Synthesis, biological evaluation (antioxidant, antimicrobial, enzyme inhibition, and cytotoxic) and molecular docking study of hydroxy methoxy benzoin/benzil analogous.

In this work, due to the biological activity evaluation, a series of hydroxy methoxy benzoins (1-8), benzils (10-16) and methoxy benzoin/benzil-O-ß-d-glucosides (17-28) were synthesized. Antioxidant (FRAP, CUPRAC, DPPH), antimicrobial (16 microorganisms, and two yeast), enzyme inhibition (α-amylase, α-glucosidase, AChE, BChE, and tyrosinase) of all synthesized benzoin/benzil analogs were investigated. Benzoins (1-8) showed the most effective antioxidant properties compared to all three methods. Compound 28 against α-amylase, compound 9 against α-glucosidase, compound 11 against AChE, compound 2 against BChE, and compound 13 against tyrosinase showed the best activities with the better or similar IC50 values as used standards. Hydroxy methoxy benzoin compounds (1-8) among all four groups were seen as the most effective against the tested microorganism. Molecular docking analysis showed that all tested compounds 1-28 (0.01-2.22 µM) had the best binding affinity against AChE enzyme. Cytotoxic effects of the many of compounds (1-16, 21, and 24) also investigated and it was found that they caused different effects in different cells. The LDH tests of compounds 1a + b, 4, 7, 8, 9, 11, 12, 21, and 24, seemed to be effective compared to the positive control cisplatin. The cytotoxicity of compounds 6 (9.24%) for MCF7 cancer cells, 8 (5.16%) and 4 (8.26%) for HT29 cancer cells, 24 (9.84%) for Hep3B cells and 8 (8.52%), 7 (5.70%), 4 (6.94) and 9 (7.22%) for C6 cells were at normal values. And also cytotoxic activity of four compounds (5, 9, 21, and 24) among the all synthetic groups, were evaluated to the HeLa and RPE. Compound 5 showed anticancer activity on HeLa and RPE cancer cells as much as or better than cisplatin which was used as standard.

New antibacterial and 5-lipoxygenase activities of synthetic benzyl phenyl ketones: Biological and docking studies.

We investigated twelve benzyl phenyl ketone derivatives which are synthetic precursors of isoflavonoids that are shown be good 5-hLOX inhibitors, especially those that have the catechol group, but these precursors never have been assayed as 5-hLOX inhibitors being a novelty as inhibitors of the enzyme, due to sharing important structural characteristics. Screening assays, half maximal inhibitory concentration (IC50) and kinetic assays of all the studied molecules (5 µg/ml in media assay) showed that 1-(2,4-dihydroxy-3-methylphenyl)-2-(3-chlorophenyl)-ethanone (K205; IC50 = 3.5 µM; Ki = 4.8 µM) and 1-(2,4-dihydroxy-3-methylphenyl)-2-(2-nitrophenyl)-ethanone (K206; IC50 = 2.3 µM; Ki = 0.7 µM) were potent, selective, competitive and nonredox inhibitors of 5-hLOX. Antioxidant behavior was also assayed by DPPH, FRAP, and assessing ROS production, and those with antibacterial and antiproliferative properties relating to 1-(2,4-dihydroxy-3-methylphenyl)-2-(2-chlorophenyl)-ethanone (K208) established it as the most interesting and relevant compound studied, as it showed nearly 100% inhibition of bacterial growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Finally, docking studies were done that helped to characterize how the inhibitor structures correlated to decreased 5-hLOX activity.

Ligand-Based Drug Design: Synthesis and Biological Evaluation of Substituted Benzoin Derivatives as Potential Antitumor Agents.

