Computational studies and synthesis of 131iodine-labeled nocardiotide A analogs as a peptide-based theragnostic radiopharmaceutical ligand for cancer targeting SSTR2

Radiolabeled peptides belong to a highly specific group of radiotracers used in oncology, particularly for diagnostics and cancer therapy. With the notable advantages of high binding affinity and selectivity to cancer cells, they have proven to be very useful in nuclear medicine. As a result, efforts have been focused on discovering new peptide sequences for radiopeptide preparation. Nocardiotide A, a cyclic hexapeptide comprising the amino acids cyclo-Trp-Ile-Trp-Leu-Val-Ala (cWIWLVA) isolated from Nocardiopsis sp., has shown significant cytotoxicity against cancer cells, rendering it a suitable candidate for the process. Therefore, the present study aimed to design a stable and effective radiopeptide by labeling nocardiotide A with iodine-131 (131I), ensuring that its affinity to SSTR2 is not compromised. In silico study showed that structural modification of nocardiotide A labeled with 131iodine exhibited good affinity value, forming hydrogen bonds with key residues, such as Q.102 and T.194, which are essential in SSTR2. Based on the results, cyclic hexapeptides of cWIWLYA were selected for further synthesis, and its peptide product was confirmed by the presence of an ionic molecule peak m/z [M + Na]+ 855.4332 (yield, 25.60%). In vitro tests conducted on cWIWLYA showed that cWIWLYA can bind to HeLa cancer cells. Radiopeptide synthesis was initiated with radiolabeling of cWIWLYA by 131I using the chloramine-T method that showed a radiochemical yield of 93.37%. Non-radioactive iodine labeling reaction showed that iodination was successful, which detected the presence of di-iodinated peptide (I2-cWIWLYA) with m/z [M + Na]+ 1107.1138. In summary, a radiopeptide derived from nocardiotide A showed great potential for further development as a diagnostic and therapeutic agent in cancer treatment.

Computational Prediction of Resistance Induced Alanine-Mutation in ATP Site of Epidermal Growth Factor Receptor

Epidermal growth factor receptor (EGFR) resistance to tyrosine kinase inhibitors can cause low survival rates in mutation-positive non-small cell lung cancer patients. It is necessary to predict new mutations in the development of more potent EGFR inhibitors since classical and rare mutations observed were known to affect the effectiveness of the therapy. Therefore, this research aimed to perform alanine mutagenesis scanning on ATP binding site residues without COSMIC data, followed by molecular dynamic simulations to determine their molecular interactions with ATP and erlotinib compared to wild-type complexes. Based on the result, eight mutations were found to cause changes in the binding energy of the ATP analogue to become more negative. These included G779A, Q791A, L792A, R841A, N842A, V843A, I853A, and D855A, which were predicted to enhance the affinity of ATP and reduce the binding ability of inhibitors with the same interaction site. Erlotinib showed more positive energy among G779A, Q791A, I853A, and D855A, due to their weaker binding energy than ATP. These four mutations could be anticipated in the development of the next inhibitor to overcome the incidence of resistance in lung cancer patients.

A Search for Cyclin-Dependent Kinase 4/6 Inhibitors by Pharmacophore-Based Virtual Screening, Molecular Docking, and Molecular Dynamic Simulations

The G1 phase of cell cycle progression is regulated by Cyclin-Dependent Kinase 4 (CDK4) as well as Cyclin-Dependent Kinase 6 (CDK6), and the acivities of these enzymes are regulated by the catalytic subunit, cyclin D. Cell cycle control through selective pharmacological inhibition of CDK4/6 has proven to be beneficial in the treatment of estrogen receptor-positive (ER-positive) breast cancer, particularly improving the progression-free survival of patients. Thus, targeting specific inhibition on CDK4/6 is bound to increase therapeutic efficiency. This study aimed to obtain CDK4/6 inhibitors through a pharmacophore-based virtual screening of the ZINC15 purchasable compound database using the in silico method. The pharmacophore model was designed based on the FDA-approved cdk4/6 inhibitor structures, and molecular docking was performed to further screen the hit compounds obtained. A total of eight compounds were selected based on docking results and interactions with CDK4 and CDK6, using palbociclib as the reference drug. According to the results, the compounds of ZINC585292724 and ZINC585291674 were the best compounds based on free binding energy, as well as hydrogen bond stability, and, therefore, exhibit potential as starting points in the development of CDK4/6 inhibitors.

