Jurnal Riset Kimia
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Pengembangan Sensor Kimia Berbasis Kertas Untuk Penetapan Kadar Kafein Sampel Kopi
Get PDFThe caffeine chemical sensor was developed by co-immobilizing sodium periodate (NaIO4), 3-methyl-2-benzothiazolinone hydrazone (MBTH), and acetic acid (CH3COOH) onto paper by using an adsorption technique. The addition of caffeine solution could change the color of the sensor from white to pale blue which can be then captured by using a flatbed scanner and quantified by the ImageJ program, known as a scanometric technique. Method validation such as linearity, LOD, LOQ, precision, and accuracy of the sensor was done by using caffeine standards. The result of caffeine analysis using the developed chemical sensor-scanometric method agreed with that of the spectrophotometric method, suggesting that the developed sensor with scanometric technique can be used as an alternative method for caffeine assay in coffee samples
Identification of Secondary Metabolites and FT-IR Analysis of Getih-Getihan Fruit Extract (Rivina humilis L.)
Get PDFGetih-getihan (Rivina humilis L.) plants can be used as antibacterial, antioxidant and natural pesticides. Most of the biological activities of natural products originated from secondary metabolites contained therein. Studies have shown the effects of leaves, branches, and fruits extract of R. humilis towards biological activities. However, identifying the phytochemical compounds of R. humilis L. fruit is less discussed. Here we proposed research on the identification of secondary metabolite compounds of R. humilis L. fruit extract using phytochemical screening tests and spectroscopic method. The extraction of R. humilis L. fruit was proceeded by maceration method using methanol solvent. The series of phytochemical screening tests signified the presence of alkaloids, terpenoids, tannins and flavonoids. Furthermore, we applied FT-IR analysis to confirm the existence of functional groups in the secondary metabolite compounds. A broad absorption band showed the hydroxyl groups (O-H) at 3265 cm-1. The sharp band at 1632 cm-1 exhibited the C=C stretching band. The presence of C-N (stretching) was signified by the absorption band at 1237 cm-1, while the C-H bond in CH3 terminals (alkanes, alkyl group) was exhibited at 1401 cm-1. All the functional groups confirmed in the FT-IR analysis corroborated the phytochemical test results
Identifikasi Struktur Protein Spike Varian Baru SARS-CoV-2 secara Bioinformatika dalam Pengembangan Kandidat Terapi COVID-19
Get PDFDespite the relatively slow evolutionary rate of SARS-CoV-2 in comparison to other RNA viruses, the extensive and rapid transmission during the COVID-19 pandemic has led to the emergence of significant genetic diversity since the virus first infected the human population. This has resulted in various variants, such as Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), among others. Of particular concern are the Delta Variant and newly recognized Variants of Concern (VOCs), including lineages of B.1.617.2, as well as other VOCs discovered through local transmission, such as Epsilon (B.1.427/29-US) and B1.1.7/E484K-UK. The interactions between these variants and the spike protein of SARS-CoV-2, as well as the Angiotensin-converting enzyme 2 (ACE2), have become a primary focus in understanding the infection and spread of the SARS-CoV-2 virus. This research aims to comprehensively identify, evaluate, and explore the structural characteristics of the macromolecular spike protein of SARS-CoV-2 in the Beta, Gamma, and Delta variants using bioinformatics approaches. The methods employed in this study include homology modeling, molecular docking simulations, and molecular dynamics simulations. The research findings indicate that the spike protein of SARS-CoV-2 in the Gamma variant exhibits a strong affinity for ACE2. Therefore, this study is expected to serve as a reference for designing effective vaccine or antiviral candidates targeting various SARS-CoV-2 variants in the treatment of COVID-19 infections
Identifikasi Aktivitas Biologis, Prediksi Toksisitas, dan Molecular Docking Senyawa Jubanine dari Tanaman Bidara Arab sebagai Kandidat Antivirus SARS-CoV-2
