Glutamine Protects against Mouse Abdominal Aortic Aneurysm through Modulating VSMC Apoptosis and M1 Macrophage Activation.

Glutamine (Gln), known as the most abundant free amino acid, is widely spread in human body. In this study, we demonstrated the protective effects of glutamine against mouse abdominal aortic aneurysm (AAA) induced by both angiotensin II (AngII) and calcium phosphate (Ca3(PO4)2) in vivo, which was characterized with lower incidence of mouse AAA. Moreover, histomorphological staining visually presented more intact elastic fiber and less collagen deposition in abdominal aortas of mice treated by glutamine. Further, we found glutamine inhibited the excessive production of reactive oxide species (ROS), activity of matrix metalloproteinase (MMP), M1 macrophage activation, and apoptosis of vascular smooth muscle cells (VSMCs) in suprarenal abdominal aortas of mice, what's more, the high expressions of MMP-2 protein, MMP-9 protein, pro-apoptotic proteins, and IL-6 as well as TNF-α in protein and mRNA levels in cells treated by AngII were down-regulated by glutamine. Collectively, these results revealed that glutamine protected against mouse AAA through inhibiting apoptosis of VSMCs, M1 macrophage activation, oxidative stress, and extracellular matrix degradation.

AGGF1 therapy inhibits thoracic aortic aneurysms by enhancing integrin α7-mediated inhibition of TGF-ß1 maturation and ERK1/2 signaling.

Thoracic aortic aneurysm (TAA) is a localized or diffuse dilatation of the thoracic aortas, and causes many sudden deaths each year worldwide. However, there is no effective pharmacologic therapy. Here, we show that AGGF1 effectively blocks TAA-associated arterial inflammation and remodeling in three different mouse models (mice with transverse aortic constriction, Fbn1C1041G/+ mice, and ß-aminopropionitrile-treated mice). AGGF1 expression is reduced in the ascending aortas from the three models and human TAA patients. Aggf1+/- mice and vascular smooth muscle cell (VSMC)-specific Aggf1smcKO knockout mice show aggravated TAA phenotypes. Mechanistically, AGGF1 enhances the interaction between its receptor integrin α7 and latency-associated peptide (LAP)-TGF-ß1, blocks the cleavage of LAP-TGF-ß1 to form mature TGF-ß1, and inhibits Smad2/3 and ERK1/2 phosphorylation in VSMCs. Pirfenidone, a treatment agent for idiopathic pulmonary fibrosis, inhibits TAA-associated vascular inflammation and remodeling in wild type mice, but not in Aggf1+/- mice. In conclusion, we identify an innovative AGGF1 protein therapeutic strategy to block TAA-associated vascular inflammation and remodeling, and show that efficacy of TGF-ß inhibition therapies require AGGF1.

Protein therapy of skeletal muscle atrophy and mechanism by angiogenic factor AGGF1.