BACKGROUND: Phosphoinositide 3-kinase α (PI3Kα) has emerged as a promising target for anticancer drug design. OBJECTIVES: Target compounds were designed to investigate the effect of the p-OCH3 motifs on ligand/PI3Kα complex interaction and antiproliferative activity. METHODS: Synthesis of the proposed compounds, biological examination tests against human colon adenocarcinoma (HCT-116), breast adenocarcinoma (MCF-7), and breast carcinoma (T47D) cell lines, along with Glide docking studies. RESULTS: A series of 1,2-bis(4-methoxyphenyl)-2-oxoethyl benzoates was synthesized and characterized by means of FT-IR, 1H and 13C NMR, and by elemental analysis. Biological investigation demonstrated that the newly synthesized compounds exhibit antiproliferative activity in human colon adenocarcinoma (HCT-116), breast adenocarcinoma (MCF-7), and breast carcinoma (T47D) cell lines possibly via inhibition of PI3Kα and estrogen receptor alpha (ERα). Additionally, results revealed that these compounds exert selective inhibitory activity, induce apoptosis, and suppress VEGF production. Compound 3c exhibited promising antiproliferative activity in HCT-116 interrogating that hydrogen bond-acceptor mediates ligand/PI3Kα complex formation on m- position. Compounds 3e and 3i displayed high inhibitory activity in MCF-7 and T47D implying a wide cleft discloses the o-attachment. Furthermore, compound 3g exerted selective inhibitory activity against T47D. Glide docking studies against PI3Kα and ERα demonstrated that the series accommodate binding to PI3Kα and/or ERα. CONCLUSION: The series exhibited a potential antitumor activity in human carcinoma cell lines encoding PI3Kα and/or ERα.

Molecular modeling based approach, synthesis, and cytotoxic activity of novel benzoin derivatives targeting phosphoinostide 3-kinase (PI3Kα).

The oncogenic potential of phosphatidylinositol 3-kinase (PI3Kα) has made it an attractive target for anticancer drug design. In this work, we describe our efforts to optimize the lead PI3Kα inhibitor 2-hydroxy-1,2-diphenylethanone (benzoin). A series of 2-oxo-1,2-diphenylethyl benzoate analogs were identified as potential PI3Kα inhibitors. Docking studies confirmed that the aromatic interaction is mediating ligand/protein complex formation and identified Lys802 and Val851 as H-bonding key residues. Our biological data in human colon carcinoma HCT116 showed that the structure analogs inhibited cell proliferation and induced apoptosis.

Microwave-assisted efficient synthesis of 2-hydroxydeoxybenzoins from the alkali degradation of readily prepared 3-aryl-4-hydroxycoumarins in water.

This paper describes an operationally simple, green and efficient approach for the synthesis of 2-hydroxydeoxybenzoins bearing diverse substituents from the microwave-assisted alkali degradation of 3-aryl-4-hydroxycoumarins in water. The latter compounds were readily prepared from the intramolecular Claisen condensation reaction of methyl 2-(2-arylacetoxy)benzoates in the presence of Cs2CO3-acetone, in excellent yields and without laborious workup procedures. This method is highly atom-economic and thus applicable for the large-scale synthesis of 2-hydroxydeoxybenzoins.

Design, synthesis and molecular simulation studies of dihydrostilbene derivatives as potent tyrosinase inhibitors.

The synthesis, molecular modeling and biological evaluation of substituted deoxybenzoins and optimized dihydrostilbenes are reported. Preliminary structure-activity relationship data were elucidated and lead compounds suitable for further optimization were discovered. Dihydrostilbene 7 is a particularly potent inhibitor (IC(50)=8.44 µM, more potent than kojic acid).

On the organocatalytic activity of N-heterocyclic carbenes: role of sulfur in thiamine.

The reaction energy profiles of the benzoin condensation from three aldehydes catalyzed by imidazol-2-ylidene, triazol-3-ylidene, and thiazol-2-ylidene have been investigated computationally. The barriers for all steps of all investigated reactions have been found to be low enough to indicate the viability of the mechanism proposed by Breslow in the 1950s. The most remarkable difference in the catalytic cycles has been the increased stability of the Breslow intermediate in case of thiazol-2-ylidene (by ca. 10 kcal/mol) compared to the other two carbenes, which results in lower energy for the coupling of the second aldehyde molecule, thus, increasing the reversibility of the reaction. Since the analogous transketolase reaction, being involved in the carbohydrate metabolism of many organisms, requires an initial decoupling-a reverse benzoin condensation-this difference provides a reasonable explanation for the presence of a thiazolium ring in thiamine instead of the otherwise generally more available imidazole derivatives. The "resting intermediate" found by Berkessel and co-workers for a triazole-based catalyst was found more stable than the Breslow intermediate for all of the systems investigated. The (gas phase) proton affinities of several carbenes were compared, the relative trends being in agreement with the available (in aqueous solution) data. The hydrolytic ring-opening reaction of the thiazole-based carbene was shown to be different from that of imidazole-2-ylidenes.

