Efficient synthesis of some [1,3]-oxazine derivatives in the presence of solid acid nano catalyst based on ferrierite and study on their activity against breast cancer through molecular docking calculation.

In this research, the magnetic solid acid nanocatalyst based on ferrierite has been prepared and used as catalyst for the green synthesis of some [1,3]-oxazine derivatives in water at room temperature. The synthesized compounds were obtained in high to excellent yields after short reaction times and the structure of synthesized products were investigated by spectroscopic methods such as: FT-IR, 1H NMR and 13C NMR. The prepared magnetic solid acid catalyst was characterized using XRD, FT-IR, FE-SEM, EDX, elemental mapping, TGA and VSM analysis methods. Magnetic catalyst has easy separation ability, which leads to better and easier recycling. The preparation and synthesis of [1,3]-oxazine derivatives were carried out at room temperature in the presence of M-FER/TEPA/SO3H. Easy workup, green solvent (water) and also short reaction times with high to excellent yield of products, are some of advantageous of presented method. Docking calculations on the structure of the synthesized compounds proved their medicinal properties against breast cancer cells.

Design, Green Synthesis and in silico Studies of New Substituted Naphtho[1,2-e][1,3]Oxazines as Potential Acetylcholinesterase Inhibitors.

Alzheimer's disease (AD) is a prevalent neurodegenerative condition characterized by progressive cognitive decline and memory impairment resulting from the degeneration and death of brain neurons. Acetylcholinesterase (AChE) inhibitors as the primary pharmacotherapy for numerous neurodegenerative conditions, leveraging their capacity to modulate acetylcholine levels crucial for cognitive function. Recently, oxazines  have brought worthy synthetic interest due to their extensive biological activities including, anti-tubercular, anti-convulsant, and anti-cancer activities. In this study, a series of novel naphtho[1,2-e][1,3]oxazine derivatives has been designed  and synthesized with potential of acetylcholinesterase (AChE) inhibition. The target products have been prepared by a one-pot and three-component condensation reaction of 2-naphthol, aromatic aldehydes, and arylmethanimine in the presence of 3-methyl-1-sulfonic acid imidazolium chloride ([Msim]Cl) as an effective and recyclable catalyst under microwave irradiation solvent-free condition. The molecular docking studies has also been performed to investigate the synthetic compounds in the the AChE active site gorge. The results showed that all these derivatives interact with the enzymes with high affinity in binding pocket. The MM-GBSA studies were performed for all synthesized derivatives and among them, compound 3-(4-Chlorophenyl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine 5f, showed the lowest the binding free energy (-48.04 kcal mol-1). In general, oxazine derivatives could be proposed as the strong AChE inhibitors.

Synthesis and Inhibitor Effect Novel Alkoxymethyl Derivatives of Dihetero Cycloalkanes on Carbonic Anhydrase and Acetylcholinesterase.

1,3-Diheterocycloalkanes derivatives are important starting materials in fine organic synthesis. These compounds can be widely used in various fields such as industry, medicine, biotechnology and chemical technology. The paper is focused on synthesis and study of alkoxymethyl derivatives of diheterocycloalkanes (M1-M15) and inhibition effect on carbonic anhydrase and acetylcholinesterase. The structures of compounds were confirmed by 1H and 13C NMR spectroscopy. Also, in this study alkoxymethyl derivatives of diheterocycloalkanes were assessed for their influence on various metabolic enzymes, including acetylcholinesterase (AChE) and human carbonic anhydrase isoenzymes (hCA I and hCA II). The results demonstrated that all these compounds exhibited potent inhibitory effects on all the target enzymes, surpassing the standard inhibitors, as evidenced by their IC50 and Ki values. The Ki values for the compounds concerning AChE, hCA I, and hCA II enzymes were in the ranges of 1.02±0.17-8.38±1.02, 15.30±3.15-58.14±5.17 and 24.05±3.70-312.94±27.24 nM, respectively.

Synthesis and Anti-Mycobacterium tuberculosis Activity of Imidazo[2,1-b][1,3]oxazine Derivatives against Multidrug-Resistant Strains.

