[1-(3,5-Difluoro-4-hydroxyphenyl)-1H-pyrrol-3-yl]phenylmethanone as a Bioisostere of a Carboxylic Acid Aldose Reductase Inhibitor

Phytochemical analysis, antioxidant and ALR2 inhibitory activity of Sorbus torminalis (L.) fruits at different maturity stages

Thirty four compounds were identified in Sorbus torminalis (L.) fruit extracts of different maturity types by means of LC-DAD-MS (ESI+) fragmentation analysis. Both immature and mature fruits were rich in flavonoid glycosides esterified with hydroxycinnamic, phenolic and dicarboxylic acids along with benzoic, phenylpropanoic and cinnamoyl quinic acid derivatives with many of them being detected for the first time in Sorbus species and in literature. Extracts and fractions were tested for their antioxidant activity (DPPH, chemiluminescence, Rancimat assays) and the estimation of the phenolic content was carried out through Folin-Ciocalteu reagent. Ethyl acetate fraction exhibited the highest scavenging activity determined as EC50 = 1.58 ± 0.22 μg/mL and EC50 = 1.64 ± 0.24 μg/mL for immature and mature fruits respectively with the DPPH test. Chemiluminescence test indicated the same fraction having the strongest antioxidant activity with an IC50 0.41 ± 0.06 μg/mL and IC50 0.50 ± 0.02 μg/mL in both maturity types. The ethyl acetate fraction of the mature fruits is considered the most potent Aldose Reductase 2 (ALR2) inhibitor with 79% demonstrating the high nutritional value of Sorbus torminalis (L.) mature fruits as a defense mechanism against the onset of diabetes mellitus secondary complications leading to the utilization of the plant for nutritional and pharmaceutical purposes.

Highlights on U.S. FDA-approved fluorinated drugs over the past five years (2018-2022)

The objective of this review is to provide an update on the fluorine-containing drugs approved by U.S. Food and Drug Administration in the span of past five years (2018-2022). The agency accepted a total of fifty-eight fluorinated entities to diagnose, mitigate and treat a plethora of diseases. Among them, thirty drugs are for therapy of various types of cancers, twelve for infectious diseases, eleven for CNS disorders, and six for some other diseases. These are categorized and briefly discussed based on their therapeutic areas. In addition, this review gives a glimpse about their trade name, date of approval, active ingredients, company developers, indications, and drug mechanisms. We anticipate that this review may inspire the drug discovery and medicinal chemistry community in both industrial and academic settings to explore the fluorinated molecules leading to the discovery of new drugs in the near future.

Cu(II)-catalyzed [4 + 1] and [4 + 3] annulation reactions: a modular approach to N-aryl/alkyl substituted 2,5-diamidopyrroles and diazepines

A one-pot copper-catalyzed [4 + 1] annulation reaction of primary amines with ynamide-derived buta-1,3-diynes for the synthesis of 2,5-diamido bearing N-aryl/alkyl pyrroles in up to excellent yields has been showcased. A broad range of primary amines having highly reactive functional groups are well tolerated. Notably, sterically demanding aniline and primary aliphatic amines are excellent amine sources. Furthermore, the current protocol may yield structurally unique diazepine derivatives. The scale-up reaction and fruitful chemical elaboration of pyrrole motifs highlight the importance of this reaction.

Aldose reductase and protein tyrosine phosphatase 1B inhibitors as a promising therapeutic approach for diabetes mellitus

Diabetes mellitus is a metabolic disease characterized by high blood glucose levels and usually associated with several chronic pathologies. Aldose reductase and protein tyrosine phosphatase 1B enzymes have identified as two novel molecular targets associated with the onset and progression of type II diabetes and related comorbidities. Although many inhibitors against these enzymes have already found in the field of diabetic mellitus, the research for discovering more effective and selective agents with optimal pharmacokinetic properties continues. In addition, dual inhibition of these target proteins has proved as a promising therapeutic approach. A variety of diverse scaffolds are presented in this review for the future design of potent and selective inhibitors of aldose reductase and protein tyrosine phosphatase 1B based on the most important structural features of both enzymes. The discovery of novel dual aldose reductase and protein tyrosine phosphatase 1B inhibitors could be effective therapeutic molecules for the treatment of insulin-resistant type II diabetes mellitus. The methods used comprise a literature survey and X-ray crystal structures derived from Protein Databank (PDB). Despite the available therapeutic options for type II diabetes mellitus, the inhibitors of aldose reductase and protein tyrosine phosphatase 1B could be two promising approaches for the effective treatment of hyperglycemia and diabetes-associated pathologies. Due to the poor pharmacokinetic profile and low in vivo efficacy of existing inhibitors of both targets, the research turned to more selective and cell-permeable agents as well as multi-target molecules.

Fluorine and Fluorinated Motifs in the Design and Application of Bioisosteres for Drug Design

The electronic properties and relatively small size of fluorine endow it with considerable versatility as a bioisostere and it has found application as a substitute for lone pairs of electrons, the hydrogen atom, and the methyl group while also acting as a functional mimetic of the carbonyl, carbinol, and nitrile moieties. In this context, fluorine substitution can influence the potency, conformation, metabolism, membrane permeability, and P-gp recognition of a molecule and temper inhibition of the hERG channel by basic amines. However, as a consequence of the unique properties of fluorine, it features prominently in the design of higher order structural metaphors that are more esoteric in their conception and which reflect a more sophisticated molecular construction that broadens biological mimesis. In this Perspective, applications of fluorine in the construction of bioisosteric elements designed to enhance the in vitro and in vivo properties of a molecule are summarized.

