Lidia M. Lima

Bioisosterism : A useful strategy for molecular modification and drug design

This review aim to demonstrate the role of bioisosterism in rational drug design as well as in the molecular modification and optimization process aiming to improve pharmacodynamic and pharmacokinetic properties of lead compounds. Bioisosterism is a strategy of Medicinal Chemistry for the rational design of new drugs, applied with a lead compound (LC) as a special process of molecular modification (1). The LC should be of a completely well known chemical structure and possess an equally well known mechanism of action, if possible at the level of topographic interaction with the receptor, including knowledge of all of its pharmacophoric group. Furthermore, the pathways of metabolic inactivation (2), as well as the main determining structural factors of the physicochemical properties which regulate the bioavailability, and its side effects, whether directly or not, should be known so as to allow for a broad prediction of the definition of the bioisosteric relation to be used. The success of this strategy in developing new substances which are therapeutically attractive has observed a significant growth in distinct therapeutic classes, being amply used by the pharmaceutical industry to discover new analogs of therapeutic innovations commercially attractive (me-too), and also as a tool useful in the molecular modification. There may be innumerous reasons for the use of bioisosterism to design new drugs, including the necessity to improve pharmacological activity, gain selectivity for a determined receptor or enzymatic isoform subtype - with simultaneous reduction of certain adverse effects -, or even optimize the pharmacokinetics the LC might present. In this paper, we will discuss bioisosterism as a strategy of molecular modification, showing its importance in building a new series of congeners compounds designed as candidate of new drugs, giving examples of successful cases in distinct therapeutic classes (3-7).

Synthesis and anti-inflammatory activity of phthalimide derivatives, designed as new thalidomide analogues.

This paper describes the synthesis and anti-inflammatory activity of new N-phenyl-phthalimide sulfonamides (3a-e) and the isosters N-phenyl-phthalimide amides (4a-e), designed as hybrids of thalidomide (1) and aryl sulfonamide phosphodiesterase inhibitor (2). In these series, compound 3e (LASSBio 468), having a sulfonyl-thiomorpholine moiety, showed potent inhibitory activity on LPS-induced neutrophil recruitment with ED(50)=2.5mg kg(-1), which was correlated with its inhibitory effect on TNF-alpha level.

Synthesis, trypanocidal activity and docking studies of novel quinoxaline-N-acylhydrazones, designed as cruzain inhibitors candidates

In this paper, we report the structural design, synthesis, trypanocidal activity and docking studies of novel quinoxaline-N-acylhydrazone (NAH) derivatives, planned as cruzain inhibitors candidates, a cysteine protease essential for the survival of Trypanosoma cruzi within the host cell. The salicylaldehyde N-acylhydrazones 7a and 8a presented IC(50) values of the same magnitude order than the standard drug nifurtimox (Nfx), when tested in vitro against epimastigote forms of Trypanosoma cruzi (Tulahuen 2 strain) and were non-toxic at the highest assayed doses rendering selectivity indexes (IC(50) (macrophages)/IC(50) (Trypanosoma cruzi)) of >25 for 7a and >20 for 8a, with IC(50) values in macrophages >400 microM.

Novel 2-chloro-4-anilino-quinazoline derivatives as EGFR and VEGFR-2 dual inhibitors

Novel 2-chloro-4-anilino-quinazolines designed as EGFR and VEGFR-2 dual inhibitors were synthesized and evaluated for inhibitory effects. EGFR and VEGFR-2 are validated targets in cancer therapy and combined inhibition might be synergistic for both antitumor activity and resistance prevention. The biological data obtained proved the potential of 2-chloro-4-anilino-quinazoline derivatives as EGFR and VEGFR-2 dual inhibitors, highlighting compound 8o, which was approximately 7-fold more potent on VEGFR-2 and approximately 11-fold more potent on EGFR compared to the prototype 7. SAR and docking studies allowed the identification of pharmacophoric groups for both kinases and demonstrated the importance of a hydrogen bond donor at the para position of the aniline moiety for interaction with conserved Glu and Asp amino acids in EGFR and VEGFR-2 binding sites.

Analgesic and Anti-Inflammatory Activities of Salicylaldehyde 2-Chlorobenzoyl Hydrazone (H2LASSBio-466), Salicylaldehyde 4-Chlorobenzoyl Hydrazone (H2LASSBio-1064) and Their Zinc(II) Complexes

Salicylaldehyde 2-chlorobenzoyl hydrazone (H2LASSBio-466), salicylaldehyde 4-chlorobenzoyl hydrazone (H2LASSBio-1064) and their complexes [Zn(LASSBio-466)H2O]2 (1) and [Zn(HLASSBio-1064)Cl]2 (2) were evaluated in animal models of peripheral and central nociception, and acute inflammation. All studied compounds significantly inhibited acetic acid-induced writhing response. Upon coordination the anti-nociceptive activity was favored in the complex 1. H2LASSBio-466 inhibited only the first phase of the formalin test, while 1 was active in the second phase, like indomethacin, indicating its ability to inhibit nociception associated with the inflammatory response. Hence coordination to zinc(II) altered the pharmacological profile of H2LASSBio-466. H2LASSBio-1064 inhibited both phases but this effect was not improved by coordination. The studied compounds did not increase the latency of response in the hot plate model, indicating their lack of central anti-nociceptive activity. All compounds showed levels of inhibition of zymosan-induced peritonitis comparable or superior to indomethacin, indicating an expressive anti-inflammatory profile.

