Nelilma C. Romeiro

Discovery of novel analgesic and anti-inflammatory 3-arylamine-imidazo[1,2-a]pyridine symbiotic prototypes

We describe herein the design, synthesis and pharmacological evaluation of novel 3-arylamine-imidazo[1,2-a]pyridine derivatives structurally designed as novel symbiotic prototypes presenting analgesic and anti-inflammatory properties. The derivatives obtained were submitted to in vivo assays of nociception, hyperalgesia and inflammation, and to in vitro assays of human PGHS-2 inhibition. These assays allowed the identification of compound LASSBio-1135 (3a) as an anti-inflammatory and analgesic symbiotic prototype. This compound inhibited moderately the human PGHS-2 enzyme activity (IC(50)=18.5 microM) and reverted the capsaicin-induced thermal hyperalgesia (100 micromol/kg, po) similarly to p38 MAPK inhibitor SB-203580 (2). Additionally, LASSBio-1135 (3a) presented activity similar to celecoxib (1) regarding the reduction of the carrageenan-induced rat paw edema (33% of inhibition at 100 micromol/kg, po). We also discovered derivatives LASSBio-1140 (3c) and LASSBio-1141 (3e) as analgesic and anti-inflammatory prototypes, which were able to attenuate the capsaicin-induced thermal hyperalgesia (100 micromol/kg, po) and reduce the carrageenan-induced paw edema (ED(50)=11.5 micromol/kg (3.3mg/kg) and 14.5 micromol/kg (4.1mg/kg), respectively), being both more active than celecoxib (1), despite the fact that their effects involve a different mechanism of action. Additionally, derivative LASSBio-1145 (3j) showed remarkable analgesic (ED(50)=22.7 micromol/kg (8.9 mg/kg)) and anti-inflammatory (ED(50)=8.7 micromol/kg (3.4 mg/kg)) profile in vivo (100 micromol/kg; po), in AcOH-induced abdominal constrictions in mice and carrageenan-induced rat paw edema models, respectively, being a novel orally-active anti-inflammatory drug candidate that acts as a selective PGHS-2 inhibitor (IC(50)=2.8 microM).

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.

Design, Synthesis, and Pharmacological Evaluation of N-Acylhydrazones and Novel Conformationally Constrained Compounds as Selective and Potent Orally Active Phosphodiesterase-4 Inhibitors

Among a small series of tested N-acylhydrazones (NAHs), the compound 8a was selected as a selective submicromolar phosphodiesterase-4 (PDE4) inhibitor associated with anti-TNF-α properties measured both in vitro and in vivo. The recognition pattern of compound 8a was elucidated through molecular modeling studies based on the knowledge of the 3D-structure of zardaverine, a PDE4 inhibitor resembling the structure of 8a, cocrystallized with the PDE4. Based on further conformational analysis dealing with N-methyl-NAHs, a quinazoline derivative (19) was designed as a conformationally constrained NAH analogue and showed similar in vitro pharmacological profile, compared with 8a. In addition 19 was found active when tested orally in LPS-evoked airway hyperreactivity and fully confirmed the working hypothesis supporting this work.

2-Acetylpyridine thiosemicarbazones: Cytotoxic activity in nanomolar doses against malignant gliomas

2-acetylpyridine N(4)-phenyl thiosemicarbazone (H2Ac4Ph), and its N(4)-ortho-tolyl (H2Ac4oT), N(4)-meta-tolyl (H2Ac4mT), N(4)-para-tolyl (H2Ac4pT), N(4)-ortho-chlorophenyl (H2Ac4oClPh), N(4)-meta-chlorophenyl (H2Ac4mClPh) and N(4)-para-chlorophenyl (H2Ac4pClPh) derivatives were assayed for their cytotoxicity against RT2 (expressing p53 protein) and against T98 (expressing mutant p53 protein) glioma cells. The compounds were highly cytotoxic against RT2 (IC50=24-1.4 nM) and T98 cells (IC50=50-1.0 nM). IC50 for cisplatin=5 (RT2) and 17 μM (T98). The thiosemicarbazones presented haemolytic activity with IC50>10(-3)M, indicating a very good therapeutic index. SAR studies suggested that stereo properties are critical to define the potential activity of the studied compounds against the RT2 cell line, while electronic properties seem to be important for interaction with the biological target in T98 cells.

Design, Synthesis and Pharmacological Evaluation of HIV-1 Reverse Transcriptase Inhibition of New Indolin-2-Ones

The design, synthesis and anti HIV-1 replication inhibition of 3-(cyclopropylethynyl)-3-hydroxy-indolin-2-ones, analogues of efavirenz (Sustivatrade mark), are described. Different substituted isatins were used to generate final products that contain pharmacophoric features for RT inhibition, such as the oxoindole and cyclopropylethynyl groups. The suitability of the indolin-2-one ring in the planned compounds in replacement to the benzoxazinone ring of efavirenz was proven, since compound 15 presented a greater activity than efavirenz against HIV-1 replication and was not significantly cytotoxic.

