Enantioselective high-performance liquid chromatography combined with spectroscopic methods and theoretical calculations: A valid strategy to determine the absolute configuration of eugenol derivatives.

The absolute configuration of three chiral eugenol derivatives was assigned by a multi-step methodology based on enantioselective HPLC combined with spectroscopic and theoretical calculations. Milligram amounts of enantiopure forms used for stereochemical characterization were isolated by HPLC on the immobilized amylose-based chiral stationary phase Chiralpak IG using normal phase elution conditions. The absolute configuration was indirectly determined for one of the three compounds by 1H NMR via methoxy-α-trifluoromethyl-α-phenylacetic acid derivatization (Mosher's acid). Comparison of the experimental and predicted electronic circular dichroism spectra confirmed the stereochemical assignment by Mosher's method and extended the absolute configuration assignment to two other chiral compounds.

Theoretically Predicted and Experimentally Detected Chirality of Dibenzocyclooctynes and Their Triazole Adducts with Azides.

Dibenzocyclooctynes have emerged as promising scaffolds for bioorthogonal ligation. An important structural aspect that has not been addressed so far relates to their chirality. Herein, we explore, by theoretical and experimental methods, this structural aspect that has been neglected so far. First, computational analysis is conducted, and the results are used as a guide for the experimental investigation. Next, an array of different experiments (high-performance liquid chromatography (HPLC) on chiral columns, chiroptical spectroscopy, and X-ray diffraction) for structure elucidation is scrutinized in concert. Finally, this work demonstrates the chirality and the stereodynamic behavior of dibenzocyclooctynes and their triazole derivatives with simple azides and also uncovers their conformational behavior.

Insight into the photolytic degradation products of Rosuvastatin: Full chiral and structural elucidation and conversion kinetics by a combined chromatographic, spectroscopic and theoretical approach.

Rosuvastatin (RSV) is a well-established lipid-lowering drug. RSV is susceptible to degradation under various stress conditions and forms two cyclic derivatives by a radical-mediated photolytic mechanism. On a structural basis, these epimeric compounds (reported as FP-B in the European Pharmacopeia monograph Rosuvastatin tablets) retain the configuration of the stereogenic carbons of RSV (3R,5S) and have opposite absolute configurations at the third stereogenic center. Herein, we report the kinetics of formation and the complete structural characterization, including the assignment of the absolute configuration, of each epimer collected after HPLC separation on a chiral stationary phase. The stereochemistry of the epimers was determined by comparison of the experimental circular dichroism data with the corresponding theoretical values. Kinetic studies revealed that RSV degrades completely to FP-B within 3 h at room temperature. Furthermore, through a multi-disciplinary approach involving chromatography (HPLC and UHPLC), circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), it was demonstrated that FP-B in turn degrades to the lactones under the mild acidic conditions of the chromatographic mobile phase. The ability of RSV to form multiple degradation products may affect the quantification of RSV-related substances and draw attention to potentially toxic RSV-like species in the environment.

Resorc[4]arene Modifiers for Supramolecular Site-Directed Immobilization of Antibodies on Multi-Walled Carbon Nanotubes.

One of the main problems in developing immunosensors featuring carbon nanotubes (CNTs) is immobilizing antibodies (Abs) onto the CNT surface to afford selective binding to target antigens (Ags). In this work, we developed a practical supramolecular Ab conjugation strategy based on resorc[4]arene modifiers. To improve the Ab orientation on the CNTs surface and optimizing the Ab/Ag interaction, we exploited the host-guest approach by synthesizing two newly resorc[4]arene linkers R1 and R2 via well-established procedures. The upper rim was decorated with eight methoxyl groups to promote selective recognition of the fragment crystallizable (Fc ) region of the Ab. Moreover, the lower rim was functionalized with 3-bromopropyloxy or 3-azidopropiloxy substituents to bind the macrocycles on the multi-walled carbon nanotubes (MWCNTs) surface. Accordingly, several chemical modifications of MWCNTs were evaluated. After the morphological and electrochemical characterization of nanomaterials, the resorc[4]arene-modified MWCNTs were deposited onto a glassy carbon electrode surface to evaluate their potential applicability for label-free immunosensor development. The most promising system showed an improved electrode active area (AEL ) of almost 20 % and a site-oriented immobilization of the SARS-CoV-2 spike protein S1 antibody (Ab-SPS1). The developed immunosensor revealed a good sensitivity (23.64 µA mL ng-1 cm-2 ) towards the SPS1 antigen and a limit of detection (LOD) of 1.01 ng mL-1 .

