Leishmanicidal, cytotoxic and apoptotic effects of Gossypium hirsutum bulb extract and its separated fractions on Leishmania major.

BACKGROUND & OBJECTIVES: Leishmaniasis is a major global health problem with no safe and effective therapeutic drugs. This study evaluated the cytotoxic and apoptotic effects of crude extract and fractions of Gossypium hirsutum bulb on Leishmania major stages using advanced experimental models. METHODS: Bulbs of G. hirsutum were collected from the Kerman province of Iran. The bulb was extracted using Soxhlet apparatus and different fractions were obtained by column chromatography (CC). Different concentrations of the extract and the fractions were evaluated against L. major and compared with Glucantime®. The cytotoxicity and apoptotic values were analysed by flow cytometry. The fractions obtained in CC were monitored by thin layer chromatography, and fractions with similar chromatographic patterns were mixed. RESULTS: The extract and two fractions, F4 and F5 inhibited the proliferation of L. major promastigotes and amastigotes in a dose-dependent manner at 72 h post-treatment. No significant cytotoxic effects were observed for extract and fractions, as the selectivity index was over 1000, far beyond >10. The mean apoptotic values for L. major were superior to those of Glucantime®. INTERPRETATION & CONCLUSION: Both the crude extract and fractions (F4 and F5) had significant antileishmanial effects on L. major stages, and were were superior relative to Glucantime®. No cytotoxic effects were associated with the extract or fractions and they showed excellent apoptotic index, a possible mechanism behind inducing parasite death. Further investigations are essential to study the effect of G. hirsutum bulb fractions in animal model and clinical settings for planning strategies for the prevention and control of leishmaniasis.

Efficacy of biogenic selenium nanoparticles against Leishmania major: in vitro and in vivo studies.

PROJECT: This study investigated the in vitro and in vivo effectiveness of biogenic selenium nanoparticles (Se NPs), biosynthesized by Bacillus sp. MSh-1, against Leishmania major (MRHO/IR/75/ER). PROCEDURE: The 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity effects of the biogenic Se NPs against both promastigote and amastigote forms of L. major. In a separate in vivo experiment, we also determined the preventive and therapeutic effects of biogenic Se NPs in BALB/c mice following subcutaneous infected with L. major. RESULTS: The MTT assays showed that the highest toxicity occurred after 72 h against both promastigote and amastigote forms of L. major. The cytotoxicity of Se NPs was higher at all incubation times (24, 48, and 72 h) against the promastigote than the amastigote form (p<0.05). The 50% inhibitory concentrations (IC50) of the Se NPs were 1.62±0.6 and 4.4±0.6 µg ml(-1) against the promastigote and amastigote forms, respectively, after a 72-h incubation period. Apoptosis assays showed DNA fragmentation in promastigotes treated with Se NPs. In an animal challenge, prophylactic doses of biogenic Se NPs delayed the development of localized cutaneous lesions. Moreover, daily administration of Se NPs (5 or 10 mg kg(-1) day(-1)) in similarly infected BALB/c mice that had not received prophylactic doses of Se NPs also abolished the localized lesions after 14 days. CONCLUSION: Based on these in vitro and in vivo studies, biogenic Se NPs can be considered as a novel therapeutic agent for treatment of the localized lesions typical of cutaneous leishmaniasis.

Screening of antileishmanial activity from marine sponge extracts collected off the Tunisian coast.

The present study reports on the in vitro antileishmanial activity of two Ircinidae (Dictyoceratida, Demospongiae, Porifera) Ircinia spinosula and Sarcotragus sp. Sampled from the east coast of Tunisia. The ethyl acetate, dichloromethane, and aqueous extracts were tested against Leishmania major promastigotes. The anti-proliferative activity was checked using different extracts concentration during 72 h. We found that the IC50 (sub-inhibitory concentration) values ranged from 1.39 to 264.67 mug/ml. The most active extract was that from sarcotragus sp dichloromethane extract. Microscopic observations showed that the extracts promoted cellular alterations and induce enlargement of the nucleus and modification of the parasite shape. These promising results in relation with in vitro antileishmanial activity open the way for complementary investigation in order to purify and identify active molecules.

Effects of osmotic stress on metabolism, shape, and amino acid content of Leishmania.

An acute decrease in osmolality causes a rapid change in the shape of the parasitic protozoan Leishmania donovani as determined by light microscopy and by flow cytometry. Incubation of the cells is an isotonic buffer supplemented with glucose. 2-deoxyglucose (2-DG), alanine, or proline also causes a shape change, presumably due to the swelling caused by the water that accompanies these substrates as they are actively transported into the cells. Hypo-osmolality also causes a rapid release of alanine and several other amino acids via a swelling activated amino acid channel. A sudden increase in osmolality causes a change in shape, an inhibition in the rates of oxidation of alanine, proline, leucine, and glucose, and in the rates of uptake of 2-aminoisobutyrate (AIB) and 2-DG. The protein kinase inhibitors staurosporine and genistein inhibited the rates of oxidation of alanine, glucose, and proline in a culture-age dependent manner and also altered the rate of release of AIB in response to hypo-osmotic stress. The possible roles of protein kinases in the culture-age dependent changes in the uptake, release and metabolism of several amino acids and of glucose are discussed.