New Antibacterial and Antioxidant Chitin Derivatives: Ultrasonic Preparation and Biological Effects.

This work focuses on the first use of ultrasonic phenol-ene coupling as a polymer analogous transformation. The ultrasonic reaction was introduced into chitin chemistry, resulting in the fast and convenient preparation of new water-soluble cationic chitin derivatives. Since water-soluble derivatives of fully deacetylated chitin are poorly described in the literature, the synthesis of each new type of these derivatives is a significant event in polysaccharide chemistry. Polycations, or cationic polymers, are of particular interest as antibacterial agents. Consequently, the resulting polymers were tested for their antibacterial activity and toxicity. We found that the highly substituted polymer of medium molecular weight exhibited the most pronounced in vitro antibacterial effect. We prepared nanoparticles using the ionic gelation technique. The most effective in vitro antibacterial chitin-based systems were tested in vivo in rats. These tests demonstrated outstanding antibacterial effects combined with an absence of toxicity. Additionally, we found that the resulting polymers, unlike their nanoparticle counterparts, also exhibited strong antioxidant effects. In summary, we demonstrated the effectiveness of ultrasound in polymer chemistry and highlighted the importance of the sonochemical approach in the chemical modification of polysaccharides. This approach enables the synthesis of derivatives with improved physicochemical and biological properties.

Crystal structure of [1,3-bis-(2,4,6-tri-methyl-phen-yl)imidazolidin-2-yl-idene]di-chlorido-(2-{[(2-methoxyeth-yl)(meth-yl)amino]-meth-yl}benzyl-idene)ruth-en-ium.

The title compound, [RuCl2(C33H43N3O)], is an example of a new generation of N,N-dialkyl ruthenium catalysts with an N-Ru coordination bond as part of a six-membered chelate ring. The Ru atom has an Addison τ parameter of 0.244, which indicates a geometry inter-mediate between square-based pyramidal and trigonal-bipyramidal. The complex shows the usual trans arrangement of the two chlorides, with Ru-Cl bond lengths of 2.3515 (8) and 2.379 (7) Å, and a Cl-Ru-Cl angle of 158.02 (3)°. One of the chlorine atoms and the atoms of the 2-meth-oxy-N-methyl-N-[(2-methyl-phen-yl)meth-yl]ethane-1-amine group of the title complex display disorder over two positions in a 0.889 (2): 0.111 (2) ratio.

Synthesis, crystal structure and Hirshfeld surface analysis of 5-[2-(di-cyano-methyl-idene)hydrazin-1-yl]-2,4,6-tri-iodo-isophthalic acid ethanol monosolvate.

The title compound, C11H3I3N4O4·C2H6O, crystallizes in the triclinic P space group with one independent mol-ecule and one ethanol solvent mol-ecule in the asymmetric unit. The benzene ring and the methyl-carbonohydrazonoyl dicyanide group of the main mol-ecule makes a dihedral angle of 57.91 (16)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link pairs of mol-ecules, forming dimers with R 2 2(14) motifs. These dimers are connected by O-H⋯O hydrogen bonds into chains along the a-axis direction, forming R 2 2(16) ring motifs. Further O-H⋯O inter-actions involving the ethanol solvent mol-ecule connect the chains into a three-dimensional network. In addition, C-I⋯π inter-actions are observed. The inter-molecular inter-actions in the crystal structure were qu-anti-fied and analysed using Hirshfeld surface analysis.

Crystal structure and Hirshfeld surface analysis of 4-cyano-N-[(4-cyano-phen-yl)sulfon-yl]-N-[2-(5-methyl-furan-2-yl)phen-yl]benzene-sulfonamide.

In the title compound, C25H17N3O5S2, intra-molecular π-π inter-actions [centroid-to-centroid distance = 3.5640 (9) Å] are observed between the furan and benzene rings of the 4-cyano-phenyl group. In the crystal, mol-ecules are connected via C-H⋯O and C-H⋯N hydrogen bonds, forming layers parallel to the (100) plane. These layers are inter-connected by C-H⋯π inter-actions and weak van der Waals inter-actions. Hirshfeld surface analysis indicates that H⋯H (30.2%), N⋯H/H⋯N (22.3%), C⋯H/H⋯C (17.9%) and O⋯H/H⋯O (15.4%) inter-actions make the most significant contributions to the crystal packing.