Photoremovable chiral auxiliary.

A new concept of a photoremovable chiral auxiliary (PCA), based on the chiral benzoin chromophore, is introduced. This moiety can control the asymmetric formation of a Diels-Alder adduct, and then be removed in a subsequent photochemical step in high chemical and quantum yields. Selective formation of the products at up to 96% ee was observed in the presence of a Lewis acid catalyst in the case of a 2-methoxybenzoinyl chiral auxiliary.

Enantioselective production of benzoin from benzoin acetate via kinetic resolution and deracemization using Rhizopus oryzae.

In this study, the production of enantiopure benzoin from rac-benzoin acetate was achieved by lipase catalyzed kinetic resolution combined with deracemization using Rhizopus oryzae (CBS111718). The growth cells were pretreated with 20 kHz and 30 kHz ultrasound irradiation and mechanical homogenization. Approximately 100% conversion and 96% enantiomeric excess of the product (S-benzoin) were obtained by applying 20 kHz ultrasound irradiation at pH 6. The deracemization process involves new and important processes that allow for the transformation of a racemate into a single stereoisomeric product in 100% theoretical yields. Moreover, the application of ultrasound increases the conversion rate by reducing mass transfer limitation.

Synthesis and structure-activity relationship study of deoxybenzoins on relaxing effects of porcine coronary artery.

Deoxybenzoins are potent antioxidants and tyrosinase inhibitors with potential to be developed as food preservatives and cosmetic ingredients. To explore the potential in cardiovascular protection, 25 polyphenolic deoxybenzoins were synthesized and evaluated for inhibitory effects on KCl-induced porcine coronary arterial contraction. The results revealed deoxybenzoins are significant inhibitors of KCl-induced arterial contraction. Among those synthesized, two-thirds of the deoxybenzoins exhibited moderate to good efficacy on relaxing contracted artery including 2,4-dihydroxydeoxybenzoin with EC50=3.30 µM (Emax=100%, n=7) and 2,4-dihydroxy-4'-methoxydeoxybenzoin EC50=3.70 µM (Emax=100%, n=5). Deoxybenzoins displayed an endothelium-dependent relaxing manner on the contracted artery; the contractile responses of neither endothelium denuded nor L-NAME deactivated rings were inhibited. The structure-activity relationships of deoxybenzoin on arterial relaxing effects concluded that the 2,4-dihydroxylated deoxybenzoins presented a potential vascular relaxing pharmacophore, with favoring substitution on ring B in the order of H≥p-OMe>p-OH>o-OMe>m,p-diOMe≥m-OMe.

Design, synthesis and biological evaluation of new (E)- and (Z)-1,2,3-triaryl-2-propen-1-ones as selective COX-2 inhibitors.

A group of (E)-and (Z)-1,2,3-triaryl-2-propen-1-one derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para position of the C-1 phenyl ring were synthesized and evaluated as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure-activity relationships were determined by varying the substituents on the C-3 propenone moiety. Among the 1,2,3-triaryl-2-propen-1-ones, (Z)-1-(4-(methylsulfonyl)phenyl)-2,3-diphenylprop-2-en-1-one (3b) showed the most potency and selectivity on COX-2 inhibition (COX-2 IC(50) = 0.07 microM; selectivity index = 201). The Z-propenones were also found to be more potent and selective than their E-isomers for COX-2 inhibitory activity. The structure-activity data acquired indicate that the geometry of propenone and also the type of substituents on the C-3 propenone are important for COX-2 inhibitory activity.

Design, synthesis, and immunosuppressive activity of new deoxybenzoin derivatives.

In the search for potential immunosuppressive agents with high efficacy and low toxicity, a series of new deoxybenzoins were synthesized and evaluated for their cytotoxicity and immunosuppressive activity. Among the synthesized compounds, four deoxybenzoin oximes (compounds 31, 32, 37, and 38) exhibited lower cytotoxicity and higher inhibitory activity toward anti-CD3/anti-CD28 co-stimulated T-cell proliferation than other compounds. More significantly, compound 31 is >100-fold less cytotoxic than cyclosporine A (CsA) and is also more potent (31: SI>684.64, CsA: SI=235.44). The preliminary inhibition mechanism of compound 31 was also identified by flow cytometry, and this compound exerts immunosuppressive activity by inducing apoptosis in activated lymph node cells in a dose-dependent manner. In addition, the mechanism of apoptosis was detected by western blot analysis.