Identifikasi Mikroba dan Analisis Kandungan Gizi dari Bahan Pangan Tradisional Gatot dan Modifikasinya

Gatot merupakan pangan olahan tradisional dari singkong yang mempunyai potensi sebagai bahan pangan pengganti, namun kualitas hasil produksi dari industri kecil sering kali kurang terjamin dan berpotensi merugikan kesehatan. Penelitian ini bertujuan untuk mengidentifikasi mikroba dan nutrisi yang terdapat dalam gatot tradisional serta serta membandingkannya dengan gatot modifikasi yang dibuat sendiri. Gatot modifikasi dibuat melalui fermentasi fase padat menggunakan pembungkus yang berbeda yaitu plastik, daun pisang dan kain. Hanya gatot modifikasi yang difermentasi dalam plastik yang menunjukkan hasil yang mendekati dengan gatot yang diproduksi di daerah asli yaitu Pacitan, dengan warna hitam pada bagian dalam dan luar, tekstur kenyal, aroma khas tidak menyengat, dan rasa gurih. Terdapat pertumbuhan Aspergillus flavus dan Aspergillus niger, Pseudomonas aeruginosa dan bakteri asam laktat Pediococcus sp pada gatot tradisional. Sampel gatot modifikasi yang difermentasi di dalam plastik teridentifikasi mengandung bakteri asam laktat Pediococcus sp dan ragi. Sedangkan sampel yang difermentasi di dalam daun pisang mengandung A. flavus dan Saccharomyces cerevicae dan Gatot yang difermentasi di dalam kain mengandung A. niger. Gatot hasil fermentasi dalam plastik memiliki kadar protein paling tinggi dibandingkan sampel lain yaitu sebesar 3,8 %, meningkat jika dibandingkan kadar protein singkong mentah. Logam berat Pb dan Cd tidak ditemukan pada semua sampel gatot. Kandungan Fe ditemukan dengan kadar sebesar 8,19 ppm pada gatot industri tradisional sedangkan gatot modifikasi memiliki kadar besi yang sangat rendah.  

Virtual screening of curcumin analogues as DYRK2 inhibitor: Pharmacophore analysis, molecular docking and dynamics, and ADME prediction

Background: Curcumin reduces the proliferation of cancer cells through inhibition of the DYRK2 enzyme, which is a positive regulator of the 26S proteasome. Methods: In the present work, curcumin analogues have been screened from the MolPort database using a pharmacophore model that comprised a ligand-based approach. The result of the screening was then evaluated by molecular docking and molecular dynamics based on binding the free energy of the interaction between each compound with the binding pocket of DYRK2. The hit compounds were then confirmed by absorption, distribution, metabolism, and excretion (ADME) prediction. Results: Screening of 7.4 million molecules from the MolPort database afforded six selected hit compounds. By considering the ADME prediction, three prospective curcumin analogues have been selected. These are:  2‐[2‐(1‐methylpyrazol‐4‐yl)ethyl]‐1H,5H,6H,7H,8H‐imidazo[4,5‐c]azepin‐4‐one (Molport-035-369-361), methyl 4‐(3‐hydroxy‐1,2‐oxazol‐5‐yl)piperidine‐1‐carboxylate (Molport-000-004-273) and (1S)‐1‐[5‐(furan‐3‐carbonyl)‐4H,6H,7H‐pyrazolo[1,5‐a]pyrazin‐2‐yl]ethanol (MolPort-035-585-822). Conclusion: Pharmacophore modelling, combined with molecular docking and molecular dynamics simulation, as well as ADME prediction were successfully applied to screen curcumin analogues from the MolPort database as DYRK2 inhibitors. All selected compounds that have better predicted pharmacokinetic properties than that of curcumin are considered for further study.

