Journal of the Chilean Chemical Society

OXYGEN REACTIVE SPECIES EFFECTIVELY SCAVENGED BY VARIOUS EXTRACTS OF LEAVES AND BARK OF EUCALYPTUS GLOBULUS

Abid Sarwar — 2023-12-31

Eucalyptus globulus is belong to a family of Myrtaceae and one of the important medicinal plants. Eucalyptus leaf extract is a used as an antioxidant in various food additives. With this in mind, fresh leaves and bark of eucalyptus were taken dried, grinded and extractive contents were measured. Various extracts of leaf and bark of Eucalyptus globulus were made and used for the estimation of phytochemicals, total flavonoids or phenolic content, and for determination of in-vitro antioxidant activity. The highest extractive contents of E. globulus leaf were 4.75±0.25% and bark 7.95±0.50% with water. Phytochemical tests showed that the water extracts of the leaves and bark contain alkaloids, flavonoids, glycosides, terpenoids, steroids, and saponins, while there are no cardiac glycosides and anthraquinones. Phenols and flavonoids studies have shown that leaves extract contain significant amounts of phenols and flavonoids (152.6±1.5 mg/g gallic acid equivalent; 42.30±0.7 mgQE/g dry weight) and 120.3±1.1 mg/g gallic acid equivalent 29.2±0.5 mgQE/g dry weight in water extract of bark. All extracts exhibited considerable DPPH (2,2-diphenyl-1-picrylhydrazyl), with the highest percentage inhibition in aqueous leaves extracts 87.41±1.2 (IC₅₀ 58.88±2.15 µg/ml), while lower in chloroform 48.39±0.6 (IC₅₀ 88.22±2.90 µg) /ml), than bark water extract: 80.15±1.1 (IC₅₀ 63.43±2.25 µg/ml; chloroform extract: 42.02±0.5 (IC₅₀ 90.10±2.95), While the percentage inhibition of BHT was 92.8±1.3, the IC₅₀ was 29.70±1.55 µg/ml was detected at 250 µg/ml concentration. Reducing capacity when compared in leaves and bark, the following order was observed: water extract˃ethanol extract˃EtOH-H₂O˃methanol extract˃MeOH-H₂O extract˃chloroform extract. This study has confirmed that water extracts of E. globulus leaves and bark have the highest antioxidant activity and may contain high amounts of flavonoids and phenolics.

SYNTHESIS OF NOVEL NEONICOTINOIDS DERIVATIVES

juan pablo González-Gutiérrez — 2023-12-31

Neonicotinoid compounds have been used as insecticides since the 1990s to effectively control Hemipteran pests such as aphids, leafhoppers, whiteflies, and additionally, for their lethal activity and low toxicity in humans. The synthesis of novel neonicotinoids compounds was achieved using (S)-(-)-(1-methyl-2-pyrrolidinyl)methanol and (±)-2-(1-methyl-2-pyrrolidinyl)ethanol with nitrobenzoyl chlorides derivatives in diethyl ether at room temperature to concentrate in vacuum to subsequently neutralize (pH = 8) with 7.4% (w/v) isopropanol HCl solution to obtain hydrochloride salts. (S)-(1-methyl-2-pyrrolidinyl)methyl and (±)-2-(1-methyl-2-pyrrolidinyl)ethyl 2-nitrobenzoate salts was not possible to form.

INTEGRAL EVALUATION OF NEUTRAL ENDOPEPTIDASE INHIBITORS AS POSSIBLE ANTIHYPERTENSIVE AGENTS BY MEANS MOLECULAR MECHANICS, FREE ENERGY CALCULATION AND ADME-TOX PROPERTIES.

Juan Alberto Castillo-Garit — 2023-12-31

The most important mechanisms in the blood pressure regulation, fluid volume and sodium-potassium balance in humans is the renin-angiotensin-aldosterone system (RAAS). This regulatory pathway plays a critical role in modulating cardiac function and vascular tone. An alteration in any of the molecules that make up this system (RAAS) could contribute to the development of arterial hypertension. In this important mechanisms, the neutral endopeptidase, also called Neprilysin (NEP) is the main enzyme for the degradation of natriuretic, therefore, it is essential proteins in controlling blood pressure. In this work, we have used docking methodology, molecular dynamics simulationa and free energy calculations method (MM-PBSA), to comprehensively evaluate the inhibitory behavior of some ligands obteined from consulted literature. The principal results obtained shown these ligands were adequately oriented in the NEP pocket. The Lig783, Lig2177, and Lig3444 compounds were those with better dynamic behavior. The energetic components that contribute to the complex's stability are the electrostatic and Van der Waals components; however, when the ADME-Tox properties were analyzed, we conclude that the best possible anti-hypertensive candidate are Lig783 and Lig3444.

