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Articles by R.E. Kartasasmita
Total Records ( 4 ) for R.E. Kartasasmita
  R.E. Kartasasmita , R. Herowati and T. Gusdinar
  Some flavonoids, including quercetin, were reported to show inhibitory activities against inducible Nitric Oxide Synthase (iNOS), an isoenzyme responsible for nitric oxide formation. The objectives of this research are to obtain binding and inhibitory parameters of some quercetin derivatives on iNOS by means of docking method and prediction of their oral absorption and distribution properties. Seven selected flavonoids and ten quercetin derivatives were used as ligands for the study. The iNOS structure was obtained from Brookhaven protein databank (PDB ID: 1M9T) and docking study was performed using ArgusLab free software. Binding energy (ΔGbind) and hydrogen bond were used to analyze interactions between ligands and active site of iNOS. The PreADMET on line program was used to predict the oral absorption and distribution properties including permeability for Caco-2 cell, HIA (human intestinal absorption) and plasma protein binding. The results showed that hydrogen bonds formed between flavonoids and iNOS always involved the amide groups of glycine (A365) and trypsine (A366) residues in iNOS active site and 4-carbonyl group of flavonoids. In the docked form, the planar region of A-ring of flavonoids oriented to the heme plane of iNOS. Thus the 4-carbonyl group and planar region of A-ring of flavonoids are essential for the binding with iNOS. Linear regression of binding energy versus negative logarithm of IC50 of flavonoids gave an equation of -log IC50 = -0.399 ΔGbind- 5.608 (R2 = 0.686; p<0.01) and predicted IC50 of Quercetin was 76.79 μM. The human intestinal absorption (HIA) and Caco-2 cell permeability values of quercetin were 63.5% and 3.4 nm sec-1 while its plasma protein binding was 93.2%, respectively. Quercetin-3-O-acetate, 6,8-dichloroquercetin-3-O-acetate and 6-bromoquercetin-3-O-acetate showed lower predicted IC50 and better absorption and distribution properties than quercetin.
  M.R. Suwitono , R.E. Kartasasmita , J.S. Pamudji and S. Ibrahim
  Thiols such as N-acetylcystein (NAC) are used to replenish glutathione (GSH) level, with regard to their function in the maintenance of cellular reduction-oxidation balance and control of oxidative stress. Thiols play a role in the reductive metabolism of nitrates to NO, an important signaling molecule in the cardiovascular system as well as other systems throughout the body. This study aimed to evaluate the influence of NAC on decomposition of different organic nitrate esters according to its potential i.e., pentaerythrityl tetranitrate (PETN) and isosorbide dinitrate (ISDN). The results showed that NAC gives a rapid and significant decrease of PETN and ISDN during the incubation period. During the experiment, about 85% of PETN were decomposed, while the decomposition of ISDN was about 20%. Detection of nitrite and elucidation of disulphide bond of NAC gives evidence that confirms the presence of reactions.
  T. Gusdinar , R. Herowati , R.E. Kartasasmita and I.K. Adnyana
  Quercetin (3,5,7,3',4'-pentahydroxyflavone) was chosen as the lead compound in development of the anti-inflammatory agent due to its low gastric ulcer side effect in addition to its COX-2 and iNOS inhibitory activities. This study aims to obtain data showing antioxidant potency and anti-inflammatory activity of quercetin-3, 3’ and 4’-triacetate. Antioxidant potency was determined by DPPH radical scavenging and lipid peroxidation inhibitory methods, while anti-inflammatory activity was determined using carrageenan induced-rat paw oedema test. The results showed that the anti-inflammatory activity of quercetin-3, 3’ and 4’-triacetate was significantly higher than that of quercetin. Percentage of oedema inhibition of quercetin-3, 3’, 4’-triacetate and quercetin was 14-49 and 2-8%, respectively. However antioxidant activity of quercetin-3, 3’ and 4’-triacetate was lower than that of quercetin. IC50 of quercetin-3, 3’, 4’-triacetate and quercetin applying DPPH radical scavenging method was 325.57 and 16.23, respectively, while that of lipid peroxidation inhibitory method was 161.5 and 5.25, respectively.
  Asmiyenti D. Djalil , R.E. Kartasasmita , Slamet Ibrahim and Daryono Hadi Tjahjono
  Tetrapyrrolic macrocycles bearing carboxylic acid groups have received considerable interest as photosensitizing agent for Photodynamic Therapy (PDT). It is necessary to consider the toxic potency of those compounds. The present study was designed to predict the toxicities of tetrapyrrolic compounds using Ecological Structure Activity Relationships (ECOSAR) and Toxtree, for further use in design and synthesis of photosensitizers. The ECOSAR prediction showed that tetrapyrrolic macrocycles with more carboxylic acid groups or hydroxyl groups showed lower toxic potency than those with fewer carboxylic acid groups or hydroxyl groups. Toxicities estimation using Toxtree to human and based on the Cramer rules, Verhaar, Structural Alerts for Reactivity in Toxtree (START) biodegradability, eye irritation/corrosion and skin irritation/corrosion, all of the compounds fell into class 3, 5, 2, 1 and 1, respectively. Application of the Benigni-Bossa method showed that all studied compounds had structural alerts for genotoxic carcinogenicity. Cytochrome P-450 mediated drug metabolism was positive for all site of metabolism except for PPIX-1OH and PPIX-2OH. Most of the studied tetrapyrrolic compounds fell into unreactive group of compounds by Michael addition classification, except for purpurin 7 and rhodin g7. Skin sensitization evaluation of all compounds were alert to Michael acceptor, except for BPhe a-OH. Moreover, Kroes Threshold of Toxicological Concern (TTC) decision tree had negligible risk for all compounds.
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