Optimasi Nanoemulsi Natrium Askorbil Fosfat melalui Pendekatan Design of Experiment (Metode Box Behnken)

Penghantaran senyawa hidrofilik secara transkutan memiliki keterbatasan karena permeabilitas rendah sehingga sulit dalam menembus lapisan stratum corneum (SC). Natrium askorbil fosfat (NAF) merupakan salah satu senyawa turunan vitamin C yang sangat hidrofil dan permeabilitas rendah terhadap lapisan kulit. Sebagaimana vitamin C, NAF dapat berfungsi sebagai antioksidan juga memiliki aktivitas sebagai antikerut karena dapat memicu pertumbuhan kolagen pada fibroblast. NAF dibuat dalam nanoemulsi, karena sediaan dengan ukuran globul yang kecil diharapkan dapat menembus lapisan SC dan membawa zat aktif berpenetrasi ke dalam lapisan kulit. Optimasi formulasi nanoemulsi dilakukan melalui pendekatan statistik design of experiment (DoE) yang terdiri dari desain faktorial dan respon surface methods (RSM hingga diperoleh hasil yang lebih efektif dan efisien. Komposisi minyak (VCO), surfaktan (Tween 80), ko surfaktan (PEG 400) dan proses pengadukan (waktu dan kecepatan) merupakan faktor yang berperan dalam optimasi formulasi. Penentuan faktor tersebut melalui desain eksperimen 2 level factorial dan dilanjutkan dengan metode Box Behnken menggunakan perangkat lunak Minitab 17. Parameter yang diamati adalah ukuran globul dan indeks polidispersitas. Berdasarkan hasil optimasi diperoleh nilai VCO 10% dan kombinasi surfaktan 24%, waktu dan kecepatan pengadukan 5 menit, 200 rpm memberikan ukuran globul ±180 nm dan indeks polidispersitas dibawah 0,5. 

ISOLATE OF HETEROTROPHIC MICROALGAE AS A POTENTIAL SOURCE FOR DOCOHEXAENOIC ACID (DHA)

Docosahexaenoic acid (DHA) is one of essential fatty acids that are beneficial to health. Nowadays, the source of docosahexaenoic acid (DHA) is mainly obtained from fish which are extracted into fish oil products. However, the fish oil products still have some drawbacks in term of purity, acceptable flavor for costumers, and also their not environmental friendly production process. As an alternative solution, heterotrophic microalgae can be used as a potential source for DHA due to their excellence compared to fish oil products. The aim of this study is to isolate the heterotropic microalgae that can produce DHA. The heterotrophic microalgae were isolated from mangrove fallen leaves (Rhizophora apiculata) by using direct planting method. The morphology of pure microalgae colony were observed through light microscope and subsequently fermented for 14 days. Fatty acids were extracted and methylated through direct transesterification method. Identification and quantification of DHA were conducted by using gas chromatography. The results were four isolates of heterotropic microalgae, namely MTKC1, MTKC2, MTKC3, and MTKC4. The extract of MTKC2 that only showed the content of DHA with value of 9.2 % w/w. Therefore MTKC2 is a potential source for DHA. The MTKC2 was further identified by using molecular biology method and confirmed as Thraustochytrium aureum.

In Silico Study, Synthesis, and Cytotoxic Activities of Porphyrin Derivatives

Five known porphyrins, 5,10,15,20-tetrakis(p-tolyl)porphyrin (TTP), 5,10,15,20-tetrakis(p-bromophenyl)porphyrin (TBrPP), 5,10,15,20-tetrakis(p-aminophenyl)porphyrin (TAPP), 5,10,15-tris(tolyl)-20-mono(p-nitrophenyl)porphyrin (TrTMNP), 5,10,15-tris(tolyl)-20-mono(p-aminophenyl)porphyrin (TrTMAP), and three novel porphyrin derivatives, 5,15-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-10,20-di(p-tolyl)porphyrin (DBECPDTP), 5,10-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-15,20-di-(methylpyrazole-4-yl)porphyrin (cDBECPDPzP), 5,15-di-[bis(3,4-ethylcarboxymethylenoxy)phenyl]-10,20-di-(methylpyrazole-4-yl)porphyrin (DBECPDPzP), were used to study their interaction with protein targets (in silico study), and were synthesized. Their cytotoxic activities against cancer cell lines were tested using 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide (MTT) assay. The interaction of porphyrin derivatives with carbonic anhydrase IX (CAIX) and REV-ERBβ proteins were studied by molecular docking and molecular dynamic simulation. In silico study results reveal that DBECPDPzP and TrTMNP showed the highest binding interaction with REV- ERBβ and CAIX, respectively, and both complexes of DBECPDPzP-REV-ERBβ and TrTMNP-CAIX showed good and comparable stability during molecular dynamic simulation. The studied porphyrins have selective growth inhibition activities against tested cancer cells and are categorized as marginally active compounds based on their IC₅₀.

