Eclética Química

In vitro and in silico evaluation of the antimicrobial potential of Celtis zenkeri roots volatile metabolites

Mon, 04 Nov 2024 00:00:00 -0300

This study is aimed at investigating the volatile constituents of the air-dried roots of Celtis zenkeri. The volatile oil was extracted using hydro-distillation method and characterised using gas chromatography-mass spectrometry (GC-MS). The volatile oil was screened against six selected bacteria and four fungi strains using the agar diffusion method. The molecular docking study of the identified compounds was conducted to investigate their binding pattern with the substrate and nucleotide complexes of Enterococcus faecium aminoglycoside-2’’-phosphotransferase-IIa [APH(2’’)-IIa] (PDB ID: 3HAM) and full-length Lanosterol 14 alpha-Demethylases of Prominent fungal pathogens Candida albicans (PDB ID: 5V5Z). The yield of the volatile oil (% w/w) root of C. zenkeri was 0.79%. Six compounds were identified in the root essential oil representing 80.07% of the volatile oil. 2-methyl-1-pentene (40.01%) was the most abundant compound in the root essential oil. The volatile oil from roots of the C. zenkeri exhibited good activity against all the screened bacteria and fungi strains at a concentration of 12.5-100 mg/mL when compared with Gentamicin for bacteria and Tioconazole for fungi.

Predicting the biological activity of selected phytochemicals in Alsophila spinulosa leaves against 4-aminobutyrate-aminotransferase: A potential antiepilepsy agents

Wed, 03 Jan 2024 00:00:00 -0300

The use of medicinal plants as an alternative mean of treating various diseases has drawn the attention of several researchers. The desire to find lasting solutions to epilepsy among humans increases every day. Thus, this work was aimed at investigating the potential capacity of the studied phytochemicals in Alsophila spinulosa against human 4-aminobutyrate-aminotransferase as well as to predict the nonbonding interactions involved in the studied complexes. In this work, ten compounds with biological activities were selected and studied using molecular docking method. The molecules selected obtained from A. spinulosa leaves were optimized and various descriptors that described the anti-4-aminobutyrate-aminotransferase features were obtained. More so, 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-3-(((2S,3R,4R,5R,6S)-3,4,5-trihydroxy-6-methyltetrahydro-2H-pyran-2-yl)oxy)-4H-chromen-4-one (compound 9) with highest binding affinity proved to have greater strength to inhibit 4-aminobutyrate-aminotransferase thereby downregulating epilepsy than other studied compounds and the reference drug (clobazam). The ADMET features of both compound 9 and clobazam were explored and reported.

Phytochemical screening, antiproliferative evaluation, and molecular docking studies of Acacia nilotica fruit from Nigeria

Thu, 18 Jan 2024 00:00:00 -0300

Acacia nilotica, (Fabaceae), is valued for its medicinal properties. We examine the antiproliferative properties of the aqueous fruit extract of A. nilotica. Aqueous extract from Acacia has been associated with potential anticancer effects in fruits and vegetables through screening, antiproliferative, and molecular docking evaluation. Phytochemical screening reveals the presence of alkaloids, saponins, tannins, flavonoids, steroids, and carbohydrates. The extracts showed significant antiproliferative effects at eight concentrations (8–50 mg mL^–1) examined in comparison to the standard (methotrexate). When compared to Sorghum bicolor seed radicles treated with methotrexate at 48, 72, and 96 h, 50 mg mL^–1 extract significantly inhibited the generation of seed radicals, with potent inhibitions of 87.06, 83.48, and 81.45%. Analysis of molecular docking results showed that [(2R,3S)-2-(3,4-dihydroxyphenyl)-3,5-dihydroxy-3,4-dihydro-2H-chromen-7-yl]3,4,5-trihydroxybenzoate (D21), (5R,9R,10R,13S,14S,17S)-17-[(2S,4R)-4-[(2S)-3,3-dimethyloxiran-2-yl]-4-hydroxybutan-2-yl]-4,4,10,13,14-pentamethyl-1,2,5,6,9,11,12,15,16,17-decahydrocyclopenta[a]phenanthren-3-one (D28) and [(2R,3S)-2-(3,4-dihydroxyphenyl)-3,7-dihydroxy-3,4-dihydro-2H-chromen-5-yl] 3,4,5-trihydroxybenzoate (D29) have strong tendency to inhibit dihydrofolate reductase (1VDR), capase-9 (6J15) and Mycobacterium tuberculosis (Mtb) (6J17) better than methotrexate and azacitidine, known antiproliferative drugs. These findings support the use of A. nilotica in traditional medicine for the treatment of tuberculosis and cancer.

