Antileishmanial and antitrypanosomal activity of the cutaneous secretion of Siphonops annulatus

Abstract

BackgroundAmong the tropical parasitic diseases, those caused by protozoans are considered a challenge to public health, being represented by leishmaniasis and Chagas disease. In view of the low effectiveness and toxicity of the current therapy, animal venoms such as amphibian secretions have been used as a promising source of new drug prototypes. The present work aimed to achieve bioguided fractionation of metabolites present in a cutaneous secretion of the caecilian Siphonops annulatus (Amphibia: Gymnophiona: Siphonopidae) with antileishmanial and antitrypanosomal activity.MethodsThrough liquid-liquid partition and chromatographic techniques, the secretion was fractionated using bioguided assays. The 50% inhibitory concentration (IC50) of the main fraction (SaFr1) was studied against Leishmania (L.) infantum promastigotes and intracellular amastigotes, trypomastigotes of Trypanosoma cruzi and mammalian cells; viability was detected by the colorimetric MTT assay. By using a spectrofluorimetric assay with the probe SYTOX® Green and transmission electron microscopy (TEM), we also investigated the potential damage caused by SaFr1 in the plasma membrane and mitochondria of Leishmania.ResultsThe bioguided assay enabled isolation of a highly purified fraction (SaFr1) with an IC50 of 0.065 μg/mL against promastigotes and 2.75 μg/mL against trypomastigotes. Due to its high toxicity to peritoneal macrophages, SaFr1 showed no selectivity towards the intracellular forms of Leishmania. Ultrastructural studies with Leishmania demonstrated severe mitochondrial damage and the formation of large cytoplasmic vacuoles, leading to the parasite’s death within a few hours. Nevertheless, it caused no alteration in the plasma membrane permeability as detected by the fluorescent probe and TEM.ConclusionsThe present study demonstrated for the first time the antiparasitic activity of the skin secretion of the caecilian S. annulatus against Leishmania and T. cruzi, confirming that skin secretions of these amphibians, similarly to those of anurans and salamanders, are also potential tools for the development of new drug candidates against neglected diseases.

Light and transmission electron microscopic structure of skin glands and dermal scales of a caecilian amphibian Gegeneophis ramaswamii, with a note on antimicrobial property of skin gland secretion

“…There are only few reports on bioactive properties of caecilian skin secretion till now. Antileishmanial and antitrypanosomal properties of the skin secretion of S. annulatus have been reported (Pinto, Antoniazzi, Jared, & Tempone, 2014). Schwartz, Schwartz, Sebben, and Mende (1997) studied the hemolytic and cardiotoxic properties of Siphonops paulensis skin secretion.…”

“…A bioactive compound “siphonopsina” occurs in the caecilian S. annulatus from South America (Sawaya, ). Cytotoxic activity of the cutaneous secretion of S. annulatus against mammalian cells is known; antileishmanial and antitrypanosomal activities have also been reported (Pinto et al, ). The cardiotoxic and hemolytic properties of skin secretion of another North American caecilian S. paulensis have also been reported (Schwartz et al, ).…”

Ergosterol isolated from the basidiomycete Pleurotus salmoneostramineus affects Trypanosoma cruzi plasma membrane and mitochondria

“…Cell viability was determined by resazurin assay as above described. Same conditions were applied to determine the CC 50 of the standard drug benznidazole, which was tested in a range concentration between 200 and 1.56 μg/mL [ 21 ]. DMSO was used to dissolve the compounds and was included in the microplate at 0.5% (v/v) to avoid toxicity.…”

“…The minimal mitochondrial membrane potential was obtained by treatment of trypomastigotes with 10 μM FCCP, a known mitochondrial uncoupler. Trypomastigotes were washed twice with PBS before fluorescence reading at λex = 540 nm and λex = 595 nm [ 21 ].…”

An insight into the skin glands, dermal scales and secretions of the caecilian amphibian Ichthyophis beddomei

“…There are only a few reports on bioactive properties of caecilian skin secretion till now. Bioactive properties of the skin secretion of a caecilian amphibian Siphonops annulatus have been reported ( Pinto et al, 2014 ). Schwartz et al (1997) studied the haemolytic and cardiotoxic properties of the skin secretions of another caecilian – Siphonops paulensis .…”