Polymorphisms of platelet ADP receptor P2RY12 in the risk of venous thromboembolism in the Korean population.

Although it was thought that platelets did not play a significant role in the pathogenesis of venous thromboembolism (VTE), several studies demonstrated that a marked activation of platelets occurs in patients with VTE. We carried out a case-control study to investigate the effect of the T744C P2RY12 polymorphism on the risk of VTE in the Korean population. We enrolled 154 consecutive patients with VTE and 415 healthy controls. Genotype frequencies for patients with TT, TC, and CC were 71.4%, 24.7%, and 3.9% and in the controls, 68.2%, 30.1%, and 1.7%, respectively. T744C P2RY12 polymorphism did not significantly affect the risk of VTE. Our study shows that T744C P2RY12 polymorphism did not significantly affect the risk of VTE in the Korean population.

Wnt5a potentiates U46619-induced platelet aggregation via the PI3K/Akt pathway.

Platelet aggregation plays crucial roles in the formation of hemostatic plugs and thrombosis. Although it was recently shown that canonical Wnt signaling negatively regulates platelet aggregation, the role of non-canonical Wnt signaling remains unknown. Here, we observed that Wnt5a, one of the non-canonical Wnts, positively regulated platelet aggregation. Platelet aggregation was potentiated by the addition of Wnt5a to collagen-or U46619-induced rat platelet rich plasma (PRP). Treatment with Wnt5a to U46619-stimulated PRP resulted in an increase in the level of phosphorylated Akt, whereas phosphorylation of PKCδ and JNK1 was unaffected. In addition, inhibition of PI3K blocked the potentiating effect of Wnt5a. Taken together, these results suggest that Wnt5a potentiates U46619-induced platelet aggregation via the PI3K/Akt pathway.

PKC inhibitors RO 31-8220 and Gö 6983 enhance epinephrine-induced platelet aggregation in catecholamine hypo-responsive platelets by enhancing Akt phosphorylation.

Impaired responsiveness of platelets to epinephrine (epi) and other catecholamines (CA) has been reported in approximately 20% of the healthy Korean and Japanese populations. In the present study, platelet aggregation induced by epi was potentiated by RO 31-8220 (RO) or Gö 6983 (Gö). Phosphorylated Akt (p-Akt) was very low in epi-stimulated PRP from CA-hypo-responders (CA-HY), whereas it was detected in those from CA-good responders (CA-GR). RO and Gö increased p-Akt, one of the major downstream effectors of phosphoinositol-3 kinase (PI3K), in epi-stimulated PRP from both groups. Wortmannin, a PI3K inhibitor, attenuated the RO or Gö-induced potentiation of p-Akt in epi-stimulated PRP, suggesting positive effects for RO and Gö on PI3K. TXA(2) formation was increased by the addition of either RO or Gö in epi-stimulated platelets. The present data also suggest that impaired Akt phosphorylation may be responsible for epinephrine hypo-responsiveness of platelets.

Platelet anti-aggregatory and blood anti-coagulant effects of compounds isolated from Paeonia lactiflora and Paeonia suffruticosa.

The roots of two Paeoniaceae family members have long been used as traditional medicines in Korea, China, and Japan. Dry roots of Paeonia lactiflora and dry root bark of P. suffruticosa are used under the traditional names of Paeoniae Radix and Moutan Cortex, respectively. Both Paeoniae Radix and Moutan Cortex have been used as remedies for cardiovascular diseases, for improving blood circulation, or for other uses. It was postulated that both plants may contain common active constituents that contribute to inhibiting blood coagulation and/or platelet aggregation. Eighteen compounds, which have been reported to be present in both plant medicines, were evaluated for their effects on platelet aggregation and blood coagulation. Paeonol (5), paeoniflorin (9), benzoylpaeoniflorin (11), and benzoyloxypaeoniflorin (12) were found to be the major common active constituents and they would collectively contribute to improving blood circulation through their inhibitory effects on both platelet aggregation and blood coagulation. In addition, methylgallate (4), (+)-catechin (7), paeoniflorigenone (8), galloylpaeoniflorin (13), and daucosterol (16) may also take part in improving blood circulation by inhibiting ether platelet aggregation and/or blood coagulation.

Platelet anti-aggregation activities of compounds from Cinnamomum cassia.

