Roger Espinosa-Saez

In this study, four quinoline–based chromophores (EP01–EP04) with distinct π–conjugated architectures were studied to understand how molecular connectivity influences their electronic structure and nonlinear optical properties. Experimental characterization was combined with DFT and TD–DFT calculations to relate molecular structure to UV–Vis absorption, frontier–orbital distribution, and calculated electronic response. EP01, which contains a vinylene bridge connecting quinoline to an alkoxy–substituted aromatic ring, exhibited the smallest HOMO–LUMO gap in the series (5.65 eV) and the most red–shifted experimental absorption in methanol (353 nm). In comparison, the principal absorption maximum of EP02 occurred at 265 nm. The results for EP03 and EP04 showed that band position and intensity depend not only on the HOMO–LUMO gap but also on the orbitals involved in each transition. The calculated solvent effect on the most intense transitions was limited, with shifts of 2–7 nm between toluene and water. EP01 also exhibited the largest calculated first and second hyperpolarizabilities, approximately 2.58 and 2.92 times those of EP02, respectively. Together, these findings show that connecting the aromatic fragments through a continuous π–pathway favors the optical response of these derivatives and provides structural guidance for designing new quinoline–based chromophores.

This study evaluates the cytotoxic and genotoxic effects of PM_2.5 collected from an open-cast coal mining area in northern Colombia. Cyclohexane (CH), dichloromethane (DCM), and acetone (ACE) extracts were obtained using Soxhlet extraction to isolate compounds of different polarities. Human lymphocytes were exposed to the extracted compounds, and cytotoxicity and genotoxicity were assessed using the cytokinesis block micronucleus (CBMN) and comet assays, incorporating FPG and ENDO III enzymes to detect oxidative DNA damage. Chemical analysis revealed that the organic fractions consisted mainly of modified hydrocarbons and volatile organic compounds. The CBMN assay showed a significant increase in micronuclei in binucleated (MNBN) and mononucleated (MNMONO) cells and nucleoplasmic bridges (NPB) in exposed lymphocytes. The comet assay revealed substantial oxidative DNA damage, particularly with the ACE extract, which significantly increased oxidized purines and pyrimidines. DCM induced similar effects, while CH showed moderate effects. CREST immunostaining revealed aneugenic activity, particularly in cells exposed to ACE and DCM extracts. These results suggest that polar fractions of PM_2.5, likely containing metals and modified PAHs, contribute to DNA damage and chromosomal instability. The study highlights the need to monitor the composition of PM_2.5 in mining regions to implement stricter environmental policies to reduce exposure and health risks.

Esta investigación evalua la actividad antiprotozoaria y antioxidante de extractos etanólicos de hojas y corteza de la especie Pilocarpus alvaradoi. La actividad antioxidante se mide usando los métodos DPPH•, ABTS•+ y FRAP. La actividad antiprotozoaria in vitro es medida frente a los parásitos de Leishmania (V.) panamensis, Tripanosoma cruzi y Plasmodium falciparum. La citotoxicidad se examina frente a células U937. Los compuestos se identifican mediante espectroscopia de RMN. Como resultado se identifican tres compuestos: sesamina, escopoletina y bergapteno. Los extractos etanólicos y subextracto en acetato de etilo de corteza muestran actividad antioxidante de 13.5 y 19.5 mg/L (ABTS•+), 17.4 y 21.1 mg/L (DPPH•) y 52.0 y 51.5 mg/L (FRAP) respectivamente. El extracto etanólico de corteza presenta moderada actividad leishmanicida, antiplásmodial y tripanocida con valores de CE₅₀ de 47.90, 28.05 y 49.06 µg/mL, respectivamente. En conclusión, las sustancias obtenidas de P. alvaradoi se reportan por primera vez para esta especie.