Crystal structures and Hirshfeld surface analyses of N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol tribromide (1/1), N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol di-bromido-iodate (1/1) and N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol di-chlorido-iodate (1/1).

In the title compounds, N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol tribromide (1/1), C4H9NO·C4H10NO+·Br3 - or [(C4H9NO)·(C4H10NO)](Br3), (I), N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol di-bromido-iodate (1/1), C4H9NO·C4H10NO+·Br2I- or [(C4H9NO)·(C4H10NO)](Br2I), (II), and N,N-di-methyl-acetamide-1-(dimethyl-λ4-aza-nyl-idene)ethan-1-ol di-chlorido-iodate (1/1), C4H9NO·C4H10NO+·Cl2I- or [(C4H9NO)·(C4H10NO)]·(Cl2I), (III), all the anions are almost linear in geometry and all the cations, except for the methyl H atoms, are essentially planar. In the crystal structure of (I), the cations are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif. These dimers also exhibit O-H⋯O hydrogen bonding. Dimerized cation pairs and anions are arranged in columns along the a axis. In the crystal of (II), the cations are linked by pairs of O-H⋯O and C-H⋯O hydrogen bonds, forming an R 4 4(14) ring motif. These groups of cations and the anions form individual columns along the a axis and jointly reside in planes roughly parallel to (011). In the crystal of (III), cations and anions also form columns parallel to the a axis, resulting in layers parallel to the (020) plane. Furthermore, the crystal structures of (I), (II) and (III) are consolidated by strong halogen (Br and/or I and/or Cl)⋯H and weak van der Waals inter-actions. In addition to the structural evaluation, a Hirshfeld surface analysis was carried out.

Crystal structure and Hirshfeld surface analysis of bis-{(Z)-N'-[(E)-(furan-2-yl)methyl-idene]carbamo-hydrazono-thio-ato}nickel(II) methanol disolvate.

In the title complex, [Ni(C6H6N3OS)2]·2CH3OH, the NiII atom is coordinated by the S and N atoms of two N'-[(Z)-(furan-2-yl)methyl-idene]carbamohydrazono-thioic acid ligands in a distorted square-planar geometry. The two mutual ligands bound to NiII are also connected by C-H⋯S inter-actions, while the H atoms of the NH2 group of the ligands form R 4 4(8) motifs with the O atoms of the solvent ethyl alcohol mol-ecules. At the same time, the OH groups of the solvent ethyl alcohol mol-ecules form parallel layers to the (011) plane by the O-H⋯N inter-actions with the ligand N atom that is not bonded to the NiII atom.. The layers are connected by van der Waals inter-actions. A Hirshfeld surface analysis indicates that the most important contacts are H⋯H (37.7%), C⋯H/H⋯C (14.6%), O⋯H/H⋯O (11.5%) and S⋯H/H⋯S (10.6%).

Crystal structure and Hirshfeld surface analysis of N-[2-(5-methyl-furan-2-yl)phen-yl]-3-nitro-N-[(3-nitro-phen-yl)sulfon-yl]benzene-sulfonamide.

In the title compound, C23H17N3O9S2, C-H⋯O hydrogen bonds link adjacent mol-ecules in a three-dimensional network, while π-π stacking inter-actions, with centroid-centroid distances of 3.8745 (9) Å, between the furan and an arene ring of one of the two (3-nitro-phen-yl)sulfonyl groups, result in chains parallel to the a axis. The Hirshfeld surface analysis indicates that O⋯H/H⋯O (40.1%), H⋯H (27.5%) and C⋯H/H⋯C (12.4%) inter-actions are the most significant contributors to the crystal packing.

Crystal structure and Hirshfeld surface analysis of 10-hy-droxy-2-(4-meth-oxy-phen-yl)-3-oxo-2,3,3a,4,10,10a-hexa-hydro-1H-9-thia-2-aza-cyclo-penta-[b]fluorene-4-carb-oxy-lic acid dimethyl sulfoxide-d6 monosolvate.

