Synthesis and pharmacological evaluation of new flosulide analogues, synthesized from natural safrole

Dissecting dietary and semisynthetic volatile phenylpropenes: A compile of their distribution, food properties, health effects, metabolism and toxicities

Phenylpropenes represent a major subclass of plant volatiles, including eugenol, and (E)-anethole. They contribute to the flavor and aroma of many chief herbs and spices, to exert distinct notes in food, i.e., spicy anise- and clove-like to fruit. Asides from their culinary use, they appear to exert general health effects, whereas some effects are specific, e.g., eugenol being a natural local anesthetic. This review represents the most comprehensive overview of phenylpropenes with respect to their chemical structures, different health effects, and their food applications as flavor and food preservatives. Side effects and toxicities of these compounds represent the second main part of this review, as some were reported for certain metabolites generated inside the body. Several metabolic reactions mediating for phenylpropenes metabolism in rodents via cytochrome P450 (CYP450) and sulfotransferase (SULT) enzymes are presented being involved in their toxicities. Such effects can be lessened by influencing their pharmacokinetics through a matrix-derived combination effect via administration of herbal extracts containing SULT inhibitors, i.e., nevadensin in sweet basil. Moreover, structural modification of phenylpropanes appears to improve their effects and broaden their applications. Hence, such review capitalizing on phenylpropenes can help optimize their applications in nutraceuticals, cosmeceuticals, and food applications.

Five-Membered-Ring-Fused Tacrines as Anti-Alzheimer’s Disease Agents

Our endeavors in the design, synthesis, and biological assessment of five-membered-ring-fused tacrines as potential therapeutic agents for Alzheimer’s disease are summarized. Particularly, we have identified racemic 4-(2-methoxyphenyl)-3-methyl-2,4,6,7,8,9-hexahydropyrazolo[4′,3′:5,6]pyrano[2,3-b]quinolin-5-amine, a pyranopyrazolotacrine, as having the best nontoxic profile at the highest concentrations used (300 μM); this allows cell viability, is less hepatotoxic than tacrine, and is a potent noncompetitive AChE inhibitor (IC50 = 1.52 ± 0.49 μM). It is able to completely inhibit the EeAChE-induced Aβ1–40 aggregation in a statistically significant manner without affecting the Aβ1–40 self-aggregation at 25 μM, and shows strong neuroprotective effects (EC50 = 0.82 ± 0.17 μM).

1 Introduction

2 Furo-, Thieno-, and Pyrrolotacrines

3 Pyrazolo-, Oxazolo-, and Isoxazolotacrines

4 Indolotacrines

5 Pyrano- and Pyridopyrazolotacrines

6 Conclusions and Outlook

Nimesulide analogues: From anti-inflammatory to antitumor agents

Nimesulide is a nonsteroidal anti-inflammatory drug possessing analgesic and antipyretic properties. This drug is considered a selective cyclooxygenase-2 (COX-2) inhibitor and, more recently, has been associated to antitumor activity. Thus, numerous works have been developed to modify the nimesulide skeleton aiming to develop new and more potent and selective COX-2 inhibitors as well as potential anticancer agents. This review intends to provide an overview on analogues of nimesulide, including the general synthetic approaches used for their preparation and structural diversification and their main anti-inflammatory and/or antitumor properties.

First synthesis of 2-(benzofuran-2-yl)-6,7-methylene dioxyquinoline-3-carboxylic acid derivatives

A facile and inexpensive synthesis of a series of novel methylenedioxy-bearing 2-(benzofuran-2-yl)-quinoline-3-carboxylic acid derivatives 3a-h via the one-pot reaction of ethyl 2-chloromethyl-6,7-methylenedioxyquinoline-3-carboxylate (5) with various substituted salicylaldehydes 6a-g as well as 2-hydroxy-1-naphthaldehyde (6h) is described. Substrate 5 was synthesized by the Friedländer condensation reaction of 2-amino-4,5-methylenedioxybenzaldehyde (4) with ethyl 4-chloro-3-oxobutanoate using KHSO(4) as catalyst under ultrasound irradiation conditions. The targeted compounds 3a-h were obtained in good yields of 52-82% and their structures were established based on spectral data and elemental analyses.

Synthesis and analgesic profile of conformationally constrained N-acylhydrazone analogues: discovery of novel N-arylideneamino quinazolin-4(3H)-one compounds derived from natural safrole

In this work we reported the synthesis and evaluation of the analgesic, anti-inflammatory, and platelet anti-aggregating properties of new 3-(arylideneamino)-2-methyl-6,7-methylenedioxy-quinazolin-4(3H)-one derivatives (3a-j), designed as conformationally constrained analogues of analgesic 1,3-benzodioxolyl-N-acylhydrazones (1) previously developed at LASSBio. Target compounds were synthesized in very good yields exploiting abundant Brazilian natural product safrole (2) as starting material. The pharmacological assays lead us to identify compounds LASSBio-1240 (3b) and LASSBio-1272 (3d) as new analgesic prototypes, presenting an antinociceptive profile more potent and effective than dipyrone and indomethacin used, respectively, as standards in AcOH-induced abdominal constrictions assay and in the formalin test. These results confirmed the success in the exploitation of conformation restriction strategy for identification of novel cyclic N-acylhydrazone analogues with optimized analgesic profile.

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.

