Leishmanicidal Metabolites from Cochliobolus sp., an Endophytic Fungus Isolated from Piptadenia adiantoides (Fabaceae)

Protozoan parasites belonging to genera Leishmania and Trypanosoma are the etiological agents of severe neglected tropical diseases (NTDs) that cause enormous social and economic impact in many countries of tropical and sub-tropical areas of the world. In our screening program for new drug leads from natural sources, we found that the crude extract of the endophytic fungus Cochliobolus sp. (UFMGCB-555) could kill 90% of the amastigote-like forms of Leishmania amazonensis and inhibit by 100% Ellman's reagent reduction in the trypanothione reductase (TryR) assay, when tested at 20 µg mL−1. UFMGCB-555 was isolated from the plant Piptadenia adiantoides J.F. Macbr (Fabaceae) and identified based on the sequence of the internally transcribed spacer (ITS) regions of its ribosomal DNA. The chromatographic fractionation of the extract was guided by the TryR assay and resulted in the isolation of cochlioquinone A and isocochlioquinone A. Both compounds were active in the assay with L. amazonensis, disclosing EC50 values (effective concentrations required to kill 50% of the parasite) of 1.7 µM (95% confidence interval = 1.6 to 1.9 µM) and 4.1 µM (95% confidence interval = 3.6 to 4.7 µM), respectively. These compounds were not active against three human cancer cell lines (MCF-7, TK-10, and UACC-62), indicating some degree of selectivity towards the parasites. These results suggest that cochlioquinones are attractive lead compounds that deserve further investigation aiming at developing new drugs to treat leishmaniasis. The findings also reinforce the role of endophytic fungi as an important source of compounds with potential to enter the pipeline for drug development against NTDs

Structure -- Property Relation of Epoxy Resin with Fique Fibers: Dynamic Behavior using Split-Hopkinson Pressure Bar and Charpy Tests

The main objective of this work is to study polymer matrix composites from epoxy resin reinforced with fique natural fibers. Laminate composite samples with 0.0, 4.0 and 8.0 wt% of fibers in a fabric configuration were fabricated. No further treatment was used in order to make the process as simple and inexpensive as possible for diverse structural applications. Microstructural characterization was analyzed by scanning electron microscopy. Impact tests evaluated by Charpy and Split-Hopkinson pressure bar (SHPB) tests were also conducted

Impact Response of Bamboo Guadua Angustifolia Kunth

The main objective of this work is to study the impact response of bamboo Guadua from Colombia (known as Guadua angustifolia Kunth or just Guadua). Guadua is a very strength material widely used in structural applications in Colombia, including construction and transportation, for which the impact and dynamic behavior is no well established. Transverse samples were tested in both Charpy and compression Split-Hopkinson pressure bar (SHPB) tests. Flexural and compression strength tests were also included. Results revealed that bamboo Guadua as potential material for dynamic applications, comparable with some of the most ductile metals