Synthesis, evaluation against Leishmania amazonensis and cytotoxicity assays in macrophages of sixteen new congeners Morita–Baylis–Hillman adducts

Leishmanicidal activity of Morita-Baylis-Hillman adducts

Leishmaniasis is a neglected disease that affects millions of people, mostly in developing countries. Although this disease has a high impact on public health, there are few drug options to treat the different leishmaniasis forms. Additionally, these current therapies have various adverse effects, including gastrointestinal disturbances, headache, pancreatitis, and hepatotoxicity. Thus, it is essential to develop new drug prototypes to treat leishmaniasis. Accordingly, the present study aimed to evaluate the leishmanicidal activity of Morita-Baylis-Hillman adducts and their O-acetylates, carboxylic acid derivatives, and acid and ester derivatives of 2-methyl-phenylpropanoids against Leishmania chagasi. Initially, we evaluated the cytotoxicity of 16 derivatives (1-16G) against J774A.1 macrophages. Eight derivatives (2G, 4G, 5G, 7G, 9G, 10G, 13G, and 15G) showed no cytotoxicity at up to the maximum concentration tested (100 μM). When evaluated for antileishmanial effect against promastigote forms, 1G, 6G, 8G, 10G, 11G, 13G, 14G, 15G, and 16G displayed significant toxicity compared to the control (0.1% DMSO). Additionally, the compounds 1G, 5G, 7G, 9G, 11G, 13G, 14G, and 16G reduced macrophage infection by amastigotes. Thus, we conclude that these derivatives have antileishmanial effects, particularly 1G, which showed activity against promastigotes and amastigotes, and low toxicity against macrophages.

Biological activity of Morita-Baylis-Hillman adduct homodimers in L. infantum and L. amazonensis: anti-Leishmania activity and cytotoxicity

This study is a report on the anti-Leishmania activity of Morita-Baylis-Hillman (MBH) homodimers adducts against the promastigote and axenic amastigote forms of Leishmania (Leishmania) infantum and Leishmania (Leishmania) amazonensis and on the cytotoxicity of these adducts to human blood cells. Both studied homodimers, MBH 1 and MBH 2, showed activity against the promastigote forms of L. infantum and L. amazonensis, which are responsible for visceral and cutaneous leishmaniasis, respectively. Additionally, the homodimers presented biological activity against the axenic amastigote forms of these two Leishmania species. The adducts exhibited no hemolytic activity to human peripheral blood mononuclear cells or erythrocytes at the tested concentrations and achieved higher selectivity indices than amphotericin B. Evaluation of cell death by apoptosis revealed that the homodimers had better apoptosis/necrosis profiles than amphotericin B in the promastigote forms of both L. infantum and L. amazonensis. In conclusion, these Morita-Baylis-Hillman adducts had anti-Leishmania activity in an in vitro model and may thus be promising molecules in the search for new drugs to treat leishmaniasis.

Synthesis of 16 New Hybrids from Tetrahydropyrans Derivatives and Morita-Baylis-Hillman Adducts: In Vitro Screening against Leishmania donovani

Leishmaniases are a group of neglected tropical diseases (NTDs) caused by protozoan parasites from >20 Leishmania species. Visceral leishmaniasis (VL), also known as kala-aza, is the most severe form of leishmaniasis, usually fatal in the absence of treatment in 95% of cases. The Morita-Baylis-Hillman adducts (MBHAs) are being explored as drug candidates against several diseases, one of them being leishmaniasis. We present here the design, synthesis and in vitro screening against Leishmania donovani of sixteen new molecular hybrids from analgesic/anti-inflammatory tetrahydropyrans derivatives and Morita-Baylis-Hillman adducts. First, acrylates were synthesized from analgesic/anti-inflammatory tetrahydropyrans using acrylic acid under TsOH as a catalyst (70%–75% yields). After the 16 new MBHAs were prepared in moderate to good yields (60%–95%) promoted by microwave irradiation or low temperature (0 °C) in protic and aprotic medium. The hybrids were evaluated in vitro on the promastigote stage of Leishmania donovani by determining their inhibitory concentrations 50% (IC₅₀), 50% hemolysis concentration (HC₅₀), selectivity index (HC₅₀/IC₅₀,), and comparing to Amphotericin B, chosen as the anti-leishmanial reference drug. The hybrid which presents the bromine atom in its chemical structure presents high leishmanicide activity and the high selectivity index in red blood cells (SI_rb > 180.19), compared with the highly-toxic reference drug (SI_rb = 33.05), indicating that the bromine hybrid is a promising compound for further biological studies.

