Aki Naemura

Tomatoes have natural anti-thrombotic effects

The prevention of arterial thrombotic diseases has a high priority in developed countries. An inappropriate diet may be an important risk factor for thrombotic events. The daily intake of an anti-thrombotic diet may offer a convenient and effective way of prevention. The aim of the present study was to test tomato extracts for anti-thrombotic effects and to identify those varieties that have such an effect. A shear-induced platelet-function test (haemostatometry) was used to test anti-thrombotic potential in vitro. Extracts from those tomato varieties that showed a significant anti-thrombotic activity in vitro were further assessed in vivo, using a laser-induced thrombosis test in mice. One tomato variety (KG99-4) showed significant anti-thrombotic activity both in vitro and in vivo. KG99-4 inhibited not only platelet-rich thrombus formation but also had a thrombolytic effect. It is concluded that haemostatometry can detect and classify the anti-thrombotic potential of fruits and vegetables and offers a simple way of screening for such effects.

Anti-thrombotic effect of strawberries.

Because of the high mortality, prevention of arterial thrombotic disease has top priority in developed countries. As inappropriate diet is known to predispose to acute thrombotic events, regular intake of an anti-thrombotic diet may offer a convenient and effective method of prevention. As part of a systematic investigation into the anti-thrombotic effect of fruits and vegetables, strawberry varieties were tested in this study. An in vitro platelet function test (haemostatometry) was used for screening strawberry filtrates. Those that showed significant antiplatelet effect were further assessed with a laser-induced thrombosis test in mice. Measurement of flow-mediated vasodilation in the femoral artery of mice reflected the effect on the vascular endothelium. Correlation between the effects on platelet reactivity in vitro and the antioxidant activity (hypoxanthine/xanthine oxidase test) or phenolic compound content was assessed. Strawberry varieties KYSt-4 (Nohime), KYSt-11 (Kurume IH-1) and KYSt-17 (Kurume 58) showed significant antiplatelet activity both in vitro and, after oral administration, in vivo. Both KYSt-11 and KYSt-17, but not KYSt-4, significantly reduced flow-mediated vasodilation; that is, caused endothelial dysfunction. Antiplatelet activities were heat stable. Significant correlation was found between antiplatelet and antioxidant activities (P = 0.049, R2 = 0.23) or total phenolic compounds (P = 0.0096, R2 = 0.36). Of the tested strawberry varieties, KYSt-4, KYSt-11 and KYSt-17 showed significant anti-thrombotic effect. The dual mechanism of the effect may involve a direct inhibition of both platelet function and antioxidant activities.

Testing various fruits for anti-thrombotic effect: I. Mulberries

Prevention of arterial thrombotic disease has high priority in developed countries. As inappropriate diet predispose to acute thrombotic events, regular intake of an antithrombotic diet may be a convenient and effective way of prevention. The present study was performed to examine antithrombotic effect of mulberry varieties. A shear-induced in vitro platelet reactivity/thrombolysis test (Gorog Thrombosis Test) was used to screen for antiplatelet and thrombolytic activities. In case of effectiveness, it was followed by an in vivo test of laser-induced thrombosis in mice. Antioxidant capacity was assessed by superoxide anion and radical scavenging activities. Total polyphenolics, anthocyanin and citrate contents were also measured. The tested varieties showed different effect in vitro on platelet reactivity and endogenous thrombolytic activity. Varieties inhibiting platelet reactivity were antithrombotic in vivo regardless inhibition or enhancement of thrombolysis. Those mulberry varieties, which enhanced platelet reactivity in vitro, were prothrombotic only if inhibitory activity on endogenous thrombolysis coexisted with the platelet effect. Antioxidant activities and polyphenolics content did not affect platelets and the overall thrombotic status. However, antioxidant activities and polyphenolics content significantly correlated with the endogenous thrombolytic activity. These data showed that mulberry varieties can be grouped into subclasses with either anti- or prothrombotic activities. Antioxidant activities and polyphenolic contents do not affect platelets but may enhance endogenous thrombolysis, thus causing an overall antithrombotic effect.

The antithrombotic effects of carrot filtrates in rats and mice.