Applications of Fluorine in Medicinal Chemistry

The role of fluorine in drug design and development is expanding rapidly as we learn more about the unique properties associated with this unusual element and how to deploy it with greater sophistication. The judicious introduction of fluorine into a molecule can productively influence conformation, pKa, intrinsic potency, membrane permeability, metabolic pathways, and pharmacokinetic properties. In addition, (18)F has been established as a useful positron emitting isotope for use with in vivo imaging technology that potentially has extensive application in drug discovery and development, often limited only by convenient synthetic accessibility to labeled compounds. The wide ranging applications of fluorine in drug design are providing a strong stimulus for the development of new synthetic methodologies that allow more facile access to a wide range of fluorinated compounds. In this review, we provide an update on the effects of the strategic incorporation of fluorine in drug molecules and applications in positron emission tomography.

Benzothiazolyl substituted iminothiazolidinones and benzamido-oxothiazolidines as potent and partly selective aldose reductase inhibitors

Two new series of oxothiazolidine benzoate and acetate derivatives were synthesized and evaluated as aldehyde reductase (ALR1) and aldose reductase (ALR2) inhibitors.

Carboxylic acid (bio)isosteres in drug design

The carboxylic acid functional group can be an important constituent of a pharmacophore, however, the presence of this moiety can also be responsible for significant drawbacks, including metabolic instability, toxicity, as well as limited passive diffusion across biological membranes. To avoid some of these shortcomings while retaining the desired attributes of the carboxylic acid moiety, medicinal chemists often investigate the use of carboxylic acid (bio)isosteres. The same type of strategy can also be effective for a variety other purposes, for example, to increase the selectivity of a biologically active compound or to create new intellectual property. Several carboxylic acid isosteres have been reported, however, the outcome of any isosteric replacement cannot be readily predicted as this strategy is generally found to be dependent upon the particular context (i.e., the characteristic properties of the drug and the drug-target). As a result, screening of a panel of isosteres is typically required. In this context, the discovery and development of novel carboxylic acid surrogates that could complement the existing palette of isosteres remains an important area of research. The goal of this Minireview is to provide an overview of the most commonly employed carboxylic acid (bio)isosteres and to present representative examples demonstrating the use and utility of each isostere in drug design.

Design and synthesis of potent and selective aldose reductase inhibitors based on pyridylthiadiazine scaffold

A series of pyrido[2,3-e]-[1,2,4]-thiadiazine 1,1-dioxide acetic acid derivatives were synthesized and tested for their inhibitory activity against aldose reductase (ALR2). These derivatives were found to be potent aldose reductase inhibitors with IC50 values ranging from 0.038 μM to 11.29 μM. Most but not all of them showed a strong ALR2 inhibition activity and significant selectivity, which were further supported by docking studies. Of these inhibitors, compound 7d exhibited highest inhibition activity. Structure-activity relationship studies indicate the requirement of N2-benzyl group with electron-withdrawing substituents and N4-acetic acid group in the pyridothiadiazine scaffold.

Permeability characteristics of novel aldose reductase inhibitors using rat jejunum in vitro

The aim of this study was to estimate in vivo permeability and bioavailability of epalrestat and newly synthesized compounds with possible therapeutic activity as aldose enzyme inhibitors (ARIs). For this purpose permeability in vitro using rat jejunum mounted in side-by-side diffusion cells was determined. Tested substances were found to be low and moderately permeable and some of them were also substrates for efflux transporters. It was shown, that the higher efflux for some derivatives was due to MRP-2, but not Pgp involvement. Tested ARIs do not share the same efflux transporter with epalrestat, the only ARI currently on the market in Japan. The most permeable compound, a 2,6-difluoro-4-pyrrol-1ylphenol derivative, is not a substrate for efflux transporters and would therefore be the most promising lead compound for further investigation of potent ARIs.

Evaluation of aldose reductase inhibition and docking studies of some secondary metabolites, isolated from Origanum vulgare L. ssp. hirtum

Five polar constituents of Origanum vulgare L. ssp. hirtum were investigated for their ability to inhibit aldose reductase (ALR2), the first enzyme of the polyol pathway implicated in the secondary complications of diabetes. The most active compound was found to be lithospermic acid B. Caffeic acid was inactive as it showed no inhibitory activity against the enzyme. The order of the inhibitory activity of the remaining compounds was: rosmarinic acid >12-hydroxyjasmonic acid 12-O-beta-glucopyranoside > p-menth-3-ene-1,2-diol 1-O-beta-glucopyranoside. Docking studies have been undertaken to gain insight into the binding mode of the investigated compounds at the active site of ALR2. The predicted hydrogen bonding and hydrophobic interactions may explain the observed inhibitory activity.

Quantitative structure-activity relationship of spirosuccinimide type aldose reductase inhibitors diminishing sorbitol accumulation in vivo

Racemate physicochemical descriptors are employed to probe the quantitative structure-activity relationship of spirosuccinimide type aldose reductase inhibitors and the in vivo inhibitory activity of sorbitol accumulation. The in vivo activity data include the percent inhibition and ED50 assay results on the literature. The derived QSAR equations show that the hydrophobic character of aldose reductase inhibitor is the major contributing factor to enhance in vivo activity. As the hydrophobicity of compounds is related to both the membrane permeability and the binding affinity to the aldose reductase, its contribution to the pharmacokinetic behavior is further scrutinized by evaluating pKa and the Caco-2 cell permeability. The high correlation between ED50 and the Caco-2 cell permeability of in vitro active compounds indicates that the membrane permeability is essential for in vivo efficacy.