Mechanistic insights into the inhibitory effect of theaflavins on virulence factors production in Streptococcus mutans.

Streptococcus mutans is the primary etiological agent associated with cariogenic process. The present study aimed to investigate the antibacterial and anti-virulence activities of theaflavins (TFs) to Streptococcus mutans UA159 as well as the underlying mechanisms. The results showed that TFs were capable of suppressing the acid production, cell adherence, water-insoluble exopolysaccharides production, and biofilm formation by S. mutans UA159 with a dosage-dependent manner while without influencing the cell growth. By a genome-wide transcriptome analysis (RNA-seq), we found that TFs attenuated the biofilm formation of S. mutans UA159 by inhibiting glucosyltransferases activity and the production of glucan-binding proteins (GbpB and GbpC) instead of directly blocking the expression of genes coding for glucosyltransferases. Further, TFs inhibited the expression of genes implicated in peptidoglycan synthesis, glycolysis, lipid synthesis, two-component system, signaling peptide transport (comA), oxidative stress response, and DNA replication and repair, suggesting that TFs suppressed the virulence factors of S. mutans UA159 by affecting the signal transduction and cell envelope stability, and weakening the ability of cells on oxidative stress resistance. In addition, an upregulated expression of the genes involved in protein biosynthesis, amino acid metabolism, and transport system upon TFs treatment indicated that cells increase the protein synthesis and nutrients uptake as one self-protective mechanism to cope with stress caused by TFs. The results of this study increase our current understanding of the anti-virulence activity of TFs on S. mutans and provide clues for the use of TFs in the prevention of dental caries.

Tooth brushing using toothpaste containing theaflavins reduces the oral pathogenic bacteria in healthy adults.

Theaflavins (TFs) are the main bioactive component in black tea. At present, little effort has been done to evaluate the influence of TFs when included in the toothpaste on the diversity of oral microbiota. In this study, eighty samples collected from the saliva and supragingival plaque of 20 healthy adults using toothpaste with the absence or presence of TFs for a period of 4 weeks were used for the oral microbiome analysis by 16S rRNA gene sequencing. Alpha and beta diversity analysis showed that tooth brushing using the toothpaste with TFs significantly increased the microbial abundance in the saliva samples, and altered the oral microbiota obtained from the saliva and supragingival plaque. The linear discriminant analysis revealed that the use of toothpaste with TFs significantly reduced the abundance of oral pathogens (e.g., Prevotella, Selenomonas, and Atopobium) while increased the abundance of oral-health associated bacteria (e.g., Streptococcus and Rothia). In addition, using toothpaste with TFs reduced the functional pathways abundance relevance to the extracellular polymeric substance (EPS) synthesis while enriched the functions in transporters, ABC transporters, two-component system, and amino acid metabolism. Collectively, our results provide evidence for the application of toothpaste containing TFs as a promising oral care product. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02699-7.

Self-assembly behavior of tail-to-tail superstructure formed by mono-6-O-(4-carbamoylmethoxy-benzoyl)-ß-cyclodextrin in solution and the solid state.

A novel mono-modified ß-cyclodextrin (ß-CD) consisting of 4-carbamoylmethoxy-benzoyl unit at the primary side was synthesized and its self-assembly behavior was determined by X-ray crystallography and NMR spectroscopy. The crystal structure shows a 'Yin-Yang'-like packing mode, in which the modified ß-CD exhibits a channel superstructure formed by a tail-to-tail dimer as the repeating motif with the substituted group embedded within the hydrophobic cavity of the facing ß-CD. The geometry of the substituted group is determined by the inclusion of the cavity and is further stabilized by two intermolecular hydrogen bonds between the carbonyl O atom and phenyl group. Furthermore, NMR ROESY investigation indicates that the self-assembly behavior of the substituted group within the ß-CD cavity is retained in aqueous solution, and the effective binding constant Ka was calculated to be 1330 M(-1) by means of (1)H NMR titration according to iterative determination.