In the title compound, C22H19NO5S·C2D6OS, the central six-membered ring has a slightly distorted boat conformation, while the fused pyrrolidine ring adopts an envelope conformation. These conformations are stabilized by O-H⋯O hydrogen bonds between the main compound and solvent mol-ecules. In addition, intra-molecular C-H⋯O hydrogen bonds in the main mol-ecule form two S(6) rings. Mol-ecules are connected by pairs of inter-molecular C-H⋯O hydrogen bonds, forming dimers with a R 2 2(8) motif. These dimers form a three-dimensional network through O-H⋯O, O-H⋯S and C-H⋯O hydrogen bonds with each other directly and through solvent mol-ecules. In addition, weak π-π stacking inter-actions [centroid-to-centroid distances = 3.9937 (10) and 3.9936 (10) Å, slippages of 2.034 and 1.681 Å] are observed. The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 41.7%, O⋯H/H⋯O 27.7%, C⋯H/H⋯C 17.0%, and S⋯H/H⋯S 7.5%.

Crystal structure and Hirshfeld surface analysis of (3aSR,6RS,6aSR,7RS,11bSR,11cRS)-2,2-dibenzyl-2,3,6a,11c-tetra-hydro-1H,6H,7H-3a,6:7,11b-di-epoxy-dibenzo[de,h]isoquinolin-2-ium tri-fluoro-methane-sulfonate.

In the cation of the title salt, C30H28NO2 +·CF3O3S-, the four tetra-hydro-furan rings adopt envelope conformations. In the crystal, pairs of cations are linked by dimeric C-H⋯O hydrogen bonds, forming two R 2 2(6) ring motifs parallel to the (001) plane. The cations and anions are connected by further C-H⋯O hydrogen bonds, forming a three-dimensional network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (47.6%), C⋯H/H⋯C (20.6%), O⋯H/H⋯O (18.0%) and F⋯H/H⋯F (9.9%) inter-actions.

Soluble Human Angiotensin- Converting Enzyme 2 as a Potential Therapeutic Tool for COVID-19 is Produced at High Levels In Nicotiana benthamiana Plant With Potent Anti-SARS-CoV-2 Activity.

The coronavirus disease 2019 (COVID-19) pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread to more than 222 countries and has put global public health at high risk. The world urgently needs a safe, cost-effective SARS-CoV-2 vaccine as well as therapeutic and antiviral drugs to combat COVID-19. Angiotensin-converting enzyme 2 (ACE2), as a key receptor for SARS-CoV-2 infections, has been proposed as a potential therapeutic tool in patients with COVID-19. In this study, we report a high-level production (about ∼0.75 g/kg leaf biomass) of human soluble (truncated) ACE2 in the Nicotiana benthamiana plant. After the Ni-NTA single-step, the purification yields of recombinant plant produced ACE2 protein in glycosylated and deglycosylated forms calculated as ∼0.4 and 0.5 g/kg leaf biomass, respectively. The plant produced recombinant human soluble ACE2s successfully bind to the SARS-CoV-2 spike protein. Importantly, both deglycosylated and glycosylated forms of ACE2 are stable at increased temperatures for extended periods of time and demonstrated strong anti-SARS-CoV-2 activities in vitro. The half maximal inhibitory concentration (IC50) values of glycosylated ACE2 (gACE2) and deglycosylated ACE2 (dACE2) were ∼1.0 and 8.48 µg/ml, respectively, for the pre-entry infection, when incubated with 100TCID50 of SARS-CoV-2. Therefore, plant produced soluble ACE2s are promising cost-effective and safe candidates as a potential therapeutic tool in the treatment of patients with COVID-19.

Crystal structure and Hirshfeld surface analysis of 2,2,2-tri-chloro-N,N-bis-{[(1RS,4SR)-1,4-di-hydro-1,4-ep-oxy-naphthalen-1-yl]meth-yl}acetamide.

In the title compound, C24H18Cl3NO3, the tetra-hydro-furan rings adopt envelope conformations. In the crystal, C-H⋯O hydrogen bonds connect mol-ecules, generating layers parallel to the (001) plane. These layers are connected along the c-axis direction by C-H⋯π inter-actions. The packing is further stabilized by inter-layer van der Waals and inter-halogen inter-actions. The most important contributions to the surface contacts are from H⋯H (36.8%), Cl⋯H/H⋯Cl (26.6%), C⋯H/H⋯C (18.8%) and O⋯H/H⋯O (11.3%) inter-actions, as concluded from a Hirshfeld surface analysis.

