共查询到20条相似文献,搜索用时 46 毫秒
1.
Z. Q. Chang M. H. Hwang M. H. Rhee K. S. Kim J. C. Kim S. P. Lee W. S. Jo S. C. Park 《World journal of microbiology & biotechnology》2008,24(2):181-187
The in vitro anti-platelet and antioxidant activities of various solvent extracts from Phellinus gilvus (PG), and the effects of hot water extract from PG (PGW) on murine cellular immunity were investigated. Chloroform extract
(CE), methanol extract (ME) and butanol extract (BE) from PG could significantly inhibit platelet aggregation induced by thrombin.
Ethyl acetate extract (EAE), BE, ME from PG had significant 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity compared
with the control, and the EAE showed the highest effect with IC50 values of 13.34 μg/ml, which is higher than that of ascorbic acid (40 μg/ml). In addition, EAE displayed the inhibition of
xanthine oxidase (XO) activity with IC50 value of 2.45 μg/ml. As to the cellular immunity activity, PGW could enhance both the lipopolysaccharide (LPS)-induced B
lymphocyte proliferation and concanavalin A (Con A)-induced T lymphocyte proliferation in vitro. The phagocytosis of both
peritoneal macrophages and RAW264.7 macrophage cells were also increased by the addition of PGW. Moreover, PGW was found to
inhibit the nitric oxide (NO) production of RAW264.7 macrophages induced by LPS in a concentration-dependant manner. 相似文献
2.
Pei-Wen Hsieh Li-Chi Hsu Chern-Hsiung Lai Chin-Chung Wu Tsong-Long Hwang Yin-Ku Lin Yang-Chang Wu 《World journal of microbiology & biotechnology》2009,25(8):1461-1469
The endophytic extracts from 19 endophytes, isolated from 13 species of Taiwanese plants, were evaluated for biological activity,
including cytotoxicity, anti-platelet aggregation, and anti-inflammatory activity. The extracts of 12 endophytes exhibited
inhibitory effects on collagen-induced platelet aggregation with IC50 values of 19.85–87.64 μg/ml. Four strains, Rahnella aquatilis, Pantoea agglomerans, Rhodotorula sp., and Penicillium paxilli, also showed inhibitory effects on thrombin-induced platelet aggregation with IC50 values of 42.80–61.54 μg/ml. Additionally 12 extracts of endophytes exhibited cytotoxicities with IC50 values of 0.12–19.83 μg/ml. However, eight extracts revealed inhibitory effects on superoxide anion generation induced by
fMLP (N-formyl-l-methionyl-l-leucyl-l-phenylalanine) in human neutrophils. The extract of Rahnella aquatilis showed anti-platelet aggregation activity, and bioassay-directed fractionation led to the isolation of six compounds, including
one isoalloxazine: lumichrome (1); two isoflavones: genistein (2) and daidzein (3); two cyclic peptides: cyclo-Pro-Val (4)
and cyclo-Pro-Phe (5); and one benzenoid: methyl 2,4,5-trimethoxybenzoate (6). These results indicated that endophytes from
Taiwanese herbal plants could be useful sources for research and development of bioactive lead compounds from nature. 相似文献
3.
Scutellariae Radix is one of the well-known tocolytic Chinese herbs. Oroxylin A is isolated from the root of Scutellaria baicalensis. The main syndrome of preterm birth is caused by uterus contractions from excitatory factors. Administration of tocolytic
agents is a strategy to prevent the occurrence of preterm births. The aim of this study was to investigate the effects of
oroxylin A on contractions of uterine strips isolated from non-pregnant female Wistar rats (250~350 g). Contractions of the
uterus were induced with acetylcholine (Ach) (1 μM), PGF2α (0.1 μM), oxytocin (10-3 U/ml), KCl (56.3 mM), tetraethylammonium (TEA; 1 and 10 mM), 4-aminopyridine (4-AP; 5 mM), glipizide (30 μM), a nitric oxide
synthase (NOS) inhibitor (LNNA; 10-3M), a β-receptor blocker (propranolol; 10 μM), and a cyclooxygenase inhibitor (indomethacin; 60 μM). The inhibitory effects
of the amplitude and frequency of spontaneous contractions by oroxylin A were antagonized with Ach (IC50 22.85 μM), PGF2α (IC5027.28 μM), oxytocin (IC50 12.34 μM), TEA; 1 and 10 mM (IC50 52.73 and 76.43 μM), 4-AP (IC50 67.16 μM), and glipizide (IC5027.53 μM), but oroxylin A was not influenced by Ca2+-free medium, LNNA, propranolol, or indomethacin. Otherwise, oroxylin A-mediated relaxation of the rat uterus might occur
through opening of uterine calcium-dependent potassium channels or adenosine triphosphate potassium channel activation. This
suggests that oroxylin A is the tocolytic principle constituent of Scutellariae Radix, and oroxylin A may provide a lead compound for new tocolytic drug development in the future. 相似文献
4.