Cinnamomum cassia is a well-known traditional medicine for improvement of blood circulation. An extract of this plant showed both platelet anti-aggregation and blood anti-coagulation effects in preliminary testing. Among the 13 compounds obtained from this plant, eugenol (2), amygdalactone (4), cinnamic alcohol (5), 2-hydroxycinnamaldehyde (7), 2-methoxycinnamaldehyde (8), and coniferaldehyde (9) showed 1.5-73-fold greater inhibitory effects than acetylsalicylic acid (ASA) on arachidonic acid (AA)-induced aggregation (50% inhibitory concentration [IC50] = 3.8, 5.16, 31.2, 40.0, 16.9, and 0.82 µM, respectively, vs. 60.3 µM) and 6.3-730-fold stronger effect than ASA on U46619 (a thromboxane A2 mimic)-induced aggregation (IC50 = 3.51, 33.9, 31.0, 51.3, 14.6, and 0.44 µM, respectively, vs. 321 µM). The other compounds, coumarin (3), cinnamaldehyde (6), cinnamic acid (10), icariside DC (11), and dihydrocinnacasside (12), also inhibited (2.5 to four times greater than ASA) U46619-induced aggregation. In addition, compounds 2, 4, 5, 6, 7, 8, and 9 were 1.3-87 times more effective than ASA against epinephrine-induced aggregation (IC50 = 1.86, 1.10, 37.7, 25.0, 16.8, 15.3, and 0.57 µM, respectively, vs. 50.0 µM). However, the 13 compounds were only very mildly effective against blood coagulation, if at all. In conclusion, compounds 2, 4, 8, and 9 showed stronger inhibitory potencies than others on AA-, U46619-, and epinephrine-induced platelet aggregation. Eugenol (2) and coniferaldehyde (9) were the two of the most active anti-platelet constituents of C. cassia.

Inhibitory activity of ginsenosides isolated from processed ginseng on platelet aggregation.

Seven ginsenosides, namely Rg6 (1), F4 (2), Rk3 (3), Rh4 (4), Rs3 (5), Rs4 (6) and Rs5 (7) isolated from processed ginseng were evaluated for their effects on platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid (AA) and U46619 (thromboxane A2 mimetic drug). Ginsenosides Rg6, F4 and Rk3 showed inhibitory activity (IC50 = 76 microM, 114 microM and 128 microM, respectively) on AA-induced platelet aggregation. The corresponding IC50 values were comparable to that of acetylsalicylic acid (ASA) (63 microM). Compared to ASA (IC50 = 468 microM) ginsenosides Rg6, F4, Rk3 and Rh4 were found to be more inhibitive (IC50 = 286 microM, 87 microM, 187 microM and 119 microM, respectively) against U46619-induced aggregation. On the other hand, most of the ginsenosides (Rg6, F4, Rh4, Rs3, Rs5) showed negligible effects on ADP and collagen-induced platelet aggregation. The acetylated ginsenosides (Rs3, Rs4 and Rs5) had only mild effects on aggregation induced by four stimulators.

Anticoagulating activities of low-molecular weight fuco-oligosaccharides prepared by enzymatic digestion of fucoidan from the sporophyll of Korean Undaria pinnatifida.

In spite of their potential as biologically active compounds, the high molecular mass and viscous natures of fucoidans have hampered their applications especially as a therapeutic agent. Herein the fucoidan-degrading enzyme activities were partially purified from the cultured cells of Sphingomonas paucimobilis PF-1 mainly by ammonium sulfate precipitation. This enzyme preparation degraded fucoidans from the Korean Undaria pinnatifida sporophyll into several low-molecular weight fuco-oligosaccharides (LMFOs) with less than 3,749 Da. The FTIR spectra of intact fucoidan and mixture of LMFOs (1,389-3,749 Da) showed no significant structural difference except for about 10% reduced level of sulfate esters in LMFOs. The LMFOs have exerted strong anticoagulating activities at which the activated partial thromboplastin time (APTT) and thrombin time (TT) were significantly prolonged, although 3 approximately 20 times weaker activities were observed than those of intact fucoidan. In addition, unlike intact fucoidan, LMFOs did not affect significantly to the prothrombin time (PT). These results suggest that the partially purified fucoidan-degrading enzyme preparation is valuable for the production of fuco-oligosaccharides having anticoagulating activities, and that the molecular weight and/or sulfate content of the fucoidan from the Korean Undaria pinnatifida sporophyll could be important factors for its anticoagulating activity.

A comparative optical aggregometry study of antiplatelet activity of taxanes from Taxus cuspidata.

