Characterization of a factor IX variant with a glycine207 to glutamic acid mutation

Factor IXTaipei9 is a factor IX variant from a hemophilia B patient with reduced levels of circulating protein molecules (cross-reacting material reduced, CRM). This variant contained a glycine (Gly) to glutamic acid (Glu) substitution at the 207th codon of mature factor IX. The functional consequences of the Gly-->Glu mutation in factor IXTaipei9 (IXG207E) were characterized in this study. Plasma-derived IXG207E exhibited a mobility similar to that of normal factor IX on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its specific activity was estimated to be 3.5% that of the purified normal factor IX in a one-stage partial thromboplastin time assay (aPTT). Cleavage of factor IXG207E by factor XIa or factor VIIa-tissue factor complex appeared to be normal. When the calcium-dependent conformational change was examined by monitoring quenching of intrinsic fluorescence, both normal factor IX and IXG207E exhibited equivalent intrinsic fluorescence quenching. Activated factor IXG207E (IXaG207E) also binds antithrombin III equally as well as normal factor IXa. However, aberrant binding of the active site probe p-aminobenzamidine was observed for factor XIa-activated factor IXG207E, indicating that the active site pocket of the heavy chain of factor IXaG207E was abnormal. Moreover, the rate of activation of factor X by factor IXaG207E, as measured in a purified system using chromogenic substrates, was estimated to be 1/40 of that of normal factor IXa. A computer-modeled heavy-chain structure of factor IXa predicts a hydrophobic environment surrounding Gly-207 and this Gly forms a hydrogen bound to the active site serine-365. The molecular mechanism of the Gly-->Glu mutation in factor IXTaipei9 might result in the alteration of the microenvironment of the active site pocket which renders the active site serine-365 inaccessible to its substrate.

The effect of 3-[2-(cyclopropylamino)ethoxy]xanthone on platelet thromboxane formation

A synthetic xanthone derivative, 3-[2-(cyclopropylamino)ethoxy] xanthone (CPEX), was investigated for its antiplatelet activities in washed rabbit platelets and human platelet-rich plasma. CPEX inhibited concentration-dependently the aggregation and ATP release of rabbit platelets caused by arachidonic acid (AA; 100 microM) and collagen (10 micrograms/ml), but not those by thrombin (0.1 U/ml), PAF (2 ng/ml), and U46619 (1 microM). The IC50 value of CPEX on AA-induced aggregation was 10.9 +/- 2.1 microM (n = 7). Thromboxane B2 formations caused by AA, collagen, and thrombin were inhibited by CPEX (20 microM), and prostaglandin D2 formation caused by AA was also inhibited. In human platelet-rich plasma, CPEX specifically inhibited the secondary aggregation and the release reaction induced by epinephrine (5 microM) and ADP (3 microM). CPEX also inhibited AA- and collagen-induced inositol-phosphate formation in [3H]myo-inositol-labeled platelets and intracellular Ca2+ increase in fura-2/AM-loaded platelets, respectively, without affecting those induced by PAF, thrombin, and U46619 in the presence of indomethacin (5 microM). These data suggest that the antiplatelet effect of CPEX is due to an inhibitory effect on the cyclooxygenase and then leads to the decrease of thromboxane formation.

Effect of norathyriol, isolated from Tripterospermum lanceolatum, on A23187-induced pleurisy and analgesia in mice