Complex compound of trinitrotriamminecobalt(III): in theoretical studies

Deni Ainur Rokhim, Muhammad Roy Asrori, Husni Wahyu Wijaya — Fri, 16 Feb 2024 00:00:00 -0300

[Co(NH₃)₃(NO₂)₃] is an octahedral complex compound that can have several isomers. The complex compound has magnetic properties. Its stability has been explained. It can be easily synthesized and is known as a bioinorganic synthesis reagent, oxidant compound and base hydrolysis.

Determination of amoxicillin: A penicillin antibiotic in pharmaceutical dosage samples by spectrophotometric method

Chand Pasha — Fri, 29 Mar 2024 00:00:00 -0300

New coupling agents such as 2,4-toluene diamine or sulphanilamide for the determination of amoxicillin spectrophotometrically are described. These methods are straightforward based on the reaction of amoxicillin with diazotized products of 2,4-toluene diamine or sulphanilamide to produce coloured azo dyes with maximum absorption at 462 or 468 nm. Amoxicillin responds linearly from 1.2–24.8 or 1.8–32.0 mg mL^–1 when coupled with diazotized 2,4-toluene diamine or sulphanilamide. The molar absorptivity and Sandell’s sensitivity of amoxicillin with 2,4-toluene diamine or amoxicillin with sulphanilamide azo dyes were 3.307 × 10⁴ or 2.632 × 10⁴ L mol^–1cm^–1 and 1.105×10^-2 or 1.388×10^-2 mg cm^-2, respectively. The regression equation, correlation coefficient (R²), detection limit and quantitation limit of amoxicillin with 2,4-toluene diamine or amoxicillin with sulphanilamide were evaluated. The percentage recoveries ranged from 97.00 to 100.50 with a relative standard deviation value was ± 0.98 to ± 1.85%. The method does not need temperature control or solvent extraction and has been applied successfully to determine amoxicillin in pharmaceutical preparation (tablets).

Influence of chitosan’s purification methodology on the formation of layer-by-layer films

Sun, 21 Apr 2024 00:00:00 -0300

Concern for the environment for the development of new biodegradable materials has been constant in scientific circles. With this in mind, this work proposes a study on the formation of self-assembled thin films using chitosan (Qt), a biodegradable material. This polyelectrolyte has several purification methodologies, but we did not identify any studies on the effect of these methodologies on film formation. Thus, after the purification process and characterization of the three forms of chitosan purification, films were produced using the layer-by-layer (LBL) technique. The growth of the films was monitored using the UV-vis technique. Spectroscopy in the Infrared region showed positions in the main bands present in chitosan and sodium nitroprusside (NP) in the formed films. Two semi-reversible processes were found for the QtN/NP and QtAc/NP films, related to the reduction of iron oxide present in the NP. The effect of pH (4.0, 7.0 and 10) on the electrochemical processes indicated that the charge transfer occurs more efficiently at pH 7.0.

Foundations and applications of the orbital theory in chemistry: A philosophical perspective

Ricardo Vivas-Reyes, Daniela Navarro, Luis Eduardo Cortes — Sun, 28 Apr 2024 00:00:00 -0300

The concept of atomic and molecular orbitals has been a fundamental pillar in modern chemistry, shedding light on the structures and reactivity of chemical compounds. This article examines the evolution and significance of orbital theory, its applications in chemistry, and the ongoing debate about the existence of orbitals from both physics and chemistry perspectives. Philosophical aspects related to the ontology of orbitals are explored, emphasizing the complex interplay between mathematical abstractions and tangible reality. The multifaceted nature of orbitals, their role in quantum mechanics, and their implications for understanding the quantum realm are discussed. While the debate surrounding the ontological status of orbitals remains ongoing, it highlights the profound nature of inquiries into the fundamental essence of reality. This exploration underscores the significance of continuous research and discourse in advancing our understanding of these fundamental constituents of the quantum world.

