strips to ATP. However, when tested on the concentration‐response curve to the slowly hydrolysable P2x‐agonist α,β‐meATP, a rightward shift was detected, suggesting that ATP contractile responses are mediated by suramine‐sensitive P2x‐purinoceptors. Uridine‐5′‐triphosphate (UTP) only induced a rapid and concentration‐dependent contraction of the rat bladder preparation, which was not desensitized by pre‐exposure to α,β‐meATP, suggesting that UTP responses were not mediated by the ‘classical’ P2X‐purinoceptor. It is therefore concluded that both P2X‐ and P2Y‐purinoceptors, which mediate ATP‐induced contraction and relaxation, respectively, are present in rat bladder. Moreover, removal of epithelium did not affect ATP‐elicited contraction, whereas ATP‐induced relaxation was significantly augmented. These data suggest that P2x‐ and P2y‐ purinoceptors are localized in smooth muscle cells and that the relaxant response is probably modulated by excitatory factor(s) released by epithelial cells.

Abstract-The vascular consequences of estrogen treatment may be driven by its initiation timing. We tested the hypothesis that the duration of ovarian hormone deprivation before estrogen reintroduction affects the role of estrogen as mediator of endothelial function and vascular relaxation in nondiseased vessels. Rats were ovariectomized and implanted with 17␤-estradiol (E 2 ) or oil capsules 1, 4, and 8 months after surgery. After the longest hypoestrogenicity period, acetylcholine-mediated aortic relaxation was attenuated and insensitive to E 2 administration despite endothelial integrity. Whereas no rapid vasorelaxant responses were elicited by an estrogen receptor (ER) ␤-selective agonist, responses to E 2 and an ER␣ selective agonist waned postovariectomy at any given time and were restored by E 2 treatment after 1 and 4 months but not 8 months postovariectomy. Accordingly, endothelial ER␣ mRNA and protein expression declined Ϸ6-fold after prolonged hypoestrogenicity and was restored by estrogen replacement starting 1 month but not 8 months postovariectomy. Furthermore, the amount of active phosphorylated endothelial NO synthase rose significantly after E 2 replacement after 1 and 4 months but not 8 months postovariectomy. The present findings document that the functional impairment of the ER␣/endothelial NO synthase signaling network after an extended period of hypoestrogenicity was not restored by E 2 administration, providing experimental support to early initiation of estrogen replacement with preferential ER␣ targeting to improve cardiovascular outcomes. Key Words: endothelium Ⅲ hormones Ⅲ pharmacology Ⅲ NO synthase Ⅲ receptors I n spite of a large body of preclinical studies attesting beneficial actions of estrogenic treatment on the cardiovascular system, large clinical trials of hormone therapy so far have failed to improve clinical outcomes (reviewed in Reference 1). In attempting to explain the apparent discrepancy between experimental and clinical results, the timing of treatment initiation has been deemed a critical factor. The timing hypothesis proposes that the earlier an estrogenic treatment starts, the more likely it is of being successful, because the time since menopause is a major risk factor for the development and progression of atherosclerosis. 2,3 This is consistent with observations that cyclic or permanent changes in circulating concentrations of estrogen in premenopausal and postmenopausal women, respectively, affect vascular responses. 4,5 Of note, estrogen deprivation in rats time-dependently impairs endothelial function, as assessed by the loss of acetylcholine-mediated dilation, but this response is restored by early 17␤-estradiol (E 2 ) replacement. 6 In addition, estrogen affects endothelial vasomotor responses per se. We demonstrated previously that ovariectomy abolishes acute estrogen dilation, which is restored by timely E 2 replacement. 7 Thus, vascular relaxation is a primary target of estrogen action in the vessel wall. This is known to occur through rapid stimulation o...

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Background-Previous reports from our group have shown that 17␤-estradiol reduces the synthesis and activity of inducible nitric oxide synthase (iNOS) in rat aortic smooth muscle cells (SMC) in response to inflammatory mediators. In this study, we investigated the effect of 17␤-estradiol on iNOS function in aortic SMC from streptozotocin-diabetic rats. Methods and Results-Comparative analysis of NO release and of iNOS mRNA and protein content after 24-hour stimulation with a cytokine mixture revealed milder iNOS activation in diabetic than in control SMC. Furthermore, 17␤-estradiol dose-dependently blocked iNOS synthesis and activity in control but not in diabetic SMC. The defective estrogen response in diabetic SMC at 24 hours could not be attributed to reduced expression of estrogen receptors (ER). In fact, mRNA and protein levels of ER␣ and, to a greater extent, of ER␤, were increased in diabetic compared with nondiabetic SMC. Cytokines decreased ER␣ and ER␤ expression in both groups. However, 17␤-estradiol dosedependently restored the expression of ER␣ but further downregulated that of ER␤, indicating a differential regulation of ER isoforms. Conclusions-Estrogenic control of iNOS was impaired in diabetic SMC. This was associated with a larger increase of ER␤ than of ER␣ protein, whereas 17␤-estradiol regulated the two isoforms in an opposite fashion. Thus, modifications in the estrogen modulation of iNOS and in the expression pattern of ER may be involved in diabetic vascular dysfunction. (Circulation. 2003;108:211-217.)