Structure-based pharmacophore of COX-2 selective inhibitors and identification of original lead compounds from 3D database searching method

A four-point pharmacophore of COX-2 selective inhibitors was derived from a training set of 16 compounds, using the Catalyst program. It consists of a H bond acceptor, two hydrophobic groups and an aromatic ring, in accordance with SAR data of the compounds and with topology of the COX-2 active site. This hypothesis, combined with exclusion volume spheres representing important residues of the COX-2 binding site, was used to virtually screen the Maybridge database. Eight compounds were selected for an in vitro enzymatic assay. Five of them show COX-2 inhibition close to that of nimesulide and rofecoxib, two reference COX-2 selective inhibitors. As a result, structure-based pharmacophore generation was able to identify original lead compounds, inhibiting the COX-2 isoform.

Synthesis, antitumour and antimicrobial activities of new peptidyl derivatives containing the 1,3-benzodioxole system

Two series of 5 and 6-substituted 1,3-benzodioxole peptidyl derivatives were synthesized and evaluated as antitumour and antimicrobial agents. The compounds that could be conveniently prepared in a few steps processes from natural safrole have been characterised by IR and 1H-NMR spectroscopy. In vivo antitumor activity tests showed that some of the compounds were able to inhibit carcinoma S-180 tumour growth in mice. The in vitro antimicrobial activity of all compounds revealed that they are able to promote the growth of some organisms, including Bacillus subtilis.

Synthesis and structure-activity relationship of novel, highly potent metharyl and methcycloalkyl cyclooxygenase-2 (COX-2) selective inhibitors

A novel series of benzo-1,3-dioxolane metharyl derivatives was synthesized and evaluated for cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) inhibition in human whole blood (HWB). In the present study, structure-activity relationships (SAR) in the metharyl analogues were investigated. The spacer group and substitutions in the spacer group were found to be quite important for potent COX-2 inhibition. Compounds in which a methylene group (8a-c), carbonyl group (12a-c), or methylidene group (7a-c) connected cycloalkyl groups to the central benzo-1,3-dioxolane template were found to be potent and selective COX-2 inhibitors. Aryl-substituted compounds linked to the central ring by either a methylene or a carbonyl spacer resulted in potent, highly selective COX-2 inhibitors. In this series of substituted-(2H-benzo[3,4-d]1,3-dioxolan-5-yl))-1-(methylsulfonyl)benzene compounds, SAR studies demonstrated that substitution at the 3-position of the aryl group optimized COX-2 selectivity and potency, whereas substitution at the 4-position attenuated COX-2 inhibition. Mono- or difluoro substitution at meta position(s), as in 22c and 22h, was advantageous for both in vitro COX-2 potency and selectivity (e.g., COX-2 IC(50) for 22c = 1 microM and COX-1 IC(50) for 22c = 20 microM in HWB assay). Several novel compounds in the (2H-benzo[3,4-d]1,3-dioxolan-5-yl))-1-(methylsulfonyl)benzene series, as shown in structures 7c, 8a, 12a, 21c, 22c, 22e, and 22h, selectively inhibited COX-2 activity by 40-50% at a test concentration of 1 microM in an in vitro HWB assay.

Design, synthesis, and pharmacological profile of novel fused pyrazolo[4,3-d]pyridine and pyrazolo[3,4-b][1,8]naphthyridine isosteres: a new class of potent and selective acetylcholinesterase inhibitors

A new family of tacrine (THA) analogues (7-9, 12), containing the azaheterocyclic pyrazolo[4,3-d]pyridine or pyrazolo[3,4-b][1,8]naphthyridine systems as isosteres of the quinoline ring of THA, has been synthesized. The compounds were tested in rat brain cholinesterases using Ellman's method, and all were fully efficacious in inhibiting the enzymes. Compounds 9 and 12b were the most potent against acetylcholinesterase (AChE), showing IC(50) of 6.0 and 6.4 microM, and were less active against rat brain butyrylcholinesterase, showing selectivity indexes of 5.3 and 20.9, respectively. Compounds 7-9 and 12 were also tested for their acute neurotoxicity in vitro, using cultured rat cortical cells. Compounds 7 and 8 were not significantly toxic; 9 was toxic at 500 microM, but not at 100 microM. The naphthyridine derivatives 12a and 12b showed a significant concentration-dependent neurotoxicity, being able to kill most cells at 500 microM. Molecular dynamic simulation using the X-ray crystal structure of AChE from Torpedo californica was used to explain the possible binding mode of these new THA isosteres.

Synthesis and antiplatelet evaluation of novel aryl-sulfonamide derivatives, from natural safrole

In the scope of a research program aiming at the synthesis and pharmacological evaluation of novel possible antiplatelet prototype compounds, exploring bioisosterism principles for molecular design, we describe in this paper the synthesis of new aryl-sulfonamides derivatives, structurally similar to known thromboxane A2 receptor antagonists. The synthetic route used to access the new compounds described herein starts from safrole, an abundant Brazilian natural product, which occurs in Sassafras oil (Ocotea pretiosa). The results from preliminary evaluation of these novel aryl-sulfonamide compounds by the platelet aggregation inhibitory test, using rabbit PRP, induced by ADP, collagen, arachidonic acid, and U46619, identified the N-[2-(4-carboxymethoxyphenyl)ethyl]-6-methyl-3,4-methylenedioxyphe nyl- sulfonamido derivative as the most active among them, presenting in IC50 value for the U-46619-induced platelet aggregation in rabbit platelet-rich plasma: 329 microM.