Imported cases of cutaneous leishmaniasis in Cuba, 2017: role of human movement.

BACKGROUND: Leishmaniasis is a vector-borne disease caused by several species from genus Leishmania. An increase in the number of cases related to human movement has been informed in the last years. Due to the increase of suspicious leishmaniasis cases arriving in Cuba during 2017, a general analysis is presented herein. METHODS: Clinical samples were collected from 5 patients suspicious of leishmaniasis, received from January to December 2017 at the Institute of Tropical Medicine Pedro Kourí, Cuba. Skin lesion samples were analyzed using different diagnostic assays: direct smear, histological examination, and molecular analysis for species identification. Epidemiological and demographic data were requested from each case and analyzed. Treatment and follow up of patient was also performed. RESULTS: Five cases were confirmed as Leishmania infection according to microscopic observation and molecular methods results. PCR-18S, PCR-N/RFLP and PCR-F/RFLP identified the following species: L. panamensis (2 cases), L. braziliensis (1 case), L.panamensis/L.guyanensis (1 case), L. mexicana complex (1 case). In treated patients, drugs were well tolerated, cure were documented and no relapse have been currently reported (3 years later). CONCLUSIONS: Clinical characteristics, demographic data, and epidemiological features of infection for each case evidence the potential risk related with travel to endemic areas of leishmaniasis. KEYWORKS: Cutaneous leishmaniasis, Epidemiology, Imported cases.

Phylogenetic analysis of the Trypanosoma genus based on the heat-shock protein 70 gene.

Trypanosome evolution was so far essentially studied on the basis of phylogenetic analyses of small subunit ribosomal RNA (SSU-rRNA) and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes. We used for the first time the 70kDa heat-shock protein gene (hsp70) to investigate the phylogenetic relationships among 11 Trypanosoma species on the basis of 1380 nucleotides from 76 sequences corresponding to 65 strains. We also constructed a phylogeny based on combined datasets of SSU-rDNA, gGAPDH and hsp70 sequences. The obtained clusters can be correlated with the sections and subgenus classifications of mammal-infecting trypanosomes except for Trypanosoma theileri and Trypanosoma rangeli. Our analysis supports the classification of Trypanosoma species into clades rather than in sections and subgenera, some of which being polyphyletic. Nine clades were recognized: Trypanosoma carassi, Trypanosoma congolense, Trypanosoma cruzi, Trypanosoma grayi, Trypanosoma lewisi, T. rangeli, T. theileri, Trypanosoma vivax and Trypanozoon. These results are consistent with existing knowledge of the genus' phylogeny. Within the T. cruzi clade, three groups of T. cruzi discrete typing units could be clearly distinguished, corresponding to TcI, TcIII, and TcII+V+VI, while support for TcIV was lacking. Phylogenetic analyses based on hsp70 demonstrated that this molecular marker can be applied for discriminating most of the Trypanosoma species and clades.

Differentiation between Trypanosoma cruzi and Trypanosoma rangeli using heat-shock protein 70 polymorphisms.

OBJECTIVE: Differential diagnosis of infection with Trypanosoma cruzi or T. rangeli is relevant for epidemiological studies and clinical practice as both species infect humans, but only T. cruzi causes Chagas' disease. Their common antigen determinants complicate the distinction between both species, while current PCR assays used for differentiation show some drawbacks. We developed and validated a generic PCR discriminating the species by restriction fragment length polymorphism (RFLP) analysis and a duplex PCR specifically amplifying a differently sized fragment of both species. METHODS: The assays are based upon a partial region of the heat-shock protein 70 gene (hsp70). The analytical sensitivity and specificity were determined for both PCRs. The assays were analytically evaluated on a panel of six T. cruzi, one T. cruzi marinkellei and four T. rangeli strains, various other infectious pathogens, a panel of spiked samples of T. cruzi, and artificially mixed infections of T. cruzi and T. rangeli. Finally, the tools were applied on 36 additional isolates of Trypanosoma species. RESULTS: The detection limit of the PCRs was between 0.05 and 0.5 parasite genomes, and 1-10 parasites spiked in 200 µl blood. In artificial mixtures, PCR-RFLP picked up both species in ratios up to 10(2) and duplex PCR up to 10(4) . In the 36 isolates tested, both single and mixed infections were identified. All assays were shown to be specific. CONCLUSION: Our PCRs show high potential for the differential diagnosis of T. cruzi and T. rangeli, which in view of their sensitivity can aid in the confirmation of infection with these parasites in vectors, reservoirs and clinical samples.