Synthesis and In Vitro Anti Leishmania amazonensis Biological Screening of Morita-Baylis-Hillman Adducts Prepared from Eugenol, Thymol and Carvacrol

Leishmaniasis represents a series of severe neglected tropical diseases caused by protozoa of the genus Leishmania and is widely distributed around the world. Here, we present the syntheses of Morita-Baylis-Hillman adducts (MBHAs) prepared from eugenol, thymol and carvacrol, and their bioevaluation against promastigotes of Leishmania amazonensis. The new MBHAs are prepared in two steps from essential oils in moderate to good yields and present IC₅₀ values in the range of 22.30–4.71 μM. Moreover, the selectivity index to the most potent compound is very high (SIrb > 84.92), far better than that of Glucantime^® (SIrb 1.39) and amphotericin B (SIrb = 22.34). Conformational analysis were carried out at the M062X//6-31+G(d,p) level of theory to corroborate a hypothesis about the nitroaromatic bioreduction mechanism.

Synthesis and Antileishmanial Activity of Natural Dehydrodieugenol and Its Mono- and Dimethyl Ethers

The study of chemistry of naturally occurring compounds and the synthesis of their derivatives is fundamentally important for the development of new drugs. In this work, dehydrodieugenol (DHDE) was obtained through oxidative coupling of eugenol, promoted by an aqueous mixture of potassium ferricyanide (K3 [Fe(CN)6 ]) and NH3  · H2 O. The partial methoxylation of DHDE with MeI and K2 CO3 mainly resulted in the molecular-shaped monomethyl ether (DHDE-1MeO) and its dimethyl ether derivative (DHDE-2MeO). The products from the reactions were characterized by (1) H- and (13) C-NMR spectroscopy. Additionally, these studies have reported the antileishmanial activity of DHDE against Leishmania amazonensis (IC50 value of 42.20 μg ml(-1) ) and shown that partial methoxylation of DHDE results in a significant increase in its antiparasitic activity (IC50 value of 13.68 μg ml(-1) ). Based on in vitro bioassays, DHDE-1MeO has shown the highest leishmanicidal activity in promastigota form. Production by direct one-step synthesis of this monomethoxylated compound can be considered to be a cost-effective and environmentally friendly method with a short reaction time.

Morita-Baylis-Hillman adduct shows in vitro activity against Leishmania (Viannia) braziliensis associated with a reduction in IL-6 and IL-10 but independent of nitric oxide

Current treatments for different clinical forms of leishmaniasis are unsatisfactory, highly toxic and associated with increasing failure rates resulting from the emergence of resistant parasites. Leishmania (Viannia) braziliensis is the main aetiological agent of different clinical forms of American tegumentary leishmaniasis, including the mucosal form for which treatment has high failure rates. The aim of this work was to investigate the activity of the Morita-Baylis-Hillman adduct, methyl 2-{2-[hydroxy(2-nitrophenyl)methyl])acryloyloxy} benzoate in vitro against isolates of L. (V.) braziliensis obtained from patients with different clinical manifestations of tegumentary leishmaniasis: localized cutaneous leishmaniasis, mucosal leishmaniasis and disseminated cutaneous leishmaniasis. The adduct effectively inhibited the growth of promastigotes of the different isolates of L. (V.) braziliensis (IC50 ⩽ 7·77 μg/ml), as well as reduced the infection rate of macrophages infected with these parasites (EC50 ⩽ 1·37 μg/ml). It is remarkable to state that the adduct was more effective against intracellular amastigotes (P ⩽ 0·0045). The anti-amastigote activity correlated with an immunomodulatory effect, since the adduct was able to decrease the production of IL-6 and IL-10 by the infected macrophages. However, its effect was independent of nitric oxide production. This work demonstrates the anti-leishmanial activity of methyl 2-{2-[hydroxy(2-nitrophenyl)methyl])acryloyloxy} benzoate and suggests its potential in the treatment of human infections caused by L. (V.) braziliensis.

Morita-Baylis-Hillman adducts: biological activities and potentialities to the discovery of new cheaper drugs

This review aims to present by the first time the Morita-Baylis-Hillman adducts (MBHA) as a new class of bioactive compounds and highlight its potentialities to the discovery of new cheaper and efficient drugs. Now, most these compounds can be prepared fast and on a single synthetic step (one-pot reaction) in high yields and using ecofriendly synthetic protocols. We highlight here the aromatic MBHA, which have shown diverse biological activities as anti-Leishmania chagasi and Leishmania amazonensis (parasites that cause cutaneous and visceral leishmaniasis), anti-Trypanosoma cruzi (parasite that cause Chagas disease), anti-Plasmodium falciparum and Plasmodium berghei (parasites that cause malaria), lethal against Biomphalaria glabrata (the snail transmitter of schistosomiasis), antibacterial, antifungal, herbicide and actives against some human tumor cell lines. Understanding of the biological mechanisms of action of this new class of molecules is still in the infancy stage. However, we report here which has been described to date on the possibilities of biological mechanisms of action, and we present new analyzes based on literature in this area. The academic and industrial interest in selecting green and cheaper experiments to the drugs development has been the prime mover of the growth on the subject.