The emergence of multidrug-resistant strains of M. tuberculosis has raised concerns due to the greater difficulties in patient treatment and higher mortality rates. Herein, we revisited the 2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine scaffold and identified potent new carbamate derivatives having MIC90 values of 0.18-1.63 µM against Mtb H37Rv. Compounds 47-49, 51-53, and 55 exhibited remarkable activity against a panel of clinical isolates, displaying MIC90 values below 0.5 µM. In Mtb-infected macrophages, several compounds demonstrated a 1-log greater reduction in mycobacterial burden than rifampicin and pretomanid. The compounds tested did not exhibit significant cytotoxicity against three cell lines or any toxicity to Galleria mellonella. Furthermore, the imidazo[2,1-b][1,3]oxazine derivatives did not show substantial activity against other bacteria or fungi. Finally, molecular docking studies revealed that the new compounds could interact with the deazaflavin-dependent nitroreductase (Ddn) in a similar manner to pretomanid. Collectively, our findings highlight the chemical universe of imidazo[2,1-b][1,3]oxazines and their promising potential against MDR-TB.

Cycloaddition of 4-Acyl-1H-pyrrole-2,3-diones Fused at [e]-Side and Cyanamides: Divergent Approach to 4H-1,3-Oxazines.

4-Acyl-1H-pyrrole-2,3-diones fused at [e]-side with a heterocyclic moiety are suitable platforms for the development of a hetero-Diels-Alder-reaction-based, diversity-oriented approaches to series of skeletally diverse heterocycles. These platforms are known to react as oxa-dienes with dienophiles to form angular 6/6/5/6-tetracyclic alkaloid-like heterocycles and are also prone to decarbonylation at high temperatures resulting in generation of acyl(imidoyl)ketenes, bidentate aza- and oxa-dienes, which can react with dienophiles to form skeletally diverse products (angular tricyclic products or heterocyclic ensembles). Based on these features, we have developed an approach to two series of skeletally diverse 4H-1,3-oxazines (tetracyclic alkaloid-like 4H-1,3-oxazines and 5-heteryl-4H-1,3-oxazines) via a hetero-Diels-Alder reaction of 4-acyl-1H-pyrrole-2,3-diones fused at [e]-side with cyanamides. The products of these transformations are of interest for drug discovery, since compounds bearing 4H-1,3-oxazine moiety are extensively studied for inhibitory activities against anticancer targets.

Efficient synthesis of 1,3-naphtoxazine derivatives using reusable magnetic catalyst (GO-Fe3O4-Ti(IV)): anticonvulsant evaluation and computational studies.

A series of 2-aryl/alkyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines (S1-S11) were synthesized with an eco-friendly and recoverable nanocatalyst (GO-Fe3O4-Ti(IV)) as an efficient magnetic composite. The new nanocatalyst was characterized by FT-IR, XRD and, EDS analysis. A conformable procedure, easy to work up and having a short reaction time with high yields are some advantages of this method. The new catalyst is also thermal-stable, reusable and, environment-friendly. The chemical structures of the synthesized 1,3-oxazine compounds were confirmed by comparing their melting points with those reported in literature. Then, the anticonvulsant activity of these compounds was assessed by the intraperitoneal pentylenetetrazole test (ipPTZ). Compounds S10 and S11 displayed considerable activity against chemically-induced seizure tests. The molecular simulation was also done to achieve their binding affinities as γ-aminobutyric acid A (GABA-A) receptor agonists as an assumptive mechanism of their anticonvulsant action. The result of molecular studies represented strongly matched with biological activity. Molecular docking simulation of the potent compound (S10) and diazepam as the positive control was performed and some critical residues like Thr262, Asn265, Met286, Phe289, and Val290 were identified. Based on the anticonvulsant results and also in silico ADME predictions, S11 can be to become a potential drug candidate as an anticonvulsant agent.

Structural investigation of a pyrano-1,3-oxazine derivative and the phenanthridinone core moiety against BRD2 bromodomains.

