Displaying publications 1 - 20 of 26 in total

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  1. Inhibitory activities of compounds from the twigs of Garcinia hombroniana Pierre on human low-density lipoprotein (LDL) oxidation and platelet aggregation
    Saputri FC, Jantan I
    Phytother Res, 2012 Dec;26(12):1845-50.
    PMID: 22422639 DOI: 10.1002/ptr.4667
    The methanol extract of the twigs of Garcinia hombroniana, which showed strong LDL antioxidation and antiplatelet aggregation activities, was subjected to column chromatography to obtain 3,5,3',5'-tetrahydroxy-4-methoxybenzophenone, 1,7-dihydroxyxanthone and eight triterpenoids, garcihombronane B, D, E and F, friedelin, glutin-5-en-3β-ol, stigmasterol and lupeol. The structures of the compounds were elucidated by spectroscopic methods. The compounds were evaluated for their ability to inhibit copper-mediated LDL oxidation and arachidonic acid (AA)-, adenosine diphosphate (ADP)-, collagen-induced platelet aggregation in vitro. Among the compounds tested, 3,5,3',5'-tetrahydroxy-4-methoxybenzophenone and 1,7-dihydroxyxanthone showed strong inhibitory activity on LDL oxidation with half-maximal inhibitory concentration (IC(50)) values of 6.6 and 1.7 µM, respectively. 3,5,3',5'-Tetrahydroxy-4-methoxybenzophenone exhibited strong activity on AA-, ADP- and collagen-induced platelet aggregation with IC(50) values of 53.6, 125.7 and 178.6 µM, respectively, while 1,7 dihydroxyxanthone showed significant and selective inhibitory activity against ADP-induced aggregation with IC(50) value of 5.7 µM. Of the triterpenoids tested, garcihombronane B showed moderate activity against LDL oxidation and garcihombronane D and F showed selective inhibition on ADP-induced platelet aggregation.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  2. Effect of prenylated flavonoids and chalcones isolated from Artocarpus species on platelet aggregation in human whole blood
    Jantan I, Mohd Yasin YH, Jamil S, Sirat H, Basar N
    J Nat Med, 2010 Jul;64(3):365-9.
    PMID: 20349149 DOI: 10.1007/s11418-010-0410-0
    Five prenylflavonoids and two prenylchalcones from Artocarpus lowii King, A. scortechinii King and A. teysmanii Miq., and acetylated derivatives of cycloheterophyllin and artonin E were investigated for their ability to inhibit arachidonic acid (AA), collagen and adenosine diphosphate (ADP)-induced platelet aggregation in human whole blood by using an electrical impedance method. Among the tested compounds, only cycloheterophyllin inhibited AA-induced platelet aggregation with an IC(50) value of 100.9 microM. It also showed strong inhibition against ADP-induced aggregation, with an IC(50) value of 57.1 microM. Isobavachalcone, 2',4'-dihydroxy-4-methoxy-3'-prenyldihydrochalcone, cycloartobiloxanthone, artonin E and artonin E triacetate showed selective inhibition against ADP-induced aggregation, with IC(50) values ranging from 55.3 to 192.0 microM, but did not show such effect against other inducers.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  3. Fulltext Effect of pyridostigmine (Mestinon) on human platelet aggregation
    Leong CF, Aini-Ardena M, Cheong SK, Norris N
    Malays J Pathol, 2009 Jun;31(1):45-52.
    PMID: 19694313 MyJurnal
    Normal platelet functions are critical for achieving primary haemostasis. Numerous medications have been shown to affect platelet functions. Pyridostigmine (Mestinon), an orally active cholinesterase inhibitor that is commonly used to treat myasthenia gravis has been documented to cause epistaxis and prolonged bleeding after a cut in anectodal reports. This study was initiated after a patient diagnosed to have myasthenia gravis, developed multiple bruises a week after being started on Mestinon. The objective of this study was to investigate the effect of Mestinon on platelet aggregation stimulated with various agonists in vitro.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  4. Antiplatelet activity of aporphine and phenanthrenoid alkaloids from Aromadendron elegans Blume
    Jantan I, Raweh SM, Yasin YH, Murad S
    Phytother Res, 2006 Jun;20(6):493-6.