20-Isopropylidene-PGE1 (Isop-PGE1) was about 10 times more potent than PGE1 in inhibition of thrombin-induced aggregation of rabbit washed platelets. Likewise, 20-isopropylidene-17(R)-methyl-carbacyclin (CS-570), a stable PGI2 analogue, was more potent than carbacyclin in the anti-aggregatory activity. In order to define the platelet-prostaglandin interactions, a binding assay was done using platelet membranes with [3H]-PGE1 as a radioligand. Isop-PGE1 (IC50μM) bound to the PG receptors more potently than PGE1 (IC50 = 2.1 μM). CS-570 (IC50=0.39 μM) was more potent than carbacyclin (C50=1.9 μM). These indicate that introduction of an isopropylidene group to the carbon 20 of PGs increases the binding ability to the receptors. These PGE1 and PGE2 analogues activated platelet membrane adenyl cyclase and increased intracellular cAMP levels with the same potency series obtained in the binding experiments. All these results suggest that the binding to the receptors by these PGs is coupled to the activation of adenyl cyclase, followed by the increase in cAMP levels in platelets and the inhibition of platelet aggregation. Thus, the increased anti-aggregatory activity of 20-isop-PGs may be explained by their increased affinity for the PG receptors and stimulation of adenyl cyclase.15-Epimeric-20-isopropylidene-PGE1 (15-Epi-isop-PGE1), which has an unnatural configuration of the 15-hydroxyl group, was much less potent than isop-PGE1 in the binding experiment and the other three investigations. This indicates that the configuration of the 15-hydroxyl group is important for the binding to the PG receptors and the consequent activities in platelets. 相似文献
5.
Prourokinase (scu-PA), a thrombolytic agent, was inserted between Gly118 and Ile119 with foreign antithrombosis functional motif (Lys-Gly-Asp-Trp-motif)
to construct a multi-functional chimeric molecule. The molecular model of a chimera was simulated and predicted. The recombinant
chimeric protein was expressed by the baculovirus-insect cell expression system and purified by affinity chromatography. The
physico-chemical characteristics of the chimeric molecule were assayed. The thrombolytic activity was determined to be 90000
IU/mg of fibrinolytic special activity by the fibrin-plate method. The anti-thrombosis activities were also assayed with IC50 of 9.6 μM by an inhibition test of ADP-induced platelet aggregation. 相似文献
6.
Diabetic neuropathy is one of the most frequent complications of diabetes. Despite some studies, the exact mechanism of glucose
neurotoxicity has not been fully elucidated. Increased reactive oxygen species (ROS) has proposed as a possible mechanism.
Crocus sativus L. (saffron) has been known as a source of antioxidants. Therefore, neuroprotective effect of saffron extract, its active
component crocin and γ-glutamylcysteinylglycine (GSH) was studied in glucose-induced neurotoxicity, using PC12 cells as a
suitable in vitro model of diabetic neuropathy. Cell viability was quantitated by MTT assay. ROS was measured using DCF-DA
by flow cytometry analysis. The result showed that glucose (13.5 and 27 mg/ml) reduced the cell viability of PC12 cells after
4 days. Saffron extract (5 and 25 mg/ml), crocin (10 and 50 μM) and GSH (10 μM) could decrease this toxicity. Glucose toxicity
was consistent with increased ROS production which reduced by saffron, crocin and GSH pretreatment. These results suggest
saffron and its carotenoid crocin could be potentially useful in diabetic neuropathy treatment. 相似文献
7.