Assessment of the effect of motorcycle autonomous emergency braking (MAEB) based on real-world crashes.

Objective: Vehicles are increasingly being equipped with Autonomous Emergency Braking (AEB) and literature highlights the utility to fit a similar active safety system in Powered Two-Wheelers (PTWs). This research attempts to analyze the efficacy of PTW Autonomous Emergency Braking (MAEB) when functioning solely, and in the case where both the PTW and Opponent Vehicle (OV) have AEB installed.Methods: 23 crashes involving motorcyclists that occurred in metropolitan areas of Italy between 2009 and 2017 were selected. The "In-depth Study of road Accidents in FlorencE (InSAFE)" provides data for the study. Each crash was reconstructed in PC-Crash 12.1 software. The obtained simulation of the crash dynamics was then used to create the dataset of cases fitted with AEB and MAEB systems. A custom MAEB system was implemented with specifications based on literature.Results: The majority of crashes occurred on urban roads, at intersections, on dry asphalt, with clear visibility, and in daylight. The passenger vehicle was the most frequent opponent vehicle (70%). Almost half the sample involved the PTW rider traveling beyond the speed limit permitted on urban roads. MAEB was found to be applicable in 19 out of 23 real-world crashes allowing the avoidance of two crashes with the progressive triggering criteria (Time to Collision (TTC) - 1.0 s) and one crash in the case where both the PTW and OV have AEB installed with more conservative setups. MAEB simulations show important trends in the reduction of the PTW impact speed (ISR) from the conservative (TTC-0.6s) to standard (TTC-0.8s) to progressive (TTC-1.0s) triggering criteria. The mean impact speed reduction (ISR) becomes 8.6 km/h, 13.8 km/h, 19.1 km/h, respectively.Conclusions: The results suggested that MAEB may be extremely effective in the PTW impact speed reduction and that an earlier MAEB intervention is beneficial in achieving higher reductions in the PTW impact speed. Further, the effect of opponent vehicles also possessing AEB was studied, and it was found that this increased the likelihood of crash avoidance and greater reduction in crash severity in unavoidable circumstances.

Kinetic and mechanism study of the spontaneous, solvent- and base-catalyzed degradation of the precursor of the ß-nitro alcohol metaraminol by combining HPLC/electronic circular dichroism/theoretical methods.

Chiral ß-nitro alcohols are key intermediates in the synthesis of a wide range of active pharmaceutical ingredients. Despite their massive use for pharmaceutical applications, in-depth kinetics studies concerning their stability during formation and transformation reactions are scarce in the literature. In this study, the (1R,2S)-1-(m-benzyloxy)-2-nitro-1-propanol) (BNA), the precursor of the metaraminol, was selected as a molecular model and the retro-Henry reaction was explored by a multidisciplinary approach involving HPLC, electronic circular dichroism and theoretical methods. The enantio-, diastereo-, and chemo-selective high-performance liquid chromatographic method for determining the purity of ß-nitro alcohol during its formation and degradation is based on the use of an amylose-derived chiral stationary phase under normal-phase eluent conditions. The influence of various factors (e.g. temperature, type of reaction solvent, basic and acid catalysts) on the degradation kinetics has been investigated. The retro-Henry reaction was found to be the major degradation of BNA, under spontaneous, solvent- and base-catalyzed conditions, resulting in the formation of its precursors 3-benzyloxybenzaldehyde and nitroethane.