    PMID: 16619347
    Six aporphine and one phenanthrenoid alkaloids isolated from Aromadendron elegans Blume were investigated for their ability to inhibit arachidonic acid (AA), collagen and ADP induced platelet aggregation in human whole blood. The antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Of the compounds tested, (-)-N-acetylnornuciferine, (-)-N-acetylanonaine and 1-(N-acetyl-N-methylamino)ethyl-3,4,6-trimethoxy-7-hydroxyphenanthrene showed strong inhibition on platelet aggregation caused by all three inducers. (-)-N-acetylanonaine was the most effective antiplatelet compound as it inhibited both arachidonic acid, collagen and ADP-induced platelet aggregation with IC(50) values of 66.1, 95.1 and 80.6 microm, respectively.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  5. Fulltext Inhibition of Human Platelet Aggregation and Low-Density Lipoprotein Oxidation by Premna foetida Extract and Its Major Compounds
    Dianita R, Jantan I
    Molecules, 2019 Apr 13;24(8).
    PMID: 31013947 DOI: 10.3390/molecules24081469
    Many Premna species have been used in traditional medicine to treat hypertension and cardiac insufficiency, and as a tonic for cardiac-related problems. Some have been reported to possess cardiovascular protective activity through several possible mechanisms, but not Premna foetida. In the present study, the methanol extract of P. foetida leaves (PFM) and its isolated compounds were evaluated for their ability to inhibit copper-mediated human low-density lipoprotein (LDL) oxidation and arachidonic acid (AA)- and adenosine diphosphate (ADP)-induced platelet aggregation. Six flavonoids, three triterpenoids, vanillic acid and stigmasterol were successfully isolated from PFM. Of the isolated compounds, quercetin was the most active against LDL oxidation (IC50 4.25 µM). The flavonols were more active than the flavones against LDL oxidation, suggesting that hydroxyl group at C-3 and the catechol moiety at B-ring may play important roles in protecting LDL from oxidation. Most tested flavonoids showed stronger inhibition towards AA-induced than the ADP-induced platelet aggregation with apigenin exhibiting the strongest effect (IC50 52.3 and 127.4 µM, respectively) while quercetin and kaempferol showed moderate activity. The results suggested that flavonoids, especially quercetin, apigenin and kaempferol were among the major constituents of P. foetida responsible for anti-LDL oxidation and anti-platelet aggregation.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  6. Fulltext Anti-inflammatory and antiplatelet activities of plasma are conserved across twelve mammalian species
    Ahmed S, Gul S, Idris F, Hussain A, Zia-Ul-Haq M, Jaafar HZ, et al.
    Molecules, 2014;19(8):11385-94.
    PMID: 25090125 DOI: 10.3390/molecules190811385
    Human plasma inhibits arachidonic acid metabolism and platelet aggregation. This helps human form a haemostatic control system that prevents the progress of certain aggregatory or inflammatory reactions. Whether this property of plasma is unique to human or extends to other species is not well known. It is speculated that this protective ability of plasma remains evolutionarily conserved in different mammals. In order to confirm this, the effect of plasma from 12 different mammalian species was investigated for its inhibitory potential against arachidonic acid metabolism and platelet aggregation. Metabolism of arachidonic acid by cyclooxygenase and lipoxygenase pathways was studies using radio-immuno assay and thin layer chromatography while platelet aggregation in the plasma of various mammals was monitored following turbedmetric method in a dual channel aggregometer. Results indicate that inhibition of AA metabolism and platelet aggregation is a common feature of plasma obtained from different mammalian species, although there exists large interspecies variation. This shows that besides human, other mammals also possess general protective mechanisms against various aggregatory and inflammatory conditions and this anti-inflammatory property of the plasma is evolutionarily conserved in mammalian species. The most likely candidates responsible for these properties of plasma include haptoglobin, albumin and lipoproteins.