Estimation of nitrogen dioxide levels on streets from Fortaleza Brazil using passive sampling and multivariate analysis

Mon, 20 May 2024 00:00:00 -0300

The increase in the fleet of motor vehicles circulating in urban centers is one of the main generators of gaseous pollutants harmful to human health and the environment. Pollutants can be economically and effectively monitored through passive sampling. This study aims to estimate NO₂ levels on roads of Fortaleza city /CE using the passive sampling method. 12 campaigns covered the rainy (March-June) and the dry (July-November) seasons in 2019. The seasonal averages of NO₂ in the rainy season were higher than the dry one, and Almirante Rubim Street showed the greatest difference in the averages: 26.6 µg m^-3 in the rainy and 19.3 µg m^-3 in the dry season. The principal component analysis applied to the averages of NO₂ concentration in the rainy and dry seasons, vehicle traffic and Height of the road/width ratio indicated that components 1, 2 and 3 explain 94.4% of the studied cases. Passive sampling proved to be efficient, contributing to the production of unpublished data about NO₂ levels in streets of Fortaleza/Ceará/Brazil from mobile sources.

Optimizing sewage water of Perum Pesona Permata Gading with the assistance of Cu/Mg electrodes as public street lighting based on green technology electricity

Tue, 21 May 2024 00:00:00 -0300

Electricity in Indonesia uses fossil fuels as an energy source. If fossil fuels run out, we will lose our largest source of electrical energy. Therefore, we need a way to reduce dependence on fossil fuels by making good use of renewable energy as a source of electrical energy. One of them is Green Technology Electricity with the utilization of sewage water to convert chemical energy into electrical energy. This study aims to determine the potential of sewage water assisted by Cu/Mg electrodes as a source of street lighting, manufacturing, and testing methods, and the effect of optimizing sewage water on electrical performance as street lighting. Lack of lighting in residential areas is also a supporting factor in this research. The stages used are preparation, incubation, construction assembly, research, and strength testing. Based on research, the sewage water from Perum Pesona Permata Gading can be used as street lighting with the highest potential difference and current strength being 4.4 V and 0.55 A for each 50 mL of the sewage water.

Determination of parameters and kinetic evaluation for chromium (VI) removal using four resins

Stamber Alvaro Ramírez-Revilla, Daniela Camacho-Valencia, Derly Ortiz-Romero — Fri, 07 Jun 2024 00:00:00 -0300

This research aimed to identify optimal studied variables for chromium (VI) removal using four resins (IRA 96, IRA 400, DOWEX 1x8, and LEWATIT). A 1,5-diphenylcarbazide method was used for the quantification of chromium (VI). A factorial design with triple replication at the center point was used to evaluate pH, resin dose (g/100 mL), and initial chromium (VI) concentration. The optimal values for the four resins were a pH of 3, a resin concentration of 0.15 g/100 mL of solution, and an initial concentration of 10 mg/L of chromium. Then, an ANOVA study was done to compare the resins results using a p-value <0.05. The DOWEX resin presented the highest removal percentage (98.39%) for a reaction period of 45 minutes, with an exponential model that fits a pseudo-first-order kinetics with a coefficient of determination equal to 0.967.