Evolution and species discrimination according to the Leishmania heat-shock protein 20 gene.

The Leishmania genus comprises up to 35 species, of which 20 are responsible for human disease. However, the taxonomic status for many of them is under discussion. The small Heat Shock Proteins (sHSPs) are physiologically relevant, protecting cellular proteins from aggregation and maintaining cellular viability under intensive stress conditions. In Leishmania, a protein of this class was previously described, the 20-kDa heat-shock protein (HSP20), which is encoded by a single gene. In the present study, we used this target, alone or in combination with hsp70 gene, to investigate the phylogenetic relationships among Leishmania species. Using a pair of degenerate primers it was possible amplifying a 370bp fragment of the hsp20 coding region in 39 strains of very different geographic origins, representing in total 16 Leishmania species (14 if L. chagasi and L. archibaldi are considered synonymous names of L. infantum and L. donovani, respectively). Nucleotide sequences were readily obtained by direct sequencing of the amplification products. Both phylogenetic trees and networks based on either hsp20 sequences or combined datasets of hsp20 and hsp70 sequences were constructed. These phylogenic analyses supported the division of the Leishmania genus into nine species: L. (L.) donovani, L. (L.) major, L. (L.) tropica, L. (L.) aethiopica, L. (L.) mexicana, L. (V.) lainsoni, L. (V.) naiffi, L. (V.) guyanensis and L. (V.) braziliensis. Additionally, by network analysis, the subspecies L. (L.) donovani infantum and L. (V.) braziliensis peruviana were recognized within the L. (L.) donovani and L. (V.) braziliensis species, respectively. Therefore, hsp20 gene was found to be a suitable molecular marker for Leishmania typing and classification purposes. In addition, this study represents a solid contribution to the objective of establishing a more reliable taxonomy for the genus Leishmania.

Screening of medicinal plants against Leishmania amazonensis.

CONTEXT: Leishmaniasis is a widespread tropical infection caused by different species of Leishmania protozoa. There is no immunoprophylaxis (vaccination) available for Leishmania infections and conventional treatments are unsatisfactory; therefore antileishmanial drugs are urgently needed. Natural products are attractive due to their structural diversity. OBJECTIVE: The present work investigated the antileishmanial action of 21 species of plants. MATERIALS AND METHODS: Plants were collected and their hydroalcoholic extracts were screened against promastigotes and amastigotes of L. amazonensis. Their toxicity was also assayed against peritoneal macrophages from BALB/c mice. RESULTS: Five extracts showed significant growth inhibitory activity against promastigote form. Only the extracts from Bidens pilosa L. (Asteraceae) and Punica granatum L. (Punicaceae) inhibited the growth of intracellular amastigotes, with IC(50) values of 42.6 and 69.6 microg/mL, respectively. In addition, a low toxicity on macrophage from BALB/c mice was observed. DISCUSSION: The antiparasitic activities of B. pilosa and P. granatum have been reported against other parasitic agents and their actions can be the results of flavonoids present in the extracts. CONCLUSION: This study supports the importance of natural products as potential sources in the search for new antileishmanial drugs.

Chemistry, cytotoxicity and antileishmanial activity of the essential oil from Piper auritum.

Leishmaniasis is one of the most important parasitic infections, but current treatments are unsatisfactory due to their toxicity, cost and resistance. Therefore, the development of new antileishmanial compounds is imperative. Many people who live in endemic areas use plants as an alternative to treat the disease. In this paper, we characterised the essential oil from Piper auritum, evaluated its cytotoxicity and determined its antileishmanial activity. The chromatogram obtained by gas chromatography revealed 60 peaks and we found that safrole was the most abundant compound, composing 87% of the oil. The oil was active against the promastigotes of Leishmania major, Leishmania mexicana, Leishmania braziliensis and Leishmania donovani with a favourable selectivity index against peritoneal macrophages from BALB/c mice. The Piper-oil inhibited the growing of intracellular amastigotes of L. donovani with an IC50 value of 22.3 +/- 1.8 microg/mL. This study demonstrates the usefulness of the essential oils as a promising alternative to treat leishmaniasis.