Exploring the Assembly of Resorc[4]arenes for the Construction of Supramolecular Nano-Aggregates.

Many biologically active compounds feature low solubility in aqueous media and, thus, poor bioavailability. The formation of the host-guest complex by using calixarene-based macrocycles (i.e., resorcinol-derived cyclic oligomers) with a good solubility profile can improve solubilization of hydrophobic drugs. Herein, we explore the ability of resorc[4]arenes to self-assemble in polar solutions, to form supramolecular aggregates, and to promote water-solubility of an isoflavone endowed with anti-cancer activity, namely Glabrescione B (GlaB). Accordingly, we synthesized several architectures featuring a different pattern of substitution on the upper rim including functional groups able to undergo acid dissociation (i.e., carboxyl and hydroxyl groups). The aggregation phenomenon of the amphiphilic resorc[4]arenes has been investigated in a THF/water solution by UV-visible spectroscopy, at different pH values. Based on their ionization properties, we demonstrated that the supramolecular assembly of resorc[4]arene-based systems can be modulated at given pH values, and thus promoting the solubility of GlaB.

Triptycene derivatives as chiral probes for studying the molecular enantiorecognition on sub-2-µm particle cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase.

Two chiral triptycene derivatives were analyzed on the Chiralpak IB-U column packed with cellulose tris(3,5-dimethylphenylcarbamate)-based sub-2-µm diameter particles. Under normal-phase conditions, sub-minute baseline enantioseparations were obtained. Differences in structural elements and chromatographic behavior of the investigated compounds were evaluated to identify the interactions that drive the chiral discrimination process. From the evaluation of the experimental chromatographic data, it was found that hydrogen bond formation is essential for the separation of enantiomers.

Motorcycle Autonomous Emergency Braking (MAEB) employed as enhanced braking: Estimating the potential for injury reduction using real-world crash modeling.

OBJECTIVE: Recent field-tests on Motorcycle Autonomous Emergency Braking system (MAEB) showed that higher levels of deceleration to improve its effectiveness were feasible. However, the potential of MAEB in mitigating rider injuries is not well understood, particularly in scenarios where the efficacy of standard MAEB is limited because the rider is manually braking. The purpose of this study was first, to assess the injury mitigation potential of MAEB and second, to test MAEB as an enhanced braking system applied in circumstances where the rider is braking before a crash. METHODS: Data from previously investigated motorcycle injury crashes that occurred on public roads in Victoria, Australia were reconstructed using a 2D model. The intervention of MAEB was applied in the simulations to test both MAEB standard and MAEB working as enhanced braking system. The effects of MAEB in mitigating crashes were separated by crash configuration and evaluated based on the modeled reductions in impact speed and injury risk, employing injury risk functions available in the literature. RESULTS: After modeling was applied, MAEB was found to be applicable in 30 cases (91% of those in which was estimated as "possibly applicable"). The modeled Impact Speed Reduction (ISR) among the 30 cases averaged 5.0 km/h. In the cases without manual braking, the mean ISR due to standard MAEB was 7.1 km/h, whereas the relative injury risk reduction ranged from 10% for MAIS2+ to 22% for fatal injuries. In the 14 cases with manual braking, the modeled application of MAEB as enhanced braking led to an average ISR ranging from 5.3 km/h to 7.3 km/h. This resulted in an injury risk reduction ranging from 9% to 12% for MAIS2+ and from 16% to 21% for fatal injuries, depending on the different modes of MAEB. CONCLUSIONS: This study modeled the potential benefits of the highest levels of intervention for MAEB field-tested to date. The findings estimate the degree to which MAEB could mitigate motorcycle crashes and reduce injury risks for motorcyclists. New strategies for MAEB intervention as enhanced braking were modeled through crash simulations, and suggest improvements in the benefits of MAEB when riders are braking before the crash. This highlighted the requirement to perform new field-based tests to assess the feasibility of MAEB deployed as enhanced braking system.