Study of the impact of irradiation and temperature on physical and chemical characteristics of paracetamol

Hussein Manaa Ali Al-Maydama, Adlia Ahmad Mohammad Abduljabbar — Mon, 22 Jul 2024 00:00:00 -0300

Pure paracetamol samples were subjected to temperature (40 °C) and light (sunlight, UV-lamp, and γ-ray) for time intervals. Treatment impact on the extent of chemical and physical impairments in the treated samples was pursued by comparing the results obtained from thermogravimetric analysis and differential scanning calorimeter (TGA/DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), high-performance liquid chromatography (HPLC), and photocatalytic decomposition process. Thermal analysis behavior, lifetime prediction, thermal stability, kinetics (i.e., E_a, Z, n), and thermodynamic (∆G*, ∆H*, and ∆S*) parameters were investigated for samples before and after exposure to heat and light from curves of the non-isothermal gravimetric analysis (TGA) at a heating rate of 10 °C min^–1 and with an association of Coats-Redfern and the other standard equations. Changes in crystallinity percentage were calculated relative to the untreated sample using measurements of DSC and XRD. In some treated samples, changes in morphology and purity were observed in SEM images and HPLC results. Kinetic parameters were determined, and the photocatalytic degradation percentage was discussed.

Evaluation of the effectiveness of new mixed ligand complexes against the vector of Dengue fever Aedes aegypti (Diptera; Culicidae)

Wed, 21 Aug 2024 00:00:00 -0300

Chloroquine phosphate with ibuprofen and sulphamethoxazole were used as mixed ligands with Ni(II), Co(II), Cu(II), and Zn(II) to prepare new transition metal complexes. Metal analysis, IR, and X-ray diffraction (XRD) spectrum analyzes were used to describe them, with some modifications to the World Health Organization (WHO) standard susceptibility test under laboratory conditions. The biological effects of ligands and new complexes against Aedes aegypti mosquito larvae were evaluated at various concentrations. To assess larvicidal efficacy, late third or early fourth instar larvae were exposed to multiple concentrations of the examined compounds, ranging from 50 to 1000 ppm. Cu(II) complexes revealed significant high activity (LC₅₀ = 100 ppm against Ae. Aegypti was compared with the rest of the metal complexes. On the other hand, the Co(II) complex showed no activity against Ae. aegypti. These mixed ligand complexes seemed to be an alternative method for manufactured insecticides to control larvae of this medically important mosquito vector Ae. aegypti. Further research on other metal complex compounds responsible for larvicidal efficacy will be required.

Development and validation of a green spectrophotometric method for simultaneous determination of combined pharmaceutical dosage form (paracetamol and caffeine) using chemometrics technique in comparison with HPLC

Tue, 17 Sep 2024 00:00:00 -0300

A green analytical method, a simple, fast, and cost-effective simultaneous spectrophotometric method using two chemometric techniques, the partial least square regression (PLS) and principal component regression (PCR), for determining a combination of paracetamol and caffeine in pharmaceutical formulations was developed. Pretreatment and separation steps are not required in the proposed method. For model construction and validation, various drug concentrations and instrumental spectra of 25 mixed solutions of paracetamol and caffeine were analyzed. The UV analysis of the prepared mixtures was recorded for a selected solvent blank in the wavelength range of 210-300 nm. The digitized absorbance was sampled at 0.2-nm intervals. R² values of 0.9993 and 0.9994 assigned for the PLS of paracetamol and caffeine and 0.9995 and 0.9991 for the PCR of paracetamol and caffeine, respectively, exhibited greater prediction efficiencies. The obtained results were statistically compared with the results of the HPLC reference method. Concerning accuracy and precision, the statistical comparison revealed no significant differences between the suggested and reference HPLC approaches.

Extraction and characterization of essential oils from fresh and dry leaves of Pinus elliottii

Thu, 03 Oct 2024 00:00:00 -0300

Essential oils are secondary metabolites whose properties have been studied mainly with emphasis on antimicrobial, biological and pharmaceutical fields, such as antibacterial, antifungal, antiviral, pest control and insect repellents. Essential oils from fresh and dry leaves of Pinus elliottii were extracted by hydrodistillation, chemically characterized and quantified by gas chromatography coupled to a mass spectrometer. The plant leaves were collected in a reforested area in the south of the state of Minas Gerais, Brazil. The two main components in both characterized essential oils were Germacrene D and β-Pinene. In the essential oil from fresh foliage, Germacrene D (47.71%) was the majority component, while in the essential oil from dry foliage, β-Pinene (30.06%) was the majority component. Literature data point that essential oils with large amount of Germacrene D may act as antibacterial and repellent agents. Additionally, literature data also support that essential oils with large amount of β-Pinene exhibit several biological properties, similar to the Germacrene D, in addition with a wide range of medicinal and pharmacological activities. Thus, from our results and with literature data, it is possible to elucidate new potential applications to essential oils from fresh and dry leaves of Pinus elliottii.

