Gabriel Jaime Arango

Antiprotozoal activities of Colombian plants

In our search for therapeutical alternatives for antiprotozoal chemotherapy, we collected a selection of 44 plants from western Colombia upon ethnopharmacological and chemotaxonomic considerations. Polar and apolar extracts of these species were examined for antimalarial activity using in vitro tests with two clones of Plasmodium falciparum. Leishmanicidal and trypanocidal activity were determined in vitro using promastigote and amastigote forms of several strains of Leishmania sp. and epimastigotes of Trypanosoma cruzi. Among the selected plants, the 15 following species showed good or very good antiprotozoal activity in vitro: Aspidosperma megalocarpon, Campnosperma panamense, Conobea scoparioides, Guarea polymera, Guarea guidonia, Guatteria amplifolia, Huberodendron patinoi, Hygrophila guianensis, Jacaranda caucana, Marila laxiflora, Otoba novogranatensis, Otoba parviflora, Protium amplium, Swinglea glutinosa and Tabernaemontana obliqua. Cytotoxicity was assessed in U-937 cells and the ratio of cytotoxicity to antiprotozoal activity was determined for the active extracts. Ten extracts from eight species showed selectivity indexes > or = 10. Among the extracts that showed leishmanicidal activity, the methylene chloride extract of leaves from C. scoparioides showed a selectivity index in the same range that the one of the Glucantime control. Several of the active leishmanicidal plants are traditionally used against leishmaniasis by the population of the concerned area.

In Vitro and In Vivo Cytotoxicities and Antileishmanial Activities of Thymol and Hemisynthetic Derivatives

ABSTRACT The in vitro and in vivo antileishmanial and cytotoxic activities of thymol and structural derivatives in comparison to those of Glucantime were studied. The results showed here suggest that thymol and hemisynthetic derivatives have promising antileishmanial potential and could be considered as new lead structures in the search for novel antileishmanial drugs.

Cytotoxicity and antileishmanial activity of Annona muricata pericarp.

Hexane, ethyl acetate and methanol extracts of Annona muricata pericarp were tested in vitro against Leishmania braziliensis and L. panamensis promastigotes, and against cell line U-937. The ethyl acetate extract was more active than the other extracts and even of Glucantime used as reference substance. Its fractionation led to the isolation of three acetogenins--annonacin, annonacin A and annomuricin A.

The breadfruit from colombia-a detailed chemical analysis

A detailed chemical analysis of the breadfruit (Artocarpus altilis) is presented, followed by an analysis of the fat and a partial amino acid analysis of the globular proteins and their isoelectric point, determined by electrophoresis.

O-glycoside sequence of pentacyclic triterpene saponins from Phytolacca bogotensis using HPLC-ESI/multi-stage tandem mass spectrometry.

INTRODUCTION The lack of pharmacopoeial methodologies for the quality control of plants used for therapeutic purposes is a huge problem that impacts directly upon public health. In the case of saponins, their great structural complexity, weak glycoside bonds and high polarity hinder their identification by conventional techniques. OBJECTIVE To apply high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI/MS(n)) to identify the O-glycoside sequence of saponins from the roots of Phytolacca bogotensis. METHODOLOGY Saponins were isolated by preparative HPLC and characterised by NMR spectroscopic experiments. Collision-induced dissociation (CID) of isolated saponins was performed producing typical degradation reactions that can be associated with several glycosidic bonds as empirical criteria. A method using solid-phase extraction (SPE) and HPLC/ESI-MS(n) for the characterisation of saponins and identification of novel molecules is described. RESULTS Three saponins reported for the first time in P. bogotensis were isolated and characterised by NMR spectroscopy. Characteristic cross ring cleavage reactions have been used as empirical criteria for the characterisation of the glycosidic bonds most frequently reported for Phytolacca saponins. One new saponin was proposed on the basis of empirical criteria, and other five saponins were identified for the first time for P. bogotensis using HPLC-ESI/MS(n). CONCLUSION Electrospray ionisation in combination with tandem mass spectrometry has been established as a powerful tool for the profiling of saponins from roots of P. bogotensis. CID proved to be a useful tool for the characterisation and identification of known and novel saponins from the plant family Phytolaccaceae and can be used for quality control purposes of crude plant extracts.

Public Memory and Public Mourning in Contemporary Colombia

Colombia today has advanced in setting experience narratives as a resource in the pedagogical practices, cultural agenda, mass media and political action. Beyond classrooms, these narratives include short stories from victims and victimizers of internal war, historical memoirs, artworks, movies, soap operas and testimonial narrative. Rather than simple historical randomization, these phenomena project the dignity and greatness of “small lives” above powerful metanarratives within the current cultural transmission crises. This paper reveals the existing asymmetrical relationship between the social practice of historical memory, as reflected on the “places of memory,” artworks, cinema, testimonial narrative, and the political as well as judicial practice of memory, as manifested in struggles for both dignity and restitution of rights, lands, and property to victims. However, the pedagogical practice of historical memory remains as an unachieved goal in Colombia. La Colombia de hoy ha avanzado en utilizar las narrativas de experiencia como recurso en las prácticas pedagógicas, la agenda cultural, la comunicación en masa y en la acción política. Más allá de los salones de clase, estas narrativas incluyen cuentos cortos de las víctimas y victimarios de las guerras internas, memoirs históricos, trabajos de arte, películas, novelas y testimonios narrativos. En lugar de ser una simple aleatorización histórica, estos fenómenos proyectan la dignidad y la grandeza de las “pequeñas vidas” sobre las metanarrativas poderosas dentro de las crisis de transmisión cultural actuales. Este trabajo revela la relación asimétrica existente entre la práctica social de la memoria histórica, la cual se encuentra reflejada en los “lugares de memoria”, trabajos de arte, cine, testimonios narrativos y la política, así como la práctica judicial de memoria manifestada en las luchas por la dignidad y la restitución de derechos, tierras y propiedades para las víctimas. Sin embargo, la práctica pedagógica de la memoria histórica permanece una meta inalcanzable en Colombia.

Trypanocidal and cytotoxic activity of extracts of Colombian plants

INTRODUCTION The treatment of Chagas disease is based on only two drugs with limited efficacy and significant side effects. The rich biodiversity of the Colombian flora makes bio-prospecting a potential alternative in the search for new antiparasitic drugs. OBJECTIVE Potential trypanocidal activity and cytotoxicity was assessed in extracts from 23 Colombian plants. MATERIALS AND METHODS Extracts of leaves, stems, or of the whole plants were obtained in solvents of a range of polarities. The activity against Trypanosoma cruzi epimastigotes and the cytotoxicity were evaluated by the MTT enzymatic micro-method. Extracts active against epimastigotes and with low cytotoxicity were also tested on trypomastigotes and intracellular amastigotes. RESULTS Among the extracts, biological activity was confirmed in 4 species. The extracts were active on epimastigotes and trypomastigotes; one was active also against amastigotes. The latter extract was isolated from the plant Hieronyma antioquensis and presented IC(50) of 3.1 mg/ml for epimastigotes, 11.5 mg/ml for trypomastigotes and 2.9 mg/ml for amastigotes. The selectivity indexes were 25, 7, and 27 respectively. CONCLUSIONS The extract from H. antioquensis proved a promising candidate for Chagas disease treatment. Futhermore, the MTT enzymatic micromethod was a useful tool for screening biological activity on epimastigotes and other stages of the parasite for further extract trials.