Chemistry, cytotoxicity and antileishmanial activity of the essential oil from Piper auritum

Leishmaniasis is one of the most important parasitic infections, but current treatments are unsatisfactory due to their toxicity, cost and resistance. Therefore, the development of new antileishmanial compounds is imperative. Many people who live in endemic areas use plants as an alternative to treat the disease. In this paper, we characterised the essential oil from Piper auritum, evaluated its cytotoxicity and determined its antileishmanial activity. The chromatogram obtained by gas chromatography revealed 60 peaks and we found that safrole was the most abundant compound, composing 87 percent of the oil. The oil was active against the promastigotes of Leishmania major, Leishmania mexicana, Leishmania braziliensis and Leishmania donovani with a favourable selectivity index against peritoneal macrophages from BALB/c mice. The Piper-oil inhibited the growing of intracellular amastigotes of L. donovani with an IC50 value of 22.3 ± 1.8 ìg/mL. This study demonstrates the usefulness of the essential oils as a promising alternative to treat leishmaniasis.

Phylogeny of Leishmania species based on the heat-shock protein 70 gene.

The 70kDa heat-shock protein (HSP70) is conserved across prokaryotes and eukaryotes, and the protein as well as its encoding gene have been applied in phylogenetic studies of different parasites. In spite of the frequent use of New World Leishmania species identification on the basis of restriction fragment length polymorphisms (RFLP) in the hsp70 gene, it was never sequenced extensively for studying evolutionary relationships. To fill this void we determined the nucleotide sequence of an 1380bp fragment of the coding region commonly used in RFLP analysis, from 43 isolates and strains of different geographic origins. Combination with previously determined sequences amounted to a phylogenetic analysis including 52 hsp70 sequences representing 17 species commonly causing leishmaniasis both in the New and Old World. The genus Leishmania formed a monophyletic group with three distinct subgenera L. (Leishmania), L. (Viannia), and L. (Sauroleishmania). The obtained phylogeny supports the following eight species: L. (L.) donovani, L. (L.) major, L. (L.) tropica, L. (L.) mexicana, L. (V.) lainsoni, L. (V.) naiffi, L. (V.) guyanensis and L. (V.) braziliensis, in some of which subspecies can be recognized: L. (L.) donovani infantum, L. (V.) guyanensis panamensis, and L. (V.) braziliensis peruviana. The currently recognized L. (L.) aethiopica, L. (L.) garnhami, and L. (L.) amazonensis did not form monophyletic clusters. These findings are discussed in relation to results from other genes and proteins, which have to be integrated in order to build a genetically supported taxonomy for the entire genus.

Chemistry, cytotoxicity and antileishmanial activity of the essential oil from Piper auritum

Leishmaniasis is one of the most important parasitic infections, but current treatments are unsatisfactory due to their toxicity, cost and resistance. Therefore, the development of new antileishmanial compounds is imperative. Many people who live in endemic areas use plants as an alternative to treat the disease. In this paper, we characterised the essential oil from Piper auritum, evaluated its cytotoxicity and determined its antileishmanial activity. The chromatogram obtained by gas chromatography revealed 60 peaks and we found that safrole was the most abundant compound, composing 87 por ciento of the oil. The oil was active against the promastigotes of Leishmania major, Leishmania mexicana, Leishmania braziliensis and Leishmania donovani with a favourable selectivity index against peritoneal macrophages from BALB/c mice. The Piper-oil inhibited the growing of intracellular amastigotes of L. donovani with an IC50 value of 22,3 ± 1,8 ìg/mL. This study demonstrates the usefulness of the essential oils as a promising alternative to treat leishmaniasis(AU)

Effect of oral treatment with the essential oil from Chenopodium ambrosioides against cutaneous leishmaniasis in BALB/c mice, caused by Leishmania amazonensis.