Simultaneous enantio- and diastereo-selective high-performance liquid chromatography separation of paroxetine on an immobilized amylose-based chiral stationary phase under green reversed-phase conditions.

A simple and green high-performance liquid chromatography method for the separation of paroxetine from its enantiomeric and diastereomeric impurities has been developed. The simultaneous chromatographic resolution was carried out on the amylose-based Chiralpak IA-3 chiral stationary phase using the mixture ethanol-water-diethylamine 80:20:0.1 (v/v/v) as a mobile phase. The effects of substitution of ethanol with methanol or acetonitrile and changes in column temperature on selectivity have been carefully investigated. The optimized single-run HPLC protocol allows the baseline separation of the enantiomers of paroxetine without suffering from interference from five other chiral and achiral impurities reported in the monograph of the European Pharmacopoeia.

On-column quantification of amino functionalities bonded to solid porous matrices packed within high performance liquid chromatography columns.

Stationary phases (SPs) based on silica matrices functionalized with amino groups linked to their surface through alkyl chains of various length have found remarkable success in performing HILIC separations, showing really effective resolution towards a wide typology of compounds of biological interest, such as carbohydrates, nucleosides, purine and pyrimidine bases. Recently, we developed an operationally simple procedure, named DNBA-M, non-destructive for the analysed SP, designed to quantify the density of basic groups (typically amino groups) chemically bonded to the surface of porous solids. In the present study the DNBA-M procedure has been suitably modified to allow the quantification of any typology of amino groups present on silica matrices packed into HPLC columns. The new approach, named OC-DNBA-M, has been successfully validated through analysis of two HPLC columns packed with aminopropyl-silica matrices. Afterwards, it was also demonstrated as the OC-DNBA-M procedure may allow the effective and in-depth analysis of the structural composition characterizing SPs packed inside HPLC columns, in which amino-groups have been differently and only partially involved in following ureidic functionalizations. It was also proved how the analysed columns can be readily re-employed for the chromatographic applications for which they have been designed, without appreciable deterioration of the respective discrimination abilities.

Chromatographic separation of the interconverting enantiomers of imidazo- and triazole-fused benzodiazepines.

The toolbox of medicinal chemists includes the 1,4-benzodiazepine scaffold as a "privileged scaffold" in drug discovery. Several biologically active small molecules containing a 1,4-benzodiazepine scaffold have been approved by the FDA for the treatment of various diseases, with most of them being used for their psychotropic effects. The therapeutic potential of 1,4-benzodiazepines has stimulated the interest of synthetic chemists in developing new synthetic strategies to a range of substituted analogues for biological evaluation. A structural variation of the classical benzodiazepine skeleton is observed e.g. in alprazolam, midazolam, and related benzodiazepines, which contain a 1,2,4-triazole or an imidazole ring fused to the benzodiazepine core. Irrespective of the presence of the fused heterocyclic ring, the seven-membered diazepine ring is far from planar, and its shape resembles a twist chair. Then, the unsymmetrical substitution pattern around the seven membered cycle renders these molecules chiral, as they lack any reflection-type symmetry element. However, chirality of this molecules is labile at room temperature, becausea simple ring flipping process converts one enantiomer into the other, and 1,4-benzodiazepines exist as a mixture of rapidly interconverting conformational enantiomers in solution at or near room temperature. Physical separation of the interconverting enantiomers of diazepam and of other related 1,4-benzodiazepin-2-ones can be accomplished by low temperature HPLC on chiral stationary phases (CSPs). If the HPLC column is cooled down to temperatures where the interconversion rate is sufficiently low, compared to the chromatographic separation rate, distinct separated peaks can be observed, provided the CSP is sufficiently enantioselctive. The apparent rate constants for the on-column enantiomerization and the corresponding free energy activation barriers were obtained by simulation of exchange-deformed HPLC profiles using a computer program based on the stochastic model. Here we report on the dynamic HPLC investigations carried out on a set of fused imidazo and triazolo-benzodiazepines (alprazolam, midazolam, triazolam and estazolam) The experimental dynamic chromatograms and the corresponding interconversion barriers reported in this paper show that the third fused heterocyclic ring increase the energy barrier by 2 kcal/mol.