EXPERIMENTAL STUDY ON HYBRID MAGNESIUM COMPOSITES FOR HUMAN BONE IMPLANTS

V.K Neela Murali — 2023-12-31

The hybrid Magnesium composite having alloying elements zinc, manganese with the reinforcement of nano TiO₂ and micron level Al₂O₃ was prepared through hot press sintering method. This study is primarily determined the effect of reinforcing multi ceramic particles in the Mg composites for their mechanical and corrosion strength to validate the human bone implants. The scanning electron microscopy and X-ray diffractogram were used to analyze the micro structural variation on the hybrid composites. The microstructural study showed that, many intermetallic phases were formed during the composite preparation process which reduces the porosity and increases density of the composites. The reinforced particles, manufacturing process and after heat treatment or stress reliving process were enhanced the mechanical and corrosion strength of the prepared hybrid composites.

DOCKING SIMULATIONS OF STEROIDAL OXIMES TOWARD ESTROGEN RECEPTOR ALPHA. ANALYSIS OF THEIR POTENTIAL ANTICANCER ACTIVITY

Dayana Alonso — 2023-12-31

Breast cancer is the most common cause of cancer deaths in women. Normal breast cells and most breast cancer cells have receptors that attach to circulating estrogen and progesterone. Estrogen and progesterone bind to the receptors and may cause cancer cells to proliferate. Drugs, currently being used to treat this disease are not so effective and cause adverse effects. For this reason, the quest of new compounds that bind to the estrogen receptor (ER), activating or inhibiting ERs selectively, is a very active field of research. In this task, molecular docking plays a vital role in drug design, either as a tool in drug discovery and analysis of protein-ligand interactions. In this work, 26 steroidal oximes, which are derivatives of diosgenin, were analyzed using docking studies, and compared against the estrogen receptor (ERa). The 3D structures of ERa were downloaded from Protein Data Bank (3ERT) and optimized using pdb2pqr.py. Modifications in rings A and B were made, and both oxime configurations (E or Z) were considered. Results for hydroximino steroids were compared with those obtained for compounds exhibiting biological activity against this type of cancer, namely, 4-hydroxytamoxifen, diosgenin and 6,23-dihydroximino diosgenin derivative. Molecular docking studies on ERa revealed that three mono oximes were found to interact with the protein more efficiently and have the best docking score. Thus, modification of diosgenin with oxime groups could lead to antiproliferative steroidal compounds, and therefore they could be considered for further research and in vivo evaluations for breast cancer treatment and management strategies

MOLECULAR DYNAMIC AND DOCKING STUDY OF CHEMICAL STRUCTURE OF NEW CORONA VIRUSES LINEAGES OF OMICRON BA.n SUB-VARIANTS (n=1-5); BA.4 OR BA.5 STRAINS EXHIBIT THE MOST CONCERN

Majid Monajjemi — 2023-12-31

The first dominant of Omicron-Covid-19 (BA.1) was produced around thirty mutations in its Spike protein in 2019. Quickly BA.1 became the dominant variant worldwide. Omicron is dangerous for public health concern due to its high infectivity and antibody evasion. Omicron has three lineages or sub variants, BA.1, BA.2, and BA.3. Among them, BA.1 is the currently prevailing sub variant. Omicron BA.1 has around 65 mutations on non-structure protein (NSP3), NSP4, NSP5, NSP6, NSP12, NSP14, S protein, envelope protein, membrane protein, and nucleus capsid proteins. BA.4 and BA.5 are two newly-designated Omicron lineages. They are Omicron viruses with a new combination of mutations containing critical spike protein as a concern for human. In terms of their mutations, BA.4 and BA.5 share mutations across their genomes with both BA.1 and BA.2, but are most similar to BA.2. L452R that previously seen in Kappa, Delta, Epsilon variants and also F486V, and R493 can be seen in both BA.4 and BA.5 where differ from one another in mutations that are outside of the spike gene Data on BA.4 and BA.5, which were first detected in South Africa in early 2022, remain limited. But, these variants seem to spread more quickly than earlier versions of Omicron, such as BA.2, and may be better at dodging the immune system’s defenses. By this work, we simulated the spike protein structures, along with peptide-like inhibitor structure of the 7QO7, 7WE9, 7WPC and 7DF4 structures including small-molecule inhibitors, via molecular dynamic and docking methods. Several genomes of various coronaviruses using BAST and MAFFT software have been evaluated.

THEORETICAL STUDY ON THE ANTIOXIDANT ACTIVITY OF NITRONES AS OH∙ FREE RADICAL TRAPPERS

José Muñoz-Espinoza — 2023-12-31

In the present article, a theoretical and computational study was carried out on the reactivity and antioxidant capacity of a series of nitrone derivatives (hBNn) in the presence of the OH∙ radical. For the antioxidant characterization of these compounds, tools such as global and local reactivity indices were used, as well as thermodynamic aspects to obtain the most energetically stable product. In addition, the NBO analysis, which described the SOMO generated by the electron radical of the spin adduct hBNn-OH. The results obtained show that the nitrone derivatives studied present the antioxidant capacity of radical trapping, forming energetically stable spin adducts. In turn, the reactivity of the systems (nitrone and radical) shows their nucleophilic and electrophilic tendencies, allowing us to propose a reaction mechanism for these radical traps.