A23187-induced pleurisy in the mouse was demonstrated in this study. The protein leakage, leukocyte accumulation, LTB4 and PGE2 production in the pleural cavity of mice were increased by A23187 in a dose-dependent manner. At 7.5 nmole A23187 intrapleural injection, the protein level peaked at 0.5-2 h, PMN leukocytes accumulation peaked at 3-4 h, and LTB4 and PGE2 production peaked at 0.5-1 h. In this in vivo model we investigated the anti-inflammatory effect of norathyriol, isolated from Tripterospermum lanceolatum. A23187-induced protein leakage was reduced by norathyriol (ID50 was about 30.6 mg/kg i.p.), indomethacin and BW755C. A23187-induced PMN leukocytes accumulation was suppressed by norathyriol (ID50 was about 16.8 mg/kg, i.p.) and BW755C, while enhanced by indomethacin. Like BW755C, norathyriol reduced both LTB4 and PGE2 production (ID50 was about 18.6 and 29.1 mg/kg i.p., respectively), while indomethacin reduced PGE2 but not LTB4 generation. We also demonstrated the analgesic effect of norathyriol on the acetic acid-induced writhing response. Acetic acid-induced writhing response was depressed by norathyriol (ID50 was about 27.9 mg/kg i.p.), indomethacin and ibuprofen. These results suggest that norathyriol, like BW755C, might be a dual, yet weak, cyclooxygenase and lipoxygenase pathway blocker. The inhibitory effect of norathyriol on the A23187-induced pleurisy and acetic acid-induced writhing response in mice is proposed to be dependent on the reduction of eicosanoids mediators formation in the inflammatory site.

Renal angiomyolipoma with a prominent angiomatous component and extramedullary hematopoiesis: a case report

Renal angiomyolipoma is a benign tumor of hamartomatous nature. A case of asymptomatic renal angiomyolipoma in a 57-year-old female is reported. Her right renal mass was incidentally discovered during the evaluation of acute hepatitis by abdominal sonography. She received right simple nephrectomy. The renal pelvic tumor was found to be an angiomyolipoma with a prominent angiomatous component containing hematopoietic elements. Unfortunately, the patient died of peritoneal carcinomatosis because of adenocarcinoma of the transverse colon five years later.

gamma-Pyrone compounds. 5. Synthesis and antiplatelet effects of xanthonoxypropanolamines and related compounds

A series of simple xanthonoxypropanolamines and related compounds were synthesized. 3-[3-(Cyclopropylamino)propoxy]-xanthone showed same potent antiplatelet effects as norathyriol tetraacetate on arachidonate-induced aggregation. 3-[3-(Cyclohexylamino)-2-hydroxypropoxy]xanthone showed more potent antiplatelet effects than norathyriol tetraacetate on collagen-induced aggregation. The various amino groups of the oxypropanolamine or oxypropylamine side chains of the synthesized compounds regulated the antiplatelet effects.

Antiplatelet constituents of formosan Rubia akane

A known steroid, in addition to triterpenoids, anthraquinones, naphthalenes and a new anthraquinone glycoside, xanthopurpurin 3-O-beta-D-glucoside, were isolated from the roots of Rubia akane grown in Taiwan. Mollugin, a naphthohydroquinone, showed strong inhibition of arachidonic acid (AA)-induced and collagen-induced platelet aggregation. In contrast, 2-methyl-1,3,6-trihydroxyl-9,10-anthraquinone, xanthopurpurin 3-O-beta-D-glucoside, and xanthopurpurin showed mainly strong inhibition of collagen-induced platelet aggregation.

Inhibitory effect of norathyriol, a xanthone from Tripterospermum lanceolatum, on cutaneous plasma extravasation

Norathyriol, a xanthone aglycon isolated from Tripterospermum lanceolatum, was demonstrated to reduce the plasma leakage elicited by the passive cutaneous anaphylactic reaction in normal as well as in adrenalectomized mice. Capsaicin pretreatment greatly suppressed the local edema caused by antidromic stimulation of the saphenous nerve. The plasma exudation of neurogenic inflammation was also reduced in mice treated with norathyriol, diphenhydramine and methysergide, but not with indomethacin. Norathyriol, cyproheptadine and diphenhydramine combined with methysergide suppressed the ear edema caused by injection of compound 48/80, bradykinin and substance P into the ear. However, indomethacin did not affect this phlogist-induced edema response. Histamine- and serotonin-induced plasma exudation in ear edema was also reduced by norathyriol. In isolated rat peritoneal mast cell preparations, norathyriol produced a dose-dependent inhibition of histamine and beta-glucuronidase release from mast cells challenged by compound 48/80, bradykinin and substance P. In compound 48/80-pretreated mice, norathyriol at higher concentrations suppressed the bradykinin- and substance P-induced ear edema to a significantly greater extent than diphenhydramine combined with methysergide did. These data indicate that the inhibitory effect of norathyriol on local edema is not due to the release of steroid hormones from the adrenal gland, but is probably partly due to suppression of mast cell degranulation and hence reduce the release of chemical mediators which increase vascular permeability, and partly, at least in higher doses, due to protection of the vasculature from challenge by various mediators.