Effects of small-scale chemistry STEM integrated with local contexts for enhancing grade 11 students’ learning achievement and learning and innovation skills

Ratanaphun Utmeemang, Khajornsak Buaraphan — Tue, 15 Oct 2024 00:00:00 -0300

This study aimed to; a) create the context-based small-scale chemistry STEM (CSSC-STEM) Model; and b) examine the effects of the CSSC-STEM model on students’ learning achievements and learning and innovation skills. The research methodology was Research and Development (R&D). In R1D1, 60 chemistry teachers and 136 students responded to reflect problems and needs about teaching and learning chemistry. In R2D2, 43 and 41 Grade 11 students were in an experiment and control groups, respectively. In R3D3, 40 and 36 students were in the experiment and control groups, respectively. The results showed that the experiment group had higher learning achievement in Rate of Chemical Reactions (t = 7.599, p < 0.05) than the control group. In addition, the experimental group had higher critical problem-solving skills (t = 20.968, p < 0.05) and creative thinking skills (t = 23.168, p < 0.05) than control group. The experiment group also gradually improved communication and teamwork skills throughout the model. The R3D3 results aligned with R2D2 showing the reliability of the CSSC-STEM model.

Quantum chemistry in public higher education institutions in the Brazilian state of Piauí: an analysis of the perceptions of undergraduate chemistry students

Wed, 12 Jun 2024 00:00:00 -0300

Quantum chemistry is a challenging required course in undergraduate chemistry. Despite its unconventional concepts, it is crucial for understanding modern chemistry. This study investigated how students perceive certain topics and the learning process. Interviews were conducted using a Likert scale questionnaire and sixteen content-specific questions. Some responses differed from the existing literature, such as students’ interpretations of the nature of light. In terms of learning, students acknowledged that the topic was complex due to the lack of mathematical foundations and the elevated level of abstraction. Students were primarily seeking the average grade required for admission. The data underscore the need for a deeper discussion of curriculum development and implementation. The curriculum matrix revision could provide space for more substantive thinking about content delivery and assessment processes.

Last decade insights on cemented carbides: A review on alternative binders, new consolidation techniques and advanced characterization

Daniela Andreina Sandoval Ravotti, Hortensia Melero Correas, Núria Cinca Luis — Thu, 04 Jul 2024 00:00:00 -0300

Cemented carbide alloys are well known powder metallurgically processed materials used for a wide range of tooling and components that require a good balance of hardness and fracture toughness, together with wear resistance. After 100 years of the first patent, research and development within this area continues to fulfil more demanding applications and adapt to new requirements. The last decade especially has witnessed important advances. In that sense, Co-free compositions are being studied due to the health issues that its use implies and its criticality in the supply chain. Secondly, the steps towards near-net-shape components by means of additive manufacturing technologies to avoid waste of powder and the technological advance of fast sintering processes are promising. Finally, new microstructural and mechanical characterization methods at micro and nanoscale provide helpful insights for a better understanding of these materials under performance.

Identification of learning difficulties and misconceptions of chemical bonding material: A review

Fri, 11 Oct 2024 00:00:00 -0300

Chemical bonds are one of the materials in chemistry that are abstract in nature so that many students have difficulty learning chemical bonding material. This study aims to identify the learning difficulties frequently faced by students in understanding chemical bonding materials and various misconceptions that commonly occur in their understanding. Data collection was carried out using a systematic literature review method with several predetermined criteria. The result is that the learning difficulties experienced by students are caused by many factors, one of which is conceptual error or misconception. At present, many methods have been developed to identify students’ misconceptions about chemical bonding material such as diagnostic tests such as two-tier, three-tier and four-tier diagnostics.

In memoriam of Cecilia Laluce (1940 - 2023)

Antonio Carlos Massabni, Maria Célia Bertolini — Thu, 01 Feb 2024 00:00:00 -0300