KARAKTERISASI DAN PEMURNIAN ZEOLIT ALAM LAMPUNG SEBAGAI KANDIDAT ANTIDOTUM KERACUNAN TIMBAL

Indonesia memiliki kelimpahan zeolit yang berpotensi dapat dikembangkan  sebagai zeolit yang berderajat farmasi. Penelitian ini bertujuan untuk mendapatkan zeolit olahan dengan karakteristik yang cocok sebagai bahan baku farmasi. Zeolit alam diproses dengan cara pencucian menggunakan masing-masing larutan HCl, aquabidest, dan EDTA lalu diikuti dengan pemanasan pada 350 °C. Sebelum dan sesudah pengolahan sampel zeolit dikarakterisasi menggunakan berbagai metode instrumental. Selanjutnya, zeolit olahan diuji kemampuannya untuk menjerap parasetamol dan timbal. Hasil analisis menunjukkan bahwa komposisi sampel zeolit > 91% berjenis klinoptilolit dengan kandungan utama unsur Si, Al dan K. Setelah pencucian dengan larutan HCl 1 M, EDTA 0,1 M dan aquabidest, kadar As dalam masing-masing sampel zeolit 4,12 ± 0,75 ppm, < 0,1 ppm dan 11,8 ± 0,56 ppm dan kadar Pb untuk seluruh sampel < 1 ppm, sedangkan Cd dari semua sampel < 1 ppm. Tidak ada perubahan struktur dalam sampel zeolit yang teramati setelah proses pencucian dan pemanasan. Zeolit yang dicuci dengan larutan EDTA mampu menjerap Pb dalam cairan lambung buatan tanpa pepsin secara efektif dengan penurunan kadar hingga 89% namun tidak mampu menjerap parasetamol secara efektif. Disimpulkan bahwa hasil proses zeolit menunjukkan karakteristik yang cocok sebagai kandidat bahan baku farmasi. Zeolit yang diberi perlakuan dengan EDTA mampu menjerap Pb secara efektif sehingga berpeluang digunakan sebagai antidot lokal dalam kasus keracunan Pb akut.Kata kunci: zeolit, klinoptilolit, logam berat. CHARACTERIZATION AND PURIFICATION OF NATURAL LAMPUNG ZEOLITE AS A CANDIDATE OF ANTIDOTE OF LEAD INTOXICATIONABSTRACTIndonesia has the abundance potential of zeolites having possibility to be developed as pharmaceutical grade zeolites. This research aimed to obtain processed zeolite showing suitable characteristics as pharmaceutical ingredient. Natural zeolite was processed by means of washing using dilute HCl, aquabidest and EDTA solutions, respectively and subsequently followed by heating at 350 oC. Prior and after processing, the zeolite samples were characterized using various instrumental methods. Furthermore, the processed zeolite was tested for its ability to adsorb paracetamol and lead. The analysis results confirmed that the composition of zeolite samples were > 91% of clinoptilolite mainly composed of Si, Al and K. After washing with 1 M HCl, 0.1 M EDTA and aquabidest, the level of As in each of zeolite samples were 4.12 ± 0.75 ppm, < 0.1 ppm and 11.8 ± 0.56 ppm and those of Pb were all < 1 ppm, while those of Cd from all samples were < 1 ppm, respectively. No structural changes in zeolite samples were observed after washing and heating treatment. EDTA treated zeolite was able to adsorb Pb in artificial gastric fluid without pepsin effectively up to 89% reduction but failed to adsorb paracetamol effectively. It was concluded that processed natural zeolite was suitable as a pharmaceutical ingredient. EDTA-treated zeolite was able to adsorb Pb effectively and hence could be possibly applied as local antidote in the case of acute Pb intoxication.Keywords: zeolite, clinoptilolite, heavy metals.

