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"A series of alkaloids isolated from the roots of N. orientalis is investigated for the inhibitory activities on in vitro agonists induced human platelet aggregation. Human platelet samples were obtained to investigate the anti-platelet activity by high throughput 96-well microtiter plate format. Adenosine diphosphate (ADP), arachidonic acid (AA), thrombin and thrombin receptor activating peptide-6 (TRAP-6) were used as agonists for in vitro human platelet aggregation. All alkaloids were inactive in the AA induced platelet aggregation. Compound 2 was the only alkaloid to inhibit ADP induced platelet aggregation with the IC50 value of 27.01 ± 7.67 pM and was more potent than the standard drug, ibuprofen (p < 0.05). The compounds 1, 3, 4, 5 and 7 were more potent than the standard drug to inhibit thrombin induced platelet aggregation with the IC50 values of 3.05 ± 0.22,4.41 ± 0.47,7.50 ± 0.22,45.69 ± 1.74 and 4.89 ±0.13 pM (p < 0.05), respectively. None of the potent alkaloids in thrombin- mediated platelet aggregation exhibited the inhibitory effect in TRAP-6 induced platelet aggregation. Compound 2 could inhibit platelet aggregation through the interference of platelet purinergic receptors (P2Y1 and P2Y12 receptors). Moreover, compounds 1, 3,4, 5 and 7 could have inhibitory effects on thrombin-induced platelet aggregation through the proteolytic inhibition without the interferences of ligand-receptor interaction."

"Dual antiplatelet therapy (DAPT) is the mainstay of secondary prevention treatment for acute coronary syndrome (ACS) and ischemic stroke, especially after coronary intervention. DAPT consists of aspirin and P2Y12 receptor inhibitor (e.g. clopidogrel), and the use of DAPT has been increased over time. The most serious and common adverse effect is gastrointestinal bleeding. Guidelines in managing such condition are available among Gastroenterologist Societies and Cardiologist Societies. Most guidelines are consistent with each other to continue the use of aspirin while withholding P2Y12. However, European Society of Cardiologist (ESC) guideline in 2017 recommends P2Y12 receptor inhibitor as the preferred antiplatelet for patient with upper gastrointestinal bleeding. This review will look on the guidelines and other supporting evidence for the justification on the antiplatelet of choice."

"ABSTRAKPada penelitian ini, dilakukan studi kinetika dan aktivitas anti platelet bromelain yang telah dimurnikan dari bonggol nanas Palembang Ananas comosus [L] Merr . Pemurnian enzim dimulai dengan isolasi enzim bromelain, kemudian dilakukan fraksionasi bertingkat menggunakan garam amonium sulfat dan dilanjutkan dengan kromatografi gel filtrasi dengan Sphadex G-50. Enzim kasar yang didapatkan dari tahap isolasi memilki aktivitas spesifik sebesar 53,580 Unit/mg. Fraksionasi dengan metode fraksinasi bertingkat menggunakan garam amonium sulfat menghasilkan fraksi enzim yang memiliki aktivitas spesifik tertinggi adalah fraksi dengan tingkat kejenuhan amonium sulfat 20 -50 , dengan aktivitas spesifik sebesar 230,970 Unit/mg dan tingkat kemurnian sebesar 8 kali lebih murni dibandingkan dengan enzim kasar. Pemurnian lebih lanjut dengan kromatografi Sphadex G-50 fraksi enzim bromelain mengalami peningkatan nilai aktivitas spesifik menjadi 431,548 Unit/mg dengan tingkat kemurnian sebesar 28 kali enzim kasar. Uji aktivitas fraksi bromelain termurni terhadap variasi pH dan suhu menunjukkan pH optimum bromelain pada pH 7 dan suhu optimum 37oC. Pada variasi konsentrasi substrat, dengan membuat plot kurva Michaelis-Menten dan Lineweaver-Burk, didapatkan konstanta Michaelis-Menten Km untuk bromelain adalah 0,777 dan nilai Vmaks sebesar 3,969 U/min. Uji aktivitas antiplatelet menunjukkan fraksi bromelain dari setiap tahap pemurnian memiliki kemampuan sebagai agen antiplatelet. Aktifitas antiplatelet tertinggi terdapat pada fraksi enzim termurni dengan nilai persen agregasi sebesar 48,64 dan persen inhibisi 47,583 . IC50 dari fraksi enzim termurni adalah sebesar 88,314 ?L/mL.

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ABSTRACTkinetic study and activity as anti platelet agent of Bromelain enzyme from Palembang Pineapple rsquo s core Ananas Comosus L Merr was performed. The purification step begins with the isolation of bromelain enzyme, then fractionation using ammonium sulfate and continued by gel filtration chromatography using sphadex G 50. Crude enzyme obtained from pineapple rsquo s core has specific activity of 53,580 Unit mg. Fractionation by multilevel saturity of ammonium sulphate salt showed highest activity at 20 50 level of saturation, with a certain Activity of 230,970 Unit mg and a purity level of 8 times purer from crude enzymes. Further purification by Sephadex G 50 chromatography has increased secific activity to 431,548 Units mg with a purity level of 28 times from crude enzymes. The purest bromelain fraction activity test against pH and temperature variations showed the optimum pH of bromelain at pH 7 and optimum temperature of 37oC. In the variation of substrate concentration, by plotting curves of Michaelis Menten and Lineweaver Burk, obtained Michaelis Menten Km constant for bromelain enzyme is 0,777 and vmax value is 3,969 U min. The antiplatelet activity test showed that fractions of the bromelain enzyme from each purification step showed the ability of an antiplatelet agent. Highest antiplatelet activity in the purest enzyme fraction with aggregate percent value of 48,64 and percentage of inhibition 47,583 . IC50 of the purest enzyme fraction, is 88,314 L mL"