Resumen La pandemia de COVID-19 generó diversas dificultades en la docencia universitaria e innovaciones en la didáctica de la química. Esta investigación presenta la percepción del estudiantado sobre las actividades de aprendizaje desarrolladas en la asignatura de Química General para Ingeniería durante el segundo semestre de 2021. Se empleó un diseño de investigación, acción participativa, a través de encuestas de percepción y grupos focales para indagar los antecedentes sociodemográficos, la satisfacción con la asignatura, la participación en clases y la percepción sobre las actividades de aprendizaje. Entre los resultados principales destaca una elevada satisfacción con la asignatura y las actividades de aprendizaje diseñadas, una participación baja y aspectos a mejorar en el formato de estas actividades. Estos resultados concuerdan con la percepción positiva de otras innovaciones empleadas en asignaturas de química y permitieron la mejora continua de estas actividades.

Abstract The COVID-19 pandemic generated various difficulties in university teaching and innovations in the didactics of chemistry. This research presents the perception of the student body on the learning activities designed in the subject of General Chemistry for Engineering during the second semester of 2021. A participatory action research design was used, through perception surveys and focus groups to investigate the background sociodemographics, satisfaction with the subject, class participation and perception of learning activities. Among the main results stands out a high satisfaction with the subject and the designed learning activities, a low participation and aspects to improve in the format of these activities. These results agree with the positive perception of other innovations used in chemistry subjects and allowed the continuous improvement of these activities.

The activity of five (1-5) abietane phenol derivatives against Leishmania infantum and Leishmania braziliensis was studied using promastigotes and axenic and intracellular amastigotes. Infectivity and cytotoxicity tests were performed with J774.2 macrophage cells using Glucantime as a reference drug. The mechanisms of action were analysed by performing metabolite excretion and transmission electron microscopy ultrastructural studies. Compounds 1-5 were more active and less toxic than Glucantime. The infection rates and mean number of parasites per cell observed in amastigote experiments showed that derivatives 2, 4 and 5 were the most effective against both L. infantum and L. braziliensis. The ultrastructural changes observed in the treated promastigote forms confirmed that the greatest cell damage was caused by the most active compound (4). Only compound 5 caused changes in the nature and amounts of catabolites excreted by the parasites, as measured by ¹H nuclear magnetic resonance spectroscopy. All of the assayed compounds were active against the two Leishmania species in vitro and were less toxic in mammalian cells than the reference drug.

Four superoxide dismutase (SOD) activities (SOD I, II, III, and IV) have been characterized in the epimastigote form of Trypanosoma cruzi. The total extract was subjected to two successive ammonium sulphate additions between 35 and 85%, and the resulting fraction was purified using two continuous chromatography processes (ion exchange and filtration). Enzymes were insensitive to cyanide but sensitive to hydrogen peroxide, properties characteristic of iron-containing SODs. The molecular masses of the different SODs were 20 kDa (SOD I), 60 kDa (SOD II), 50 kDa (SOD III) and 25 kDa (SOD IV), whereas the isoelectric points were 6.9, 6.8, 5.2 and 3.8, respectively. Subcellular location and digitonin experiments have shown that these SODs are mainly cytosolic, with small amounts in the low-mass organelles (SOD II and SOD I) and the mitochondrion (SOD III), where these enzymes play an important role in minimizing oxidative damage.

An excreted iron superoxide dismutase (FeSODe) of pI 3.6 with a molecular weight of 28-30 kDa was detected in the in vitro culture of Phytomonas isolated from Euphorbia characias (SODeCHA) and from Lycopersicon esculentum (SODeTOM), in Grace's medium without serum. These FeSODe excreted into the medium had immunogenic capacity: the positivity of the anti-SODeCHA serum persisted to a dilution of 1/30,000, and for the anti-SODeTOM to 1/10,000 by Western blot. In addition, cross reaction was detected between the anti-SODe serum of Phytomonas isolated from E. characias against SODeTOM, and the anti-SODe serum from L. esculentum with SODeCHA. This characteristic offers the possibility of its use to diagnose plant trypanosomatids. The validation of the test was confirmed by experimental inoculation of tomato fruits with Phytomonas isolated from L. esculentum. At 7, 10, 15, and 21 days post infection, it was possible to detect the presence of the parasites with the anti-SODe serum of Phytomonas isolated from L. esculentum at a dilution of 1/250. These serological results were confirmed by visualization of the parasites by optical microscopy. The data of this study confirm that the SOD is sufficient to identify a trypanosomatid isolated from plants as belonging to the genus Phytomonas.

There is no effective chemotherapy against diseases caused by Phytomonas sp., a plant trypanosomatid responsible for economic losses in major crops. We tested three triazolo-pyrimidine complexes [two with Pt(II), and another with Ru(III)] against promastigotes of Phytomonas sp. isolated from Euphorbia characias. The incorporation of radiolabelled precursors, ultrastructural alterations and changes in the pattern of metabolite excretion were examined. Different degrees of toxicity were found for each complex: the platinun compound showed an inhibition effect on nucleic acid synthesis, provoking alterations on the levels of mitochondria, nucleus and glycosomes. These results, together with others reported previously in our laboratory about the activity of pyrimidine derivatives, reflect the potential of these compounds as agents in the treatment of Phytomonas sp.

A protozoan flagelate has recently been isolated from Amaranthus retroflexus. This plant grows near economically important crops in southeastern Spain, which are known to be parasitized by Phytomonas spp. The present study focuses on the characterization of the energy metabolism of this new isolate. These flagellates utilize glucose efficiently as their primary energy source, although they are unable to completely degrade it. They excrete ethanol, acetate, glycine, and succinate in lower amount, as well as ammonium. The presence of glycosomes was indicated by the early enzymes of the glycolytic pathway, one enzyme of the glycerol pathway (glycerol kinase), and malate dehydrogenase. No evidence of a fully functional citric-acid cycle was found. In the absence of catalase activity, these flagellates showed significant superoxide dismutase activity located in the glycosomal and cytosolic fractions. These trypanosomes, despite being morphologically and metabolically similar to other Phytomonas isolated from the same area, showed significant differences, suggesting that they are phylogenetically different species.