(E)-N'-[3-(4-Chloro-benzo-yloxy)benzyl-idene]pyridine-4-carbohydrazide acetic acid monosolvate monohydrate.

In the Schiff base mol-ecule of the title compound, C(20)H(14)ClN(3)O(3)·CH(3)COOH·H(2)O, the central benzene ring makes dihedral angles of 36.26 (7) and 27.59 (8)°, respectively, with the terminal chloro-phenyl and pyridine rings. In the crystal, the three components are linked by O-H⋯O, N-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds into a double-tape structure along the a axis.

The binding behavior of a helical column supramolecule formed by 6-deoxy-6-(2-pyrimidinethio)-ß-cyclodextrin in both solution and the solid state.

The mono-modified ß-cyclodextrin, 6-deoxy-6-(2-pyrimidinethio)-ß-cyclodextrin, was synthesized and characterized. Its self-assembly behavior was measured in both solution and the solid state. The crystal structure shows that the pyrimidine group penetrates deeply into the hydrophobic cavity of the adjacent ß-cyclodextrin from the second side, and the molecules are stacked along the twofold screw axis to form a head-to-tail helical columnar superstructure. Furthermore, the effective binding constant K and the aggregation number n were calculated to be 354M(-1) and 2.1, respectively, by means of (1)H NMR spectroscopy titration. The results indicate that the intramolecular/intermolecular interactions are a critical factor in determining the self-assembly behavior.

(E)-N'-[5-chloro-3-methoxy-2-(4-methylphenylsulfonyloxy)benzylidene]isonicotinohydrazide acetic acid solvate: hydrogen-bonded network of alternating R4(4)(42), R5(5)(33) and R6(6)(40) rings.

In the title compound, C21H18ClN3O5S x C2H4O2, a combination of O-H...O, N-H...O, C-H...O and C-H...N hydrogen bonds links the components into a complex network containing alternating R4(4)(42), R5(5)(33) and R6(6)(40) rings.

An investigation of the inclusion complex of beta-cyclodextrin with p-nitrobenzoic acid in the solid state.

The weak inclusion complex of cyclomaltoheptaose (beta-cyclodextrin, betaCD) with p-nitrobenzoic acid was investigated in the solid state. Crystallography shows that two betaCD molecules co-crystallize with two p-nitrobenzoic acids and 28.5 water molecules [2(C(42)H(70)O(35))x2(C(7)H(5)NO(4))x28.5H(2)O] in the triclinic system.

Encapsulation of quinine by beta-cyclodextrin: excellent model for mimicking enzyme-substrate interactions.

An inclusion complex formed by beta-cyclodextrin and quinine has been investigated in solution and in the solid state, in which the quinoline ring and the aliphatic ring locate in different hydrophobic cavities, respectively. The study on the inclusion geometry and weak interactions shows that the difference in conformation for this complex is a result of three main packing arrangement considerations, which can provide an ideal model mimicking enzyme-substrate interactions.

The molecular crystal structure and self-assembly behavior of 6(I)-O-(3-nitrophenyl)cyclomaltoheptaose.

The mono-modified beta-cyclodextrin derivative, 6(I)-O-(3-nitrophenyl)cyclomaltoheptaose{mono[6-O-(3-nitrophenyl)]-beta-cyclodextrin} was synthesized, and its crystal structure was determined by single-crystal X-ray analysis. The crystal structure suggests that the 3-nitrophenyl substituent group is inserted into the adjacent beta-cyclodextrin cavity from the secondary hydroxyl side, and the molecules are stacked along the twofold screw axis to form an infinite one-dimensional polymeric chain.

Binding ability and self-assembly behavior of linear polymeric supramolecules formed by modified beta-cyclodextrin.

[structure: see text] The binding ability and self-assembly behavior of molecular interpenetration by newly synthesized mono[6-O-(4-formyl-phenyl)-beta-cyclodextrin has been investigated, revealing the formation mechanism of modified cyclodextrin from solution aggregation to solid linear polymeric supramolecules.