Metronidazole-deoxybenzoin derivatives as anti-Helicobacter pylori agents with potent inhibitory activity against HPE-induced interleukin-8.

A series of new metronidazole-deoxybenzoin derivatives were synthesized and evaluated for their antimicrobial activity against Helicobacter pylori. Highly selective anti-H. pylori activity was also observed in synthesized compounds. Compound 34 exhibited the most potent activity, similar to the positive control amoxicillin. Furthermore, compounds 17 and 34 were able to significantly decrease H. pylori water extract (HPE)-induced production of interleukin-8 (IL-8) in gastric mucosal cells, which did not show any effect on the cell viability.

Design and synthesis of novel deoxybenzoin derivatives as FabH inhibitors and anti-inflammatory agents.

Beta-ketoacyl-acyl carrier protein synthase III (FabH) catalyzes the initial step of fatty acid biosynthesis via a type II fatty acid synthase in most bacteria. The important role of this essential enzyme combined with its unique structural features and ubiquitous occurrence in bacteria has made it an attractive new target for the development of new FabH inhibitors. The synthesis and biological evaluation halide-deoxybenzoins derivatives are described in this Letter. Potent FabH inhibitory and selective anti-Gram-negative bacteria activities were observed in deoxybenzoin derivatives. Furthermore, compound 19 was able to reduce the ECE-induced IL-8 production in gastric mucosal cells significantly. Based on the biological data and molecular docking, compound 19 is a potential FabH inhibitor and anti-inflammatory agent deserving further research.

Potential antioxidants and tyrosinase inhibitors from synthetic polyphenolic deoxybenzoins.

Deoxybenzoins (DOBs) are one-pot synthetic precursors of isoflavones with feature analogous to those beneficial polyphenols such as resveratrol (stilbene) and phloretin (dihydrochalcone). In this study, seventeen polyphenolic DOBs were synthesized and evaluated by various antioxidant assays and tyrosinase inhibitory effect in vitro. Results displayed that these DOBs are powerful antioxidants; for example, 2,3,4-trihydroxy-3',4'-dimethoxydeoxybenzoin possesses an excellent anti-lipid peroxidation activity (IC(50)=0.72+/-0.16 microM), whilst 2,4,4',5-tetrahydroxydeoxybenzoin showed good DPPH radical scavenging activity (IC(50)=0.69+/-0.04 microM), which were better than Trolox and vitamin C. Besides exhibiting a weak metal chelating effect, these DOBs were effective in scavenging ABTS(+) and superoxide anion (O2-) radicals. DOBs also exhibited potent mushroom tyrosinase inhibitory activity; for example 2,3,4'-trihydroxy-4-methoxydeoxybenzoin displayed stable and significant inhibitory effect on tyrosinase activity, with IC(50) values 43.37, 43.10 and 46.10 microM at incubation intervals of 0.5, 1.5, and 2.5h, respectively. These results suggest that, with the advantage of being readily synthesizable small molecules, DOBs can be potentially developed into clinical and industrial antioxidants.

Chiral cobalt-catalyzed enantiomer-differentiating oxidation of racemic benzoins by using molecular oxygen as stoichiometric oxidant.

An efficient enantioselective oxidative reaction catalyzed by a chiral cobalt complex has been developed by using molecular oxygen as the stoichiometric oxidant (see scheme). The very mild reaction conditions of the catalytic system provide access to a wide range of benzoins (alpha-hydroxyketones) in high yield and excellent enantioselectivity (s (k(f)/k(s)) up to 47). This method is very versatile because the sole by-product of our oxidation process is water, which makes our system more eco-friendly and green.

Carboligation reactions with benzaldehyde lyase immobilized on superparamagnetic solid support.