Motorcycle helmet selection and usage for improved safety: A systematic review on the protective effects of helmet type and fastening.

OBJECTIVE: Motorcycle helmets are the most common and effective protective device to reduce head injuries and mortality in crashes among powered two-wheeler riders. Even if they are globally recognized as effective, there are still concerns regarding their correct use, which is necessary to achieve maximum head protection. The goal of this systematic review is to assess which characteristics of helmet design and use showed a positive influence on rider safety, in order to provide insights to improve end-user helmet usage. METHODS: A literature search was carried out combining two sets of keywords, one related with either motorcycle or rider and the other referring to either protective equipment or injuries. After the exclusion of duplicates, 977 papers were screened by reviewers, thus identifying 32 papers that were analyzed in group discussions. RESULTS: Among the papers included in this study, no strong conflicting conclusions emerged in their results. The studies focusing on the use of different types of helmets highlighted that full-face helmets, compared with other standard helmets, have a positive influence on head injuries and facial injuries. Correct fastening was clearly beneficial for head and facial injuries, induced injuries, and helmet ejection. CONCLUSIONS: This systematic review provides important insights to improve the usage of helmets by end-users. Correct fastening is a crucial factor to avoid helmet roll-off during a crash. Most studies agreed that full-face helmets provide higher protection in comparison with other standard helmets, especially for facial injuries, and no negative influence with respect to neck and spinal injuries.

Comparison of Coated and Immobilized Chiral Stationary Phases Based on Amylose tris-[(S)-α-Methylbenzylcarbamate] for the HPLC Enantiomer Separation of α-Lipoic Acid and Its Reduced Form.

The couple of chiral sulfur compounds α-lipoic acid (ALA)/α-dihydrolipoic acid (DHALA) has attracted considerable attention in recent years owing to its remarkable anti-inflammatory and antioxidant properties. It is well known that the chirality of the C6 plays a key role in determining the biological activity of ALA. The natural occurring (R)-ALA enantiomer is an essential cofactor for key oxidative metabolism enzyme complexes and, after oral administration of the racemic mixture, it shows higher plasma concentration than (S)-ALA. Differently, the in vivo enantioselective action difference between the enantiomers of DHALA has not yet been studied. This lacking is perhaps due to the unavailability of analytical methods capable of determining the enantiomeric composition of biological samples during pharmacokinetic and pharmacodynamic events. In the present work, the direct and baseline enantioresolution of both chiral acids by HPLC on two amylose-derived chiral stationary phases is presented. The proposed chiral enantioselective protocol, therefore, does not require pre- or on-column derivatization. The performance of the coated Chiralpak AS-H CSP and the new immobilized Chiralpak IH-3 CSP, which have the same chiral selector amylose tris-[(S)-α-methylbenzylcarbamate], were compared using conventional normal-phase mobile phases containing ethanol or 2-propanol as alcoholic solvents and a fixed percentage of trifluoroacetic acid. Nonconventional eluents containing dichloromethane, ethyl acetate, and 2-methyltetrahydrofuran as organic cosolvents were applied in the separation of the enantiomers of two carboxylic acids on the immobilized Chiralpak IH-3 CSP. The effect of the column temperature was carefully evaluated in order to improve enantioselectivity. Adequate amounts of enantiomers were isolated by an analytical-size Chiralpak IH-3 column and submitted to chiroptical measurements. The absolute configuration assignment of the isolated enantiomers was determined by a multidisciplinary procedure based on the comparison of the experimental and calculated chiroptical properties.

