Oligolignans in the wood of Picea obovata Ledeb.
We studied the chemical composition of the phenolic complex and the structure of oligomeric lignans in Siberian spruce (Picea obovata Ledeb.). We used the wood of Siberian spruce collected near the city of Irkutsk. The extractives were isolated from ground wood (particle size: 10–15 mm; humidity: 5.9%) by three-stage acetone extraction. The extract was separated by consecutive treatment with the solvents with increasing polarity: hexane, ethyl acetate and n-butanol. The main amount of phenolic compounds (lignans) was concentrated in the ethyl acetate fraction and it was 0.7% in absolutely dry wood (adw).The ethyl acetate fraction of spruce wood extract was separated by silica gel column; a chloroform-acetone mixture was used as the eluent (the concentration of acetone in the mixture was increased from 0 to 100%). Monomeric lignans (~60–65% of the ethyl acetate fraction of spruce wood extract), oligomeric lignans (~20–25%), and polymer lignans (~12–15%) were isolated.We also obtained 13C nuclear magnetic resonance (NMR) spectra for the main monomeric, oligomeric and polymeric lignan compounds of phenolic complexes. It was found that oligomeric and polymeric fractions contain monomeric lignan units with the butyrolactone cycle, primarily, the fragments with hydroxymatairesinol structure. Oligomeric lignans contain the fragments with a pinoresinol and lariciresinol structure. All the monomeric structural units are characterized by the guaiacyl substitution type of the aromatic cycles.A preliminary study has been performed on the antiviral and antioxidant activity of the ethyl acetate fraction of acetone extract of Siberian spruce wood. It was found that the lignan complex is active against Coxsackie B4 virus in cell culture and in the pancreatitis model in white mice, reducing the activity of enteroviruses in the cell culture approximately 100 times. The antioxidant activity rate of polyphenol complex of Siberian spruce wood is comparable to that of a known antioxidant dihydroquercetin.
Phenolic Compounds of Picea obovata Ledeb. Bark
Chemical composition of a phenolic complex of the Siberian spruce bark (Picea obovata Ledeb.) and a structure of oligomeric phenolic compounds composing the bark were studied. The samples of the spruce bark were collected in the vicinity of Lake Baikal in September 2015. Extractive substances were recovered from the crushed bark by extraction with ethyl acetate at the boiling point of the solvent for 4 h. The resinous substances were extracted from the ethyl acetate extracts with hexane by infusion for three days. The samples of bark after extraction with ethyl acetate were dried from solvent residues, and then water-soluble substances were isolated by extraction with distilled water at 90°C for 4 h. The yields of the extractive substances extracted with ethyl acetate and water from the spruce bark on absolutely dry matter were 3.4 and 6.9%, respectively. The relative percentage content of phenolic compounds in the ethyl acetate extract of the spruce bark was 42.4%. The ethyl acetate extract of a spruce bark, pretreated with hexane, was fractionated on a silica gel column using a mixture of chloroform–acetone as the eluent with an increase in the fraction of the latter (from 0 to 100%). The content of monomeric and oligomeric, polymeric phenolic compounds in the extract was determined. Based on the data of 1Н and 13C NMR spectroscopy, it was established that the flavonoid dihydroquercetin and stilbene glycosides isorhapontin and astringin were the main monomeric phenolic extractive substances of Siberian spruce bark. It was shown that the structure of oligomeric phenolic compounds of the spruce bark includes structural fragments of stilbene glycosides, mainly monomeric blocks with the structure of isorhapontin and astringin.
Assessment of fractures in endodontically treated teeth restored with and without root canal posts using high-resolution cone beam computed tomography
Background Root fractures are a diagnostic challenge for dentists in endodontic treatment. This study aimed to determine the relationship between the characteristics of tooth fractures and the presence of root canal posts in endodontically treated teeth using high-resolution cone beam computed tomography (CBCT). Material and Methods Fifty high-resolution CBCT scans of endodontically treated teeth with a diagnosis of fracture were obtained, of which 30 were from women and 20 were from men. These scans were acquired with three Veraviewepocs 3D units and one 3D Accuitomo 170 unit, with a 40 × 40-mm field of view and 125 μm voxel size. The variables assessed included the type of fracture, extent of fracture, type of retention, post length, cause of endodontic failure, location of the lesion, and time required to detect the fracture (difficulty score). For data analysis, the chi-squared test, Student’s t-test, and multiple linear regression (α <0.05) were used. Results No association was found between the type of fracture and type of retention or between the type of fracture and its extent (P>0.05). On the other hand, the type of fracture significantly influenced the time required for its detection. Additionally, the most difficult plane for detecting the fracture and the difficulty score were associated, with statistically significant results. Conclusions The type of fracture in endodontically treated teeth was not associated with the type of post used for restoration. All of the CBCT systems used to detect tooth fracture showed the same efficiency. Key words:Cone-Beam CT, Tooth Fracture, Root Canal Post.