Platelets are highly reactive components of the circulatory system. The cytoskeleton of a platelet is an important structure for platelet aggregation as stimulated by several agonists. An anticancer agent, taxol, has been suggested to exert platelet anti-aggregating activity by stabilizing microtubules during the aggregation process. An activity-guided fractionation was performed with a methanol extract of the leaves and twigs of Taxus cuspidata to isolate taxanes with platelet anti-aggregating effects. Compounds 1 to 7 - taxinine (1), taxinine A (2), taxinine B (3), 2-deacetoxytaxinine B (4), taxacin (5), taxchinin B (6), and taxol (7) - were obtained as the antiplatelet components of this plant. These taxane compounds present the possibility of securing new antiplatelet compounds which differ from currently available antiplatelet agents in chemical structure and possibly in mechanisms of action. All compounds showed stronger inhibitory effects than acetylsalicylic acid (ASA) on platelet aggregation induced by arachidonic acid (AA) (IC(50): 14.4, 64.5, 35.5, 16.0, 21.9, 28.6 and 48.2 versus 63.0microM) or U46619 (IC(50): 34.8, 24.9, 36.2, 35.0, 46.9, 71.9 and 68.7 versus 340microM). Compounds 1, 3, 4 and 5, with a cinnamoyl group at the C(5) position, showed strong inhibitory effects against AA-induced aggregation compared to compound 2 (with an -OH group at C(5)) or compounds with an oxetane ring at C(4),(5), such as compounds 6 and 7. All of the seven compounds were 5-13-fold more strongly inhibitory than ASA against U46619-induced aggregation.

Platelet antiaggregating activity of ginsenosides isolated from processed ginseng.

Four dammarane glycosides, namely ginsenosides Rk1 (1), Rg5 (2), 20(S)-Rg3 (3), and 20(R)-Rg3 (4), isolated from a new processed ginseng, were evaluated for their inhibitory activity against platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid (AA) and U46619 (thromboxane A2 mimetic agent). Ginsenoside Rk1 and Rg5 inhibited AA-induced platelet aggregation in a dose dependent manner. Their activity against AA-induced platelet aggregation were found to be 8-22 fold higher than that of a known antiplatelet drug acetylsalicylic acid (ASA). They also inhibited U46619-induced platelet aggregation. Ginsenoside 20(S)-Rg3 and 20(R)-Rg3 showed mild inhibitory activity against AA and U46619-induced aggregation.

Elevated plasma concentration of NO and cGMP may be responsible for the decreased platelet aggregation and platelet leukocyte conjugation in platelets hypo-responsive to catecholamines.

Impaired responsiveness to epinephrine and other catecholamines (CA) were previously reported in platelets of 20 approximately 30% healthy Japanese and Koreans. In the present study, the possible mechanisms of different responsiveness to CA in platelets of CA hypo-responders (CA-HY) and CA good-responders (CA-GR) were investigated. Increased platelet-leukocyte conjugate (PLC) formations were observed with whole blood of CA-GR than with that of CA-HY in both non-stimulated [mean fluorescence intensity (MFI) values: 1.33 +/- 0.26 vs. 1.16 +/- 0.19] and ADP (MFI: 5.54 +/- 3.46 vs. 2.15 +/- 1.13) or TRAP (MFI: 5.11 +/- 2.32 vs. 3.38 +/- 1.47) activated states. The platelets of CA-GR, when stimulated with ADP (10 microM), released approximately twice the amount of ATP than those of CA-HY (0.88 +/- 0.65 and 0.45 +/- 0.36 nmole, respectively). Nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) levels were significantly higher in non-stimulated PRP of CA-HY than in that of CA-GR (70.3 +/- 24.1 microM and 14.1 +/- 4.9 nM vs. 41.1 +/- 15.8 microM and 6.7 +/- 2.4 nM, respectively). The platelet-monocyte conjugation induced with either ADP or TRAP was significantly reduced in CA-GR with the addition of linsidomine, a NO donor, (MFI: 2.78 +/- 0.43 vs. 3.73 +/- 0.90, or 4.28 +/- 0.95 vs. 5.76 +/- 1.33, respectively). Moreover, the degree of platelet aggregation and the ATP secretion induced by epinephrine in CA-GR were significantly retarded with the addition of either linsidomine or 8-Bromo-cGMP (a cGMP analog) with more substantial effects on ATP release than aggregation. The results suggested that elevated NO and/or cGMP plasma levels may be responsible for the lower platelet aggregation and PLC formation observed in CA-HY than that in CA-GR.