This study aimed to evaluate the antioxidant activities of a cultured medicinal fungus—Armillariella mellea (Vahl. ex Fr.) Karst. (AM). Three antioxidant assay systems, namely cytochrome c, xanthine oxidase inhibition, and FeCl2-ascorbic acid stimulated lipid peroxidation in rat tissue homogenate tests, were used. Total flavonoid and phenol contents
of AM extracts were also analyzed. Results showed that both aqueous (AM-H2O) and ethanolic (AM-EtOH) extracts of solid state cultured AM showed antioxidant activities in a concentration-dependent
manner. At concentrations 1–100 μg/ml, the free radical scavenging activity was 73.7–92.1% for AM-H2O, and 60.0–90.8% for AM-EtOH. These extracts also showed an inhibitory effect on xanthine oxidase activity, but with a lesser
potency (IC50 is 9.17 μg/ml for AM-H2O and 7.48 μg/ml for AM-EtOH). In general, AM-H2O showed a stronger antilipid peroxidation activity on different rat’s tissues than AM-EtOH. However, both AM extracts displayed
a weak inhibitory effect on lipid peroxidation in plasma. Interestingly, the antilipid peroxidation activity of AM-H2O (IC50–6.66 μg/ml) in brain homogenate was as good as IC50–5.42 μg/ml. AM-H2O (80.0 mg/g) possessed a significantly higher concentration of total flavonoids than AM-EtOH (30.0 mg/g), whereas no difference
was noted in the total phenol content between these two extracts. These results conclude that AM extracts possess potent free
radical scavenging and antilipid peroxidation activities, especially the AM-H2O in the brain homogenate.
Published in Russian in Prikladnaya Biokhimiya i Mikrobiologiya, 2007, Vol. 43, No. 4, pp. 495–500.
The text was submitted by the authors in English. 相似文献
8.
During antioxidant screening using 1,1-diphenyl-picrylhydrazyl (DPPH) and a lipid peroxidation assay, a streptomycete strain
was found to produce herbimycin A and dihydroherbimycin A as antioxidants in the culture filtrate. These molecules were identified
by using spectral analyses, including infrared, ultraviolet, mass spectrum, and nuclear magnetic resonance assays. In the
DPPH radical-scavenging assay, dihydroherbimycin A exhibited more potent antioxidant activity (IC50, 1.3 μM) than α-tocopherol (IC50, 2.7 μM) that was used as a reference compound. In the lipid peroxidation assay, both herbimycin A and dihydroherbimycin
A demonstrated antioxidant activities of 61% and 72%, respectively, at 100 μg/ml, while α-tocopherol exhibited an activity
of 93% at the same concentration. Therefore, dihydroherbimycin A might have the potential to be developed into a new therapeutic
agent. 相似文献
9.
J. A. Hemmingson R. Falshaw R. H. Furneaux K. Thompson 《Journal of applied phycology》2006,18(2):185-193
The galactofucan sulfate extract (GFS) obtained from the brown seaweed Undaria
pinnatifida by extraction with dilute acid is a potent inhibitor of the herpes viruses HSV-1, HSV-2 and HCMV, with IC50 values determined in vitro of 1.1, 0.2 and 0.5 μgmL−1, respectively. Fractionation of GFS by anion exchange chromatography gave three fractions which differed in their uronic acid and sulfate contents and in their antiviral activity, as well as in having somewhat reduced molecular weights compared to GFS. The low uronic acid/high sulfate fraction (F2M), obtained in 63% yield, had similar molar proportions of galactopyranosyl and fucopyranosyl residues, little associated protein and was equipotent with GFS (IC50 values of 1.1, 0.1 and 0.5 μgmL−1, respectively). The high uronic acid/low sulfate fraction (F1M), obtained in 18% yield, had a much lower proportion of galactopyranosyl residues and was less active (IC50 values of 4.6, 1.0 and 4.0 μgmL−1, respectively). The minor low uronic acid/high sulfate fraction (F4M) had a significant amount of associated protein and was also less active (IC50 = 3.1, 1.0 and 2.0 μgmL−1, respectively). The structure of the major fraction (F2M) was shown to be complex by glycosyl linkage analysis before and after solvolytic desulfation, with many component sugar residues being identified, although 3-linked fucopyranosyl 2,4-disulfate residues were a prominent feature. 相似文献
10.
Priyanka Srivastava Naresh Kasoju Utpal Bora Rakhi Chaturvedi 《Plant Cell, Tissue and Organ Culture》2009,99(1):1-7
Several secondary metabolites are present in Lantana camara L. as its leaves serve as reservoirs for various bioactive compounds. Callus cultures of L. camara were induced from leaf discs incubated on Murashige and Skoog medium supplemented with 5 μM 6-benzyladenine, 1 μM 2,4-dichlorophenoxyacetic
acid, and 1 μM α-naphthalene acetic acid (NAA). An aqueous extract (0.23%), obtained from these calli (50 g dry mass), had
an apparent cytotoxic effect on HeLa cells with an IC50 value of 1,500 μg/ml in 36 h. A dose-time dependent activity of the extract was established wherein higher dosage exhibited
increased activity; however, over time cell necrosis was observed. 相似文献
11.