    Matched MeSH terms: Platelet Aggregation/drug effects
  7. Fulltext Glycoprotein IIb/IIIa and P2Y12 induction by oligochitosan accelerates platelet aggregation
    Periayah MH, Halim AS, Yaacob NS, Saad AZ, Hussein AR, Rashid AH, et al.
    Biomed Res Int, 2014;2014:653149.
    PMID: 25247182 DOI: 10.1155/2014/653149
    Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro.
    Matched MeSH terms: Platelet Aggregation/drug effects
  8. In vitro capacity of different grades of chitosan derivatives to induce platelet adhesion and aggregation
    Periayah MH, Halim AS, Hussein AR, Saad AZ, Rashid AH, Noorsal K
    Int J Biol Macromol, 2013 Jan;52:244-9.
    PMID: 23063426 DOI: 10.1016/j.ijbiomac.2012.10.001
    Chitosan-derived hemostatic agents with various formulations may have distinct potential in hemostasis. This study assessed the ability of different grades and forms of chitosan derivatives as hemostatic agents to enhance platelet adhesion and aggregation in vitro. The chitosan derivatives utilized were 2% NO-CMC, 7% NO-CMC (with 0.45 mL collagen), 8% NO-CMC, O-C 52, 5% O-CMC-47, NO-CMC-35, and O-C 53. Samples of chitosan derivatives weighing 5mg were incubated at 37°C with 50 μL of phosphate buffer saline (PBS) (pH 7.4) for 60 min. The morphological features of the platelets upon adherence to the chitosan were viewed using scanning electron microscope (SEM), and the platelet count was analyzed with an Automated Hematology Analyzer. For platelet aggregation, we added an adenosine diphosphate (ADP) agonist to induce the chitosan-adhered platelets. O-C 52 bound with platelets exhibited platelet aggregates and clumps on the surface of the membrane layer with approximately 70-80% coverage. A statistically significant correlation (p<0.01) for the platelet count was identified between the baseline value and the values at 10 min and 20 min. The results indicate that O-C 53 and O-C 52 were able to promote clotting have the potential to induce the release of platelets engaged in the process of hemostasis.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  9. Inhibitory effect of compounds from Zingiberaceae species on human platelet aggregation
    Jantan I, Raweh SM, Sirat HM, Jamil S, Mohd Yasin YH, Jalil J, et al.
    Phytomedicine, 2008 Apr;15(4):306-9.
    PMID: 17913483
    Twelve compounds isolated from Alpinia mutica Roxb., Kaempferia rotunda Linn., Curcuma xanthorhiza Roxb., Curcuma aromatica Valeton and Zingiber zerumbet Smith (Family: Zingiberaceae) and three synthesized derivatives of xanthorrhizol were evaluated for their ability to inhibit arachidonic acid- (AA), collagen- and ADP-induced platelet aggregation in human whole blood. Antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Among the compounds tested, curcumin from C. aromatica, cardamonin, pinocembrine and 5,6-dehydrokawain from A. mutica and 3-deacetylcrotepoxide from K. rotunda showed strong inhibition on platelet aggregation induced by AA with IC(50) values of less than 84 microM. Curcumin was the most effective antiplatelet compound as it inhibited AA-, collagen- and ADP-induced platelet aggregation with IC(50) values of 37.5, 60.9 and 45.7 microM, respectively.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  10. Platelets of habitual smokers have reduced susceptibility to aggregating agent
    Foo LC, Roshidah I, Aimy MB
    Thromb. Haemost., 1991 Mar 4;65(3):317-9.