Upregulation of PTEN by CKD712, a synthetic tetrahydroisoquinoline alkaloid, selectively inhibits lipopolysaccharide-induced VCAM-1 but not ICAM-1 expression in human endothelial cells.

AIMS: We examined our hypothesis that CKD712, (S)-1-(alpha-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, selectively inhibits vascular adhesion molecule-1 (VCAM-1) but not intracellular adhesion molecule-1 (ICAM-1) expression via activation of PTEN in human umbilical vein endothelial cells (HUVECs) activated with lipopolysaccharide (LPS). METHODS AND RESULTS: In order to do this, cells were pretreated with CKD712 1h prior to stimulate with LPS (1microg/ml) for 16h, and VCAM-1 and ICAM-1 levels were measured by Western blot. We found that CKD712 dose-dependently inhibited VCAM-1 but not ICAM-1 expression after LPS stimulation in HUVECs. Furthermore CKD712 blocked the attachment of monocytes (U937) to HUVECs by LPS. Differential effect of CKD712 on adhesion molecules was mediated via regulation of PI3K/Akt signaling. It was found that CKD712 is able to significantly upregulate PTEN activity through its dephosphorylation. The inhibitory effect of CKD712 in activated HUVECs was reversed by siPTEN. In addition, administration of CKD712 (10mg/kg) inhibited VCAM-1 but not ICAM-1 expression in thoracic aorta of LPS (10mg/kg)-treated rats. CONCLUSION: Our results indicate that upregulation of PTEN by CKD712 selectively inhibit VCAM-1 expression in LPS-treated HUVECs. Thus CKD712 may be beneficial in the treatment of cardiovascular disorders such as atherosclerosis.

(S)-1-(alpha-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (CKD712) reduces rat myocardial apoptosis against ischemia and reperfusion injury by activation of phosphatidylinositol 3-kinase/Akt signaling and anti-inflammatory action in vivo.

We examined our hypothesis that (S)-1-(alpha-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (CKD712) inhibits apoptosis in myocardial ischemia and reperfusion (I/R) injury in vivo via activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and by reducing inflammation during I/R. To do this, we induced a 30-min period of ischemia by occlusion of the left anterior descending coronary artery of the rat followed by a 2-h (for phosphorylation of Akt), 6-h (for biochemical analysis), or 24-h (for functional analysis) period of reperfusion to determine the effect of CKD712 treatment. Pretreatment with CKD712 significantly improved myocardial function as evidenced by an increase in the +/-dP/dt and a decrease in the infarct size, which were antagonized by a PI3K inhibitor, wortmannin (WT). Interestingly, CKD712 increased the phosphorylation of Akt and cAMP-response element-binding protein and increased the expression of the Bcl-2 gene, but it reduced the expression of the Bax gene. CKD712 decreased not only the expression but also the activity of the caspase-3 protein in the myocardium after reperfusion. Thus, all of the antiapoptotic effects of CKD712 were significantly inhibited by WT. Furthermore, the antiapoptotic effects of CKD712 and its inhibition by WT in myocardium after reperfusion were confirmed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining. Finally, CKD712 was found to reduce the serum levels of the high-mobility group box 1 protein, tumor necrosis factor-alpha, and the cardiac troponin I protein in addition to tissue levels of malondialdehyde and myeloperoxidase activity in I/R hearts. Taken together, both the activation of PI3K/Akt and its anti-inflammatory action prevent apoptosis in myocardial I/R injury by CKD712.

Augmentation of U46619 induced human platelet aggregation by aspirin.

Aspirin is known to suppress platelet function markedly. However, aspirin at concentrations higher than 1 mM was observed to augment 1.3 microM U46619 (a stable thromboxane receptor (TP receptor) agonist) induced human platelet aggregation in this study. Moreover, at a concentration as low as 250 microM aspirin increased the aggregation induced by U46619 in 13% of normal and healthy individuals. The degree of platelet aggregation and the amount of ATP release were enhanced in U46619 stimulated platelet rich plasma by the addition of aspirin (>250 microM). U46619 was previously reported to inhibit forskolin-stimulated adenyl cyclase and to reduce the cAMP formation. Both of the augmentation effects of aspirin on U46619-induced aggregation and ATP release were blocked by MeSAMP, a P2Y(12) receptor antagonist. U46619 induced aggregation was suppressed by the addition of ADP scavenger (CP/CPK) with no significant change on ATP measured and the effect of CP/CPK could not be reversed by aspirin. In addition, aspirin augmented the inhibitory effect of U46619 on the cAMP production. Our present results suggested that the potentiation effect of aspirin on U46619 induced aggregation was related with the secreted ADP and the subsequent P2Y(12)/Gi related signaling.