The prevention of arterial thrombotic disease has a high priority in developed countries. An inappropriate diet is known to enhance the risk for acute thrombotic events and a regular diet with proven antithrombotic effects might be a beneficial way to prevent disease. The present study was undertaken as a part of a series of investigations to examine vegetables and fruits for antithrombotic activity. A shear-induced in vitro platelet reactivity/thrombolysis method [Global Thrombosis Test, formerly Gorog Thrombosis Test] was used to screen 15 different varieties of carrot for antiplatelet and thrombolytic activities. Effective varieties were further investigated using an in vivo, laser-induced thrombosis model in mice. The different carrot varieties demonstrated a variable effect on thrombosis in vitro and in vivo. In particular, a variety designated SAKATA-0421 exerted an antithrombotic effect in vivo independent from heat treatment of the filtrate at 100°C for 10 min. There was no significant correlation between antithrombotic activity and the levels of polyphenolics and any other biochemical parameter, including antioxidant activity, α-carotene and β-carotene, α-tocopherol and ascorbic acid. Different varieties of carrot demonstrated a range of antithrombotic and prothrombotic activities. After oral intake, the particular heat resistant variety (SAKATA-0421) showed antithrombotic effect in vivo possibly due to antiplatelet reactivity and/or spontaneous thrombolytic activity. The present study added a new variety to the list of antithrombotic fruits and vegetables.

Long-term intake of rosemary and common thyme herbs inhibits experimental thrombosis without prolongation of bleeding time.

OBJECTIVE Our earlier study demonstrated an inhibition of experimental thrombogenesis after acute administration of rosemary and common thyme. The present study aimed to investigate the effect of long-term intake of these herbs on platelets, thrombus formation and bleeding time. METHODS Western-style high-fat diet containing 5% or 0.5% dried rosemary or common thyme was given to male 6 week old C57BL/6 mice for 12 weeks. Shear-induced platelet reactivity was measured in vitro by haemostatometry. The antithrombotic effect was assessed by the laser-induced thrombosis technique in the carotid artery of mice. Bleeding time was tested by the tail cut method. Endothelial function was assessed by the flow-mediated vasodilation test. RESULTS Rosemary (5% and 0.5%) significantly inhibited arterial thrombus formation. Only the higher concentration of common thyme (5%) had a significant antithrombotic effect. In 5% concentration, both rosemary and common thyme significantly inhibited platelet reactivity and enhanced the flow-mediated vasodilation. CONCLUSIONS Long-term daily intake of rosemary and common thyme has an antithrombotic effect, which is probably due to inhibition of platelets and stimulation of endothelial cells. The antithrombotic effect was not accompanied by prolongation of bleeding time.

An Experimentally Antithrombotic Strawberry Variety Is Also Effective in Humans

Prevention of arterial thrombotic diseases is of high priority in developed countries. As inappropriate diet is regarded as an important risk factor of thrombotic events, daily intake of an antithrombotic diet may offer a convenient and effective way of prevention. Earlier we used animal models of thrombosis to find fruits and vegetables with potential antithrombotic activity. Among various strawberry varieties tested, a particular variety (KYSt-4, Nohime) showed a significant antithrombotic effect. The aim of the present investigation was to extend this study to humans, by testing the experimentally active KYSt-4 and inactive KYSt-10 variety for effectiveness in humans after oral intake. Filtrates of strawberries were prepared and administered orally. Thrombotic status was tested by a novel global test (Gorog Thrombosis Test). The strawberry variety (KYSt-4; Nohime) which earlier inhibited experimental thrombosis showed antithrombotic effects in humans, while the experimentally inactive variety (KYSt-10) as well as the relevant control (water) were ineffective.

Impaired endothelial function may be due to decreased aortic tetrahydrobiopterin, assessed by a new flow-mediated vasodilation in vivo in hypercholesterolemic/ atherogenic mice

Tetrahydrobiopterin (BH4) is an important cofactor for endothelial nitric oxide synthase activity. The relationship between endothelial function in vivo and aortic BH4 level is not fully understood, however. In the present study, we aimed to clarify whether reduction of aortic BH4 levels contributes to endothelial dysfunction in vivo using spontaneously hyperlipidemic mice. To estimate endothelial function in vivo and in real-time state, we developed a flow-mediated vasodilation (FMV) method in mice, which measured changes in the diameter of the femoral artery in response to increased blood flow. C57BL/6 mice and apoE/low-density lipoprotein receptor double knock-out mice were fed a low-fat diet (LFD) or a high-fat diet (HFD) for 12 weeks from 6 weeks of age. HFD feeding impaired FMV in double knock-out mice, but not in C57BL/6 mice. Furthermore, HFD feeding reduced plasma NOx concentration and aortic BH4 level in double knock-out mice. Conversely, exogenous injection of BH4 (2 mg/kg) markedly increased aortic BH4 levels and restored endothelial function. In conclusion, we demonstrated that HFD feeding impaired nitric oxide-mediated endothelial function and reduced BH4 level in vivo, and that acute augmentation of aortic BH4 levels improved endothelial function. These findings indicate that BH4 is a critical determinant of nitric oxide-mediated endothelial function in hypercholesterolemia.