Isolation and characterization of dihydromonacolin-MV from <Emphasis Type="Italic">Monascus purpureus</Emphasis> for antioxidant properties 总被引:4,自引:0,他引:4
Dhale MA Divakar S Kumar SU Vijayalakshmi G 《Applied microbiology and biotechnology》2007,73(5):1197-1202
The methanolic extract of Monascus purpureus cultivated by solid-state fermentation on rice showed strong 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity
and better yield as compared to other polarity based extracted fractions. It was selected for further purification of the
antioxidant. The activity-guided repeated fractionation of methanolic extract on a silica gel column chromatography yielded
a compound that exhibited strong antioxidant activity. Based on the spectroscopic analysis by UV, IR, 1H NMR, 13C NMR, 2D-HSQCT NMR, and MS, the antioxidant isolated was elucidated as a derivative of dihydromonacolin-K, where the ester
group is 2-methyl propionate, designated as dihydromonacolin-MV. The DPPH radical was significantly scavenged by the dihydromonacolin-MV
(IC50 20±1 μg ml−1). The dihydromonacolin-MV showed strong inhibition of lipid peroxidation in a liposome model with an IC50 value of 5.71±0.38 μg ml−1 and superoxide radical scavenging activity with an IC50 value of 163.97±2.68 μg ml−1. 相似文献
12.
Resveratrol (RES), a component of red wine, possesses anti-inflammatory properties. The studies described in the present work
were aimed at evaluating the potential for RES and related stilbene analogs (piceatannol, PIC; pterostilbene, TPS; trans-stilbene, TS; and trans-stilbene oxide, TSO) to exhibit toxicity towards RAW 264.7 mouse macrophages. The effect of TS, TSO, RES and TPS on RAW 264.7
macrophage viability was determined by two standard methods: (a) the MTT assay and (b) the trypan blue dye exclusion test.
Whereas macrophages were more sensitive to PIC (LC50 trypan ∼ 1.3 μM) and to TPS (LC50 trypan ∼ 4.0 μM and LC50 MTT ∼ 8.3 μM) than to RES (LC50 trypan ∼ 8.9 μM and LC50 MTT ∼ 29.0 μM), they were relatively resistant to TSO (LC50 trypan ∼ 61.0 μM and LC50 MTT > 100 μM) and to TS (LC50 trypan ≥ 5.0 μM and LC50 MTT ≥ 5.0 μM). The ability of selected stilbenes (RES, TPS and PIC) to exhibit growth inhibitory effects was also examined. Although
RES and TPS were observed to inhibit cell proliferation in macrophages (IC50 ≤ 25 μM), these cells were resistant to growth inhibition by PIC (IC50 ≥ 50 μM). The data obtained in the present analysis demonstrate that substituted stilbene compounds such as RES have the
capacity to exhibit cytotoxic and anti-proliferative activities in macrophages. 相似文献
13.
Identification of Antihypertensive Peptides from Peptic Digest of Two Microalgae, Chlorella vulgaris and Spirulina platensis 总被引:7,自引:0,他引:7
The peptidic fractions that inhibited angiotensin I–converting enzyme (ACE) were separated from the peptic digests of 2 microalgae,
Chlorella vulgaris and Spirulina platensis, by ion exchange chromatography and gel filtration. Oral administration of peptidic fractions into spontaneously hypertensive
rats at 200 mg/kg of body weight resulted in marked antihypertensive effects. Further separation of the peptidic fractions
by ODS high-performance liquid chromatography furnished the following active peptides: Ile-Val-Val-Glu (inhibitory against
ACE with an IC50 of 315.3 μM), Ala-Phe-Leu (63.8 μM), Phe-Ala-Leu (26.3 μM), Ala-Glu-Leu (57.1 μM), and Val-Val-Pro-Pro-Ala (79.5 μM) from
C. vulgaris; Ile-Ala-Glu (34.7 μM), Phe-Ala-Leu, Ala-Glu-Leu, Ile-Ala-Pro-Gly (11.4 μM), and Val-Ala-Phe (35.8 μM) from S. platensis.