BACKGROUND: The aromatic herb Chenopodium ambrosioides is widely known for its antiparasitic activity. The aim of this study was to investigate the antileishmanial effect of Chenopodium oil administered by the oral route at different doses and to compare its action to conventional, clinically used drugs. MATERIALS AND METHODS: BALB/c mice were infected with Leishmania amazonensis and treated with 30, 60, 90, 120, and 150 mg/kg of the essential oil for 15 days. A second experiment was performed to compare the antileishmanial effect of Chenopodium oil with glucantime (28 mg/kg), amphotericin B (1 mg/kg), and pentamidine (4 mg/kg), which were administered daily over 15 days by the intraperitoneal route. RESULTS: Statistically significant differences were observed between BALB/c mice treated with all the doses of the product compared with untreated animals and the mice treated with the vehicle. A dose of 150 mg/kg was the most effective and no macroscopic toxic effects were observed. The size of lesion showed a linear correlation at each point (R > 0.8322), with a 50% effective concentration of 51.4 mg/kg. At 150 mg/kg, the essential oil showed better activity compared with animals treated with glucantime, amphotericin B, and pentamidine. CONCLUSION: C. ambrosioides caused a promising therapeutic effect against cutaneous leishmaniasis caused by L. amazonensis, which could be explored to develop a new alternative treatment for cutaneous leishmaniasis.

PCR-RFLP y RAPD para la tipificación de Leishmania neotropical / PCR-RFLP and RAPD for typing neotropical Leishmania

Introducción. El análisis de la longitud de los fragmentos de restricción del producto amplificado y el estudio del ADN polimórfico amplificado al azar han demostrado ser herramientas útiles para la tipificación de Leishmania. Objetivos. Estudiar la utilidad de las técnicas moleculares para la identificación y tipificación de cepas de referencia de Leishmania spp. del Nuevo Mundo y valorar su aplicabilidad a muestras clínicas. Materiales y métodos. Se aplicó PCR para amplificar el gen que codifica la cisteíno-proteinasa B, y el análisis de la longitud de los fragmentos de restricción del producto amplificado utilizando ácido desoxirribonucleico de 16 cepas de referencia de Latinoamérica y de muestras clínicas de pacientes colombianos con leishmaniasis, y la técnica del ácido desoxirribonucleico polimórfico amplificado al azar utilizando ocho cepas de referencia. Se establecieron los patrones de bandas en cada caso. Resultados. Se obtuvo producto de amplificación en la PCR para Leishmania braziliensis, L. peruviana, L. panamensis y L. guyanensis. Para el resto, no fue posible amplificar el gen con los cebadores utilizados. La restricción mostró un patrón de bandas común para L. peruviana, L. guyanensis y L. panamensis, mientras L. braziliensis, presentaba un perfil individual único. El análisis de restricción del producto amplificado generó un patrón de bandas similar en los cinco pacientes estudiados, que se correspondía con el patrón generado por L. peruviana, L. guyanensis o L. panamensis. Mediante la amplificación al azar se obtuvieron patrones de bandas reproducibles con todas las cepas estudiadas, que posibilitaron la diferenciación. Se discuten las ventajas y limitaciones de ambos procederes. Conclusiones. El combinar ambas metodologías resultaría útil para identificar especies de importancia médica, tomando en cuenta sus ventajas y desventajas.

[PCR-RFLP and RAPD for typing neotropical Leishmania]. / PCR-RFLP y RAPD para la tipificación de Leishmania neotropical.

INTRODUCTION: The analysis of the PCR-restriction fragment length polymorphism and random amplified polymorphic DNA have been useful tools for Leishmania identification. OBJECTIVES: Molecular procedures were demonstrated for identification and typing of reference strains of New World Leishmania and their applicability was validated for clinical samples. MATERIALS AND METHODS: DNA was extracted from 16 reference strains of Latin American Leishmania as well as from clinical samples of leishmaniasis patients. A sequence coding for cysteine proteinase B was amplified by PCR and subjected to restriction fragment length polymorphism analysis. The enzyme used was Taq1. For eight of the reference strains, the random amplified polymorphic desoxyribonucleic acid technique (RAPD) was applied. Band patterns for Leishmania species differentiation were established each each method. The sample size of the clinical sample was of 5. RESULTS: PCR products of the cysteine proteinase B gene were obtained for L. braziliensis, L. peruviana, L. panamensis and L. guyanensis. For the other species, L. mexicana, L. amazonensis, L. garnhami, L. lainsoni, L. chagasi, L. naiffi, no amplification occurred. The patterns of restriction fragments revealed band patterns in common for L. peruviana, L. guyanensis and L. panamensis, whereas L. braziliensis had a distinctive pattern. When human samples were examined, amplification occurred for all cases, and the profiles corresponded to the common profile of L. peruviana, L. guyanensis and L. panamensis. The RAPD technique demonstrated reproducible and distinctive patterns for each of the 8 reference strains, L. mexicana, L. amazonensis, L. garnhami, L. lainsoni, L. chagasi, L. naiffi, making possible to differentiate all them. The advantages and limitations of each procedure are discussed. CONCLUSIONS: The combination of RFP and RAPD methodologies provide useful tools to identify medical important species of Leishmania by recognizing DNA sequences characteristic of each species.