STIGMASTEROL CONTENT OF ARTEMISIA ANNUA L. AND THE PHYTOSTEROL PROFILE

<p>ABSTRACT<br />Objective: To find the stigmasterol source of Artemisia annua L. and to study the profile of phytosterol types in A. annua hairy root cultures.<br />Methods: Stigmasterol content determination was done based on stigmasterol content in the methylene chloride extract of A. annua using high<br />performance liquid chromatography in wild-type plant, plant tissue cultures, and hairy root cultures. The optimal resolution was achieved by<br />suitability system, and stigmasterol calibration curve was generated with stigmasterol concentrations series. Phytosterol types in A. annua hairy root<br />cultures were performed by gas chromatography-mass spectrophotometry.<br />Results: Highest stigmasterol content in A. annua is shown by hairy root cultures of A. annua in the 5<br /> week harvesting time, which is 1.5 g/100 g (w/w)<br />extract. The phytosterol profile in A. annua hairy root cultures encompassed stigmasterol 74.6%, β-sitosterol 13.5%, and campesterol 11.9%.<br />th<br />Conclusion: A. annua hairy root cultures in 5-week harvesting time prove its potential as stigmasterol source alternative. The highest phytosterol type<br />in A. annua hairy root cultures is stigmasterol. This is the first report stigmasterol content and its phytosterol profile of A. annua hairy root cultures<br />extract.<br />Keywords: Artemisia annua L., Wild-type plant, Plant tissue cultures, Hairy root cultures, Stigmasterol.</p>

Tetrabutylammonium methacrylate as a novel receptor for selective extraction of sulphonylurea drugs from biological fluids using molecular imprinting

Glibenclamide (GLIB), an oral antidiabetic medication of the sulphonylurea drug family, was stoichiometrically imprinted using tetrabutylammonium methacrylate as the functional monomer, for the first time in molecular imprinting, and utilising the sulphonylurea affinity for carboxylate anions. Solution association between the drug and the novel functional monomer was studied by ¹H-NMR titrations, whereby evidence of sulphonylurea deprotonation followed by the formation of "narcissistic" GLIB dimers was found when tested in CDCl₃, while an affinity constant in excess of 10⁵ L mol^-1 was measured in DMSO-d₆. Detailed analysis of GLIB binding on the subsequently prepared imprinted and non-imprinted polymers confirmed the deactivation of binding sites by exchange of a proton between GLIB and methacrylate, followed by extraction of the tetrabutylammonium counterion from the polymer matrix, resulting in overall reduced binding capacities and affinities by the imprinted material under equilibrium conditions. An optimised MI-SPE protocol, which included a binding site re-activation step, was developed for the extraction of GLIB from blood serum, whereby recoveries of up to 92.4% were obtained with an exceptional sample cleanup.

Optimasi Reaksi Transesterifikasi Minyak Kelapa Sawit (Elaeis guineensis Jacq.) dan Penetapan Kadar Metil Ester Asam Lemak Menggunakan Kromatografi Gas