The BET (bromodomain and extra-terminal) family of proteins recognize the acetylated histone code on chromatin and play important roles in transcriptional co-regulation. BRD2 and BRD4, which belong to the BET family, are promising drug targets for the management of chronic diseases. The discovery of new scaffold molecules, a pyrano-1,3-oxazine derivative (NSC 328111; NS5) and phenanthridinone-based derivatives (L10 and its core moiety L10a), as inhibitors of BRD2 bromodomains BD1 and BD2, respectively, has recently been reported. The compound NS5 has a significant inhibitory effect on BRD2 in glioblastoma. Here, the crystal structure of BRD2 BD2 in complex with NS5, refined to 2.0 Šresolution, is reported. Moreover, as the previously reported crystal structures of the BD1-NS5 complex and the BD2-L10a complex possess moderate electron density corresponding to the respective ligands, the crystal structures of these complexes were re-evaluated using new X-ray data. Together with biochemical studies using wild-type BRD2 BD1 and BD2 and various mutants, it is confirmed that the pyrano-1,3-oxazine and phenanthridinone derivatives are indeed potent inhibitors of BRD2 bromodomains.

Synthesis of new coumarin[1,3]oxazine derivatives of 7-hydroxy-6-isobornyl-4-methylcoumarin and their antioxidant activity.

In this work, we synthesized a series of new 9,10-dihydro-2H,8H-chromeno[8,7e][1,3]oxazine-2-on derivatives which incorporate isobornylcoumarin and 1,3-oxazine moieties. A structure-antioxidant activity relationship was analyzed. A comparative evaluation of their radical scavenging activity, antioxidant and membrane-protective properties was carried out in test with DPPH, as well as on the models of Fe2+ /ascorbate-initiated lipid peroxidation and oxidative hemolysis of mammalian red blood cells. The results suggest that all the obtained coumarin[1,3]oxazine derivatives of 7-hydroxy-6-isobornyl-4-methylcoumarin are capable of exhibiting antioxidant activity in various model systems. Compound 7 with a phenyl fragment, combining high radical scavenging activity and the ability to inhibit Fe2+ /ascorbate-initiated peroxidation of animal lipids in a heterogeneous environment, also proved to be the most effective membrane protector and antioxidant in the model of H2 O2 -induced erythrocyte hemolysis.

1,3-Oxazine-2-one derived dual-targeted molecules against replicating and non-replicating forms of Mycobacterium tuberculosis.

The high mortality rate and increasing prevalence of resistant Mtb are the major concerns for the Tuberculosis (TB) treatment in this century. To curtail the prevalence of resistant Mtb, we have prepared 1,3-oxazine-2-one based dual targeted molecules. Compound 67 and 68 were found to be equally active against replicating and non-replicatiing form of Mtb (MICMABA 3.48 and 2.97 µg/ml; MICLORA 2.94 and 2.15 µg/ml respectively). They had found to suppress the biosynthesis of alfa, methoxy and keto-mycolate completely, as well as inhibit enzymatic activity of MenG (IC50 = 9.11 and 6.25 µg/ml respectively for H37Ra; IC50 = 11.76 and 10.88 µg/ml respectively for M smegmatis).

Novel 1,3-oxazine-tetrazole hybrids as mushroom tyrosinase inhibitors and free radical scavengers: Synthesis, kinetic mechanism, and molecular docking studies.

A variety of 5-(2H-tetrazol-5-yl)-4-thioxo-2-(substituted phenyl)-4,5-dihydro-1,3-oxazin-6-ones (3a-k) have been synthesized from 1,3-oxazine-5-carbonitriles (2a-k). The protocol represents an efficient, facile, and novel route from easily available precursors to unprecedented structures that share 1,3-oxazine and tetrazole motifs of utmost value. All the synthesized compounds (3a-k) were evaluated for their inhibitory potential against mushroom tyrosinase. Results revealed that all examined 1,3-oxazine-tetrazole hybrids exhibited significant tyrosinase inhibitory activity while compound 3d having 2-bromophenyl moiety was the most potent among the series with IC50 value 0.0371 ± 0.0018 µM as compared to the reference kojic acid (IC50  = 16.832 ± 0.73 µM). Inhibitory kinetics showed that compound 3d behaves as a competitive inhibitor. The molecular docking analysis was performed against target protein to investigate the binding mode. Moreover, compounds 3j and 3k displayed superior DPPH radical scavenging activity than other analogues.