    PMID: 2048056 DOI: 10.1055/s-0038-1648142
    Platelet aggregation to collagen, and productions of 6-keto-prostaglandin-F1-alpha and thromboxane B2 during aggregation were measured after an overnight fast, involving both food and cigarettes, in 19 clinically healthy habitual smokers (10 or more cigarettes/day) and 23 non-smokers receiving the same diet. The subjects (all males; ages = 21-30 years) were residents of a school hostel. Mean platelet aggregation was significantly lower in smokers than non-smokers (23.2 ohms vs 31.5 ohms, p less than 0.005). Non-smokers had significantly higher mean concentration of 6-keto-prostaglandin-F1-alpha than smokers (109.8 pmol/l vs 92.3 pmol/l, p less than 0.05). The level of thromboxane B2 did not differ significantly between the two groups. These observations suggest that the role of smoking as a risk factor for ischaemic heart disease is unlikely to be related to a direct enhancement of aggregation. On the contrary, the observations seem to suggest that habitual smoking may directly reduce platelet aggregability.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  11. Fulltext Effect of ultrapure lipopolysaccharides derived from diverse bacterial species on the modulation of platelet activation
    Vallance TM, Ravishankar D, Albadawi DAI, Layfield H, Sheard J, Vaiyapuri R, et al.
    Sci Rep, 2019 12 03;9(1):18258.
    PMID: 31796818 DOI: 10.1038/s41598-019-54617-w
    Platelets are small circulating blood cells that play essential roles in the maintenance of haemostasis via blood clotting. However, they also play critical roles in the regulation of innate immune responses. Inflammatory receptors, specifically Toll-like receptor (TLR)-4, have been reported to modify platelet reactivity. A plethora of studies have reported controversial functions of TLR4 in the modulation of platelet function using various chemotypes and preparations of its ligand, lipopolysaccharide (LPS). The method of preparation of LPS may explain these discrepancies however this is not fully understood. Hence, to determine the impact of LPS on platelet activation, we used ultrapure preparations of LPS from Escherichia coli (LPSEC), Salmonella minnesota (LPSSM), and Rhodobacter sphaeroides (LPSRS) and examined their actions under diverse experimental conditions in human platelets. LPSEC did not affect platelet activation markers such as inside-out signalling to integrin αIIbβ3 or P-selectin exposure upon agonist-induced activation in platelet-rich plasma or whole blood whereas LPSSM and LPSRS inhibited platelet activation under specific conditions at supraphysiological concentrations. Overall, our data demonstrate that platelet activation is not largely influenced by any of the ultrapure LPS chemotypes used in this study on their own except under certain conditions.
    Matched MeSH terms: Platelet Aggregation/drug effects
  12. Fulltext Modulation of platelet functions by crude rice (Oryza sativa) bran policosanol extract
    Wong WT, Ismail M, Imam MU, Zhang YD
    BMC Complement Altern Med, 2016 Jul 28;16:252.
    PMID: 27465266 DOI: 10.1186/s12906-016-1223-9
    Rice bran is bioactive-rich and has proven health benefits for humans. Moreover, its source, the brown rice has antioxidant, hypolipidemic and other functional properties that are increasingly making it a nutritional staple especially in Asian countries. This study investigated the antiplatelet aggregation mechanisms of crude hexane/methanolic rice bran extract, in which policosanol was the targeted bioactive. Platelets play a vital role in pathogenesis of atherosclerosis and cardiovascular diseases, and their increased activities could potentially cause arterial thrombus formation or severe bleeding disorders. Thus, in this study, platelet aggregation and adhesion of platelets to major components of basal lamina were examined in vitro. In addition, cellular protein secretion was quantified as a measurement of platelet activation.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  13. Fulltext Effect of palm-based tocotrienols and tocopherol mixture supplementation on platelet aggregation in subjects with metabolic syndrome: a randomised controlled trial
    Gan YL, Fu JY, Lai OM, Chew BH, Yuen KH, Teng KT, et al.
    Sci Rep, 2017 09 14;7(1):11542.