Frangulin B, an antagonist of collagen-induced platelet aggregation and adhesion, isolated from Rhamnus formosana

Emodin and its glycoside frangulin B were isolated from the plant Rhamnus formosana. Emodin inhibited the aggregation of rabbit platelets induced by arachidonic acid and collagen, without affecting that by ADP or PAF, while emodin acetate had no any antiplatelet effect. Frangulin B inhibited selectively and concentration-dependently collagen-induced aggregation and ATP release in rabbit platelets, without affecting those induced by arachidonic acid, ADP, PAF and thrombin. Frangulin B also inhibited the platelet aggregation induced by trimucytin which was reported to be a collagen receptor agonist isolated from Trimeresurus muscrosquamatus snake venom. The aggregability of platelets inhibited by frangulin B could be recovered after washing the platelets. Frangulin B also selectively suppressed the thromboxane B2 formation caused by collagen, but not those by arachidonic acid and thrombin. Similarly, the formation of inositol phosphate caused by collagen was also suppressed by frangulin B, while that of PAF or thrombin was not affected. In the presence of PGE1, frangulin B also decreased Mg(2+)-dependent platelet adhesion to collagen. It is concluded that frangulin B may be an antagonist of collagen receptor in platelet membrane.

Brown bowel syndrome: report of two cases

Brown bowel syndrome is a rare intestinal disorder associated with the deposition of lipofuscin pigment in the smooth muscle cells. We report two such cases presenting with intestinal pseudo-obstruction, abdominal pain, and body weight loss. Both cases had malabsorption and fatty liver. Exploratory laparotomy revealed brownish discoloration of the small bowel wall and enlargement of mesenteric lymph nodes. Light microscopy, autofluorescence and ultrastructure studies confirmed the deposition of lipofuscin pigments in the intestinal muscle cells and reticuloendothelial cells of mesenteric lymph nodes. In addition, the calf muscle biopsy of case 1 displayed myopathy and fatty replacement. Skeletal muscle strength of both patients was partially restored after parenteral and oral vitamin E supplement and other conservative treatment, but gastrointestinal symptoms of both patients continued to deteriorate. Thus, brown bowel syndrome associated with prolonged and severe malnutrition and possibly vitamin E deficiency appears only partially responsive to vitamin E supplementation.

Xanthonolol: a calcium channel and beta-adrenoceptor blocker with vasodilating properties

1. Xanthonolol (0.1-5.0 mg/kg, i.v.) reduced the blood pressure, heart rate, and L-isoproterenol (0.05 microgram/kg, i.v.)-induced tachycardia in rats. 2. In the isolated guinea-pig right atrium, xanthonolol (10(-6)-3 x 10(-4) M) produced long-lasting negative, inhibited L-isoproterenol-induced positive chronotropic effects, prevented the rate-increasing effects of increased extracellular Ca2+ (3.0-9.0 mM), and inhibited Ca2+ (3.0-9.0 mM)-induced heart rate-increase. 3. In the isolated guinea-pig thoracic aorta, the contractions induced by CaCl2 (0.1-5.0 mM) were inhibited by xanthonolol (10(-6)-10(-4) M). 4. Xanthonolol is suggested to have a calcium channel and beta adrenergic blocking effect with vasodilating properties.