Novel 6-methanesulfonamide-3,4-methylenedioxyphenyl-N-acylhydrazones: orally effective anti-inflammatory drug candidates.

We described herein the molecular design of novel in vivo anti-inflammatory 6-methanesulfonamide-3,4-methylenedioxyphenyl-N-acylhydrazone derivatives (1) planned by applying the molecular hybridization approach. This work also points out to the discovery of LASSBio-930 (1c) as a novel anti-inflammatory and anti-hyperalgesic prototype, which was able to reduce carrageenan-induced rat paw edema with an ED(50) of 97.8 micromol/kg, acting mainly as a non-selective COX inhibitor.

In Vitro Anti-HMPV Activity of Meroditerpenoids from Marine Alga Stypopodium zonale (Dictyotales)

In this paper, we evaluated the antiviral activity against HMPV replication of crude extract of the marine algae Stypopodium zonale and of two meroditerpenoids obtained from it, atomaric acid and epitaondiol, and a methyl ester derivative of atomaric acid. Their selectivity indexes were 20.78, >56.81, 49.26 and 12.82, respectively. Compared to ribavirin, the substances showed a relatively low cytotoxicity on LLC-MK2 cells, with a significant antiviral activity, inhibiting at least 90% of viral replication in vitro, which demonstrates the potential of these marine natural products to combat infections caused by HMPV in vitro.

Structure-based design and biological profile of (E)-N-(4-Nitrobenzylidene)-2-naphthohydrazide, a novel small molecule inhibitor of IκB kinase-β.

In this study, we describe the rational design, molecular modeling and pharmacological profile of a novel IKK-β inhibitor (E)-N-(4-nitrobenzylidene)-2-naphthohydrazide (LASSBio-1524). The design based on the IKK-β active site, and a privileged structure template yielded a novel IKK-β inhibitor scaffold with significant selectivity over IKK-α and CHK2, as assessed by an in vitro kinase assay. For a better understanding of the structural requirements of IKK-β inhibition, molecular dynamics simulations of LASSBio-1524 (3) were performed. The NAH derivative LASSBio-1524 (3), was able to suppress arachidonic acid-induced edema formation in a dose-dependent manner, demonstrating an in vivo anti-inflammatory effect. The molecular architecture of this novel, low-molecular weight IKK-β inhibitor is encouraging for further lead optimization toward the development of innovative anti-inflammatory drug candidates.

Structural and Functional Characterization of the Protein Kinase Mps1 in Arabidopsis thaliana

In eukaryotes, protein kinases catalyze the transfer of a gamma-phosphate from ATP (or GTP) to specific amino acids in protein targets. In plants, protein kinases have been shown to participate in signaling cascades driving responses to environmental stimuli and developmental processes. Plant meristems are undifferentiated tissues that provide the major source of cells that will form organs throughout development. However, non-dividing specialized cells can also dedifferentiate and re-initiate cell division if exposed to appropriate conditions. Mps1 (Monopolar spindle) is a dual-specificity protein kinase that plays a critical role in monitoring the accuracy of chromosome segregation in the mitotic checkpoint mechanism. Although Mps1 functions have been clearly demonstrated in animals and fungi, its role in plants is so far unclear. Here, using structural and biochemical analyses here we show that Mps1 has highly similar homologs in many plant genomes across distinct lineages (e.g. AtMps1 in Arabidopsis thaliana). Several structural features (i.e. catalytic site, DFG motif and threonine triad) are clearly conserved in plant Mps1 kinases. Structural and sequence analysis also suggest that AtMps1 interact with other cell cycle proteins, such as Mad2 and MAPK1. By using a very specific Mps1 inhibitor (SP600125) we show that compromised AtMps1 activity hampers the development of A. thaliana seedlings in a dose-dependent manner, especially in secondary roots. Moreover, concomitant administration of the auxin IAA neutralizes the AtMps1 inhibition phenotype, allowing secondary root development. These observations let us to hypothesize that AtMps1 might be a downstream regulator of IAA signaling in the formation of secondary roots. Our results indicate that Mps1 might be a universal component of the Spindle Assembly Checkpoint machinery across very distant lineages of eukaryotes.

Design, synthesis and activity against Trypanosoma cruzi of azaheterocyclic analogs of megazol.

This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic derivatives (4-8). These compounds were designed as megazol (1) analogs based on bioisosterism tools and were synthesized to investigate the possible pharmacophoric contribution of the 1,2,4-triazole nucleus, the position of the heterocyclic nucleus and presence of the nitro group, to the activity against the bloodstream trypomastigote forms of Trypanosoma cruzi. The most potent compound was 6, a nitro derivative obtained by substitution of a thiadiazole by a triazole ring and by moving the nitro group from C-5 position, as in 1, to the C-4 position. Finally, we have used semi-empirical theoretical calculations to discuss the correlation of some stereo electronic properties with biological activity in an attempt to understand the possible mechanism of action of the designed series of compounds.