Discovery of new orally effective analgesic and anti-inflammatory hybrid furoxanyl N-acylhydrazone derivatives

We report the design, the synthesis and the biological evaluation of the analgesic and anti-inflammatory activities of furoxanyl N-acylhydrazones (furoxanyl-NAH) by applying molecular hybridization approach. Hybrid compounds with IL-8-release inhibition capabilities were identified. Among them, furoxanyl-NAH, 17, and benzofuroxanyl-derivative, 24, together with furoxanyl-NAH derivative, 31, without IL-8 inhibition displayed both orally analgesic and anti-inflammatory activities. These hybrid derivatives do not have additional LOX- or COX-inhibition activities. For instance, LOX-inhibition by furoxanyl-NAH derivative, 42, emerged as a structural lead to develop new inhibitors. The lack of mutagenicity of the active derivatives 17, 31, and 42, allow us to propose them as candidates for further clinical studies. These results confirmed the success in the exploitation of hybridization strategy for identification of novel N-acylhydrazones (NAH) with optimized activities.

Design, Synthesis, and Pharmacological Evaluation of Novel Hybrid Compounds to Treat Sickle Cell Disease Symptoms. Part II: Furoxan Derivatives

Phthalimide derivatives containing furoxanyl subunits as nitric oxide (NO)-donors (3a-g) were designed, synthesized, and evaluated in vitro and in vivo for their potential uses in the oral treatment of sickle cell disease symptoms. All compounds (3a-g) demonstrated NO-donor properties at different levels. Moreover, compounds 3b and 3c demonstrated analgesic activity. Compound 3b was determined to be a promising drug candidate for the aforementioned uses, and it was further evaluated in K562 culture cells to determine its ability to increase levels of γ-globin expression. After 96 h at 5 μM, compound 3b was able to induce γ-globin expression by nearly three times. Mutagenic studies using micronucleus tests in peripheral blood cells of mice demonstrated that compound 3b reduces the mutagenic profile as compared with hydroxyurea. Compound 3b has emerged as a new leading drug candidate with multiple beneficial effects for the treatment of sickle cell disease symptoms and provides an alternative to hydroxyurea treatment.

Design, synthesis, and pharmacological evaluation of novel hybrid compounds to treat sickle cell disease symptoms.

A novel series of thalidomide derivatives (4a-f) designed by molecular hybridization were synthesized and evaluated in vitro and in vivo for their potential use in the oral treatment of sickle cell disease symptoms. Compounds 4a-f demonstrated analgesic, anti-inflammatory, and NO-donor properties. Compounds 4c and 4d were considered promising candidate drugs and were further evaluated in transgenic sickle cell mice to determine their capacity to reduce the levels of the proinflammatory cytokine tumor necrosis factor α (TNFα). Unlike hydroxyurea, the compounds reduced the concentrations of TNFα to levels similar to those induced with the control dexamethasone (300 μmol/kg). These compounds are novel lead drug candidates with multiple beneficial actions in the treatment of sickle cell disease symptoms and offer an alternative to hydroxyurea treatment.

Novel phthalimide derivatives, designed as leukotriene D4 receptor antagonists

A series of phthalimide acid derivatives was synthesized and evaluated as leukotriene D(4) receptor antagonists. The tetrazolephthalimide LASSBio 552 (7) was shown to be able to inhibit the contractile activity induced by 100 nM of LTD(4) in guinea-pig tracheal strips with an IC(50) = 31.2 microM. In addition, LASSBio 552 (7) has been showed to present a better efficacy than zafirlukast (1) used as standard.

Docking, Synthesis and Antiproliferative Activity of N-Acylhydrazone Derivatives Designed as Combretastatin A4 Analogues

Cancer is the second most common cause of death in the USA. Among the known classes of anticancer agents, the microtubule-targeted antimitotic drugs are considered to be one of the most important. They are usually classified into microtubule-destabilizing (e.g., Vinca alkaloids) and microtubule-stabilizing (e.g., paclitaxel) agents. Combretastatin A4 (CA-4), which is a natural stilbene isolated from Combretum caffrum, is a microtubule-destabilizing agent that binds to the colchicine domain on β-tubulin and exhibits a lower toxicity profile than paclitaxel or the Vinca alkaloids. In this paper, we describe the docking study, synthesis, antiproliferative activity and selectivity index of the N-acylhydrazone derivatives (5a–r) designed as CA-4 analogues. The essential structural requirements for molecular recognition by the colchicine binding site of β-tubulin were recognized, and several compounds with moderate to high antiproliferative potency (IC50 values ≤18 µM and ≥4 nM) were identified. Among these active compounds, LASSBio-1586 (5b) emerged as a simple antitumor drug candidate, which is capable of inhibiting microtubule polymerization and possesses a broad in vitro and in vivo antiproliferative profile, as well as a better selectivity index than the prototype CA-4, indicating improved selective cytotoxicity toward cancer cells.