Gamma-pyrone compounds as potential anti-cancer drugs

The gamma-pyrones, artomunoxanthotrione epoxide, cyclocommunol, cyclomulberrin, and cyclocommunin exhibited potent inhibition of human PLC/PRF/5 and KB cells in-vitro. Dihydroisocycloartomunin showed significant and potent inhibition of human PLC/PRF/5 and KB cells in-vitro, respectively. Cyclomorusin, dihydrocycloartomunin and artomunoxanthone showed significant inhibition of KB cells in-vitro. Based on the above finding and the reported antileukaemic activity of xanthone psorospermin, a series of natural gamma-pyrones was prepared and the inhibition of human PLC/PRF/5 and KB cells in-vitro was measured. Structure-activity analysis indicated the epoxide group substituted at 3-hydroxyl and 2,6-; 3,6-; and 3,5-dihydroxyl xanthone enhanced the anti-tumour activity. The epoxide group substituted at the 6-hydroxyl group of 1,6-dihydroxyxanthone did not show anti-tumour activity.

Antiplatelet effects and vasorelaxing action of some constituents of Formosan plants

Various xanthones as well as quercetin have been shown to exhibit antiplatelet activity. A series of anthraquinones analogues structurally related to xanthones and a series of quercetin-related compounds were tested for their antiplatelet effects. Emodin, frangulin B, kaempferol tetraacetate, quercetin-3-O-galactoside octaacetate, rhamnazin triacetate, and rhamnetin tetraacetate were found to be potent antiplatelet agents, and 1,8-dihydroxy-6-methoxy-3-methylanthraquinone 8-O-rhamnosyl-(1-->2)-glucoside, rhamnustrioside undecaacetate, rutin decaacetate, and quercetin-3-O-(6-O-alpha-L-arabinopyranosyl)-beta-D-galactopyranos ide decaacetate showed significant antiplatelet effects. Quercetin showed vasorelaxing action in rat thoracic aorta.

Bilateral simultaneous hypertensive intracerebral hemorrhages

Bilateral simultaneous hypertensive intracerebral hemorrhages (HICH) are a rare occurrence. Computed tomography (CT) enables us to diagnose such a condition which is difficult to recognize clinically. In the series, six patients (2.6%) from a series of 553 HICH cases had suffered from simultaneous rehemorrhage in the contralateral hemisphere. It comprised four males and two females. Their ages ranged from 54 to 64 years with a mean age of 58 years. The clinical symptoms were excessively sever and were characterized by severe consciousness disturbance (semicoma to coma, 6 cases), aphasia (5 cases) and bilateral paresis (3 cases). CT density profiles were identical, implying that the hematomas were of similar age but located areas; two were bilateral basal ganglia, one was bilateral specular thalamus, pontine-ganglia (right), thalamo (left)-ganglia (right) and occipito (right)-thalamus (left) individually. All of the hematomas had ruptured into the ventricles. The predominant sites of hemorrhage were in the putamen (50%, 6/12) and the thalamus (33%, 4/12). Two patients received emergency craniotomy for evacuation of the hematomas. However, they died soon after the operations. In the remaining four non-surgical cases, two died of central failure, another died of pneumonia and the remain one survived but retained hemiplegia sequelae. The serious surgical results and outcome in bilateral HICH was compared that of unilateral HICH. Hemodynamically, poor cerebral blood flow and diaschisis phenomenon may contribute to the poor prognosis in these patients.

Antiplatelet activity of some prenylflavonoids

Eight naturally occurring prenylflavonoids were tested for their antiplatelet activities in rabbit platelet suspension. Cyclomorusin and artomunoxanthone showed strong inhibition of platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) induced platelet aggregation. Cyclomulberrin, dihydroisocycloartomunin, cyclocommunol and cyclocommunin showed strong inhibition of arachidonic acid (AA)- and collagen-induced platelet aggregation. Cyclomorusin also inhibited markedly collagen-induced platelet aggregation. Cyclocommunin, dihydroisocycloartomunin and cyclomulberrin also showed slight but significant antiplatelet effects on the aggregation induced by PAF. Of the compounds tested, cyclocommunin exhibited the most potent inhibition of platelet aggregation induced by collagen (IC50 = 14.4 microM) and AA (IC50 = 12.5 microM). Thromboxane B2 formation caused by AA was suppressed by cyclocommunin and artomunoxanthone.