Received July 7, 2000; accepted January 15, 2001 相似文献
14.
Neda S. Lakić Neda M. Mimica-Dukić Jelena M. Isak Biljana N. Božin 《Central European Journal of Biology》2010,5(3):331-337
The antioxidant properties of methanol extracts of Lady’s Bedstraw (Galium verum L., Rubiaceae) herb from two different localities in Serbia were evaluated. Antioxidant activity was assessed in four different
model systems. Free radical scavenging capacity (RSC) was examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil
(DPPH) and hydroxyl radical (OH), as well as on hydrogen peroxide. In addition, the protective effects of lipid peroxidation
(LP) in corn oil were evaluated by the TBA-assay using the Fe2+/ascorbate system of induction. The amount of dried extract, the content of total phenolics, flavonoids and chlorophylls was
also determined. Extracts from both locations expressed very strong scavenger activity, reducing the DPPH⊙ (IC50=3.10 μg/mland 8.04 μg/ml) and OH radical formation (IC50=0.05 μg/ml and 0.54 μg/ml) and neutralising H2O2 (IC50=4.98 μg/ml and 3.80 μg/ml), in a dose dependant manner. Also, examined extracts showed notable inhibition of LP (IC50=11.69 μg/ml and 19.47 μg/ml). The observed differences in antioxidant activity could be partially explained by the levels
of phenolics (2.44–4.65 mg and 4.57–5.16 mg gallic acid equivalents/g dry extract), flavonoids (6.38–10.70 μg and 15.56–17.96
μg quercetin equivalents/g dry extract) and chlorophylls in the investigated Lady’s Bedstraw extracts. 相似文献
15.
Joanna Saluk Michał Bijak Joanna Kołodziejczyk-Czepas Małgorzata M. Posmyk Krystyna M. Janas Barbara Wachowicz 《Central European Journal of Biology》2012,7(4):655-663
Red cabbage belongs to cruciferous vegetables recognized as a rich source of anthocyanins. Anthocyanins have a wide range of therapeutic advantages without adverse effects, including cardiovascular protective properties. For development of cardiovascular diseases, platelet activation is crucial; therefore compounds which inhibit platelet activation are sought after. The anti-platelet activity of anthocyanins has only been described and is still unclear. In our study, the extract of anthocyanins, obtained from fresh leaves of red cabbage, was used in vitro to examine their antioxidative effects on platelets under oxidative stress conditions which are responsible for hyperactivity of these cells. The antiplatelet and antioxidative activities were determined by platelet aggregation and specific markers of the arachidonate cascade with O2−· generation, and oxidative changes (carbonyl groups and 3-nitrotyrosine). Extracts (5–15 μM) protected platelet proteins and lipids against oxidative damage, and diminished platelet activation. Anthocyanins from red cabbage provided beneficial anti-platelet effects and might help prevent cardiovascular diseases. 相似文献
16.
Krysko A. A. Malovichko O. L. Kabanova T. A. Mazepa A. V. 《Russian Journal of Bioorganic Chemistry》2004,30(6):534-538
m-[4-Oxo-4-(piperazin-1-yl)butyrylamino)benzoyl-D,L--(3,4-methylenedioxyphenyl)--alanine, a new mimetic of the peptide RGDF, was synthesized. This compound inhibited ADP-induced platelet aggregation in human blood plasma enriched with platelets with IC50 = 3.5 × 10–8 M. 相似文献
17.