BACKGROUND: Skeletal muscle atrophy is a common condition without a pharmacologic therapy. AGGF1 encodes an angiogenic factor that regulates cell differentiation, proliferation, migration, apoptosis, autophagy and endoplasmic reticulum stress, promotes vasculogenesis and angiogenesis and successfully treats cardiovascular diseases. Here, we report the important role of AGGF1 in the pathogenesis of skeletal muscle atrophy and attenuation of muscle atrophy by AGGF1. METHODS: In vivo studies were carried out in impaired leg muscles from patients with lumbar disc herniation, two mouse models for skeletal muscle atrophy (denervation and cancer cachexia) and heterozygous Aggf1+/- mice. Mouse muscle atrophy phenotypes were characterized by body weight and myotube cross-sectional areas (CSA) using H&E staining and immunostaining for dystrophin. Molecular mechanistic studies include co-immunoprecipitation (Co-IP), western blotting, quantitative real-time PCR analysis and immunostaining analysis. RESULTS: Heterozygous Aggf1+/- mice showed exacerbated phenotypes of reduced muscle mass, myotube CSA, MyHC (myosin heavy chain) and α-actin, increased inflammation (macrophage infiltration), apoptosis and fibrosis after denervation and cachexia. Intramuscular and intraperitoneal injection of recombinant AGGF1 protein attenuates atrophy phenotypes in mice with denervation (gastrocnemius weight 81.3 ± 5.7 mg vs. 67.3 ± 5.1 mg for AGGF1 vs. buffer; P < 0.05) and cachexia (133.7 ± 4.7 vs. 124.3 ± 3.2; P < 0.05). AGGF1 expression undergoes remodelling and is up-regulated in gastrocnemius and soleus muscles from atrophy mice and impaired leg muscles from patients with lumbar disc herniation by 50-60% (P < 0.01). Mechanistically, AGGF1 interacts with TWEAK (tumour necrosis factor-like weak inducer of apoptosis), which reduces interaction between TWEAK and its receptor Fn14 (fibroblast growth factor-inducing protein 14). This leads to inhibition of Fn14-induced NF-kappa B (NF-κB) p65 phosphorylation, which reduces expression of muscle-specific E3 ubiquitin ligase MuRF1 (muscle RING finger 1), resulting in increased MyHC and α-actin and partial reversal of atrophy phenotypes. Autophagy is reduced in Aggf1+/- mice due to inhibition of JNK (c-Jun N-terminal kinase) activation in denervated and cachectic muscles, and AGGF1 treatment enhances autophagy in two atrophy models by activating JNK. In impaired leg muscles of patients with lumbar disc herniation, MuRF1 is up-regulated and MyHC and α-actin are down-regulated; these effects are reversed by AGGF1 by 50% (P < 0.01). CONCLUSIONS: These results indicate that AGGF1 is a novel regulator for the pathogenesis of skeletal muscle atrophy and attenuates skeletal muscle atrophy by promoting autophagy and inhibiting MuRF1 expression through a molecular signalling pathway of AGGF1-TWEAK/Fn14-NF-κB. More importantly, the results indicate that AGGF1 protein therapy may be a novel approach to treat patients with skeletal muscle atrophy.

Angiogenic factor AGGF1 blocks neointimal formation after vascular injury via interaction with integrin α7 on vascular smooth muscle cells.

Angiogenic factor AGGF1 (AngioGenic factor with G-patch and FHA (Forkhead-Associated) domain 1) blocks neointimal formation (formation of a new or thickened layer of arterial intima) after vascular injury by regulating phenotypic switching of vascular smooth muscle cells (VSMCs). However, the AGGF1 receptor on VSMCs and the underlying molecular mechanisms of its action are unknown. In this study, we used functional analysis of serial AGGF1 deletions to reveal the critical AGGF1 domain involved in VSMC phenotypic switching. This domain was required for VSMC phenotypic switching, proliferation, cell cycle regulation, and migration, as well as the regulation of cell cycle inhibitors cyclin D, p27, and p21. This domain also contains an RDDAPAS motif via which AGGF1 interacts with integrin α7 (ITGA7), but not α8. In addition, we show that AGGF1 enhanced the expression of contractile markers MYH11, α-SMA, and SM22 and inhibited MEK1/2, ERK1/2, and ELK phosphorylation in VSMCs, and that these effects were inhibited by knockdown of ITGA7, but not by knockdown of ITGA8. In vivo, deletion of the VSMC phenotypic switching domain in mice with vascular injury inhibited the functions of AGGF1 in upregulating α-SMA and SM22, inhibiting MEK1/2, ERK1/2, and ELK phosphorylation, in VSMC proliferation, and in blocking neointimal formation. Finally, we show the inhibitory effect of AGGF1 on neointimal formation was blocked by lentivirus-delivered shRNA targeting ITGA7. Our data demonstrate that AGGF1 interacts with its receptor integrin α7 on VSMCs, and this interaction is required for AGGF1 signaling in VSMCs and for attenuation of neointimal formation after vascular injury.

Endothelial cell metabolic memory causes cardiovascular dysfunction in diabetes.