Cytotoxic principles and their derivatives of Formosan Solanum plants

The new steroidal alkaloid capsimine-3-O-beta-D-glucoside [1] was isolated from the root bark of Solanum capsicastrum, and carpesterol [2], 3 beta-(p-hydroxy)-benzoyloxy-22 alpha-hydroxy-4 alpha-methyl-5 alpha-stigmast-7-en-6-one [3], and a new steroidal glycoside named indioside A [4] were isolated from the fruit of Solanum indicum. Indioside A was characterized as 3 beta-O-[alpha-L-rhamnopyranosyl-(1-->2), beta-D-glucopyranosyl-(1-->4), beta-D-glucopyranosyl-(1-->3)-]alpha-L-rhamnopyranosyl-(-->2)]-beta-D- glucopyranosyl]-diosgenin. Khasianine, dihydrosolasodine, capsimine, and capsimine-3-O-beta-D-glucoside exhibited strong activity against liver damage induced by CCl4. Capsimine and narigenin exhibited significant cytotoxic effect against human PLC/PRF/5 and KB cells in vitro, and capsicastrine and etioline exhibited significant cytotoxicity against human PLC/PRF/5 cells in vitro.

Effects of xanthone glycoside on ephedrine-induced biting behavior and motor activity

1-Hydroxy-3,4,7,8-tetramethoxyxanthone, beta-sitosterol, uvaol-3-palmitate, and sweroside have been isolated from the fresh whole plant of Tripterospermum lanceolatum (Hayata) Haraex Satake (Gentianaceae). Our results on the pharmacological studies of xanthone glycoside and lanceoside suggested that they have a CNS depressant effect.

gamma-Pyrone compounds. IV: Synthesis and antiplatelet effects of mono- and dioxygenated xanthones and xanthonoxypropanolamine

Xanthodilol, mono- and dioxygenated xanthones, and 1,3-, 2,3-, 3,4-, 3,5-, 1,6-, 2,6- and 3,6-dioxygenated xanthones were synthesized from benzophenone precursors by Friedel-Crafts acylation and subsequent base-catalyzed cyclization to eliminate methanol. 3-Hydroxy-xanthone, xanthodilol, 2,3-dihydroxyxanthone diacetate, and 3,4-dihydroxyxanthone and its diacetate showed potent antiplatelet effects on arachidonate- and collagen-induced aggregation. 3,5-Dihydroxyxanthone and its diacetate, 1,6-dimethoxyxanthone, and 3,6-dihydroxyxanthone and its diacetate showed potent antiplatelet effects on arachidonate-induced aggregation.

Gamma-pyrone compounds. II: Synthesis and antiplatelet effects of tetraoxygenated xanthones

Norathyriol and its analogues, 1,3,5,6-, 3,4,5,6-, 3,4,6,7- and 2,3,6,7-tetrahydroxyxanthone, were synthesized from benzophenone precursors by Friedel-Crafts acylation and subsequent base-catalyzed cyclization to eliminate methanol. Both 3,4,6,7- and 2,3,6,7-tetrahydroxyxanthone tetraacetate showed potent anti-platelet aggregation effects on arachidonic acid-induced platelet aggregation. 3,4,6,7-Tetrahydroxyxanthone tetraacetate and 1,3,5,6-tetrahydroxyxanthone showed potent and significant anti-platelet aggregation effects on collagen-induced platelet aggregation.

[Neurogenic pulmonary edema: five cases report]

Five patients with neurogenic pulmonary edema (NPE) were reported. The edemas were caused by head injuries in four patients and by a craniotomy in the fifth. The onset of NPE was either acute (3 hours after injury) or was slow to develop (4 days later). Clinical symptoms included the sudden onset of coughing, tachypnea, tachycardia, and pink bubbly sputum. Moreover, the patients also suffered cyanosis, confusion, or respiratory failure. The distribution of the resulting pulmonary edema was diffuse in 4 cases and localized within a single lobe of the lung in 1 case. Treatment of the NPE included reducing intracranial pressure (glycerol), diuresis (furosemide and mannitol), narcotics (morphine, phenobarbital), and blocking the peripheral effect of sympathetic reflex activity (hydralazine, sodium nitroprusside). Mechanical ventilation support (CPU-1) in combination with controlled hyperventilation may also be necessary. The inability to correct hypoxemia without toxic levels of oxygen necessitates the use of PEEP (positive end-expiratory pressure, +5-10 cmH2O). Resolution of symptoms was noted 24 to 48 hours after treatment in 4 patients. Early diagnosis and intensive care of the pulmonary edema may have a significant bearing on the recovery of lung functions. Unfortunately, 4 of the patients failed to survive because of central nervous system failure. We therefore want to emphasize that NPE can cause secondary deterioration of neurological functions. In conclusion, when dealing with respiratory distress patients with CNS injuries, the possibility of additional damage from a NPE must be taken into consideration.