PCR-RFLP y RAPD para la tipificación de Leishmania neotropical / PCR-RFLP and RAPD for typing neotropical Leishmania

El análisis de la longitud de los fragmentos de restricción del producto amplificado y el estudio del ADN polimórfico amplificado al azar han demostrado ser herramientas útiles para la tipificación de Leishmania.Objetivos. Estudiar la utilidad de las técnicas moleculares para la identificación y tipificación de cepas de referencia de Leishmania spp. del Nuevo Mundo y valorar su aplicabilidad a muestras clínicas.Materiales y métodos. Se aplicó PCR para amplificar el gen que codifica la cisteíno-proteinasa B, y el análisis de la longitud de los fragmentos de restricción del producto amplificado utilizando ácido desoxirribonucleico de 16 cepas de referencia de Latinoamérica y de muestras clínicas de pacientes colombianos con leishmaniasis, y la técnica del ácido desoxirribonucleico polimórfico amplificado al azar utilizando ocho cepas de referencia. Se establecieron los patrones de bandas en cada caso(AU)

Combined effect of the essential oil from Chenopodium ambrosioides and antileishmanial drugs on promastigotes of Leishmania amazonensis.

To date, there are no vaccines against Leishmania, and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs of choice used for leishmaniasis therapy are significantly toxic, expensive and with a growing frequency of refractory infections. Because of these limitations, a combination therapy is the better hope. This work demonstrates that the essential oil from Chenopodium ambrosioides shows a synergic activity after incubation in conjunction with pentamidine against promastigotes of Leishmania amazonensis. However, an indifferent effect has been found for combinations of meglumine antimoniate or amphotericin B and the essential oil.

Combined effect of the essential oil from Chenopodium ambrosioides and antileishmanial drugs on promastigotes of Leishmania amazonensis

To date, there are no vaccines against Leishmania, and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs of choice used for leishmaniasis therapy are significantly toxic, expensive and with a growing frequency of refractory infections. Because of these limitations, a combination therapy is the better hope. This work demonstrates that the essential oil from Chenopodium ambrosioides shows a synergic activity after incubation in conjunction with pentamidine against promastigotes of Leishmania amazonensis. However, an indifferent effect has been found for combinations of meglumine antimoniate or amphotericin B and the essential oil.

Até hoje não temos vacina contra a Leishmania e a quimioterapia é a indicação para o controle desta doença. Os remédios que hoje utilizamos são tóxicos e muito caros e além disso o resultado não é sempre o desejado. Por isso, uma terapia de combinação é a melhor opção. Este trabalho mostra que o óleo de essência de C. ambrosioides tem atividade sinérgica junto com a pentamidina sobre os promastigotas de L. amazonensis, diferente do resultado da combinação de antimônio de meglumine e anfotericina B e o óleo de essência.

Combined effect of the essential oil from Chenopodium ambrosioides and antileishmanial drugs on promastigotes of Leishmania amazonensis

To date, there are no vaccines against Leishmania, and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs of choice used for leishmaniasis therapy are significantly toxic, expensive and with a growing frequency of refractory infections. Because of these limitations, a combination therapy is the better hope. This work demonstrates that the essential oil from Chenopodium ambrosioides shows a synergic activity after incubation in conjunction with pentamidine against promastigotes of Leishmania amazonensis. However, an indifferent effect has been found for combinations of meglumine antimoniate or amphotericin B and the essential oil(AU)

PCR-RFLP/Hsp70 para identificar y tipificar Leishmania de la región neotropical / PCR-RFLP/Hsp70 for identification and tipification of Leishmania from the tropical region