Experimental antithrombotic effects of sesame seed whole grains and extracts.

Prevention of arterial thrombotic diseases has a high priority in developed countries. An inappropriate diet is known to enhance the risks for acute thrombotic events, and nutritional products experimentally shown to be antithrombotic, might contribute beneficial effects. The present study forms part of a series of investigations into the antithrombotic effect of various foods and vegetables. Roasted and crushed whole grains from six varieties of sesame seeds were added to the diet of mice. Antithrombotic activity was measured in the carotid artery in vivo, using a He-Ne laser-induced thrombosis technique after 12 weeks. Col/Chichibu/Maruteru-2/1995 and T016 varieties showed significant antithrombotic activity, whilst 00037803 was prothrombotic. The acute effects of purified ingredients, sesamin, sesamolin and sesamol, given orally or intra-arterially, were also examined after a single dose. The most effective ingredient was sesamol, followed by sesamolin and sesamin. Daily intake of specific antithrombotic sesame whole grains or purified active ingredients might help to prevent atherothrombotic diseases.

Mechanism of the Antithrombotic Effect of Dietary Diacylglycerol in Atherogenic Mice

Introduction: We have shown earlier that diacylglycerol (DAG) but not triacylglycerol (TAG) inhibited thrombus formation. The aim of the present study was to investigate the mechanism of this antithrombotic effect of DAG. Materials and Methods: Four different diets, the (1) Western-style high-fat diet (HFD) containing 20% lipid and 0.05% cholesterol (w/w), (2) TAG-rich and (3) DAG-rich HFDs containing 20% lipid and 0.05% cholesterol, but all lipid replaced by TAG or DAG oil with very similar fatty acid composition and the (4) Japanese-style low-fat diet (LFD) containing 7% oil but no cholesterol were given to apolipoprotein E and low-density lipoprotein (LDL) receptor double-deficient mice. Atherogenicity was assessed by morphology, mapping the whole aorta and measuring the total area of lipid-stained lesions. Endothelial function was measured by the flow-mediated vasodilation test. Platelet reactivity was assessed from native blood sample by a shear-induced platelet function test (hemostatometry). Serum lipoprotein profile was measured by HPLC. Results: Both the Western-style and the TAG-rich HFDs have accelerated atherosclerosis. In contrast, DAG-rich HFD inhibited the atherosclerotic process to an extent comparable with the Japanese-style LFD. There was no significant difference in platelet and coagulant activity between the studied diet groups. DAG-rich but not the TAG-rich HFD significantly suppressed serum LDL cholesterol level. Conclusions: The present findings suggest that the mechanism of antithrombotic and anti-atherogenic effect of DAG may involve the protection of the vascular endothelium from injury and lowered serum LDL cholesterol.

A rice variety (HYJA-Ri4) enhances arterial thrombus formation in an animal model of thrombosis.

Epidemiological evidence exists for a causative role of inappropriate diets in the development and clinical outcome of thrombotic diseases. Our previous studies have shown that some fruits and vegetables have antithrombotic activity. As rice is a principal ingredient of everyday food in Japan, the aim of the present study was to determine rice varieties with antithrombotic effect. Western-style high-fat diet containing flour prepared from whole-grain rice of different varieties was fed to atherosclerosis-prone (apolipoprotein E- and low density lipoprotein receptor-deficient) mice for 3 months. A laser-induced carotid-artery thrombosis model was used. None of the five tested rice varieties showed an antithrombotic effect. The effect of HYJA-Ri1, HYJA-Ri2, HYJA-Ri3 and HYJA-Ri5 rice on experimental thrombus formation did not differ significantly from the controls. However, HYJA-Ri4 rice significantly enhanced the thrombotic reaction (p = 0.0078), thus having a prothrombotic effect. Our findings suggest that HYJA-Ri4 rice should not be included in an antithrombotic diet.