Sterols Content of Fruiting Bodies of Medicinal Artist's Bracket Mushroom Ganoderma applanatum (Agaricomycetes) Collected in Armenia.

The qualitative analysis of hexane extracts obtained from different trama layers (WT, T1-T4) of dried fruiting bodies of medicinal bracket fungus Ganoderma applanatum collected in the Tavoush region of North-East Armenia was performed by GC-MS analysis. Three sterols [(7.22-ergostadienon, ergosterol and ergosta-14.22-diene-3-ol (3ß, 5α, 22E)] have been identified. The results have shown that the content and ratio of sterols differ in analyzed trama samples. The highest amount of sterols was detected in middle parts of T2 and T3 layers, while content of sterols gradually decreased to the upper cortical (T4) and lower hymenial (T1) layers. The chromatographic profiles of identified compounds indicate that different sterols dominated in each layer: 7.22-ergostadienon in T4, ergosterol in T3, T2, and T1. The average weight loss of analyzed trama samples during six days of drying was about 40 wt.% (37.0-43.49 wt.%) of the total weight of basidiome, which decreased up to 5 wt.% in the next two days. The complete extraction of sterols lasted six days. Its further prolongation leads to stationary phase without an increase in the amount of extracted sterols.

A detailed discussion of the influence of the amount of deposited polymer on the retention properties of polymer-coated silicas.

Problems of the modification of the surface of micro-spherical silica gel with layers of polymer and the influence of the quantity of the coated polymer on the chromatographic properties of the resulting sorbents have been considered. The polymer modification of the surface of wide-pore micro-spherical silica gel obtained by means of hydrothermal treatment of the meso-porous silica gel under autoclave conditions is described. The polymer layer itself is formed by an octadecylmethacrylate-methylmethacrylate co-polymer. As a result, packings for RP-HPLC were obtained. An increase of the capacity factor (k) has been observed with an increase of the quantity of the polymer deposited during the polymer modification process. The indicated phenomenon depends on the increase of the number of C18 groups in the packing.

Changes in the pore character of silicas caused by surface bonding and polymer coating.

The pore character of packings for liquid chromatography, especially reversed-phase (RPLC) packings, has been studied by means of the nitrogen adsorption method (BET method). Micro-spherical silica gels with 9, 12, 30, 40 and 50 nm average pore diameter have been used as carriers. These silica gels have been modified with monochlorodimethyloctadecylsilane and several polymers (polyoctadecylmethacrylate-methylmethacrylate co-polymer, polyacrylamide gel, polyvinyl alcohol, poly-2-hydroxyethyl-methacrylate). A larger decrease in the specific surface area values was observed in the case of the polymer coating with the polyoctadecylmethacrylate-methylmethacrylate co-polymer compared with the derivatization by silanes or the modification with polymers without C18-groups. A new approach has been suggested to explain some questions concerning the interpretation of the data obtained during the measurements of the pore characteristics of the derivatized packings. An attempt has been made to reveal peculiarities connecting values of the measured surface of RP-packings with the specific surface area values of the initial silica, as well as with the chromatographically accessible surface.