1,3-<i>syn</i>-Diaxial Repulsion of Typical Protecting Groups Used in Carbohydrate Chemistry in 3‑<i>O</i>‑Substituted Derivatives of Isopropyl d‑Idopyranosides

The strength of 1,3-<i>syn</i>-diaxial repulsion was evaluated for main types of protecting groups (alkyl, silyl, and acyl) usually used in carbohydrate chemistry. As molecular probes for this study, derivatives of isopropyl 2-<i>O</i>-benzyl-4,6-<i>O</i>-benzylidene-α-d-idopyranoside bearing allyl, acetyl, and <i>tert</i>-butyldiphenylsilyl (TBDPS) protecting groups at O-3 were prepared from <i>p</i>-methoxyphenyl d-galactopyranoside. The equilibrium between ^<i>O</i><i>S</i>₂ and ⁴<i>C</i>₁ conformations in these compounds was investigated using ³<i>J</i>_H,H and ³<i>J</i>_C,H coupling constants that were determined from 1D ¹H NMR and 2D <i>J</i>-resolved HMBC spectra in various solvents. The analysis of the corresponding coupling constants calculated using DFT/B3LYP/pcJ-1 approximation applied to conformations optimized at DFT/B3LYP/6-311++G** level supported the investigation. Proportions of conformers in the equilibrium revealed the highest repulsion between the 3-allyloxy group and the isopropoxy aglycon and its dependence on the solvent polarity. Differences in the conformational behavior of 3-<i>O</i>-allyl and 3-<i>O</i>-acetyl-α-d-idopyranoside derivatives complied with the notion that higher electron density on O-3 increased 1,3-<i>syn</i>-diaxial repulsion. 3-<i>O</i>-TBDPS derivative existed mainly in ⁴<i>C</i>₁ conformation. The attenuation of the 1,3-<i>syn</i>-diaxial repulsive interaction indicates that TBDPS has stereoelectronic properties that may have significance in context of fixing unnatural pyranoside conformation with the help of silyl groups but have been disregarded until now

Table_3_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.docx

The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p

Table_2_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.docx

The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p

Table_1_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.DOCX

The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p

Data_Sheet_1_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.DOCX

The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p