Facile Total Synthesis of (+)-Spinoxazine B.

Herein we describe a short total synthesis of (+)-spinoxazine B, which inhibits nitric oxide (NO) production in BV-2 microgrial cells. Spinoxazine B is the first example of a natural alkaloid containing an oxazinone-pyrrolidone nucleus, and it is expected to serve as a novel drug lead compound as well as a drug discovery scaffold.

Synthesis, carbonic anhydrase inhibitory activity and antioxidant activity of some 1,3-oxazine derivatives.

Hit, Lead & Candidate Discovery A series of 1-(6-methyl-2-substituted phenyl-4-thioxo-4H-1,3-oxazin-5-yl)ethanones (3a-n) were synthesized by the reaction of benzoyl isothiocyanates with active methylene compound acetylacetone in the presence of triethyl amine in a one-pot process. The structures of the products were elucidated by elemental analyses, FT-IR, 1 H NMR, 13 C NMR, and mass spectroscopy. These new 1,3-oxazine derivatives were evaluated for their inhibitory activity against carbonic anhydrase II. Results for in vitro assay revealed that compound 3b having 4-methoxy phenyl moiety was the most potent inhibitor with IC50 value of 0.144 ± 0.008 µM. It exhibited higher enzyme inhibitory activity as compared to the standard acetazolamide (IC50 = 0.997 ± 0.061 µM). The compounds 3c, 3h, and 3n also displayed superior inhibitory activities compared to the rest of the synthesized oxazine derivatives. The radical scavenging activity of oxazine derivatives was also performed and it was found that compounds showed moderate antioxidant activity. Lipinski rule confirmed the therapeutic potential of the synthesized compounds. Molecular docking studies were also performed to further understand the binding affinity of these compounds with PDBID 1V9E which confirmed that the synthesized derivatives bind in the active binding site of the target protein. Based upon our results, it is proposed that compound 3b may serve as a lead structure to design more potent carbonic anhydrase inhibitors.

Scaffold Hopping Strategy for the Design, Synthesis and Biological Activity Evaluation of Novel Hexacyclic Scutellarein Derivatives with a 1,3-Oxazine Ring Fused at A-ring.

BACKGROUND: Discovery of novel agents with anticoagulant and antioxidant activity is very important to treat cerebrovascular disease. Lead compound LR3d discovered in our laboratory exhibited stronger anticoagulant ability and good antioxidant activity, compared with scutellarein (2), which is the major in vivo active metabolite of the natural product scutellarin (1). OBJECTIVE: Design and synthesis novel scutellarein derivatives with improved anticoagulant and antioxidant activity. METHODS: By utilizing a scaffold hopping strategy on LR3d, we describe the design and synthesis of a series of novel hexacyclic scutellarein derivatives 4 with a 1,3-oxazine ring fused at positions 7 and 8 in A ring. The thrombin inhibitory activities of all these new compounds were studied by the analysis of thrombin time (TT), activated partial thromboplastin time (APTT), prothrombin time (PT) and fibrinogen (FIB). The antioxidant abilities of these analogs were evaluated by using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) method through 1,1- diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) assay. RESULTS: Nine new hexacyclic scutellarein derivatives with a 1,3-oxazine ring fused at A-ring were synthesized, the results of the biological activity evaluation showed that compound 4e exhibited stronger anticoagulant and antioxidant ability compared to LR3d. CONCLUSION: 4e could be used for further development to treat ischemic cerebrovascular disease.

Sonochemical synthesis of novel pyrano[3,4-e][1,3]oxazines: A green protocol.

