A total of 115 different plant extracts from our collection, representing 96 plant species, have been evaluated for in vitro antileishmanial activity against L. amazonensis promastigotes. In addition, the extracts were screened for cytotoxic activity against BALB/c mouse macrophages in order to assess a selectivity index. Crude extracts that showed a selectivity index (CC50 for macrophage / IC50 for promastigotes) ≥ 5 or with IC50 < 12.5 μg/mL against promastigotes, a total of 28 extracts, were further screened for anti-amastigote activity. A total of 25 extracts showed promising activity against L. amazonensis promastigotes with low cytotoxic activity. Ten of these extracts showed selectivity indices, (CC50 for macrophages / IC50 for amastigotes) greater than 10 and are considered “hits”, worthy candidates for further phytochemical exploration: Conostegia xalapensis methanol bark extract, Endiandra palmerstonii bark extract, Eugenia monteverdensis acetone bark extract, Eugenia sp. “fine leaf” acetone bark extract, Exothea paniculata chloroform bark extract, Mallotus paniculatus ethanol bark extract, Matelea pseudobarbata ethanol extract, Quercus insignis ethanol bark extract, Sassafras albidum dichloromethane bark extract, and Stemmadenia donnell-smithii acetone bark extract.
Historically, natural products have been a rich source of lead molecules in drug discovery. In particular, products to treat infectious diseases have been developed and several reports about potentialities of essential oils (EO) against Leishmania could be found. In this study, we report the chemical characterization, anti-leishmanial effects and cytotoxicity of the EO from Artemisia absinthium L. Chemical analysis revealed the EO to be composed of 18 compounds, 11 of which were identified, accounting for 64.1% of the composition. The main component of the EO was trans-sabinyl acetate, which made up 36.7%. In vitro anti-leishmanial screening showed that the A. absinthium EO inhibited the growth of promastigotes (14.4 3.6 g/mL) and amastigotes (13.4 ± 2.4 g/mL) of L. amazonensis; while cytotoxicity evaluation caused 6 fold higher values than those for the parasites. In a model of experimental cutaneous leishmaniasis in BALB/c mice, five doses of EO at 30 mg/kg by intralesional route demonstrated control of lesion size and parasite burden (p< 0.05) compared with animals treated with glucantime and untreated mice. In conclusion, in vitro and in vivo results showed the potential of EO from A. absinthium as a promising source for lead or active compounds against Leishmania, which could be explored.
Background: Leishmaniasis is a zoonotic disease caused by protozoan parasites from Leishmania genus. Currently, there are no effective vaccines available and the available therapies are far from ideal. In particular, the development of new therapeutic strategies to reduce the infection caused by Leishmania amazonensis could be considered desirable. Different plant-derived products have demonstrated antileishmanial activity, including the essential oil (EO) from Artemisia absinthium L. (EO-Aa), Asteraceae. Methods: In the present study, the EO-Aa formulated in nanocochleates (EO-Aa-NC) was investigated in vitro against intracellular amastigotes of L. amazonensis and non-infected macrophages from BALB/c mice. In addition, the EO-Aa-NC was also evaluated in vivo against on experimental cutaneous leishmaniasis, which body weight, lesion progression, and parasite load were determined. Results: EO-Aa-NC displayed IC50 values of 21.5 ± 2.5 μg/mL and 27.7 ± 5.6 μg/mL against intracellular amastigotes of L. amazonensis and non-infected peritoneal macrophage, respectively. In the animal model, the EO-Aa-NC (30 mg/kg/intralesional route/every 4 days 4 times) showed no deaths or weight loss greater than 10%. In parallel, the EO-Aa-NC suppressed the infection in the murine model by approximately 50%, which was statistically superior (p < 0.05) than controls and mice treated with EO-Aa. In comparison with Glucantime®, EO-Aa-NC inhibited the progression of infection as efficiently (p > 0.05) as administration of the reference drug. Conclusions: Encochleation of EO-Aa resulted in a stable, tolerable, and efficacious antileishmanial formulation, facilitating systemic delivery of EO, with increased activity compared to administration of the free EO-Aa. This new formulation shows promising potential to future studies aimed at a new therapeutic strategy to treat leishmaniasis.
Leishmaniasis is a neglected tropical disease caused by Leishmania parasitic protozoa, which currently lacks efficient treatment. Natural products have shown promise as a potential source for antiprotozoal drugs. This work focuses on the antileishmanial potential of Sassafras albidum (Lauraceae) bark extract. The crude bark extract of S. albidum showed excellent antileishmanial activity with an IC50 value less than 12.5 μg/mL against promastigotes of L. amazonensis. The chloroform stem bark extract of S. albidum was subjected to preparative column chromatography. Five compounds were isolated, purified by recrystallization, and identified as sesamin, spinescin, β-sitosterol, hexatriacontanal, and 1-triacontanol. Antileishmanial and cytotoxic screening were performed on these compounds. Sesamin exhibited the best activity against L. amazonensis with an IC50 of 15.8 μg/mL and was not cytotoxic to mouse macrophage cells ( CC50 > 100 μg/mL).
Leishmaniasis is a group of neglected tropical diseases caused by protozoan parasites of the Leishmania genus. The absence of effective vaccines and the limitations of current treatments make the search for effective therapies a real need. Different plant-derived essential oils (EOs) have shown antileishmanial effects, in particular from Bixa orellana L. (EO-Bo) and Dysphania ambrosioides (L.) Mosyakin & Clemants (EO-Da). In the present study, the EO-Bo and EO-Da, formulated in nanocochleates (EO-Bo-NC and EO-Da-NC, respectively), were evaluated in vitro and in vivo against L. amazonensis. The EO-Bo-NC and EO-Da-NC did not increase the in vitro inhibitory activity of the EOs, although the EO-Bo-NC showed reduced cytotoxic effects. In the animal model, both formulations (30 mg/kg/intralesional route/every 4 days/4 times) showed no deaths or weight loss greater than 10%. In the animal (mouse) model, EO-Bo-NC contributed to the control of infection (p < 0.05) in comparison with EO-Bo treatment, while the mice treated with EO-Da-NC exhibited larger lesions (p < 0.05) compared to those treated with EO-Da. The enhanced in vivo activity observed for EO-Bo-NC suggests that lipid-based nanoformulations like nanocochleates should be explored for their potential in the proper delivery of drugs, and in particular, the delivery of hydrophobic materials for effective cutaneous leishmaniasis treatment.
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