Departamento de Química

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http://repositorioabierto.uantof.cl/handle/uantof/223

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Aqueous Dried Extract of Skytanthus acutus Meyen as Corrosion Inhibitor of Carbon Steel in Neutral Chloride Solutions
(2021) Luis Cáceres; Yohana Frez; Felipe Galleguillos; Alvaro Soliz; Benito Gómez-Silva; Jorge Borquez
The implementation of corrosion engineering control methods and techniques is crucial to extend the life of urban and industrial infrastructure assets and industrial equipment affected by natural corrosion. Then, the search of stable and environmentally friendly corrosion inhibitors is an important pending task. Here, we provide experimental evidence on the corrosion inhibitory activity of aqueous extracts of Skytanthus acutus Meyen leaf, a native plant from the Atacama Desert in northern Chile. Skytanthus extracts as a powder should be prepared at 55 °C to avoid thermal decomposition and loss of corrosion inhibitory activity. Corrosion of carbon steel AISI1020 immersed in 0.5 M NaCl was evaluated in the presence of different doses of Skytanthus extract by complementary and simultaneous linear polarization, electrochemical impedance spectroscopy, and weight-loss technique under high hydrodynamic conditions. Mixed Potential Theory was applied to confirm the electrochemical activity of the extract inhibitory capabilities. The Skytanthus extracts reached a 90% corrosion inhibitory efficiency when tested at 100 to 1200 ppm in a time span of 48 h, through an electrochemical interaction between the extract inhibitor component and the carbon steel surface. The corrosion inhibition activity observed in Skytanthus dry extracts involves a protective film formation by a mechanism that includes an iron dissolution at the expense of either oxygen reduction and/or hydrogen evolution, followed by a ferrous-ferric iron cycling, the formation of an iron complex and adsorption to the metal surface, and, finally, desorption or degradation of the protecting film. The water-soluble plant extract was subjected to HPLC-MS analyses that rendered 14 major signals, with quinic acid, protocatechuic acid, chlorogenic acid isomers, vanillic acid hexoside, and patuletin 3-methoxy-7-glucoside as the most abundant components. Then, we propose that a phenolic derivative is responsible for the corrosion inhibitory activity found in Skytanthus extracts.
Chemical Profiling, Antioxidant, Anticholinesterase, and Antiprotozoal Potentials of Artemisia copa Phil. (Asteraceae)
(2020) Maria José Larrazábal-Fuentes; Carlos Fernández-Galleguillos; Jenifer Palma-Ramírez; Javier Romero-Parra; Kevin Sepúlveda; Jorge González; Adrián Paredes; Jorge Bórquez; Mario J. Simirgiotis; Javier Echeverría; Alexandra Galetović
Artemisia copa Phil. (Asteraceae) (known as copa-copa) is a native species of Chile used as an infusion in traditional medicine by Atacameños people in the Altiplano, highlands of northern Chile. In this research, we have investigated for the first time the cholinesterase inhibition potential against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and the chemical profiling of the infusions prepared from the aerial parts of A. copa by high resolution spectrometry. In addition, total phenolic, total flavonoid content, antioxidant (DPPH, FRAP, and ORAC) and antiprozoal activity were tested. Artemisia copa showed good inhibitory activity against AChE and BChE (3.92 ± 0.08 µg/ml and 44.13 ± 0.10 µg/ml). The infusion displayed a total phenolics content of 155.6 ± 2.9 mg of gallic acid equivalents/g and total flavonoid content of 5.5 ± 0.2 mg quercetin equivalents/g. Additionally, trypanocidal activity against Trypanosoma cruzi was found (LD50 of 131.8 µg/ml). Forty-seven metabolites were detected in the infusion of A. copa including several phenolic acids and flavonoids which were rapidly identified using ultrahigh performance liquid chromatography orbitrap mass spectrometry analysis (UHPLC-Orbitrap-MS) for chemical profiling. The major compounds identified in the infusions were studied by molecular docking against AChE and BChE. The UHPLC-MS fingerprints generated can be also used for the authentication of these endemic species. These findings reveal that A. copa infusions can be used as beverages with protective effects.
Effect of Lampaya medicinalis Phil. (Verbenaceae) and Palmitic Acid on Insulin Signaling and Inflammatory Marker Expression in Human Adipocytes
(2024) Gabriela Yuri; Mariana Cifuentes; Pedro Cisternas; Adrián Paredes; Paulina Ormazabal
Background: Aging and obesity are associated with insulin resistance (IR) and low-gradeinflammation. Molecularly, IR is characterized by a reduction in glucose uptake and insulin signaling(IRS-1/Akt/AS160 pathway), while inflammation may result from upregulated NF-κB pathwayafter low Tyr-IκBαphosphorylation. Upregulated phosphatase activity of PTP1B is associated withimpaired insulin signaling and increased inflammation. Plasma levels of palmitic acid (PA) areelevated in obesity, triggering inflammation and disruption of insulin signaling. Traditional medicinein Northern Chile uses oral infusions ofLampaya medicinalisPhil. (Verbenaceae) to treat inflammatoryconditions. Significant amounts of flavonoids are found in the hydroethanolic extract of Lampaya(HEL), which may account for its biological activity. The