Get PDFCoronavirus disease (COVID-19) is a disease of the respiratory tract caused by the coronavirus (SARS-CoV-2). Jubanine A, jubanine B, jubanine C, jubanine G, and jubanine H compounds in the arabian bidara plant (Ziziphus spina-christi L.) are known to treat viral and bacterial infections. The purpose of this study was to test the affinity of the compounds jubanine A, jubanine B, jubanine C, jubanine G, and jubanine H in the arabian bidara plant to the non-structural protein 15 (Nsp15) receptor. This research was carried out by identifying the physicochemical properties of the test compounds using the swissADME server. After that, geometry optimization was performed using the Quantum ESPRESSO 6.6 software, then macromolecule preparation was accomplished using the BIOVIA Discovery Studio 2020 software. Furthermore, method validation and molecular docking simulations were demonstrated using MGLTools 1.5.6 software with AutoDock Tools 4.2. Then the analysis of the molecular docking results was carried out using the BIOVIA Discovery Studio 2020 software. Finally, the toxicity of the test compound was predicted using the Toxtree 3.1.0 software. Based on the results of free binding energy (∆G), jubanine H has the best affinity among the other five compounds with the lowest binding energy value of −6.51 kcal/mol
Struktur, Sifat Dielektrik dan Optik Senyawa Aurivillius (Ca0,5Ba0,5)Bi4Ti4O15 yang Disintesis dengan Teknik Lelehan Garam
Get PDFSynthesis of ferroelectric material based onAurivillius phases, (Ca0.5Ba0.5)Bi4Ti4O15 (CBBT), have been done using a molten salts technique.The results of X-ray diffraction (XRD) analysis showed the characteristic peaks at 2θ = 12.93°, 17.31°, 21.64°, 23.23°, 27.71°, 30.33°, and 32.90° which was correspond to the four-layers of Aurivillius phase.Refinement structure using the Le Bail method, the sample is suitable for orthorhombic structures with the A21am space group. The orthorhombicity of the CBBT is small and nearer to tetragonal symmetry.Fourier Transform Infra-red (FTIR) spectra show distortion of TiO6 octahedral at 847 cm-1 and strain vibrations of TiO6 octahedra at 545 cm-1 due to A-O bonds.Analysis using Scanning Electron Microscopy (SEM) shows the morphology of the sample in the form of plate-like which is characteristic of Aurivillius phase.The ferroelectric to paraelectric phase transition temperature (Tc) was obtained at 635ºC.The band gap value of the CBBT compound was 3.17 eV, relatively the same with the CaBi4Ti4O15 (CBT) compound
Pengaruh Lama Penyimpanan dan Pengenceran Lindi Hitam Terhadap Karakteristik Lignin Kraft Acacia mangium
Get PDFThis study aimed to investigate the effects of storage time and dilution of black liquor (BL) from Acacia mangium kraft pulping on the characteristics of isolated Lignin. Lignin isolation was carried out by 1 and 2 steps of isolation using HCL 1M to precipitate Lignin, diluted before isolation. Isolated Lignin was analyzed for its acid-soluble Lignin (ASL), insoluble acid lignin (AIL), functional groups by FTIR, solubility in dioxane and NaOH and thermal properties. The effect of BL storage time was also evaluated on the characteristics of the Lignin produced. The results suggest that the longer BL is stored, the higher the lignin yield. When compared to the isolation approach without dilution, the dilution process produced a higher yield and ash content up to 84% and 21%, respectively. Without dilution, the AIL isolated was lower than the dilution during BL storage. The longer the storage duration, the higher the lignin purity. Compared to two-step lignin isolation, dilution treatment in single-step isolation improves yield and purity. The thermal stability of lignin isolation without dilution (184 ⁰C and 167 ⁰C for 1 and 2 steps, respectively) was higher than that of isolated Lignin with dilution (154.8 ⁰C and 160.9 ⁰C for 1 and 2 steps, respectively), according to thermal study. Both lignin isolates with and without dilution have comparable functional groups, as shown by FTIR spectra. Due to the high yield and purity of isolated Lignin, BL dilution could be a viable alternative in lignin isolation from BL. Moreover, the properties of isolated Lignin are also influenced by BL storage
The Effect Of Sulphur (S) Doping and K+ Adsorption To The Electronic Properties Of Graphene: A Study By DFTB Method
Get PDFA study on the effect of S doping and K+ adsorption to the electronic properties of graphene has been conducted by DFTB (Density Functional Tight Binding) calculation. The supercell of 40 x 40 x 1 configured from the 4x4x1 unit cell of graphene was optimized. The calculation shows that the Fermi level of graphene shifted from -4.67 eV into -3.57 eV after S doping. In addition, the S presence caused the formation of gap within the Dirac K of valence band and conduction band. Meanwhile, K+ charge distribution was dominantly occurred within the S-graphene than the graphene