Hafedh Hajlaoui Najla Trabelsi Emira Noumi Mejdi Snoussi Hanen Fallah Riadh Ksouri Amina Bakhrouf 《World journal of microbiology & biotechnology》2009,25(12):2227-2238
The composition of the essential oils and methanolic extracts of two cultivated mint species (M. longifolia and M. pulegium), as well as the in vitro antimicrobial and antioxidant activities of the essential oil and methanol extract of Mentha longifolia and Mentha pulegium were compared. GC-MS analysis of the essential oil identified 41 compounds constituting 96.66 and 96.13% of the total oil
from M. longifolia and M. pulegium, respectively. The later oils were rich on pulegone (47.15 and 61.11%, respectively). Moreover, 1,8 cineole (11.54%), menthone
(10.7%), α-pinene (3.57%), α-terpineol (3.17%) and d-cadinene (3.53%) were only present in M. longifolia oil, while isomenthone (17.02%), and piperitone (2.63%), were characteristic of M. pulegium oil. Shoot extract of the two species showed significantly different contents in total polyphenols (89.1 and 37.41 mg GAE/g
DW), flavonoids (63.93 and 33.83 mg CE/g DW) and tannins (1.47 and 3.07 mg CE/g DW), respectively in M. longifolia and M. pulegium. The essential oils showed strong antimicrobial activity against all 16 microorganisms tested, whereas the methanol extracts
were inactive. Moreover, the essential oils showed higher antioxidant activity than the methanolic extracts against the DPPH
and superoxide radical scavenging. In fact, antioxidant activities of the oils were the same for both M. longifolia and M. pulegium against DPPH (IC50 = 9 and 10 μg/ml, respectively) and 2-fold and 4-fold higher than shoot extracts (IC50 = 20 and 48 μg/ml, respectively). Moreover, both oils showed the same antioxidative abilities as compared to the positive
control (butylated hydroxytoluene). In the same way, the capacity to inhibit superoxide anion was very significant for the
two oils (0.1 μg/ml for M. longifolia and 0.11 μg/ml for M. pulegium). 相似文献
18.
Soluble materials of salivary glands fromHaemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified
to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longicomin, is a protein of molecular weight 16 000 on SDS-PAGE under both
reduced and nonreduced conditions. Collagen-mediated aggegation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effectors,
including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate
acetate, was observed. Longiconin had no effect on platelet adhension to collagen. Not only platelet aggregation but also
release reaction, and increase of intracellar ca2+ level of platelets in response to collagen were completely eliminated by longicomin. Increasing amounts of collagen are able
to overcome the inhibition of aggregation by longicomin, indicating that longicomin probably shares with collagen a common
receptor. In addition, collagen fibers did not emit fluorescence after incubation with isothocyanate-conjugated longicornin,
indicating that longicomin did not bind directly to collagen fibers. The identification and isolation of longicomin demonstrates
the existence of a new type of platelet inhibitor that should be useful to better undentand the mechanism of collagen stimulation
of platelets.
Project supported by the National Natural Science Foundation of China (Grant No. 39170591). 相似文献
19.
Aggregation of calf platelets by platelet activating factor was characterized by a spectrophotometric method. The aggregation
kinetics of both platelet-rich plasma and purified platelets showed concave up double-reciprocal plots and linear Hill plots
withh > 1 (1.7 ± 02) consistent with positive cooperativity. Comparable values of maximum rates of aggregation(R) were obtained with platelet-rich plasma (0.25 ± 0.08) and purified platelets (0.28 ± 0.18) but the half-maximal saturation
concentration (S0.5) differed greatly between platelet-rich plasma (6 ± 3 nM) and purified platelets (0.28 ± 0.18 nM). An Arrhenius activation
energy of 21 ±2 kcal/mol was found for aggregation of purified platelets. Diltiazem was inhibitory with half-maximal inhibitory
concentration (I0.5) of 4 M but the inhibition was not competitive. Diltiazem inhibited rates but not the extent of shape-change. The receptor-antagonist
and sulphydryl reagent N-ethylmaleimide and the platelet antagonistic omega-3-fatty acid, 5,8,11,14,17-eicosa pentaenoic acid,
inhibited both rates and extent of shape-change reactions and inhibited aggregation competitively (I0.5 ∼ 5 M). Eicosa pentaenoic acid at > 25 M could abolish shape-change reactions and at 50 M served as an activator of platelets
and the activation was enhanced by aspirin (1 mM). Although N-ethylmaleimide at > 20 M could also induce platelet activation
it failed to induce aggregation and aspirin had no effect on the shape-change reactions induced by it. 相似文献
20.
《FEBS letters》1999,442(2-3):162-166
S-Nitroso-cysteine (SNC), a putative endothelium-derived relaxing factor, potently inhibited collagen- and arachidonic acid-induced platelet aggregation (IC50=100 nM) and thromboxane A2 (TxA2) synthesis of human blood platelets. ODQ, a selective inhibitor of the soluble guanylyl cyclase, inhibited SNC-induced formation of cGMP but did not reverse inhibition by SNC of collagen- and arachidonic acid-induced platelet aggregation. Combination of ODQ with SQ-29548, a specific platelet TxA2 receptor antagonist, did not modify the antiaggregatory action of SNC. Our study shows that SNC inhibits platelet aggregation by cGMP-independent mechanisms that may involve inhibition of TxA2 synthesis in human platelets. 相似文献