Macdiel Acevedo-Quiroz

Umbelliferone (7-hydroxycoumarin) is a bioactive scaffold whose pharmacological profile may be modified through coordination to metal centers. Five coordination compounds of umbelliferone with the main-group elements Bi(III), In(III), Ga(III), Sb(III), and Te(IV) were synthesized by alkali-assisted deprotonation of the phenolic group followed by reaction with the corresponding metal salt, and characterized by melting point, FT-IR, ¹H and ¹³C NMR spectroscopy, FAB⁺ mass spectrometry, and elemental microanalysis. Disappearance of the phenolic ν(O–H) band (3113 cm⁻¹) and of the ¹H signal at 10.5 ppm in U-Bi, U-In, U-Ga and U-Te, with a minor residual signal persisting for U-Sb, together with preservation of the aromatic and vinylic resonances of the coumarin core and a shift in ν(C=O) from 1701 cm to ¹ to 1667–1683 cm⁻¹, is consistent with metal binding through the C7-phenolato oxygen. Antiproliferative activity and cytotoxicity were evaluated in MCF-7 and MDA-MB-231 breast cancer cells and in non-tumorigenic MCF-10A cells at 24 and 48 h, by crystal violet (CV) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The coordination compounds displayed metal- and cell-line-dependent activity relative to free umbelliferone. U-Te (IC₅₀ = 7.4 µM) and U-Sb (9.5 µM) were the most potent in MCF-7 cells, while U-Bi (9.8 µM) was the most active in MDA-MB-231 cells, all at 24 h. IC₅₀ values in MCF-10A cells were ≥181 µM for every compound at 24 h, yielding selectivity indices >17 for the most active members of the series. Treated tumor cells showed morphological changes consistent with cytotoxicity (rounding, loss of adhesion, and monolayer disruption). These findings identify U-Sb, U-Te, and U-Bi as the most active and selective compounds of the series and support further investigation of umbelliferone-derived coordination compounds as potential antiproliferative agents. However, further investigation is needed to determine the relative contributions of intact compounds and solution-derived species to the observed biological effects.

The synthesis of a multidentate Schiff base ligand including two carboxylic donor groups is described. The reactivity toward diorganotin oxides was studied under 1:1 and 1:2 stoichiometric conditions. A 1:1 ratio led to mononuclear complexes via ONO complexation, whereas a 1:2 ratio promoted the additional coordination through carboxylate groups, yielding a dimeric macrocycle. These results highlight the role of the ligand as a stoichiometry-dependent directing building block for organotin assembly. For macrocyclic compounds, the 1H NMR experiments indicated the presence of two species with identical diffusion coefficients, suggesting structural isomers with the same molecular mass. DFT calculations for the two isomeric proposals revealed only a small energy difference (0.90 kcal·mol⁻¹), supporting their simultaneous formation. Biological assays showed negligible activity for the free ligand but enhanced antibacterial activity upon complexation. The monomeric complex 2a exhibited the highest activity, while 2d showed a broader spectrum. Macrocycle 3b was also active, though limited by poor solubility.

Cervical cancer (CC) represents a major public health concern, ranking as the fourth most frequently diagnosed cancer and one of the leading causes of cancer-related mortality among middle-aged women worldwide. CC is caused by persistent infection with high-risk human papillomaviruses (HR-HPVs), with HPV 16 being the cause of more than 50% of CC cases. In this study, the exometabolome of the HPV 16-positive cell lines SiHa and Ca Ski, as well as the HPV 16-negative control cell line C-33 A, was evaluated. The exometabolome was validated through molecular signatures using a transcriptomic approach to identify genes encoding cellular metabolic enzymes. The exometabolome was analyzed using ¹H nuclear magnetic resonance spectroscopy (¹H-NMR). Exometabolomic profiles were subsequently compared through both multivariate and univariate statistical analyses to identify significant differences between cell lines. Molecular signatures were analyzed from the GSE9750 dataset obtained from the GEO database. Exometabolic profiling of the HPV 16 positive cell lines showed higher concentrations of leucine, isoleucine, valine, lysine, methionine, glutamine, ornithine, choline, glucose, and tryptophan. An expression analysis showed increased expression of enzymes involved in amino acid synthesis, the tricarboxylic acid cycle, glycolysis, the pentose phosphate pathway, galactose metabolism, and HIF-1α. These data suggest metabolites and metabolism-associated genes that can be used as non-invasive, stable diagnostic and prognostic biomarkers, as well as therapeutic targets for CC in the presence of HPV 16.

The C=C double bond is a typical feature in biodiesel components associated with their physicochemical behaviors, including metal degradation. In this work, copper was exposed to the gas-phase atmospheres of Methyl Hexanoate (MH) at 145 °C and 25% Methyl Trans-3-Hexenoate in Methyl Hexanoate (MT3H in MH) at 158 °C during 1000 h, representing saturated and unsaturated thermal degradation environments of biodiesel surrogates. FTIR, ¹H NMR, and GC-MS were used to characterize the chemical changes in the gas-phase atmospheres, whereas SEM allowed us to inspect the copper surfaces. Weight loss assays enabled the estimation of corrosion rates for copper exposed to HM and MT3H in MH atmospheres of 3.81 ± 1.27 and 5.08 ± 1.27 μm/year, respectively. Electrochemical measurements (linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS)) were used to evaluate the corrosion behavior of copper using aqueous extracts of condensed compounds from gas-phase degraded environments. Our electrochemical results indicate that similar corrosion processes occur in both extracts, remaining nearly unchanged with increasing exposure time. A porous layer of corrosion products on copper revealed that it is more active in the products generated with the MT3H in MH extract, suggesting the significant impact of the C=C bond on copper deterioration.