Reduced GPIIb/IIIa expression in platelets hyposensitive to catecholamines when activated with TRAP.

INTRODUCTION: A previous report assigned 35 healthy Koreans into five groups (groups A to E) based on their platelet responsiveness to catecholamines (CA). The present work aimed to elucidate the possible mechanism of heterogeneous responsiveness to CA in normal subjects. MATERIALS AND METHODS: The degrees of aggregation in platelet rich plasma (PRP) were measured with a turbidimetric method. The expression of platelet glycoprotein and activation maker was analyzed with flow cytometric method in whole blood. RESULTS AND CONCLUSIONS: The degrees of aggregation in response to other aggregation inducing agents (AA, ADP, and U46619) were significantly lower in platelets hyporesponsive to CA. The flow cytometric analysis showed that GPIIb, GPIIIa and GPIIb/IIIa expressions were 20.1%, 25.7%, and 38.2%, respectively, higher in the CA-responsive group than in the CA-hyporesponsive group when the groups were in a TRAP activated state, while no differences were observed between the two groups when in a resting state.

Anti-platelet effects of flavonoids and flavonoid-glycosides from Sophora japonica.

A methanol extract of Sophora japonica was subjected to anti-platelet activity guided fractionation affording the isolation of four flavonoids and six flavonoid-glycosides: biochanin A (1), irisolidone (2), genistein (3), sissotrin (4), sophorabioside (5), genistin (6), tectoridin (7), apigenin (8), quercitrin (9), and rutin (10). The structure of each compound was determined by a variety of spectroscopic methods. Among the compounds, 1, 3, and 7 showed approximately 2.5-6.5 fold greater inhibitory effects on arachidonic acid (AA) and U46619 induced platelet aggregation (IC50: 19.9 and 99.8 microM; 20.3 and 53.8 microM; 25.9 and 123.4 microM, respectively) than acetylsalicylic acid (ASA, IC50: 63.0 and 350.0 microM). Compound 2 was an approximately 22-40 fold stronger inhibitor than ASA on AA and U46619 induced aggregation (IC50: 1.6 and 15.6 microM, respectively).

HO-1 and JAK-2/STAT-1 signals are involved in preferential inhibition of iNOS over COX-2 gene expression by newly synthesized tetrahydroisoquinoline alkaloid, CKD712, in cells activated with lipopolysacchride.

We found that CKD712, an S enantiomer of YS49, strongly inhibited inducible nitric oxide synthase (iNOS) and NO induction but showed a weak inhibitory effect on cyclooxygenase-2 (COX-2) and PGE(2) induction in LPS-stimulated RAW 264.7 cells. We, therefore, investigated the molecular mechanism(s) responsible for this by using CKD712 in LPS-activated RAW264.7 cells. Treatment with either SP600125, a specific JNK inhibitor or TPCK, a NF-kappaB inhibitor, but neither ERK inhibitor PD98059 nor p38 inhibitor SB203580, significantly inhibited LPS-mediated iNOS and COX-2 induction. CKD712 inhibited NF-kappaB (p65) activity and translocation but failed to prevent JNK activation. However, AG490, a specific JAK-2/STAT-1 inhibitor, efficiently prevented LPS-mediated iNOS induction but not the induction of COX-2, and CKD712 completely blocked STAT-1 phosphorylation by LPS, suggesting that the NF-kappaB and JAK-2/STAT-1 pathways but not the JNK pathway are important for CKD712 action. Interestingly, CKD712 induced heme oxygenase 1 (HO-1) gene expression in LPS-treated cells. LPS-induced NF-kappaB and STAT-1 activation was partially prevented by HO-1 overexpression. Furthermore, HO-1 siRNA partly reversed not only the LPS-induced NF-kappaB activation and STAT-1 phosphorylation but also inhibition of these actions by CKD 712. Additionally, silencing HO-1 by siRNA prevented CKD712 from inhibiting iNOS expression but not COX-2. When examined plasma NO and PGE(2) levels and iNOS and COX-2 protein levels in lung tissues of mice injected with LPS (10 mg/kg), pretreatment with CKD712 greatly prevented NO and iNOS induction in a dose-dependent manner and slightly affected PGE(2) and COX-2 production as expected. Taken together, we conclude that inhibition of JAK-2/STAT-1 pathways by CKD 712 is critical for the differential inhibition of iNOS and COX-2 by LPS in vitro and in vivo where HO-1 induction also contributes to this by partially modulating JAK-2/STAT-1 pathways.