Crystal structure and Hirshfeld surface analysis of dimethyl 5-[2-(2,4,6-trioxo-1,3-diazinan-5-yl-idene)hydrazin-1-yl]benzene-1,3-di-carboxyl-ate 0.224-hydrate.

In the crystal, the whole mol-ecule of the title compound, C14H12N4O7·0.224H2O, is nearly planar with a maximum deviation from the least-squares plane of 0.352 (1) Å. The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond, generating an S(6) ring motif. In the crystal, mol-ecules are linked by centrosymmetric pairs of N-H⋯O hydrogen bonds, forming ribbons along the c-axis direction. These ribbons connected by van der Waals contacts, forming sheets parallel to the ac plane. There are also inter-molecular van der Waals contacts and and C-H⋯π inter-actions between the sheets. A Hirshfeld surface analysis indicates that the most prevalent inter-actions are O⋯H/H⋯O (41.2%), H⋯H (19.2%), C⋯H/H⋯C (12.2%) and C⋯O/ O⋯C (8.4%).

Crystal structure and Hirshfeld surface analysis of 5,7-diphenyl-1,2,3,5,6,7-hexa-hydro-imidazo[1,2-a]pyridine-6,6,8-tricarbo-nitrile methanol mono-solvate.

In the title compound, C22H17N5·CH4O, the imidazolidine ring of the 1,2,3,5,6,7-hexa-hydro-imidazo[1,2-a]pyridine ring system is a twisted envelope, while the 1,2,3,4-tetra-hydro-pyridine ring adopts a twisted boat conformation. In the crystal, pairs of mol-ecules are linked by O-H⋯N and N-H⋯O hydrogen bonds via two methanol mol-ecules, forming a centrosymmetric R 4 4(16) ring motif. These motifs are connected to each other by C-H⋯N hydrogen bonds and form columns along the a axis. The columns form a stable mol-ecular packing, being connected to each other by van der Waals inter-actions. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (43.8%), N⋯H/H⋯N (31.7%) and C⋯H/H⋯C (18.4%) contacts.

Crystal structure and Hirshfeld surface analysis of (E)-3-[(4-methyl-benzyl-idene)amino]-5-phenylthiazolidin-2-iminium bromide N,N-di-methyl-formamide monosolvate.

In the cation of the title salt, C17H18N3S+·Br-·C3H7NO, the central thia-zolidine ring adopts an envelope conformation with puckering parameters Q(2) = 0.310 (3) Šand φ(2) = 42.2 (6)°. In the crystal, each cation is connected to two anions by N-H⋯ Br hydrogen bonds, forming an R 4 2(8) motif parallel to the (10) plane. van der Waals inter-actions between the cations, anions and N,N-di-methyl-formamide mol-ecules further stabilize the crystal structure in three dimensions. The most important contributions to the surface contacts are from H⋯H (55.6%), C⋯H/H⋯C (17.9%) and Br⋯H/H⋯Br (7.0%) inter-actions, as concluded from a Hirshfeld analysis.

Crystal structure and Hirshfeld surface analysis of (E)-1-(2,6-di-chloro-phen-yl)-2-(2-nitro-benzyl-idene)hydrazine.

In the title compound, C13H9Cl2N3O2, the 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring form a dihedral angle of 21.16 (14)°. In the crystal, face-to-face π-π stacking inter-actions occur along the a-axis direction between the centroids of the 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring. Furthermore, these mol-ecules show intra-molecular N-H⋯Cl and C-H⋯O contacts and are linked by inter-molecular N-H⋯O and C-H⋯Cl hydrogen bonds, forming pairs of hydrogen-bonded mol-ecular layers parallel to (20). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (23.0%), O⋯H/H⋯O (20.1%), Cl⋯H/H⋯Cl (19.0%), C⋯C (11.2%) and H⋯C/C⋯H (8.0%) inter-actions.