Human error in motorcycle crashes: A methodology based on in-depth data to identify the skills needed and support training interventions for safe riding.

OBJECTIVE: Human error by either rider or other vehicle driver is the primary contributing factor in crashes involving powered-two-wheelers. A human-factor-based crash analysis methodology is key to enhancing the road safety effectiveness of rider training interventions. Our aim is to define a methodology that uses in-depth data to identify the skills needed by riders in the highest risk crash configurations to reduce casualty rates. METHODS: The methodology is illustrated through a case study using in-depth data of 803 powered-two-wheeler crashes. Seven types of high-risk crash configuration based on pre-crash trajectories of the road-users involved were considered to investigate the human errors as crash contributors. Primary crash contributing factor, evasive maneuvers performed, horizontal roadway alignment and speed-related factors were identified, along with the most frequent crash configurations and those with the greatest risk of severe injury. RESULTS: Straight Crossing Path/Lateral Direction was the most frequent crash configuration and Turn Across Path/Opposing Direction was identified as that with the highest risk of serious injury. Multi-vehicle crashes cannot be considered as a homogenous category of crashes to which the same human failure is attributed, as different interactions between motorcyclists and other road users are associated with both different types of human error and different rider reactions. Human error in multiple-vehicle crashes differed between those configurations related to crossroads and those related to rear-end and head-end crashes. Both single-vehicle crashes and multi-vehicle head-on crashes frequently occur along curves. The involved collision avoidance maneuvers of the riders differed significantly among the highest risk crash configurations. The most relevant lack of skills are identified and linked to their most representative context. In most cases a combination of different skills was required simultaneously to avoid the crash. CONCLUSIONS: The results contribute to understand the motorcyclists' responses in high-risk crash scenarios. The findings underline the need to group accident cases, beyond the usual single-vehicle versus multi-vehicle collision approach. The different interactions with other road users should be considered to identify the competencies of the motorcyclists needed to reduce crash risks. Our methodology can be applied to increase the motorcyclists' safety by supporting preventive actions based on riders' training and eventually ADAS design.

Molecular Recognition of the HPLC Whelk-O1 Selector towards the Conformational Enantiomers of Nevirapine and Oxcarbazepine.

The presence of stereogenic elements is a common feature in pharmaceutical compounds, and affording optically pure stereoisomers is a frequent issue in drug design. In this context, the study of the chiral molecular recognition mechanism fundamentally supports the understanding and optimization of chromatographic separations with chiral stationary phases. We investigated, with molecular docking, the interactions between the chiral HPLC selector Whelk-O1 and the stereoisomers of two bioactive compounds, the antiviral Nevirapine and the anticonvulsant Oxcarbazepine, both characterized by two stereolabile conformational enantiomers. The presence of fast-exchange enantiomers and the rate of the interconversion process were studied using low temperature enantioselective HPLC and VT-NMR with Whelk-O1 applied as chiral solvating agent. The values of the energetic barriers of interconversion indicate, for the single enantiomers of both compounds, half-lives sufficiently long enough to allow their separation only at critically sub-ambient temperatures. The chiral selector Whelk-O1 performed as a strongly selective discriminating agent both when applied as a chiral stationary phase (CSP) in HPLC and as CSA in NMR spectroscopy.

Phenyl(thio)phosphon(amid)ate Benzenesulfonamides as Potent and Selective Inhibitors of Human Carbonic Anhydrases II and VII Counteract Allodynia in a Mouse Model of Oxaliplatin-Induced Neuropathy.