Enantioselective synthesis of (R)-(+)- and (S)-(-)-higenamine and their analogues with effects on platelet aggregation and experimental animal model of disseminated intravascular coagulation.

Optically active tetrahydroisoquinoline alkaloids, (R)-(+)-higenamine (1R) and (S)-(-)-higenamine (1 S), and their optically active 1-naphthylmethyl analogues (2 and 3), were synthesized by enantioselective hydrogenation of the corresponding dihydroisoquinoline intermediates 7 as a key step. The evaluation of the platelet anti-aggregation effect demonstrated clearly that the (S)-(-)-enantiomers, 1S, 2S, and 3S, had higher inhibitory potency than the corresponding (R)-(+)-antipodes, 1R, 2R, and 3R, respectively, to platelet aggregation induced by epinephrine. 1S enantiomer was superior to the corresponding 1R enantiomer in attenuating all of the disseminated intravascular coagulation (DIC) and multiple organ failure (MOF) parameters tested, while the S enantiomers 2S and 3S ameliorated some of the DIC and MOF parameters more effectively than the corresponding antipodes 2R and 3R.

Differential regulations of quercetin and its glycosides on ligand-gated ion channels.

Quercetin, one of the flavonoids, is a compound of low molecular weight found in various plants and shows a wide range of diverse neuropharmacological actions. In fruits and vegetables, quercetin exists as monomer- (quercetin-3-O-rhamnoside) (Rham1), dimer- (Rutin), or trimer-glycosides [quercetin-3-(2G-rhamnosylrutinoside)] (Rham2) at carbon-3. In the previous studies, we demonstrated that quercetin inhibits both glycine and 5-hydroxytryptamine type 3, (5-HT3A) receptor channel activities expressed in Xenopus oocytes. However, the effects of quercetin glycosides on glycine and 5-HT3A receptor channel activities are not well known. In the present study, we investigated the effects of quercetin glycosides on the human glycine alpha1 receptor and mouse 5-HT3A receptor channel activities expressed in Xenopus oocytes using a two-electrode voltage clamp technique. In oocytes expressing glycine or 5-HT3A receptors, quercetin- or its glycosides-induced inhibitions on glycine- (IGly) and 5-HT-induced current (I5-HT) were dose-dependent and reversible. Applications of quercetin and its glycosides inhibited IGly in order of quercetin>Rutin> or =Rham1>Rham2. Applications of quercetin and its glycosides inhibited I5-HT in order of Rham2> or =quercetin>Rutin=Rham1. The inhibitions of IGly by quercetin glycosides were non-competitive and voltage-sensitive, whereas the inhibitions of I5-HT by quercetin glycosides were competitive and voltage-insensitive manners. These results also indicate that quercetin glycosides might regulate the human glycine alpha1 and mouse 5-HT3A receptors with differential manners.

YS 49, 1-(alpha-naphtylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, regulates angiotensin II-stimulated ROS production, JNK phosphorylation and vascular smooth muscle cell proliferation via the induction of heme oxygenase-1.

Overexpression of the gene for heme oxygenase (HO)-1 leads to a reduction in pressor responsiveness to angiotensin II (Ang II) in experimental animals. Using rat vascular smooth muscle cells (VSMCs), we tested whether YS 49 [1-(alpha-naphtylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline] inhibits Ang II-stimulated proliferation of VSMCs via induction of HO-1. YS 49 induced HO-1 protein production in a dose-and time-dependent manner in VSMCs. Treatment with YS 49 significantly and dose-dependently inhibited Ang II-induced VSMC proliferation, ROS production, and phosphorylation of JNK, but not P38 MAP kinase or ERK1/2. The antiproliferation effect of YS 49 was reversed by pretreatment with the HO-1 inhibitor zinc protoporphyrin IX (ZnPPIX), or with hemoglobin, a carbon monoxide (CO) scavenger. Similarly, VSMC proliferation, ROS production and phosphorylation of JNK by Ang II were significantly inhibited in VSMCs transfected with the HO-1 gene. Thus, HO-1 and the HO-1 product CO play, at least in part, a crucial role in Ang II-stimulated VSMC proliferation through the regulation of ROS production and JNK phosphorylation. Therefore, YS 49 has potential as a therapeutic strategy for the pathogenesis of Ang II-related vascular diseases such as hypertension and atherosclerosis, via the induction of HO-1 gene activity.