Inhibition of Moloney murine leukemia virus reverse transcriptase activity by tetrahydroxyxanthones isolated from the Chinese herb, Tripterospermum lanceolatum (Hyata)

Five tetrahydroxyxanthones (THXs) isolated from Tripterospermum lanceolatum (Hyata) have been shown to have a strong inhibitory effect on Moloney murine leukemia virus reverse transcriptase (Mo-MLV RT) activity when (rA)n-(dT)15 and (rC)n-(dT)12-18 were used as template-primers. 50% inhibitory concentrations of 1,3,5,6-THX, 2,3,6,7-THX 1,3,6,7-THX, 3,4,5,6-THX, and 3,4,6,7-THX were determined to be 0.15, 0.27, 0.58, 0.12, and 0.12 microM, respectively. Their effects were concentration-dependent, and the mode of inhibition was found to be by competitive inhibition with respect to template-primer. The tetrahydroxyl groups of THXs were shown to be important for their inhibitory activity. Acylation of THXs with various groups resulted in a moderate or strong decrease in their inhibitory activity.

The significance of immunosuppression and hormonal alteration in neurotraumatology

Thirty head trauma patients receiving no steroid treatment were investigated for a period of 20 days. The patients were divided into three groups according to their Glasgow Coma Scale (GCS) scores: GCS = 4-8 and GCS = 9-13. We studied their immunological and hormonal status with special reference to the relationship among severity of trauma, immunosuppression and hormonal alteration. The immunity tests included lymphocyte transformation, lymphocyte phenotyping and delayed hypersensitivity (DH) skin tests. The hormone study consisted of serum cortisol and ACTH level determinations. The following results were obtained: (1) The entire group suffered from significant suppression in lymphocyte responses to mitogens PHA and Con A on day 1 and day 10 after injury, but later they improved; (2) There was a significant fall (P less than 0.05) in OKT3 OKT4 and active T-cell on day 10, especially in patients with GCS less than or equal to 8; (3) A significant increase in OKT8 and decrease in OKT4 was concurrently noted causing an inversion in the ratio of OKT4 to OKT8 on the 10th day (patients 0.96:1, normal 1.6:1, P less than 0.01); (4) No significant change was observed in the number of B-cells, suggesting that cell-mediated immunity may be affected earlier and more severely than antibody producing capacity; (5) Delayed hypersensitivity skin test showed a high incidence of anergy in the severe (GCS less than or equal to 8) and fetal cases. A high mortality in anergic cases was also noted; (6) Elevated ACTH and cortisol levels detected upon arrival rapidly declined to normal value at day 5. In addition, we found no correlation between the curve of serum ACTH and cortisol alteration and the biphasic suppression curve of lymphocyte transformation in later study period. These findings suggest that the severity of natural resistance impairment seems to be related to the gravity of clinical manifestations and to the serum hormonal alteration only in the initial stages. Also, we find that the development of anergy may be an index of poor prognosis.