Crystal structure and Hirshfeld surface analysis of (E)-4-{2,2-di-chloro-1-[(3,5-di-methyl-phen-yl)diazen-yl]ethen-yl}-N,N-di-methyl-aniline.

In the title compound, C18H19Cl2N3, the planes of the benzene rings subtend a dihedral angle of 77.07 (10)°. In the crystal, mol-ecules are associated into inversion dimers via short Cl⋯Cl contacts [3.3763 (9) Å]. A Hirshfeld surface analysis indicates that the most important contact percentages for the different types of inter-actions are H⋯H (43.9%), Cl⋯H/H⋯Cl (22.9%), C⋯H/H⋯C (20.8%) and N⋯H/H⋯N (8.0%).

(E)-1-(2,6-Di-chloro-phen-yl)-2-(3-nitro-benzyl-idene)hydrazine: crystal structure and Hirshfeld surface analysis.

The stabilized conformation of the title compound, C13H9Cl2N3O2, is similar to that of the isomeric compound (E)-1-(2,6-di-chloro-phen-yl)-2-(2-nitro-benzyl-idene)hydrazine. The 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring form a dihedral angle of 26.25 (16)°. In the crystal, face-to-face π-π stacking inter-actions along the a-axis direction occur between the centroids of the 2,6-di-chloro-phenyl ring and the nitro-substituted benzene ring. The mol-ecules are further linked by C-H⋯O contacts and N-H⋯O and C-H⋯Cl hydrogen bonds, forming pairs of hydrogen-bonded mol-ecular layers parallel to (100). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (22.1%), Cl⋯H/H⋯Cl (20.5%), O⋯H/H⋯O (19.7%), C⋯C (11.1%) and C⋯H/H⋯C (8.3%) inter-actions.

Crystal structure and Hirshfeld surface analysis of phen-yl(5,7,8a-triphenyl-1,2,3,7,8,8a-hexa-hydro-imidazo[1,2-a]pyridin-6-yl)methanone with an unknown solvent.

In the title compound, C32H28N2O, the imidazolidine and pyridine rings of the central hexa-hydro-imidazo[1,2-a]pyridine ring system adopt envelope and screw-boat conformations, respectively. The mol-ecule exhibits two weak intra-molecular π-π inter-actions between phenyl rings. In the crystal, mol-ecules are linked via pairs of C-H⋯ O hydrogen bonds, forming inversion dimers. The dimers are further linked by pairs of C-H⋯π inter-actions, forming infinite chains along the c-axis direction. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (73.4%), C⋯H/H⋯C (18.8%) and O⋯H/H⋯O (5.7%) contacts. The contribution of some disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. The solvent contribution was not included in the reported mol-ecular weight and density.

Crystal structure and Hirshfeld surface analysis of 4-{2,2-di-chloro-1-[(E)-2-(4-methyl-phen-yl)diazen-1-yl]ethen-yl}-N,N-di-methyl-aniline.

In the tile compound, C17H17Cl2N3, the dihedral angle between the benzene rings is 62.73 (9)°. In the crystal, there are no classical hydrogen bonds. Mol-ecules are linked by a pair of C-Cl⋯π inter-actions, forming an inversion dimer. A short inter-molecular HL⋯HL contact [Cl⋯Cl = 3.2555 (9) Å] links the dimers, forming a ribbon along the c-axis direction. The Hirshfeld surface analysis and two-dimensional fingerprint plots reveal that the most important contributions for the crystal packing are from H⋯H (45.4%), Cl⋯H/H⋯Cl (21.0%) and C⋯H/H⋯C (19.0%) contacts.

Crystal structure and Hirshfeld surface analysis of (E)-3-(benzyl-idene-amino)-5-phenyl-thia-zolidin-2-iminium bromide.

The central thia-zolidine ring of the title salt, C16H16N3S+·Br-, adopts an envelope conformation, with the C atom bearing the phenyl ring as the flap atom. In the crystal, the cations and anions are linked by N-H⋯Br hydrogen bonds, forming chains parallel to the b-axis direction. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (46.4%), C⋯H/H⋯C (18.6%) and H⋯Br/Br⋯H (17.5%) inter-actions.