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Updated: May 11, 2026
Deciphering the Molecular Mechanism and Function of Pore-Forming Toxins Using Leishmania major
Published on: October 28, 2022
Differential lethal action of octyl and oct-4E-enyl p-nitrobenzoates in Leishmania spp. - a mechanistic study
Camila S de Freitas1, Daniela P Lage1, Breno L Pimenta1
1Infectiology and Tropical Medicine, Medicine Faculty, Federal University of Minas Gerais, Belo Horizonte, MG, 30130-100, Brazil.
Abstract:
Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. Current treatments, mainly based on pentavalent antimonials and amphotericin B, are limited by severe side effects, high costs, and the emergence of resistant strains, highlighting the need for new therapeutic scaffolds. Gibbilimbol B, an alkylphenol derivative isolated from the Brazilian plant Piper malacophyllum, has shown antileishmanial potential, prompting the design of analogues to optimize its biological activity. Previous studies have investigated gibbilimbol B-inspired derivatives to enhance potency, selectivity, and ADMET properties. Structural modifications of the phenolic ring and side chain improved potency and drug-like properties, particularly in 4-nitrobenzamide derivatives with C8 side chains. Therefore, the present study investigates two ester analogues - octyl 4-nitrobenzoate (1) and oct-4E-enyl 4-nitrobenzoate (2), as well as 4-nitrobenzoic acid (3) - for their in vitro antileishmanial activity against L. infantum, L. amazonensis, and L. braziliensis promastigotes and intracellular amastigotes. Compound 1, which has a saturated C8 side chain, exhibited significant activity, with EC50 values of 5.8 ± 0.2, 13.5 ± 0.2 and 1.0 ± 0.1 μg/mL for promastigotes of L. infantum, L. amazonensis and L. braziliensis, respectively. This compound displayed also reduced cytotoxicity to macrophages in vitro (CC50 = 201 ± 10 μg/mL) and a high selectivity index (SI > 200 for L. braziliensis). In contrast, compound 2, featuring a double bond at the C-4 position of a C8 side chain, exhibited moderate activity. Meanwhile, compound 3, the original benzoic acid derivative, was inactive. Mechanistic assays with compound 1 revealed mitochondrial depolarization and reactive oxygen species (ROS) generation without loss of plasma membrane integrity, suggesting an apoptotic-like death pathway. Given its simple structure and promising results, octyl-4-nitrobenzoate (1) can be considered a promising candidate for further SAR (structure-activity relationship) optimization for the development of new antileishmanial drugs.
Insights
Octyl 4-nitrobenzoate, a novel compound inspired by Gibbilimbol B, shows potent antileishmanial activity against Leishmania parasites. This promising drug candidate exhibits low cytotoxicity and a high selectivity index, offering a new avenue for treating leishmaniasis.
Area of Science:
- Medicinal Chemistry
- Parasitology
- Drug Discovery
Background:
- Leishmaniasis is a neglected tropical disease with limited treatment options due to side effects and resistance.
- Existing therapies like antimonials and amphotericin B face challenges, necessitating novel therapeutic agents.
- Gibbilimbol B derivatives have shown antileishmanial potential, with structural modifications improving activity and drug-like properties.
Purpose of the Study:
- To synthesize and evaluate novel ester analogues of Gibbilimbol B for antileishmanial activity.
- To investigate the in vitro efficacy of octyl 4-nitrobenzoate (1) and oct-4E-enyl 4-nitrobenzoate (2) against Leishmania species.
- To assess the cytotoxicity and selectivity index of the most active compounds.
Main Methods:
- Synthesis of octyl 4-nitrobenzoate (1), oct-4E-enyl 4-nitrobenzoate (2), and 4-nitrobenzoic acid (3).
- In vitro evaluation of antileishmanial activity against promastigotes and intracellular amastigotes of L. infantum, L. amazonensis, and L. braziliensis.
- Assessment of cytotoxicity against macrophages and determination of selectivity index.
Main Results:
- Octyl 4-nitrobenzoate (1) demonstrated significant antileishmanial activity (EC50 values as low as 1.0 ± 0.1 μg/mL) and low cytotoxicity (CC50 = 201 ± 10 μg/mL).
- Compound 1 exhibited a high selectivity index (>200 for L. braziliensis), indicating a favorable safety profile.
- Mechanistic studies suggested an apoptotic-like death pathway involving mitochondrial depolarization and ROS generation.
Conclusions:
- Octyl 4-nitrobenzoate (1) is a potent antileishmanial agent with a promising safety profile.
- The compound's simple structure and significant activity make it a strong candidate for further structure-activity relationship optimization.
- This study highlights the potential of Gibbilimbol B-inspired compounds for developing new leishmaniasis treatments.
