Synthesis and in vitro evaluation of leishmanicidal activity of 7-hydroxy-4-phenylcoumarin derivatives

3-styrylcoumarin scaffold-based derivatives as a new approach for leishmaniasis intervention: biological and molecular modeling studies

Seven 3-styrylcoumarins were tested for antileishmanial activity against Leishmania (Viannia) panamensis amastigotes. Cytotoxic activity was also evaluated against mammalian U-937 cells. The 3-methoxy-4-hydroxy coumarin derivative 6 was the most active with an IC50 of 40.5 µM, and did not reveal any conspicuous toxicity toward mammalian U-937 cells. Therefore, it may have potential to be considered as candidate for antileishmanial drug development. Further, among several druggable Leishmania targets, molecular docking studies revealed that compound 6 had docking preference by the N-myristoyltransferase (Lp-NMT) of Leishmania panamensis, showing a higher docking score of - 10.1 kcal mol-1 than positive controls and making this protein as a presumably druggable target for this compound. On the other hand, molecular dynamics simulations affirm the docking hypothesis, showing a conformational stability of the 6/Lp-NMT complex throughout 100 ns simulation. Moreover, the molecular mechanics/Poisson-Boltzmann surface area method also support the docking findings, revealing a total free energy of binding of - 47.26 ± 0.08 kcal mol-1, and identifying through energy decomposition analysis that those key aminoacids are contributing strongly to ligand binding. Finally, an optimal pharmacokinetic profile was also estimated for 6. Altogether, coumarin 6 could be addressed as starting point for further pharmacological studies concerning the therapeutic leishmaniasis intervention.

Graphical abstract

Recent advancements in anti-leishmanial research: Synthetic strategies and structural activity relationships

Leishmaniasis is a parasitic neglected tropical disease caused by various species of Leishmania parasite. Despite tremendous advancements in the therapeutic sector and drug development strategies, still the existing anti-leishmanial agents are associated with some clinical issues like drug resistance, toxicity and selectivity. Therefore, several research groups are continuously working towards the development of new therapeutic candidates to overcome these issues. Many potential heterocyclic moieties have been explored for this purpose including triazoles, chalcones, chromone, thiazoles, thiosemicarbazones, indole, quinolines, etc. It is evident from the literature that the majority of anti-leishmanial agents act by interacting with key regulators including PTR-I, DHFR, LdMetAP1, MAPK, 14 α-demethylase and pteridine reductase-I, etc. Also, these tend to induce the production of ROS which causes damage to parasites. In the present compilation, authors have summarized various significant synthetic procedures for anti-leishmanial agents reported in recent years. A brief description of the pharmacological potentials of synthesized compounds along with important aspects related to structural activity relationship has been provided. Important docking outcomes highlighting the possible mode of interaction for the reported compounds have also been included. This review would be helpful to the scientific community to design newer strategies and also to develop novel therapeutic candidates against leishmaniasis.

Investigation of 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one as a promising coumarin compound for the development of a new and orally effective antileishmanial agent

Changes in host immunity and parasite resistance to drugs are among the factors that contribute to decreased efficacy of antiparasitic drugs such as the antimonial compounds pentamidine, amphotericin (AMP B) and miltefosine. Bioactive natural products could be alternatives for the development of new drugs to treat neglected human diseases such as leishmaniasis. Natural coumarins and synthetic analogues have shown leishmanicidal activity, mainly in vitro. This study investigated the in vitro and in vivo leishmanicidal activity of synthetic coumarin compounds (C1-C5) in parasites Leishmania (L.) amazonensis and L. (L.) infantum chagasi. The cytotoxicity of these compounds in mammalian cells and their influence on production of reactive oxygen species was also investigated. In vitro assays showed that 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one (C4) was as active as AMP B mainly in the amastigote form (p < 0.05); C4 presented a selectivity index (65.43) four times higher than C2 (15.4) in L. amazonensis and six times higher (33.94) than C1 (5.46) in L. infantum chagasi. Additionally, coumarin C4 reduced the H₂O₂ concentration 32.5% more than the control group in L. amazonensis promastigotes during the lag phase of proliferation. No interference of C4 was observed on the mitochondrial membrane potential of the parasites. In vivo, coumarin C4 in corn oil (oral route) led to a reduction in the number of amastigotes from L. infantum chagasi to 1.31 × 10⁶ and 4.09 × 10⁴ in the spleen and liver, respectively (p < 0.05). Thus, C4 represents a candidate for further studies aiming at new treatments of leishmaniasis.

In vitro and in vivo trypanocidal activities of 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-cromen-2-one, a new synthetic coumarin of low cytotoxicity against mammalian cells

Natural and synthetic coumarins have been described as prototypes of new drug candidates against Chagas' disease. During a typical screening with new compounds, we observed the potential of a new synthetic nitrobenzoylcoumarin (1) as trypanocidal against Trypanosoma cruzi epimastigotas. Then, we decided to prepare and evaluate a set of analogues from 1 to check the major structural requirements for trypanocidal activity. The structural variations were conducted in six different sites on the original compound and the best derivative (3) presented activity (IC₅₀ 28 ± 3 μM) similar to that of benznidazole (IC₅₀ 25 ± 10 μM). The enhancement of trypanocidal activity was conditioned to a change in the side chain at C6 (allyl to n-propyl group) and the preservation of coumarin nucleus and the nitrobenzoyl group at C3. Exposure of 3 to H9C2 cells showed low toxicity (CC₅₀  > 200 μM) and its activity on T. cruzi amastigotes (IC₅₀ 13 ± 0.3 μM) encouraged us to perform an evaluation of its potential when given orally to mice infected with trypomastigote forms. Derivative 3 was able to reduce parasitemia when compared to the group of untreated animals. Taken together, these results show the potential therapeutic application of the synthetic coumarins.

QSAR, docking, ADMET, and system pharmacology studies on tormentic acid derivatives for anticancer activity

To explore the anticancer compounds from tormentic acid derivatives, a quantitative structure-activity relationship (QSAR) model was developed by the multiple linear regression methods. The developed QSAR model yielded a high activity-descriptors relationship accuracy of 94% referred by regression coefficient (r² = .94) and a high activity prediction accuracy of 91%. The QSAR study indicates that chemical descriptors, chiV5, T_T_Cl_7, T_2_T_4, SsCH3count, and Epsilon3 are significantly correlated with anticancer activity. This validated model was further been used for virtual screening and thus identification of new potential breast cancer inhibitors. Lipinski's rule of five, ADMET risk and synthetic accessibility are used to filter false positive hits. Filtered compounds were then docked to identify the possible target binding pocket, to obtain a set of aligned ligand poses and to prioritize the predicted active compounds. The scrutinized compounds, as well as their metabolites, were predicted and analyzed for different pharmacokinetics parameters such as absorption, distribution, metabolism, excretion, and toxicity. Finally, the top-ranked compound NB-12 was evaluated by system pharmacology approach. Later studied the metabolic networks, disease biomarker networks, pathway maps, drug-target networks and generate significant gene networks. The strategy applied in this research work may act as a framework for rational design of potential anticancer drugs.