AIMS: The aim of this study was to identify the molecular mechanism for hyperglycaemia-induced metabolic memory in endothelial cells (ECs), and to show its critical importance to development of cardiovascular dysfunction in diabetes. METHODS AND RESULTS: Hyperglycaemia induces increased nuclear factor-κB (NF-κB) signalling, up-regulation of miR-27a-3p, down-regulation of nuclear factor erythroid-2 related factor 2 (NRF2) expression, increased transforming growth factor-ß (TGF-ß) signalling, down-regulation of miR-29, and induction of endothelial-to-mesenchymal transition (EndMT), all of which are memorized by ECs and not erased when switched to a low glucose condition, thereby causing perivascular fibrosis and cardiac dysfunction. Similar metabolic memory effects are found for production of nitric oxide (NO), generation of reactive oxygen species (ROS), and the mitochondrial oxygen consumption rate in two different types of ECs. The observed metabolic memory effects in ECs are blocked by NRF2 activator tert-butylhydroquinone and a miR-27a-3p inhibitor. In vivo, the NRF2 activator and miR-27a-3p inhibitor block cardiac perivascular fibrosis and restore cardiovascular function by decreasing NF-κB signalling, down-regulating miR-27a-3p, up-regulating NRF2 expression, reducing TGF-ß signalling, and inhibiting EndMT during insulin treatment of diabetes in streptozotocin-induced diabetic mice, whereas insulin alone does not improve cardiac function. CONCLUSIONS: Our data indicate that disruption of hyperglycaemia-induced EC metabolic memory is required for restoring cardiac function during treatment of diabetes, and identify a novel molecular signalling pathway of NF-κB/miR-27a-3p/NRF2/ROS/TGF-ß/EndMT involved in metabolic memory.

ADAMTS16 activates latent TGF-ß, accentuating fibrosis and dysfunction of the pressure-overloaded heart.

AIMS: Cardiac fibrosis is a major cause of heart failure (HF), and mediated by the differentiation of cardiac fibroblasts into myofibroblasts. However, limited tools are available to block cardiac fibrosis. ADAMTS16 is a member of the ADAMTS superfamily of extracellular protease enzymes involved in extracellular matrix (ECM) degradation and remodelling. In this study, we aimed to establish ADAMTS16 as a key regulator of cardiac fibrosis. METHODS AND RESULTS: Western blot and qRT-PCR analyses demonstrated that ADAMTS16 was significantly up-regulated in mice with transverse aortic constriction (TAC) associated with left ventricular hypertrophy and HF, which was correlated with increased expression of Mmp2, Mmp9, Col1a1, and Col3a1. Overexpression of ADAMTS16 accelerated the AngII-induced activation of cardiac fibroblasts into myofibroblasts. Protein structural analysis and co-immunoprecipitation revealed that ADAMTS16 interacted with the latency-associated peptide (LAP)-transforming growth factor (TGF)-ß via a RRFR motif. Overexpression of ADAMTS16 induced the activation of TGF-ß in cardiac fibroblasts; however, the effects were blocked by a mutation of the RRFR motif to IIFI, knockdown of Adamts16 expression, or a TGF-ß-neutralizing antibody (ΝAb). The RRFR tetrapeptide, but not control IIFI peptide, blocked the interaction between ADAMTS16 and LAP-TGF-ß, and accelerated the activation of TGF-ß in cardiac fibroblasts. In TAC mice, the RRFR tetrapeptide aggravated cardiac fibrosis and hypertrophy by up-regulation of ECM proteins, activation of TGF-ß, and increased SMAD2/SMAD3 signalling, however, the effects were blocked by TGF-ß-NAb. CONCLUSION: ADAMTS16 promotes cardiac fibrosis, cardiac hypertrophy, and HF by facilitating cardiac fibroblasts activation via interacting with and activating LAP-TGF-ß signalling. The RRFR motif of ADAMTS16 disrupts the interaction between ADAMTS16 and LAP-TGF-ß, activates TGF-ß, and aggravated cardiac fibrosis and hypertrophy. This study identifies a novel regulator of TGF-ß signalling and cardiac fibrosis, and provides a new target for the development of therapeutic treatment of cardiac fibrosis and HF.

Targeting AGGF1 (angiogenic factor with G patch and FHA domains 1) for Blocking Neointimal Formation After Vascular Injury.