Histidine-tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) was efficiently immobilized to surface-modified magnetic particles with affinity ligand binding. In addition to conventional benzoin condensation reactions, two important representative BAL-catalyzed carboligation reactions, were also performed with this magnetically responsive biocatalyst. The results obtained from the carboligation reactions that were performed with this simple and convenient heterogenous biocatalyst were comparable to that of free-enzyme-catalyzed reactions.

Bidirectional metalation of hydrobenzoin: direct access to new chiral ligands and auxiliaries.

A bidirectional ortho metalation of the readily available chiral diol hydrobenzoin has been developed that provides direct access to new ortho-functionalized hydrobenzoin derivatives. This one-pot procedure should broaden the utility of hydrobenzoin as an auxiliary and ligand in asymmetric synthesis.

The reaction of singlet oxygen with enecarbamates: a mechanistic playground for investigating chemoselectivity, stereoselectivity, and vibratioselectivity of photooxidations.

Photochirogenesis, the control of chirality in photoreactions, is one of the most challenging problems in stereocontrolled photochemistry, in which the stereodifferentiation has to be imprinted within the short lifetime of the electronically excited state. Singlet oxygen (1O2), an electronically excited molecule that is known to be sensitive to vibrational deactivation, has been selected as a model case for testing stereoselective control by vibrational deactivation. The stereoselectivity in the reaction of 1O2 with E/Z enecarbamates 1, equipped with the oxazolidinone chiral auxiliary, has been examined for the mode selectivity ([2 + 2]-cycloaddition versus ene-reaction) and the stereoselectivity in the oxidative cleavage of the alkenyl functionality to the methyldesoxybenzoin (MDB) product. Through the appropriate choice of substituents in the enecarbamate, the mode selectivity (ene versus [2 + 2]), which depends on the alkene geometry (E or Z), the steric bulk of the oxazolidinone substituent at the C-4 position, and the C-3' configuration on the side chain, may be manipulated. Phenethyl substitution gives exclusively the [2 + 2]-cycloaddition product, irrespective of the alkene geometry. The stereoselection in the resulting methyldesoxybenzoin (MDB) product is examined in a variety of solvents as a function of temperature by using chiral GC analysis. The extent (% ee) as well as the sense (R versus S) of the stereoselectivity in the MDB formation for the E isomer depends significantly on solvent and temperature, whereas the corresponding Z isomers are not affected by such variations. The complex temperature and solvent effects are scrutinized in terms of the differential activation parameters (DeltaDeltaS++, DeltaDeltaH++) for the photooxygenation of E/Z-enecarbamates in various solvents at different temperatures. The enthalpy-entropy compensations provide a mechanistic understanding of the temperature dependence of the ee values for the MDB product and the difference in the behavior between the Z and E enecarbamates. The E enecarbamates show a relatively high contribution from the entropy term and an appreciable contribution from the enthalpy term; both terms possess the same sign. In contrast, the corresponding relative insensitivity of Z enecarbamates to temperature and solvent variation is convincingly explained by the near-zero DeltaDelta S++ and DeltaDelta H++. Such effects, associated with temperature- and solvent-dependent conformational factors, are most likely dictated by the stereogenic center at the C-3' phenethyl substituent. The high stereocontrol during the photooxygenation of the chiral enecarbamates is shown to be independent of the steric demand of the oxazolidinone substituent at the C-4 position. In view of the reduced stereocontrol on deuteration of the oxazolidinone substituent at the C-4 position, we propose that the unusual stereoselective vibrational quenching of the attacking singlet oxygen (excited-state reactivity), a novel mechanistic concept, works in concert with the usual steric impositions (ground-state reactivity) exercised by the substituents to afford the high stereoselectivity observed in the dioxetane product during the [2 + 2] cycloaddition. Such synergistic interplay is held responsible for the highly stereoselective photooxidative cleavage of the chiral enecarbamates. The efficacy of stereocontrol in this photooxidation is demonstrated by kinetically resolving the epimers of the enecarbamate cleavage product (MDB) in essentially perfect stereoselectivity, a new methodology that we coin "photo-Pasteur-type kinetic resolution".

Methylene-bridged bis(benzimidazolium) salt as a highly efficient catalyst for the benzoin reaction in aqueous media.

Benzoin reactions are catalyzed effectively by a methylene-bridged bis(benzimidazolium) salt to yield alpha-hydroxy ketones, and the reactions proceed in water as the aqueous medium under mild conditions.