aim of this work was to study the effect ofHEL and PA on insulin signaling and glucose uptake as well as inflammatory marker expression inhuman adipocytes. Methods: We studied HEL effects on PA-induced impairment on insulin signaling,glucose uptake and inflammatory marker content in human SW872 adipocytes. HEL cytotoxicity wasassessed in adipocytes at different concentrations (0.01 to 10 g/mL). Adipocytes were incubated or notwith PA (0.4 mM, 24 h) with or without HEL (2 h pre-incubation), and then stimulated with insulin(10 min, 100 mM) or a vehicle. Phospho-IRS-1, phospho-Akt, phospho-AS160, phospho-NF-κB andphospho-IκBα, as well as protein levels of PTP1B, were assessed using Western blotting, and glucoseuptake was evaluated using the 2-NBDG analogue. Results: At the assessed HEL concentrations, nocytotoxic effects were observed. PA decreased insulin-stimulated phospho-Akt and glucose uptake,while co-treatment with HEL increased such markers. PA decreased phospho-IRS-1 and phospho-Tyr-IκBα. On the other hand, incubation with HEL+PA decreased phospho-AS160 and phospho-NF-κBcompared with cells treated with PA alone. Conclusion: Our results suggest a beneficial effect ofHEL by improving PA-induced impairment on molecular markers of insulin signaling, glucoseuptake and inflammation in adipocytes. Further studies are necessary to elucidate whether lampayamay constitute a preventive strategy for people whose circulating PA levels contribute to IR andinflammation during aging and obesity.
Epibiotic bacterial community composition varies during different developmental stages of Octopus mimus: Study of cultivable representatives and their secondary metabolite production
(2024) Martha B. Hengst; Stephanie Trench; Valezka Alcayaga; Cristian Sepulveda Muñoz; Jorge Bórquez; Mario Simirgiotis; Fernando Valenzuela; Mario Lody; Lenka Kurte; Coral Pardo Esté
Marine microbial communities colonizing the skin of invertebrates constitute the primary barrier between host and environment, potentially exerting beneficial, neutral, or detrimental effects on host fitness. To evaluate the potential contribution of epibiotic bacteria to the survival of early developmental stages of Octopus mimus, bacterial isolates were obtained from eggs, paralarvae, and adults. Their enzymatic activities were determined, and antibacterial properties were assessed against common marine pathogens. The isolates belonged to the phyla Proteobacteria, Actinomycetota, Bacteroidota, and Bacillota, represented by 21 genera and 27 species. Specific taxa were associated with each developmental stage, with only three species shared among different stages: Bacillus pumilus, B. megaterium, and Shewanella algae, which also inhibited the growth of all assayed pathogens. Organic extracts from Bacillus megaterium M8-1 were obtained, and UHPLC-MS analysis detected seventeen putative compounds, including two phenolic acids, three indole derivatives, and twelve oxylipins. Our findings provide novel data on cultivable bacterial representatives isolated from Octopus mimus capable of synthesizing chemical compounds with bioactive properties. These results contribute to a better understanding of the role of microbial communities in the survival of this invertebrate species during critical early life stages.
Sulfate Nutrition Modulates the Oxidative Response against Short-Term Al3+-Toxicity Stress in Lolium perenne cv. Jumbo Shoot Tissues
(2024) Hernan Vera Villalobos; Lizzeth Lunario Delgado; Anita S. Gálvez; Domingo Román Silva; Ana Mercado Seguel; Cristián Wulff Zottele
Al3+-toxicity in acidic soils is among the main abiotic stress factors that generate adverse effects in plant growth; in leaves, it affects several physiological parameters such as photosynthesis and ROS balance, leading to limited crop production. On the other hand, sulfur is a macronutrient that has a key role against oxidative stress and improves plant growth in acidic soils; however, the implication of sulfate nutritional status in the modulation of short-term Al3+-toxicity tolerance mechanisms in plant leaves are barely reported. This study is focused on the role of sulfate on the leaf response of an Al3-sensitive perennial ryegrass (Lolium perenne cv. Jumbo) after 48 h of exposure. Lolium perenne cv. Jumbo seeds were cultivated in hydroponic conditions with modified Taylor Foy solutions supplemented with 120, 240, and 360 μM sulfate in the presence or absence of Al3+-toxicity. The L. perenne cv. Jumbo leaves were collected after 48 h of Al3+-toxicity exposure and processed to evaluate the effects of sulfate on Al3+ toxicity, measuring total proteins, mineral uptake, photosynthesis modulation, and ROS defense mechanism activation. The plants exposed to Al3+-toxicity and cultivated with a 240 μM sulfate amendment showed a recovery of total proteins and Ca2+ and Mg2+ concentration levels and a reduction in TBARS, along with no changes in the chlorophyll A/B ratio, gene expression of proteins related to photosynthesis (Rubisco, ChlAbp, and Fered), or ROS defense mechanism (SOD, APX, GR, and CAT) as compared with their respective controls and the other sulfate conditions (120 and 360 μM). The present study demonstrates that adequate sulfate amendments have a key role in regulating the physiological response against the stress caused by Al3+ toxicity.

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