BACKGROUND: Despite recent improvements in angioplasty and placement of drug-eluting stents in treatment of atherosclerosis, restenosis and in-stent thrombosis impede treatment efficacy and cause numerous deaths. Research efforts are needed to identify new molecular targets for blocking restenosis. We aim to establish angiogenic factor AGGF1 (angiogenic factor with G patch and FHA domains 1) as a novel target for blocking neointimal formation and restenosis after vascular injury. METHODS AND RESULTS: AGGF1 shows strong expression in carotid arteries; however, its expression is markedly decreased in arteries after vascular injury. AGGF1+/- mice show increased neointimal formation accompanied with increased proliferation of vascular smooth muscle cells (VSMCs) in carotid arteries after vascular injury. Importantly, AGGF1 protein therapy blocks neointimal formation after vascular injury by inhibiting the proliferation and promoting phenotypic switching of VSMCs to the contractile phenotype in mice in vivo. In vitro, AGGF1 significantly inhibits VSMCs proliferation and decreases the cell numbers at the S phase. AGGF1 also blocks platelet-derived growth factor-BB-induced proliferation, migration of VSMCs, increases expression of cyclin D, and decreases expression of p21 and p27. AGGF1 inhibits phenotypic switching of VSMCs to the synthetic phenotype by countering the inhibitory effect of platelet-derived growth factor-BB on SRF expression and the formation of the myocardin/SRF/CArG-box complex involved in activation of VSMCs markers. Finally, we show that AGGF1 inhibits platelet-derived growth factor-BB-induced phosphorylation of MEK1/2, ERK1/2, and Elk phosphorylation involved in the phenotypic switching of VSMCs, and that overexpression of Elk abolishes the effect of AGGF1. CONCLUSIONS: AGGF1 protein therapy is effective in blocking neointimal formation after vascular injury by regulating a novel AGGF1-MEK1/2-ERK1/2-Elk-myocardin-SRF/p27 signaling pathway.

Platelet releasates promote the proliferation of hepatocellular carcinoma cells by suppressing the expression of KLF6.

Platelets in the primary tumor microenvironment play crucial roles in the regulation of tumor progression, but the mechanisms underlying are poorly understood. Here, we report that platelet releasates exerted a proliferative effect on hepatocellular carcinoma (HCC) cells both in vitro and in vivo. This effect depended on a reduction of KLF6 expression in HCC cells. After incubation with either platelets or platelet granule contents, SMMC.7721 and HepG2 cells exhibited significant increases in proliferation and decreases in apoptosis. However, no effect was observed when incubating cancer cells with resuspended activated platelet pellet which exhausted of releasates. Platelet releasates also increased the population of HCC cells in the S and G2/M phases of the cell cycle and reduced the cell population in the G0/G1 phase. Moreover, knocking down KLF6 expression significantly diminished the platelet-mediated enhancement of HCC growth. In addition, blocking TGF-ß signaling with the TGF-ß receptor inhibitor SB431542 counteracted the effect of platelets on KLF6 expression and proliferation of HCC cells. Based on these findings, we conclude that platelet releasates, especially TGF-ß, promote the proliferation of SMMC.7721 and HepG2 cells by decreasing expression of KLF6. This discovery identifies a potential new therapeutic target for the prevention and treatment of hepatocellular carcinoma.

Simvastatin prevents lipopolysaccharide-induced septic shock in rats.

Simvastatin is a hypolipidemic drug that inhibits hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase to control elevated cholesterol, or hypercholesterolemia. Previous studies have shown that simvastatin may attenuate inflammation in ischemia-reperfusion injury and sepsis. Herein, we hypothesized that simvastatin may prevent rats from lipopolysaccharide (LPS)-induced septic shock. In our study, rats were divided into a saline group, an LPS group and an LPS plus simvastatin group. Male Sprague-Dawley (SD) rats were pretreated with simvastatin (1 mg/kg) for 30 min before the addition of LPS (8 mg/kg), with variations in left ventricular pressure recorded throughout. Ninety min after LPS injection, whole blood was collected from the inferior vena cava, and neutrophils were separated from the whole blood using separating medium. The neutrophils were then lysed for Western blotting to detect the levels of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1). In addition, mesentery microcirculations of inlet diameter, outlet diameter and blood flow rate were measured in all three groups. The results indicated that simvastatin significantly promoted heart systolic function and increased the level of uPA while simultaneously inhibited the expression of PAI-1 as compared with LPS group. Moreover, simvastatin reversed the LPS-induced inhibition of mesentery microcirculation. Taken together, it was suggested that simvastatin can effectively protect the rats from LPS-induced septic shock.

