I. V. Chernyshova

Application of Supercritical Fluid Extraction to the Development of New Potential Biocides on the Basis of Garlic (Allium sativum L.)

Garlic (Allium sativum L.) extracts were obtained using CO2-supercritical extraction. The extracts were separated into individual components by the preparative HPLC and GC methods. Some of the isolated substances (allicin, ajoene, diallyl disulfide, and diallyl trisulfide), along with their two synthetic analogues with disulfide structure, were tested as potential biocides using a number of test objects (Candida utilis, Bacillus cereus, Pseudomonas aurantiaca, and Escherichia coli). Some of the tested substances exhibited a high efficiency as biocides, in particular, against gram-negative cultures. The results obtained are indicative of good prospects of using sulfur-containing garlic components and their synthetic analogues as potential antimicrobial agents.

Preparation of porous ultrahigh-molecular-weight polyethylene using subcritical water

We developed a method of subcritical water extraction of NaCl from ultrahigh-molecular-weight polyethylene (UHMWPE) samples as a step in the preparation of a porous polymeric product, a promising material for implant production. Optimum process conditions were determined to be as follows: pressure 250 bar, temperature 120°C, and water flow rate 3 g/min. This method allows decreasing ten-fold (from 10 to 1 h) the time of salt extraction from the samples. The UHMWPE obtained was shown by scanning electron microscopy to have a porous structure with a main pore diameter from 80 to 700 μm.

Stability of thiosulfinates from garlic ( Allium sativum L.) supercritical extracts in polar and nonpolar solvents

For the first time a systematic investigation of the decomposition process of allicin and other thiosulfinates from garlic supercritical extracts (SCEs) in solvents of different polarity (water, ethanol, acetonitrile, dimethyl sulfoxide, dichloromethane, and hexane) was performed. Qualitative and quantitative analysis of the garlic thiosulfinate decomposition products was carried out. A new HPLC analytical procedure was developed; it allows simultaneous determination of both starting thiosulfinates and sulfur-containing products of their decomposition. It was shown that the decomposition of SCE thiosulfinates can be directed toward the formation of target substances (ajoenes, dithiins, trisulfides, etc.) by changing the solvent polarity. The results obtained and methodical developments can be used in biomedical research of garlic-based drugs, as well as in the processes of their preparation, storage, and analysis.

Components of supercritical extracts of garlic and synthetic nonsymmetrical allyl disulfides as potential antimicrobial preparations

Extracts of garlic (Allium sativum L.) were obtained using supercritical carbon dioxide extraction and were separated into individual compounds using preparative high performance liquid and gas chromatography. A series of nonsymmetrical allyl disulfides with different substituents were synthesized. The compounds isolated from the supercritical garlic extract and the synthetic nonsymmetrical allyl disulfides (SNA) were tested as potential antimicrobial agents using a number of test objects: Candida utilis, Bacillus cereus, Pseudomonas aurantiaca, and Escherichia coli. It was shown that the SNA exhibit high antimicrobial activity, which was much higher that the activities of individual components of garlic and in some cases were comparable in efficiency with antibiotics of the floxacin series widely used in clinical practice. The data obtained suggest the potential for using SNA as antimicrobial agents.

Sulfur-containing components of supercritical garlic extracts and their synthetic analogs as potential biocides

We have shown that a specific component of supercritical (SC) garlic extract and some synthetic disulfide analogs are active as antimicrobials. In the course of this study, six compounds (diallyl disulfide, 1-propenylallyl disulfide, methylallyl disulfide, diallyl trisulfide, 2-vinyl-4H-1,3-dithiin, and 3-vinyl-4H-1,2-dithiin) were isolated from SC garlic extract and identified. Also, two novel sulfoxide-containing garlic analogs were synthesized. All isolated and synthetic substances were tested as potential antimicrobials against gram-positive bacteria Bacillus cereus, Mycobacterium smegmatis, and Micrococcus luteus and gram-negative bacteria Pseudomonas aurantiaca. Diallyl disulfide and diallyl trisulfide exhibited the best activity against both gram-positive and gram-negative bacteria.

The solubility of synthetic asymmetric allyl disulfides in subcritical and supercritical media

The solubility of two synthetic asymmetric allyl disulfides, allyl 8-quinolyl disulfide and allyl benzothiazol-2-yl disulfide, in subcritical Freon R22 and Freon R410a, as well as supercritical carbon dioxide, at a temperature of 40°C and a pressure of 200 bar is determined by a dynamic flow method. It is shown that Freon R22 is a promising solvent for practical applications of allyl disulfides.

Xenogenic bone matrix treated with supercritical carbon dioxide as a potential osteoplastic material

A multistage environmentally safe method for processing xenogenic bone matrix using suband supercritical media has been developed. This method provides fast matrix delipidization in a medium of supercritical carbon dioxide and deproteinization by treatment with a 3% hydrogen peroxide solution followed by washing with subcritical water for removal of polar substances. The final treatment with supercritical carbon dioxide serves to remove residual nonpolar components. A method to control the porosity of xenogenic bone matrix at different stages of its purification has been suggested. Preliminary data indicate that a cellular test system based on an allogenic osteoid cell line Th-1 could be used for evaluation of primary adhesion and proliferation of cells on the surface of purified bone matrix.

Production of new haemostatic materials by deposition of dispersed proteins onto porous matrices using supercritical carbon dioxide

The main features of microparticle formation from protein substances (trypsin, lysozyme) using supercritical fluids (SAA method) are studied. Optical and scanning electron microscopies are employed to examine the morphology of the particles. The size distribution of the particles is studied using a cascade impactor. A method of deposition of particles onto Collachit-G haemostatic material is developed.

Impregnation of Ultrahigh-Molecular-Weight Polyethylene with Amoxicillin in Subcritical Freon R22 Media

The method of impregnation of ultrahigh-molecular-weight polyethylene (UHMWPE) with amoxicillin in subcritical Freon R22 media is developed. For the first time, the possibility of polymer impregnation with a polar substance (a standard antibiotic amoxicillin) in the absence of cosolvents is shown. Cosolvents increase the polarity of the medium and removal of them from the polymer matrix is usually a serious problem. Amoxicillin desorption curves from the impregnated UHMWPE samples are obtained by high-performance liquid chromatography (HPLC). Polymeric samples impregnated with amoxicillin are active against gram-positive and gram-negative microorganisms S. aureus, S. epidermidis, E. faecalis, B. subtilis, and E. coli, allowing them to be considered as real implant models for replacement of bone tissue.

Application of Sub- and Supercritical Freons in Xenogenic Bone Matrix Processing

Sub- and supercritical freons can be successfully used in the bone matrix cleaning process. In the case of freon R22 the duration of bone matrix cleaning significantly decreases as compared to the same procedure with supercritical carbon dioxide. Freons R23, R134 and R407c which do not contain chlorine atoms are almost ineffective in this process.