    PMID: 28912593 DOI: 10.1038/s41598-017-11813-w
    Tocotrienols, the unsaturated form of vitamin E, were reported to modulate platelet aggregation and thrombotic mechanisms in pre-clinical studies. Using a Food and Drug Administration (FDA)-approved cartridge-based measurement system, a randomised, double-blind, crossover and placebo-controlled trial involving 32 metabolic syndrome adults was conducted to investigate the effect of palm-based tocotrienols and tocopherol (PTT) mixture supplementation on platelet aggregation reactivity. The participants were supplemented with 200 mg (69% tocotrienols and 31% α-tocopherol) twice daily of PTT mixture or placebo capsules for 14 days in a random order. After 14 days, each intervention was accompanied by a postprandial study, in which participants consumed 200 mg PTT mixture or placebo capsule after a meal. Blood samples were collected on day 0, day 14 and during postprandial for the measurement of platelet aggregation reactivity. Subjects went through a 15-day washout period before commencement of subsequent intervention. Fasting platelet aggregation reactivity stimulated with adenosine diphosphate (ADP) did not show substantial changes after supplementation with PTT mixture compared to placebo (p = 0.393). Concomitantly, changes in postprandial platelet aggregation reactivity remained similar between PTT mixture and placebo interventions (p = 0.408). The results of this study highlight the lack of inhibitory effect on platelet aggregation after short-term supplementation of PTT mixture in participants with metabolic syndrome.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  14. Fulltext Impact of specific functional groups in flavonoids on the modulation of platelet activation
    Ravishankar D, Salamah M, Akimbaev A, Williams HF, Albadawi DAI, Vaiyapuri R, et al.
    Sci Rep, 2018 Jun 22;8(1):9528.
    PMID: 29934595 DOI: 10.1038/s41598-018-27809-z
    Flavonoids exert innumerable beneficial effects on cardiovascular health including the reduction of platelet activation, and thereby, thrombosis. Hence, flavonoids are deemed to be a molecular template for the design of novel therapeutic agents for various diseases including thrombotic conditions. However, the structure-activity relationships of flavonoids with platelets is not fully understood. Therefore, this study aims to advance the current knowledge on structure-activity relationships of flavonoids through a systematic analysis of structurally-related flavones. Here, we investigated a panel of 16 synthetic flavones containing hydroxy or methoxy groups at C-7,8 positions on the A-ring, with a phenyl group or its bioisosteres as the B-ring, along with their thio analogues possessing a sulfur molecule at the 4th carbon position of the C-ring. The antiplatelet efficacies of these compounds were analysed using human isolated platelets upon activation with cross-linked collagen-related peptide by optical aggregometry. The results demonstrate that the hydroxyl groups in flavonoids are important for optimum platelet inhibitory activities. In addition, the 4-C=O and B ring phenyl groups are less critical for the antiplatelet activity of these flavonoids. This structure-activity relationship of flavonoids with the modulation of platelet function may guide the design, optimisation and development of flavonoid scaffolds as antiplatelet agents.
    Matched MeSH terms: Platelet Aggregation/drug effects
  15. Benzophenones and xanthones from Garcinia cantleyana var. cantleyana and their inhibitory activities on human low-density lipoprotein oxidation and platelet aggregation
    Jantan I, Saputri FC
    Phytochemistry, 2012 Aug;80:58-63.
    PMID: 22640928 DOI: 10.1016/j.phytochem.2012.05.003
    Three benzophenones, 2,6,3',5'-tetrahydroxybenzophenone (1), 3,4,5,3',5'-pentahydroxybenzophenone (3) and 3,5,3',5'-tetrahydroxy-4-methoxybenzophenone (4), as well as a xanthone, 1,3,6-trihydroxy-5-methoxy-7-(3'-methyl-2'-oxo-but-3'-enyl)xanthone (9), were isolated from the twigs of Garcinia cantleyana var. cantleyana. Eight known compounds, 3,4,5,3'-tetrahydroxy benzophenone (2), 1,3,5-trihydroxyxanthone (5), 1,3,8-trihydroxyxanthone (6), 2,4,7-trihydroxyxanthone (7), 1,3,5,7-tetrahydroxyxanthone (8), quercetin, glutin-5-en-3β-ol and friedelin were also isolated. The structures of the compounds were elucidated by spectroscopic methods. The compounds were investigated for their ability to inhibit low-density lipoprotein (LDL) oxidation and platelet aggregation in human whole blood in vitro. Most of the compounds showed strong antioxidant activity with compound 8 showing the highest inhibition with an IC₅₀ value of 0.5 μM, comparable to that of probucol. Among the compounds tested, only compound 4 exhibited strong inhibitory activity against platelet aggregation induced by arachidonic acid (AA), adenosine diphosphate (ADP) and collagen. Compounds 3, 5 and 8 showed selective inhibitory activity on platelet aggregation induced by ADP.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  16. Fulltext Antiplatelet aggregation and platelet activating factor (PAF) receptor antagonistic activities of the essential oils of five Goniothalamus species
    Moharam BA, Jantan I, Ahmad Fb, Jalil J
    Molecules, 2010 Aug;15(8):5124-38.