Simvastatin Prevents Lipopolysaccharide-induced Septic Shock in Rats / 华中科技大学学报（医学）（英德文版）

Simvastatin is a hypolipidemic drug that inhibits hydroxymethylglutaryl coenzyme A (HMGCoA) reductase to control elevated cholesterol,or hypercholesterolemia.Previous studies have shown that simvastatin may attenuate inflammation in ischemia-reperfusion injury and sepsis.Herein,we hypothesized that simvastatin may prevent rats from lipopolysaccharide (LPS)-induced septic shock.In our study,rats were divided into a saline group,an LPS group and an LPS plus simvastatin group.Male Sprague-Dawley (SD) rats were pretreated with simvastatin (1 mg/kg) for 30 min before the addition of LPS (8 mg/kg),with variations in left ventricular pressure recorded throughout.Ninety min after LPS injection,whole blood was collected from the inferior vena cava,and neutrophils were separated from the whole blood using separating medium.The neutrophils were then lysed for Western blotting to detect the levels of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1).In addition,mesentery microcirculations of inlet diameter,outlet diameter and blood flow rate were measured in all three groups.The results indicated that simvastatin significantly promoted heart systolic function and increased the level ofuPA while simultaneously inhibited the expression of PAI-1 as compared with LPS group.Moreover,simvastatin reversed the LPS-induced inhibition of mesentery microcirculation.Taken together,it was suggested that simvastatin can effectively protect the rats from LPS-induced septic shock.

Up-regulation of miR-95-3p in hepatocellular carcinoma promotes tumorigenesis by targeting p21 expression.

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers. To elucidate new regulatory mechanisms for heptocarcinogenesis, we investigated the regulation of p21, a cyclin-dependent kinase (CDK) inhibitor encoded by CDKN1A, in HCC. The expression level of p21 is decreased with the progression of HCC. Luciferase assays with a luciferase-p21-3' UTR reporter and its serial deletions identified a 15-bp repressor element at the 3'-UTR of CDKN1A, which contains a binding site for miR-95-3p. Mutation of the binding site eliminated the regulatory effect of miR-95-3p on p21 expression. Posttranscriptional regulation of p21 expression by miR-95-3p is mainly on the protein level (suppression of translation). Overexpression of miR-95-3p in two different HCC cell lines, HepG2 and SMMC7721, significantly promoted cell proliferation, cell cycle progression and cell migration, whereas a miR-95-3p specific inhibitor decreased cell proliferation, cell cycle progression and cell migration. The effects of miR-95-3p on cellular functions were rescued by overexpression of p21. Overexpression of miR-95-3p promoted cell proliferation and tumor growth in HCC xenograft mouse models. Expression of miR-95-3p was significantly higher in HCC samples than in adjacent non-cancerous samples. These results demonstrate that miR-95-3p is a potential new marker for HCC and regulates hepatocarcinogenesis by directly targeting CDKN1A/p21 expression.

Antiplatelet activity of chrysin via inhibiting platelet αIIbß3-mediated signaling pathway.

SCOPE: Propolis is thought to help prevent thrombotic and related cardiovascular diseases in humans. Chrysin, a bioflavonoids compound found in high levels in propolis and in honey, has been reported to possess antiplatelet activity. However, the mechanism by which it inhibits platelet function is unclear. METHODS AND RESULTS: The effects of chrysin on agonist-activated platelet-aggregation, granule-secretion, and integrin αIIbß3 activation were examined. Its effects on the phosphorylation of Akt, GSK3ß, MAPKs, and several proteins of the glycoprotein VI (GPVI) signaling pathway were also studied on collaged-activated platelets. In addition, human platelet spreading on immobilized fibrinogen was also tested. We found that chrysin dose dependently inhibited platelet aggregation and granule secretion induced by collagen, as well as platelet aggregation induced by ADP, thrombin, and U46619. Chrysin also markedly reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen. Biochemical analysis revealed that chrysin inhibited collagen-induced activation of Syk, PLCγ2, PKC, as well as the phosphorylation of Akt and ERK1/2. Additionally, chrysin attenuated phosphorylation of molecules such as FcγRIIa, FAK, Akt, and GSK3ß in platelet spreading on immobilized fibrinogen. CONCLUSIONS: Our findings indicate that chrysin suppresses not only integrin αIIbß3-mediated "inside-out" signaling, but also the "outside-in" signal transmission. This implies that chrysin may represent a potential candidate for an antiplatelet agent.