The atom-efficient and green protocol for formation of pyrano[3,4-e][1,3]oxazines utilizing dimethyl carbonate under ultrasound irradiation in a presence of KF/basic alumina was reported. We provide a novel series of pyrano[3,4-e][1,3]oxazine derivatives interesting for biological screening tests. In general, it was found that ultrasound irradiations enable the reactions to occur which could not be carried out under silent conditions. These remarkable effects appeared in sonicated reactions can be reasonably interpreted in terms of acoustic cavitation phenomenon. Structures of the products were established on analytical and spectral data. This protocol offers several advantages attain many principles of green chemistry including, save energy, atom economy, clean reactions, inexpensive green reagent and use catalysts rather than stoichiometric reagents.

Design, synthesis and SARs of novel salicylanilides as potent inhibitors of RANKL-induced osteoclastogenesis and bone resorption.

Inhibiting osteoclastogenesis is a promising therapeutic target for treating osteoclast-related diseases. Herein, we synthesized a series of modified salicylanilides and their corresponding 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione and 10-phenyldibenzo[b,f][1,4]oxazepin-11(10H)-one derivatives, and investigated the effects of such compounds on RANKL-induced osteoclast formation. Among them, a salicylanilide derivative (A04) and its 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione derivative (B04) markedly suppressed RANKL-induced osteoclast differentiation and showed no significant cytotoxic effects at doses higher than that required to inhibit osteoclast formation. Both compounds reduced osteoclast formation and bone resorptive activity of osteoclasts in a dose-dependent manner. Further, the anti-osteoclastogenic effects of A04 and B04 may operate through reducing the RANKL-induced nuclear translocation of NFATc1. Accordingly, we present the potent anti-osteoclastogenic compounds A04 and B04 as promising candidates for further optimization as anti-resorptive agents.

Synthesis and anti-tubercular activity of 2-nitroimidazooxazines with modification at the C-7 position as PA-824 analogs.

Tuberculosis (TB) is a major global health problem, and new drug targets and scaffolds need to be identified to combat the emergence of drug resistant TB. The nitroimidazooxazine PA-824 represents a new class of bio-reductive drug to treat TB. In this study we report a 2-nitroimidazooxazine derivative with modification at the C-7 position that exhibited better activity than PA-824 against Mycobacterium tuberculosis (Mtb) H37Rv strain in vitro. From 7a as a key intermediate, we functionalized with benzyl ether (8), phenyl ether (9), benzyl carbonate (10) and benzyl carbamate (11). Among the 23 compounds produced, 8a-R (MIC=0.078 µM) with trifluoromethoxy benzyl group was 5-fold more potent than PA-824 (MIC=0.390 µM) in the in vitro assays against the wild-type Mtb, and the phenyl ether compound 9g-R (MIC=0.050 µM) exhibited the most potent antimycobacterial activity.

Synthesis of antiproliferative 13α-d-homoestrones via Lewis acid-promoted one-pot Prins-Ritter reactions of d-secosteroidal δ-alkenyl-aldehydes.

A simple one-pot Prins-Ritter route was developed for the synthesis of 16-acylamino-17a-hydroxy-d-homoestrone 3-benzyl and 3-methyl ethers in the 13α-estrone series. The d-secosteroidal δ-alkenyl-aldehydes were allowed to react with different nitriles in the presence of BF3·OEt2 as a Lewis acid catalyst. Prins cyclizations afforded 17a-hydroxy-16-carbenium ions, which underwent Ritter reactions with nitriles, leading to 16α- or 16ß-acylamino derivatives. A side-product in which a dihydro-1,3-oxazine was bridged to six-membered ring D at positions 16α,17aα was formed in each reaction. The antiproliferative properties of the novel 13α-d-homosteroids were determined on a panel of human adherent cancer cell lines (HeLa, MCF-7, T47D, MDA-MB-231, MDA-MB-361, A2780 and A431) by means of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays. Some compounds proved to be more effective (with submicromolar IC50 values) than the reference agent cisplatin. One of the most potent compounds substantially increased the rate of tubulin polymerization. Cell cycle analyses by flow cytometry indicated a concentration-dependent accumulation of the G2/M cell population.