Indonesia merupakan produsen minyak kelapa sawit (Elaeis guineensis Jacq.) terbesar di dunia. Pengolahan menjadi produk turunannya dapat meningkatkan nilai ekonomi minyak kelapa sawit. Salah satu produk turunannya adalah metil ester asam lemak yang memiliki banyak kegunaan dalam industri pangan, farmasi dan kosmetik. Metil ester asam lemak dihasilkan melalui reaksi transesterifikasi minyak kelapa sawit. Penelitian ini bertujuan untuk menentukan kondisi optimum reaksi transesterifikasi minyak kelapa sawit. Optimasi diamati berdasarkan penetapan kadar metil ester asam lemak secara semikuantitatif menggunakan metode kromatografi gas. Metil ester asam lemak disintesis dari minyak kelapa sawit menggunakan katalis natrium hidroksida dan kalium hidroksida masing-masing pada suhu 40, 50 dan 60 ºC selama 1, 2 dan 3 jam. Metil ester asam lemak yang diperoleh dinetralkan dan dicuci. Baku metil ester asam lemak disintesis dari asam palmitat. Kadar metil ester asam lemak ditentukan menggunakan kromatografi gas dengan kolom DB-Wax 30 m x 0,25 mm, detektor FID, dan kondisi oven pada suhu 50 ºC selama 1 menit, kemudian dinaikkan 25 ºC /menit sampai 200 ºC, lalu dinaikkan kembali 3 ºC /menit sampai 230 ºC dan ditahan selama 18 menit. Kadar asam lemak bebas dari minyak kelapa sawit dan metil ester asam lemak ditentukan dengan metode titrasi. Rata-rata bobot hasil reaksi transesterifikasi menggunakan katalis natrium hidroksida dan kalium hidroksida adalah masing-masing 84,63±2,63 dan 84,25±4,77 g. Rata-rata kadar asam lemak bebas metil ester asam lemak hasil reaksi transesterifikasi menggunakan katalis natrium hidroksida dan kalium hidroksida adalah 0,68±0,03% dan 0,65±0,03 %. Kondisi optimum reaksi transesterifikasi minyak kelapa sawit (Elaeis guineensis Jacq.) menggunakan katalis natrium hidroksida dan kalium hidroksida masing-masing adalah pada suhu 60 ºC selama 1 jam, sebesar 34,20% (b/v) dan pada suhu 50 ºC selama 2 jam, sebesar 32,40% (b/v).Kata kunci: Transesterifikasi, minyak kelapa sawit, metil ester asam lemak, kromatografi gas, katalis basa. AbstractIndonesia is the largest producer of crude palm oil (Elaeis guineensis Jacq.) in the world. Processing into derived products can increase the economic value of crude palm oil. One of the derived products is the fatty acid methyl esters that have many uses in the food, pharmaceuticals and cosmetic industry. Fatty acid methyl ester is produced through transesterification reaction of crude palm oil. The aim of this research is to obtain the optimum condition of transesterification reaction of crude palm oil. Optimization was observed by the assay of fatty acid methyl esters as semi-quantitative using gas chromatography method. Fatty acid methyl esters were synthesized from crude palm oil using catalysts sodium hydroxide and potassium hydroxide respectively at 40, 50 and 60 ºC for 1, 2 and 3 hours. The fatty acid methyl esters obtained were neutralized and washed. The standard of fatty acid methyl ester was made by palmitic acid synthesis. The assay of fatty acid methyl esters was carried out using gas chromatography equipped with 30 m x 0,25 mm DB-Wax column, flame ionization detector (FID), using oven temperature at 50 °C, 1 minute, 25 °C /minute to 200 °C, 3 °C /minute to 230 °C, 18 minutes and determination of free fatty acid content from crude palm oil and fatty acid methyl esters. The average mass of the result of the transesterification reaction using sodium hydroxide and potassium hydroxide as catalyst were 84.63±2.63 and 84.25±4.77 g, respectively. The average of free fatty acid content of fatty acid methyl ester synthesized using sodium hydroxide and potassium hydroxide as catalyst were 0.68±0.03 % and 0.65±0.03 %. The optimum conditions of the transesterification reaction of crude palm oil (Elaeis guineensis Jacq.) using sodium hydroxide and potassium hydroxide as catalyst were at 60 ºC for 1 hour and at 50 ºC for 2 hours, which were 34.20% (w/v) and 32.40% (w/v), respectively.Keywords: Transesterification, crude palm oil, fatty acid methyl ester, gas chromatography, base catalyst.

Modifikasi Metode Penentuan Amina Aromatik Primer Tidak Tersulfonasi dalam Bahan Baku Zat Warna Tartrazin Dihitung sebagai Anilina secara Spektofotometri UV-Sinar Tampak