Pentamethylquercetin (PMQ) reduces thrombus formation by inhibiting platelet function.

Flavonoids exert both anti-oxidant and anti-platelet activities in vitro and in vivo. Pentamethylquercetin (PMQ), a polymethoxylated flavone derivative, has been screened for anti-carcinogenic and cardioprotective effects. However, it is unclear whether PMQ has anti-thrombotic effects. In the present study, PMQ (20 mg/kg) significantly inhibited thrombus formation in the collagen- epinephrine- induced acute pulmonary thrombosis mouse model and the ferric chloride-induced carotid injury model. To explore the mechanism, we evaluated the effects of PMQ on platelet function. We found that PMQ inhibited platelet aggregation and granule secretion induced by low dose agonists, including ADP, collagen, thrombin and U46619. Biochemical analysis revealed that PMQ inhibited collagen-, thrombin- and U46619-induced activation of Syk, PLCγ2, Akt, GSK3ß and Erk1/2. Therefore, we provide the first report to show that PMQ possesses anti-thrombotic activity in vivo and inhibited platelet function in vitro, suggesting that PMQ may represent a potential therapeutic candidate for the prevention or treatment of thrombotic disorders.

Antiplatelet activity of loureirin A by attenuating Akt phosphorylation: In vitro studies.

Loureirin A is a flavonoid extracted from Dragon׳s Blood that has been used to promote blood circulation and remove stasis in Chinese traditional medicine. However, the mechanisms of these effects are not fully understood. We explored the anti-platelet activity and underlying mechanism of loureirin A in vitro. Our results indicated that loureirin A negatively affected agonist-induced platelet aggregation such as collagen, collagen-related peptide (CRP), ADP and thrombin. Loureirin A inhibited collagen-induced platelet ATP secretion and thrombin-stimulated P-selectin expression in a dose-dependent manner. Platelet spreading on immobilized fibrinogen was significantly impaired in the presence of loureirin A. Immunoblotting analysis indicated that 100µM of loureirin A almost completely eliminated collagen-induced Akt phosphorylation at Ser473. Interestingly, a submaximal dose (50µM) of loureirin A had an additive inhibitory effect with the phosphoinositide 3-kinase (PI3K) inhibitor Ly294002 on collage-induced Akt phosphorylation in platelets. Taken together, loureirin A had an inhibitory effect on platelet activation, perhaps through an impairment of PI3K/Akt signaling.

2,3,5,4'-tetrahydroxystilbene-2-O-ß-D-glucoside (THSG) attenuates human platelet aggregation, secretion and spreading in vitro.

INTRODUCTION: 2,3,5,4'-tetrahydroxystilbene-2-O-ß-D-glucoside(THSG) is a water-soluble component of the rhizome extract from the traditional Chinese herb Polygonum multiflorum. Recent studies have demonstrated that THSG has potent anti-oxidative and anti-inflammatory effects. In this study, we investigated the anti-platelet aggregation, secretion and spreading of THSG with different methods. The purpose was to explore the anti-platelet effect of THSG and the underlying mechanism. MATERIALS AND METHODS: We investigated the anti-platelet activity of THSG on platelet aggregation induced by collagen (2 µg/mL), thrombin(0.04U/mL), U46619 (3 µM) and ADP (2 µM). ATP secretion induced by collagen (2 µg/mL) was also investigated. P-selectin expression and PAC-1 binding were measured by flow cytometry. In addition, human platelet spreading on immobilized fibrinogen and immunoblotting were also tested. RESULTS: THSG dose-dependently inhibited platelet aggregation and ATP secretion induced by collagen. It inhibited platelet P-selectin expression and PAC-1 binding induced by thrombin(0.1U/mL). THSG also inhibited human platelet spreading on immobilized fibrinogen, a process mediated by platelet outside-in signaling. Western blot analysis showed that THSG could inhibit platelet Fc γ RIIa, Akt(Ser473)and GSK3ß(Ser9) phosphorylation. CONCLUSIONS: Our study indicates that THSG has potent anti-platelet activity to collagen induced aggregation. THSG is likely to exert protective effects in platelet-associated thromboembolic disorders by modulating human platelet.