Ekstraksi Tanin dari Limbah Kulit Biji Asam dan Penggunaannya Sebagai Biomordan pada Pewarnaan Tenun Timor Secara Alami
Get PDFTannins from tamarind seed husk were extracted and applied as a biomordant for natural dyeing process of Timor woven fabrics. Tannins were extracted using hot distilled water, qualitatively and quantitatively analyzed and applied as a color binder to the woven fabrics. The color characteristics of woven fabrics with tannins were compared to the woven fabrics that mordanted with Al2(SO4)3 and FeSO4 at the concentration of 15%. Tamarind seed husk tannins are in the form of a brownish red powder. Qualitative and quantitative tests showed that tamarind seed coat contained condensed tannins with a total concentration of 70.08 ± 0.14%. Tannins identification by FT-IR spectroscopy showed a strong band absorption at 3369 cm-1 for O-H group and a weak absorption at 1721 cm-1 due to the C=O stretch. A strong absorption at 1611-1608 cm-1 was observed for C=C group in the aromatic ring and was strengthened with a strong absorption at 1520 cm-1, C-O-C group which is specific for condensed tannins was observed at 1285 cm-1. Application of 15% tannin as a biomordant without natural dye on Timor woven fabric produced a brownish red color, while the use of 15% tannin and turmeric dye showed a brownish yellow color. Tannin exhibited a better color fastness than metalic mordants in natural dyeing of Timor woven fabrics
Potensi Antimikroba dan Toksisitas Minyak Atsiri yang Diisolasi dari Biji Jintan (Carum carvi L.)
Get PDFCaraway (Carum carvi L.) is one of the oldest medicinal plants found in various countries such as West Asia, North Africa, Pakistan, India, North America, Northern Europe, Iran, Russia, and Indonesia. This plant has been use for traditional medicines to treat digestive disorders, flatulence, colic in infants, headaches, coughs, hypertension, eczema, pneumonia, diabetes, scabies, mouthwash and as an antiseptic. This plant is reported to contain around 1-9% essential oil in the seeds with various components and potential as bioactive compounds. In this study, essential oils were isolated from caraway seeds and determined their chemical content as well as their antimicrobial and toxicity. Isolation of essential oils was carried out by hydrodistillation and analysis of the chemical components of the isolated essential oils was carried out using the Gas Chromatography-Mass Spectrometry (GC-MS) method. The results of the GC-MS analysis showed the presence of 35 compounds with four main compounds, namely carvone (62.54%), limonene (23.39%), and trans-dihydrocarvone (8.20%). The antimicrobial activity test was carried out using the disc diffusion method, which showed strong activity against Staphylococcus aureus at a concentration of ≥75%, and against the fungus Candida albicans. The results of the toxicity test using the Brine Shrimp Lethality Test (BSLT) method showed that caraway seed essential oil was low toxic against Artemia salina Leach shrimp larvae with an LC50 value 568.3292 mg/L
Validation and Uncertainty Evaluation of an LC-DAD Method for Simultaneous Quantification of Benzoic Acid, Methylparaben, and N-Butylparaben in Soy Sauce
Get PDFChemical food preservation is the common strategy used by human to preserve the natural properties and to increase the shelf life of food. Although preservatives are useful to keep the food fresh and to stop the bacterial growth, there are certain preservatives that are harmful if taken in more than the prescribed limits. Some of the typical used—benzoic acid, methylparaben, and n-butylparaben—were employed in this work with the aim of establishing a simultaneous liquid chromatography (LC) method for detecting each in soy sauce matrices. Liquid and C18 solid phase extraction were performed in this procedure prior to LC using Diode Array Detector analysis. In gradient elution of a format buffer (pH 4.4) and acidified acetonitrile, the target components were successfully separated. Calibration curve ranged from 0.61–140 mg/kg linearly while the limit of quantification for benzoic acid, methylparaben, and n-butylparaben were 0.41, 0.10, and 0.11 mg/kg, respectively. The intermediate precision and recovery were in the range between 0.15-1.89% and 100.5-103.3%, respectively. The expanded uncertainty (k=2) in sample measurement was estimated at 3.4-6.5%. The offered method was conformed to the validation acceptance criteria and can be applied as a routine method in the laboratory at ppm level