    PMID: 20714290 DOI: 10.3390/molecules15085124
    Nine essential oils, hydrodistilled from different parts of five Goniothalamus species (G. velutinus Airy-Shaw, G. woodii Merr., G. clemensii Ban, G. tapis Miq. and G. tapisoides Mat Salleh) were evaluated for their ability to inhibit platelet aggregation in human whole blood using an electrical impedance method and their inhibitory effects on platelet activating factor (PAF) receptor binding with rabbit platelets using 3H-PAF as a ligand. The chemical composition of the oils was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The bark oil of G. velutinus was the most effective sample as it inhibited both arachidonic acid (AA) and ADP-induced platelet aggregation with IC(50) values of 93.6 and 87.7 microg/mL, respectively. Among the studied oils, the bark oils of G. clemensii, G. woodii, G. velutinus and the root oil of G. tapis showed significant inhibitory effects on PAF receptor binding, with IC(50 )values ranging from 3.5 to 10.5 microg/mL. The strong PAF antagonistic activity of the active oils is related to their high contents of sesquiterpenes and sesquiterpenoids, and the individual components in the oils could possibly produce a synergistic effect in the overall antiplatelet activity of the oils.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  17. Platelet-activating factor (PAF) receptor-binding antagonist activity of Malaysian medicinal plants
    Jantan I, Rafi IA, Jalil J
    Phytomedicine, 2005 Jan;12(1-2):88-92.
    PMID: 15693713
    Forty-nine methanol extracts of 37 species of Malaysian medicinal plants were investigated for their inhibitory effects on platelet-activating factor (PAF) binding to rabbit platelets, using 3H-PAF as a ligand. Among them, the extracts of six Zingiberaceae species (Alpinia galanga Swartz., Boesenbergia pandurata Roxb., Curcuma ochorrhiza Val., C. aeruginosa Roxb., Zingiber officinale Rosc. and Z. zerumbet Koenig.), two Cinnamomum species (C. altissimum Kosterm. and C. pubescens Kochummen.), Goniothalamus malayanus Hook. f. Momordica charantia Linn. and Piper aduncum L. are potential sources of new PAF antagonists, as they showed significant inhibitory effects with IC50 values ranging from 1.2 to 18.4 microg ml(-1).
    Matched MeSH terms: Platelet Aggregation/drug effects*
  18. Effect of the Novel Biodegradable N, O-Carboxymethylchitosan and Oligo-Chitosan on the Platelet Thrombogenicity Cascade in von Willebrand Disease
    Periayah MH, Halim AS, Mat Saad AZ, Yaacob NS, Hussein AR, Abdul Karim F, et al.
    Thromb Res, 2015 Sep;136(3):625-33.
    PMID: 26254703 DOI: 10.1016/j.thromres.2015.07.027
    Von Willebrand disease (vWD) is the second least common hemostatic disorder in Malaysia, and it has a low prevalence. This study examined the underlying platelet thrombogenicity cascades in the presence of different formulations of chitosan-derivatives in vWD patients. This paper aimed to determine the significant influence of chitosan biomaterial in stimulating the platelet thrombogenicity cascades that involve the von Willebrand factor, Factor 8, Thromboxane A2, P2Y12 and Glycoprotein IIb/IIIa in vWD.