Biodiesel is a mixture of saturated and unsaturated Fatty Acid Methyl Esters (FAMEs) whose composition affects the corrosion behavior of metal containers during storage. This study examines the effect of the C=C bond present in selected FAMEs (Methyl Stearate, Methyl Oleate, and Methyl Linoleate) in aluminum corrosion in the absence of oxygen. First, mass loss assays were carried out at 100, 200, and 280 °C for 1000 h using pure Methyl Stearate (MS), 5% Methyl Oleate in Methyl Stearate (MS-5% MO), and 5% Methyl Linoleate in Methyl Stearate (MS-5% ML). Next, chemical changes in FAMEs were studied using FTIR, TGA, and GC/MS. SEM/EDS analysis allowed us to inspect the aluminum surfaces and their chemical characterization. We estimated higher corrosion rates for MS assays than those of unsaturated methyl ester mixtures. In a separate set of experiments, we used electrochemical techniques (potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy) to investigate aluminum corrosion induced by thermal-degraded products from FAMEs at 100, 200, and 280 °C for 300 h able to dissolve in aqueous extracts. These electrochemical experiments revealed that the products in the aqueous extracts from the unsaturated methyl ester mixture form a passive layer on the Al surface thicker than pure MS at the corresponding degradation temperatures.

The number of elderly people is projected to double in the next 50 years worldwide, resulting in an increased prevalence of neurodegenerative diseases. Aging causes changes in brain tissue homeostasis, thus contributing to the development of neurodegenerative disorders. Current treatments are not entirely effective, so alternative treatments or adjuvant agents are being actively sought. Antioxidant properties of phenolic compounds are of particular interest for neurodegenerative diseases whose psychopathological mechanisms strongly rely on oxidative stress at the brain level. Moreover, phenolic compounds display other advantages such as the permeability of the blood–brain barrier (BBB) and the interesting molecular mechanisms that we reviewed in this work. We began by briefly outlining the physiopathology of neurodegenerative diseases to understand the mechanisms that result in irreversible brain damage, then we provided an overall classification of the phenolic compounds that would be addressed later. We reviewed in vitro and in vivo studies, as well as some clinical trials in which neuroprotective mechanisms were demonstrated in models of different neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), Parkinson’s disease (PD), ischemia, and traumatic brain injury (TBI).

Objective: To aromatically aminate refined rice bran oil (RBO), a by-product of the rice agro-industry,through a chemical-enzymatic epoxidation based on Novozym 435 and p-xylylenediamine insertion. Design/Methodology/Approach: Refined RBO was epoxidized with H2O2/Novozym 435. The resulting epoxidized rice bran oil (eRBO) was functionalized with the p-xylylenediamine aromatic diamine via epoxy ring-opening (X-eRBO), using ZnCl2 as catalyst. Iodine value (IV), saponification value (SV), and oxirane oxygen content (OOC) were determined to evaluate structural changes in oils. The RBO, the eRBO, and the X-eRBO were identified using FTIR, 1H, and 13C NMR. Results: The IV, the SV, and the OOC suggest that the synthesis of eRBO and X-eRBO were effective. The increase of molecular weight in eRBO point to the formation of 6 epoxy rings per original triglyceride. The OOC value of X-eRBO was 22% lower than the OOC value of eRBO, implying that an effective aromatic amination was achieved. The FTIR, 1H and 13C NMR spectroscopy analysis confirmed the epoxidation and amination of the RBO. Study Limitations/Implications: X-eRBO may be a feasible precursor for value-added products, such as crosslinked polymers or corrosion inhibitors. Findings/Conclusions: Refined rice bran oil was aromatically aminated after two stages under mild thermal conditions. This result was achieved with an epoxidation sequence with H2O2/Novozym 435, followed by functionalization with p-xylylenediamine.

Objective: To obtain acrylated refined rice bran oil (RBO) using a combined functionalization: first,epoxidation with H2O2/Novozym 435 lipase, followed by acrylate group insertion.Design/Methodology/Approach: After being epoxidized with H2O2/Novozym 435, the refined rice branoil was acrylated via epoxy ring-opening, using triethanolamine as catalyst and 4-methoxyphenol as inhibitor.The experimental conditions of temperature (T=100 and 110 °C) and reaction time (t=3 and 4 hours), as wellas the ratio of g eRBO (epoxidized oil) to g acrylic acid (1.5 and 2.0) were considered for the functionalization.The functionalizations were monitored using iodine value (IV), saponification value (SV), and oxirane oxygencontent (OOC), Fourier transform infrared (FTIR), and nuclear magnetic resonance (1H NMR), which allowedthe estimation of the %Acrylation.Results: The 1H NMR studies indicate that the acrylation of rice bran oil is efficient, which is confirmed withthe evolution of IV, SV, and OOC. Using the OOC, the best acrylation condition was identified at T=110°C, t=3 hours, and ratio of g eRBO to g acrylic acid=1.5, obtaining a %Acrylation of 85.89% via 1H NMR.Study Limitations/Implications: Partially acrylated rice bran oil may become an intermediate in thebiorefining of this oil and be used in the synthesis of crosslinked polymers.Findings/Conclusions: Refined rice bran oil was efficiently acrylated using two consecutive steps: it wasinitially epoxidized with H2O2/Novozym 435, followed by functionalization with acrylate group.