Senyawa amina aromatik primer tidak tersulfonasi merupakan suatu cemaran yang dapat ditemukan di dalam zat warna. Disebabkan toksisitasnya, kadar cemaran ini dibatasi pada tingkat maksimum tertentu, secara khusus ditetapkan sebagai anilina dengan batas maksimum sebesar 100 ppm. Pada kompendial resmi yang dikeluarkan oleh Joint FAO/WHO Expert Committee on Food Additives (JECFA) penentuan senyawa amina aromatik primer tidak tersulfonasi dilakukan melalui reaksi diazotisasi dan kopling diazo dengan menggunakan senyawa garam natrium 2-naftol-3,6 disulfonat sebagai pereaksi pengkopling. Penelitian ini bertujuan untuk mendapatkan metode alternatif pada penentuan kadar amina aromatik primer tidak tersulfonasi dalam tartrazin, sebagai zat warna yang paling banyak digunakan di Indonesia, menggunakan 2-naftol sebagai pereaksi pengkopling. Anilina diekstraksi dari tartrazin dengan menggunakan toluen pada pH 12,3 dan kemudian diekstraksi kembali dari fasa organik dengan menggunakan larutan asam hidroklorida 3 N. Anilina yang terlarut dalam bentuk garam klorida mengalami reaksi dengan asam nitrit, yang diperoleh secara in situ dengan mereaksikan natrium nitrit dan asam hidroklorida, membentuk suatu garam diazonium. Untuk menghilangkan kelebihan asam nitrit dilakukan penambahan urea ke dalam campuran reaksi. Garam diazonium kemudian dikopling dengan 2-naftol pada pH 9,0. Absorbansi larutan diukur pada panjang gelombang 540 nm. Metode ini memberikan kurva kalibrasi linier pada rentang konsentrasi 2-10 ppm dengan persamaan garis regresi Y = 0,0952X "“ 0,0005 dan r2 = 0,9997. Batas deteksi dan batas kuantisasi metode ini dihitung secara statistik sebesar 0,16 dan 0,54 ppm. Perolehan kembali kadar anilina dalam tartrazin dengan menggunakan metode penambahan baku pada konsentrasi 0,6; 0,8 dan 0,9 ppm adalah 82,7; 86,7 dan 85,6% dengan nilai simpangan baku relatif (RSD) pada semua penetapan kurang dari 5%. Berdasarkan hasil tersebut, dapat disimpulkan bahwa metode ini dapat digunakan sebagai metode alternatif dari metode resmi yang terdapat dalam compendium JECFA untuk penentuan amina aromatik primer tidak tersulfonasi dalam tartrazin.Kata kunci: amina aromatik primer tidak tersulfonasi, anilina, tartrazin, 2- naftol, diazotisasi, kopling, spektrofotometri.Unsulfonated primary aromatic amines are impurities which could be present in food colours. Due to their toxicities, the concentration of these impurities is limited to a certain maximum level, typically stated as aniline with the maximum level of 100 ppm. The official compendium of Joint FAO/WHO Expert Committee on Food Additives (JECFA) describes the determination of unsulfonated primary aromatic amines applying diazotation reaction in which 2-naphthol-3,6 disulfonic acid disodium salt is used as coupling reagent. The aim of this research was to obtain alternative method for the determination of unsulfonated primary aromatic amines in tartrazine as the most applied food colours in Indonesia using 2-naphthol as coupling reagent. Aniline was extracted from tartrazine using toluene under pH value of 12.3 and then re-extracted from organic phase using a 3 N hydrochloric acid solution. Aniline dissolved as hydrochloric acid salt was reacted with nitrous acid produced in situ from sodium nitrite and hidrochloric acid to form a diazonium salt. To remove excess nitrous acid urea was added to reaction mixture. The diazonium salt was then coupled with 2-naphthol under pH value of 9.0. The Absorbance of the solution was then measured at 540 nm. This method gave a linear calibration curve in the concentration range of 2.0 to 10 ppm with a regression equation of Y = 0.0952X "“ 0.0005 and r2 = 0.9997. The limit of detection and limit of quantification of this method were statistically calculated to be 0.16 and 0.54 ppm, respectively. The recovery of tartrazine at the concentration levels of 0.6, 0.8 and 0.9 were respectively determined using standard addition method and found to be 82.7, 86.7 and 85.6%. The relative standard deviations of all the determinations were less than 5%. Based on these results, it was concluded that this method was suitable to applied as alternative method to official method described in the official compendium of JECFA for the determination of unsulfonated primary aromatic amines in tartrazine.Keywords: unsulfonated primary aromatic amine, aniline, tartrazine, 2-naphtol, diazotization, coupling, spectrophotometry

QUERCETIN DERIVATIVES DOCKING BASED ON STUDY OF FLAVONOIDS INTERACTION TO CYCLOOXYGENASE-2

Due to their ability to inhibit cyclooxygenase-2 (COX-2), certain flavonoids show anti-inflammatory effects. Quercetin is a flavonoid suitable to be chosen as the lead compound for development of safe anti-inflammatory agent, because in addition to its anti-inflammatory effect, quercetin shows also protective effect in gastrointestinal track. The objective of this research is to study the binding modes of certain flavonoids and predict the quercetin derivatives inhibiton activity on COX-2 by means of docking method using ArgusLab 4.0.1 software. Some flavonoids (7-hydroxyflavone, apigenin, galangin, kaempferol, quercetin, naringenin and daidzein) and quercetin derivatives were used as ligands for docking study. The COX-2 structure was obtained from Brookhaven protein databank. After assigning hydrogen atoms and charges, computational docking was performed. The docking results were evaluated based on the binding energy and hydrogen bonding of  the ligands on binding site of COX-2. A curve constructed by plotting binding energy versus logarithm of IC50 of flavonoids shows a good correlation with a regression equation of log IC50 = 0.8069 ΔGbind + 9.4456 (r = 0.9226; P