Se realizó la estandarización de las condiciones de amplificación del gen que codifica para la proteína de choque térmico de 70 kDa (Hsp70) de Leishmania mediante la reacción en cadena de la polimerasa (PCR-Hsp70), así como el análisis posterior de la longitud de los fragmentos de restricción (RFLP) del producto amplificado, utilizando como molde ADN puro de una cepa de referencia de Leishmania mexicana. Se estudió la sensibilidad y especificidad analíticas de la PCR, así como la reproducibilidad, utilizando ADN de L. mexicana, L. amazonensis, L. guyanensis y L. lainsoni. Se obtuvo una banda de 1,3 Kpb, demostrándose la amplificación del gen que codifica para la Hsp70. Los patrones de bandas obtenidos tras la digestión enzimática, utilizando la enzima Hae III, permitieron establecer diferencias entre las especies estudiadas: L. guyanensis y L. lainsoni se diferencian entre sí y estas a su vez de L. mexicana y L. amazonensis, que mostraron un patrón de bandas común. La sensibilidad y especificidad analíticas de la técnica fueron adecuadas. Se demostró la factibilidad de identificar y tipificar especies del continente americano mediante la PCR-RFLP/Hsp70, y de utilizar la restricción enzimática del producto amplificado para distinguir entre Leishmania spp. y Trypanosoma cruzi, dándose un primer paso en el establecimiento de estos métodos moleculares en el laboratorio de referencia del instituto(AU)

PCR-RFLP/Hsp70 para identificar y tipificar Leishmania de la región neotropical / PCR-RFLP/Hsp70 for identification and tipification of Leishmania from the tropical region

Se realizó la estandarización de las condiciones de amplificación del gen que codifica para la proteína de choque térmico de 70 kDa (Hsp70) de Leishmania mediante la reacción en cadena de la polimerasa (PCR-Hsp70), así como el análisis posterior de la longitud de los fragmentos de restricción (RFLP) del producto amplificado, utilizando como molde ADN puro de una cepa de referencia de Leishmania mexicana. Se estudió la sensibilidad y especificidad analíticas de la PCR, así como la reproducibilidad, utilizando ADN de L. mexicana, L. amazonensis, L. guyanensis y L. lainsoni. Se obtuvo una banda de 1,3 Kpb, demostrándose la amplificación del gen que codifica para la Hsp70. Los patrones de bandas obtenidos tras la digestión enzimática, utilizando la enzima Hae III, permitieron establecer diferencias entre las especies estudiadas: L. guyanensis y L. lainsoni se diferencian entre sí y estas a su vez de L. mexicana y L. amazonensis, que mostraron un patrón de bandas común. La sensibilidad y especificidad analíticas de la técnica fueron adecuadas. Se demostró la factibilidad de identificar y tipificar especies del continente americano mediante la PCR-RFLP/Hsp70, y de utilizar la restricción enzimática del producto amplificado para distinguir entre Leishmania spp. y Trypanosoma cruzi, dándose un primer paso en el establecimiento de estos métodos moleculares en el laboratorio de referencia del instituto.

Necesidad del uso de cromógenos para cuantificar promastigotes de Leishmania en placas de 96 pozos / Necessity of the cromógenos use to quantify promastigotes of Leishmania in badges of 96 wells

Las dificultades que aún persisten en el tratamiento de las leishmaniosis justifican el ensayo de la acción de nuevos productos sobre formas del parásito, en la búsqueda de una alternativa terapéutica a esta parasitosis. Dada la necesidad de establecer un procedimiento para evaluar la actividad in vitro de productos naturales y sintéticos en las condiciones cubanas, el propósito de este trabajo fue definir la utilidad del uso del p-nitrofenilfosfato como sustancia cromógena para la cuantificación de parásitos en placas de 96 pozos. Para normalizar este método colorimétrico se establecieron las etapas de la curva de crecimiento del parásito. El estudio de linealidad y selección del volumen de muestra que resultaba óptimo para la realización de los ensayos mostró que con 200 mm se obtuvo el máximo coeficiente de determinación lineal. Asimismo, se comparó el coeficiente de variación en presencia y ausencia del cromógeno y se estudió la influencia de los cambios del medio de cultivo en la lectura de las absorbancias. El límite de cuantificación establecido demostró la necesidad del uso del cromógeno para los propósitos de este trabajo y los resultados en general permiten recomendar esta metodología, menos subjetiva, simple de ejecutar y rápida, para ensayar los productos que resulten de interés en este campo(AU)