Human carbonic anhydrase (CA; EC 4.2.1.1) isoforms II and VII are implicated in neuronal excitation, seizures, and neuropathic pain (NP). Their selective inhibition over off-target CAs is expected to produce an anti-NP action devoid of side effects due to promiscuous CA modulation. Here, a drug design strategy based on the observation of (dis)similarities between the target CA active sites was planned with benzenesulfonamide derivatives and, for the first time, a phosphorus-based linker. Potent and selective CA II/VII inhibitors were identified among the synthesized phenyl(thio)phosphon(amid)ates 3-22. X-ray crystallography depicted the binding mode of phosphonic acid 3 to both CAs II and VII. The most promising derivatives, after evaluation of their stability in acidic media, were tested in a mouse model of oxaliplatin-induced neuropathy. The most potent compound racemic mixture was subjected to HPLC enantioseparation, and the identification of the eutomer, the (S)-enantiomer, allowed to halve the dose totally relieving allodynia in mice.

Site-Directed Antibody Immobilization by Resorc[4]arene-Based Immunosensors.

One of the main problems in the development of immunosensors is to overcome the complexity of binding antibodies to the sensor surface. Most immobilizing methods lead to a random orientation of antibodies with a lower binding site density and immunoaffinity. In order to control the orientation of antibody immobilization, several resorc[4]arene derivatives were designed and synthesized. After the spectroscopic characterization of resorc[4]arene self-assembled monolayers (SAMs) onto gold films, the surface coverage and the orientation of insulin antibody (Ab-Ins) were assessed by a surface plasmon resonance (SPR) technique and compared with a random immobilization method. Experimental results combined with theoretical studies confirmed the dipole-dipole interaction as an important factor in antibody orientation and demonstrated the importance of the upper rim functionalization of resorcarenes. Accordingly, resorcarene 5 showed a major binding force towards Ab-Ins thanks to the H-bond interactions with the amine protein groups. Based on these findings, the resorcarene-based immunosensor is a powerful system with improved sensitivity providing new insight into sensor development.

1,3-Dipolar Cycloaddition, HPLC Enantioseparation, and Docking Studies of Saccharin/Isoxazole and Saccharin/Isoxazoline Derivatives as Selective Carbonic Anhydrase IX and XII Inhibitors.

Two series of saccharin/isoxazole and saccharin/isoxazoline hybrids were synthesized by 1,3-dipolar cycloaddition. The new compounds showed to be endowed with potent and selective inhibitory activity against the cancer-related human carbonic anhydrase (hCA) IX and XII isoforms in the nanomolar range, while no affinity was encountered for off-targets, such as hCA I and II. Successive enantioseparation on a milligram scale of the most representative compounds led to the discovery that (S)-isomers were more potent than their corresponding (R)-enantiomers. Lastly, molecular modeling studies were conducted to define those structural requirements that were responsible for the discrimination among selected human isoforms of carbonic anhydrases. Two nanomolar hCA IX and XII inhibitors were also screened for their selective toxicity against non tumoral primary cells (fibroblasts) and against a breast adenocarcinoma cell line (MCF7) in hypoxic environment. The efficacious combination of these compounds with doxorubicin on MCF7 cells was demonstrated after 72 h of treatment.

High-performance liquid chromatography enantioseparation of chiral 2-(benzylsulfinyl)benzamide derivatives on cellulose tris(3,5-dichlorophenylcarbamate) chiral stationary phase.

Recently it has been reported that immobilized chlorinated-type chiral stationary phases based on cellulose tris(3,5-dichlorophenylcarbamate) are able to express an outstanding enantioselectivity towards the structure of 2-(benzylsulfinyl)benzamide. We now introduce two homologue series of chiral sulfoxides based on the same 2-(sulfinyl)benzoyl core as the prototype of new selectands for HPLC, whose enantioselectivity could be modulable through the replacement of the benzyl group with an unbranched alkyl chain varying in length from 1 to 5 carbon atoms. HPLC parameters such as mobile phase composition and column temperature have been carefully evaluated in order to get pertinent structure-enantioselectivity relationships. The enantiomer elution order was unambiguously determined by a combined strategy involving theoretical and experimental procedures. Two cases of temperature-dependent inversion of the elution order of enantiomers in the operative temperature range of chiral chromatographic support were observed.