ADEQUACY OF LOW-COST TECHNIQUE FOR SOIL BACTERIAL ALGINATE/ZEIN ENCAPSULATION AT LABORATORY SCALE

Álvaro Gutiérrez — 2023-12-31

In the contemporary context, the utilization of microorganisms across various disciplines has emphasized the growing significance of comprehending their fundamental mechanisms and enhancing delivery techniques, particularly in agriculture. Microencapsulation is one notably viable technique that establishes a controlled microenvironment, thus safeguarding microorganisms, offering superior handling, stability, and precisely controlled release. To evaluate a low-cost technique adaptation, this study explores the encapsulation of one plant growth-promoting bacteria isolated from burned soil, utilizing the ion gelation method facilitated by a simplified syringe pump model. The core materials comprise sodium alginate and LB medium as the support matrix, complemented by zein as the protective coat. The best result for capsule formation with viable bacteria was obtained with a 5% sodium alginate matrix compound in 2.5% Luria Bertani broth and 5% Zein for coating.

Additionally, in-depth insights into the chemical properties of the capsules and their components were obtained through ATR-FTIR spectroscopy, revealing vital interactions within these structures. In summary, this study represents a significant advancement in addressing contemporary agricultural challenges, especially those exacerbated by climate change. By introducing an economical and exploratory laboratory-scale technique for encapsulating soil bacteria, this research contributes to the development of sustainable agricultural practices. It underscores the potential of encapsulation in enhancing soil health, promoting plant vitality, and mitigating the adverse effects of climate change on agricultural ecosystems.

THEORETICAL STUDY OF AU-S INTERACTION IN CLUSTERS MODELS OF A α-CYCLODEXTRIN COMPLEX

Carlos Orellana — 2023-12-31

Theoretical calculations were correlated to elucidate the interface interaction between thiol groups of host-guest systems and gold cluster. The 1-octanethiol molecule acts as guest into α-cyclodextrin host to form a supramolecular complex in which is stabilizing gold clusters. The intermolecular interaction and the vibrational frequencies nature between a host-guest system and gold cluster were elucidated by a theoretical point of view at the MP2, SCS-MP2, and PBE-D3 methods. It is showing a van der Waals interaction and a good vibrational frequencies correlation.

MULTIVARIATE OPTIMIZATION OF MICROWAVE-ASSISTED ENZYME DIGESTION OF α-CASEIN FOR GENERATION OF BIOACTIVE PEPTIDES

Katherine López — 2023-12-31

Caseins are the principal milk proteins and serve as an important source of bioactive peptides with diverse beneficial effects for human health, such as antihypertensive, immunomodulating, anti‐inflammatory, and antithrombotic. The objective of this study was to optimize, using the design of the experiment, the production of bioactive peptides from α-casein applying microwave-assisted enzyme digestion (MAED). The optimal MAED conditions (time, temperature, and enzyme/protein ratio) were established for pepsin (digestion time 4 min, temperature 41°C, and E:P ratio 1:40) and trypsin (digestion time 10 min, temperature 37°C and E:P ratio 1:200.) enzymes. Digestion yields and the intensity of different bioactivities, i.e., antimicrobial, antioxidant, and acetylcholinesterase and α-glucosidase inhibitory activities, evaluated by the HPTLC-bioassay technique were used as response variables. Trypsin-formed α-casein peptides showed antimicrobial, antioxidant, and acetylcholinesterase inhibition activities, while pepsin-formed showed antimicrobial, antioxidant, and α-glucosidase inhibition activities. These results demonstrate that MAED is a fast and effective technique for bioactive peptide production from casein proteins.

POLYMERS IN CIRCULAR ECONOMY: A COMPREHENSIVE APPROACH TO SUSTAINABILITY. AN OVERVIEW.

Francisca L. Aranda — 2023-12-31

The circular economy has emerged as a fundamental paradigm in the search for sustainable solutions in the global economic context, as an innovative approach that seeks to transform the way we consume and produce goods and services. Its fundamental principles are based on the reduction, reuse and recycling of resources, promoting sustainability and minimizing waste. This new way of thinking has applications in a variety of sectors, from manufacturing to waste management.

The implementation of government policies and regulations play an important role in promoting the circular economy by setting standards and requirements for responsible resource management. However, there are challenges and barriers that need to be

overcome, such as resistance to change and the need for upfront investments. Despite these obstacles, there are successful examples of circular economy around the world, demonstrating the tangible benefits of this approach in terms of waste reduction. This paper presents an exploration and analysis of the circular economy, providing a vision of its foundation, applications and challenges in promoting a more sustainable management of resources and products globally.