    Matched MeSH terms: Platelet Aggregation/drug effects
  19. Fulltext Inhibitory effects of phylligenin and quebrachitol isolated from Mitrephora vulpina on platelet activating factor receptor binding and platelet aggregation
    Moharam BA, Jantan I, Jalil J, Shaari K
    Molecules, 2010 Nov 03;15(11):7840-8.
    PMID: 21060292 DOI: 10.3390/molecules15117840
    Phylligenine, together with quebrachitol, stigmasterol and two aporphine alkaloids--oxoputerine and liriodenine--were isolated from the twigs of Mitrephora vulpina C.E.C. Fisch. They were evaluated for their ability to inhibit platelet activating factor (PAF) receptor binding to rabbit platelets using 3H-PAF as a ligand and their antiplatelet aggregation effect in human whole blood induced by arachidonic acid (AA), collagen and adenosine diphosphate (ADP). Of all the compounds tested, phylligenin and quebrachitol exhibited potent and concentration-dependent inhibitory effects on PAF receptor binding, with IC(50) values of 13.1 and 42.2 µM, respectively. The IC(50) value of phylligenin was comparable to that of cedrol (10.2 µM), a potent PAF antagonist. Phylligenin also showed strong dose-dependent inhibitory activity on platelet aggregation induced by AA and ADP.
    Matched MeSH terms: Platelet Aggregation/drug effects*
  20. CYP2C19 genotypes and their impact on clopidogrel responsiveness in percutaneous coronary intervention
    Mejin M, Tiong WN, Lai LY, Tiong LL, Bujang AM, Hwang SS, et al.
    Int J Clin Pharm, 2013 Aug;35(4):621-8.
    PMID: 23661171 DOI: 10.1007/s11096-013-9783-y
    BACKGROUND: Cytochrome P450 2C19 (CYP2C19) loss-of-function polymorphisms are more common in Asian populations and have been associated with diminished antiplatelet response to clopidogrel. In this era of 'personalised medicine', combining genotyping and phenotyping as a strategy to personalise antiplatelet therapy warrants further exploration.

    OBJECTIVE: This study aimed to investigate the prevalence and impact of CYP2C19*2, *3 and *17 genotypes on clopidogrel responsiveness in a multiethnic Malaysian population planned for percutaneous coronary intervention.

    SETTING: Between October 2010 and March 2011, a total of 118 consecutive patients planned for percutaneous coronary intervention were enrolled in Sarawak General Hospital, Borneo. All patients received at least 75 mg aspirin daily for at least 2 days and 75 mg clopidogrel daily for at least 4 days prior to angiography.

    METHOD: Genotyping for CYP2C19*2 (rs4244285, 681G > A), *3 (rs4986893, 636G > A) and *17 (rs11188072, -3402C > T) alleles were performed by polymerase chain reaction-restriction fragment linked polymorphism method. Whole blood ADP-induced platelet aggregation was assessed with multiple electrode platelet aggregometry (MEA) using the Multiplate Analyzer.

    MAIN OUTCOME MEASURES: The distribution of CYP2C19*2, *3 and *17 among different ethnic groups and the association between genotype, clopidogrel responsiveness and clinical outcome were the main outcome measures.

    RESULTS: The highest prevalence of poor metabolisers (carriers of at least one copy of the *2 or *3 allele) was among the Chinese (53.7 %), followed by the Malays (26.9 %), Ibans (16.4 %) and other races (3.0 %). Poor metabolisers (PMs) had the highest mean MEA (303.6 AU*min), followed by normal metabolisers (NMs) with 270.5 AU*min and extensive metabolisers (EMs) with 264.1 AU*min (p = 0.518). Among poor responders to clopidogrel, 65.2 % were PMs and NMs, respectively, whereas none were EMs (p = 0.350). Two cardiac-related deaths were reported.

    CONCLUSION: There was a diverse inter-ethnic difference in the distribution of CYP2C19 polymorphism. The findings of this study echo that of other studies where genotype appears to have a limited impact on clopidogrel responsiveness and clinical outcome in low-risk patients.

    Matched MeSH terms: Platelet Aggregation/drug effects
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