Assessments of nutritional status and immunological responses in head trauma: alterations in zinc and C-reactive protein

A prospective longitudinal evaluation of zinc and C-reactive protein (CRP) in serum and 24-hour urine was carried out in 24 head-trauma patients. The patients were divided into two groups: group I (14 patients) with Glasgow Coma Scale scores between 4 and 8, and group II (10 patients) with Glasgow Coma Scale scores between 9 and 13. To understand the influence of severity of injury on the two acute-phase reactants, all patients were studied for a period of up to 20 days after hospital admission. The average serum zinc concentration in all patients decreased from day 1 to day 5, but gradually increased thereafter. The hypozincemia was more severe in group I than in group II. All patients lost zinc throughout the study period and urinary zinc excretion was greater in group I than in group II patients. In group I, the mean peak urinary zinc loss exceeded 5000 micrograms/day (normal value less than 800 micrograms/day). Serum C-reactive protein levels were markedly elevated on admission especially in group I, then gradually declined but were still above the normal range on day 20. Acute zinc deficiency with concomitant elevation of CRP supports the hypothesis that acute hypozincemia observed in our patients may be stress-induced and zinc activity may be part of altered nutritional and metabolic responses to severe head injury.

Inhibition of thromboxane formation as the antiplatelet mechanism of 3,4-dihydroxyxanthone and quercetin pentaacetate

3,4-Dihydroxyxanthone and quercetin pentaacetate were shown to inhibit the aggregation and ATP release of washed rabbit platelets induced by collagen and arachidonic acid, but were not induced by PAF. This inhibition was reversible and in a concentration-dependent manner. The thromboxane B2 formation of washed rabbit platelets, which was caused by arachidonic acid and collagen, was also suppressed by both antiplatelet agents. In human platelet-rich plasma, 3,4-dihydroxyxanthone and quercetin pentaacetate inhibited the secondary, but not the primary aggregation induced by ADP and epinephrine. Both antiplatelet agents also inhibited collagen- and arachidonic acid-induced aggregation in whole blood in a dose-dependent manner. It is concluded that the antiplatelet effects of 3,4-dihydroxyxanthone and quercetin pentaacetate are due to the inhibition of thromboxane formation.

Antihaemostatic and antithrombotic effect of some antiplatelet agents isolated from Chinese herbs

Five antiplatelet agents have been isolated from Chinese herbs. Apigenin and magnolol are inhibitors of thromboxane synthesis, while osthole, protopine and norathyriol are inhibitiors of phosphoinositide breakdown. Thirty min after intraperitoneal (i.p.) administration of these drugs, tail bleeding time of mice was prolonged markedly in a dose-dependent manner by norathyriol, protopine, osthole and magnolol, but not by apigenin. However, the antiplatelet agents (up to 200 mg kg-1, i.p.) could not prevent acute thromboembolic death in mice. In endotoxin-induced experimental disseminated intravascular coagulation in rats, norathyriol (50-100 mg kg-1, i.p.) prevented the decrease in platelet counts and fibrinogen, and the prolongation of plasma prothrombin time. Norathyriol (100 mg kg-1, i.p.) also suppressed ex-vivo platelet aggregation induced by collagen and ADP in rat plasma.

Vasorelaxation of rat thoracic aorta caused by norathyriol isolated from Gentianaceae

The pharmacological effects of norathyriol on isolated rat thoracic aorta were examined. In the high-K+ (60 mM) medium, Ca2+ (0.03 to 3 mM)-induced vasocontraction was inhibited concentration dependently by norathyriol. Given as pretreatment norathyriol (20 to 200 microM) also inhibited the norepinephrine (NE, 3 microM)-induced tonic contraction. However, the phasic contraction was inhibited only by high concentrations of norathyriol (200 and 400 microM). The tonic contraction elicited by NE was also relaxed by the addition of norathyriol. This relaxing effect of norathyriol was not antagonized by methylene blue (50 microM) or indomethacin (20 microM) and was still seen in denuded rat aorta. Although the cAMP level was not changed by norathyriol, the cGMP level was increased by a high concentration of norathyriol (400 microM). [3H]Inositol monophosphate formation caused by NE was not affected by norathyriol at concentration of either 100 or 400 microM. The 45Ca2+ influx caused by either NE or high K+ was inhibited by norathyriol in a concentration-dependent manner. It is concluded that norathyriol relaxed the rat thoracic aorta mainly by suppressing the Ca2+ influx through both voltage-dependent and receptor-operated calcium channels.