Browsing by Author "Boldescu, Veaceslav"

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CYCLODEXTRINS – FIELDS OF APPLICATION. PART I
(Academia de Știinițe a Moldovei, 2008) Duca, Gheorghe; Boldescu, Veaceslav
This review is dedicated to different fi elds of use of cyclodextrins, a family of three cyclic natural oligosaccharides and their derivatives. The fi rst part of the review gives a brief description of the main and the most recent developed applications of cyclodextrins in food, cosmetic industry, environmental protection technologies and agriculture. Different products based on inclusion complexes with cyclodextrins and technologies with different use of cyclodextrins and inclusion complexes are described.
NANOSTRUCTURILE PE BAZĂ DE CICLODEXTRINE ÎN TEHNOLOGIA MEDICAMENTELOR
(CEP USM, 2008) Boldescu, Veaceslav
One of the main problems of the contemporary pharmaceutical technology is rel ease of drugs into the environment. Consequently, resistance of target cells towards these medicines develops. In order to reduce the amount of pharmaceuticals released into the environment and to enhance their pharmacokinetics, the use of nanostructures on the bases of cyclodextrins has been proposed. Cyclodextrins are cyclic torus-shaped molecules with a hydrophilic outer surface and a hydrophobic central cavity that can accommodate a variety of drug entities. Different technologies have been designed for drug-cyclodextrin encapsulation: physical mixture, kneading,coprecipitation, co-evaporation, lyophilization. The efficiency of these technologies in the inclusion complexes preparation is discussed in this paper.
PĂTRUNDEREA ŞI TRANSFORMĂRILE CHIMICE ALE SUBSTANŢELOR ANTIBACTERIENE ÎN MEDIUL ÎNCONJURĂTOR
(2005) Boldescu, Veaceslav; Gladchi, Viorica
Summary: Recently, pharmaceuticals and personal care products (PPCPs) with their metabolites have been detected as common contaminants in surface waters throughout the world. The most frequently detected compounds were hormones, antibiotics, analgesics, fragrances, disinfectants, diagnostic agents, sunscreen agents, tranquilizers. The major possible impact of antibiotics and other antibacterial products is development of resistant bacteria and potential to disturb environmental bacterial community and processes. One of the main physico-chemical processes of PPCPs degradation is considered photolysis. This work is dedicated to the photodegradation of the antibiotic oxytetracycline hydrochloride. The study has been performed with and without addition of the copper (II) ions which are main catalysts in natural redox processes. It has been found that the photodegradation rate of oxytetracycline hydrochloride for the model system with addition of Cu2+ is lower than for the system without addition of Cu2+. Moreover, there exists a qualitative difference between transformational products formed with and without addition of Cu2+. It is obvious that the formation of Cu-antibiotic complexes causes these differences in the rates and products. Obtained results emphasize the importance of identifying the transformation products and the degradation rates of PPCPs in the presence of natural transition ions (Cu2+, Fe3+, Mn4+) and other cations (Ca2+, Mg2+), which can form complexes with PPCPs, in order to obtain results closer to the real environmental conditions.
PĂTRUNDEREA ŞI TRANSFORMĂRILE CHIMICE ALE SUBSTANŢELOR ANTIBACTERIENE ÎN MEDIUL ÎNCONJURĂTOR
(2005) Boldescu, Veaceslav; Gladchi, Viorica
Recently, pharmaceuticals and personal care products (PPCPs) with their metabolites have been detected as common contaminants in surface waters throughout the world. The most frequently detected compounds were hormones, antibiotics, analgesics, fragrances, disinfectants, diagnostic agents, sunscreen agents, tranquilizers. The major possible impact of antibiotics and other antibacterial products is development of resistant bacteria and potential to disturb environmental bacterial community and processes. One of the main physico-chemical processes of PPCPs degradation is considered photolysis. This work is dedicated to the photodegradation of the antibiotic oxytetracycline hydrochloride. The study has been performed with and without addition of the copper (II) ions which are main catalysts in natural redox processes. It has been found that the photodegradation rate of oxytetracycline hydrochloride for the model system with addition of Cu2+ is lower than for the system without addition of Cu2+. Moreover, there exists a qualitative difference between transformational products formed with and without addition of Cu2+. It is obvious that the formation of Cu-antibiotic complexes causes these differences in the rates and products. Obtained results emphasize the importance of identifying the transformation products and the degradation rates of PPCPs in the presence of natural transition ions(Cu2+, Fe3+, Mn4+) and other cations (Ca2+, Mg2+), which can form complexes with PPCPs, in order to obtain results closer to the real environmental conditions.
PROCESSES OF RADICAL AUTO-PURIFICATION OF AQUATIC SYSTEMS
(Tipografia Academiei de Ştiinţe a Moldovei, 2005) Boldescu, Veaceslav; Gladchi, Viorica
SPECTROPHOTOMETRIC STUDIES OF SANGUINARINE- Β - CYCLODEXTRIN COMPLEX FORMATION
(Academia de Știinițe a Moldovei, 2008) Boldescu, Veaceslav; Kacso, Irina; Bratu, Ioan; Duca, Gheorghe
The main aim of this study was to investigate the infl uence of pH and the presence of hydrophilic polymer polyvinylpyrrolidone on the formation of sanguinarine-β-cyclodextrin (SANG-β-CD) inclusion complex. Spectrophotometric studies of the SANG-β-CD systems in the presence and without 0.1 % PVP at the pH 5.0 did not show any evidence of the complex formation. However, the same systems showed several obvious evidences at the pH 8.0: the hyperchromic and the hypochromic effects and the presence of the isosbestic point in the region of 200 – 210 nm. The association constants calculated by three linear methods: Benesi-Hildebrand, Scott and Scatchard, were two times higher for the systems with addition of 0.1% PVP than for the systems without it.
STUDIU DE SPECTROSCOPIE ÎN INFRAROŞU AL UNOR PRODUSE TERNARE DE SUBSTANŢE ANTIVIRALE DIN GRUPA AMANTADINELOR CU CICLODEXTRINE
(CEP USM, 2008) Boldescu, Veaceslav
Rimantadine hydrochloride (rimantadine) and amantadine hydrochloride (amantadine) are synthetic antiviral drugs,inhibitors of M2 membrane protein ion channel of the influenza A virus. Both amantadine and rimantadine are slowlyabsorbed after the oral administration and induce significant gastrointestinal adverse effects. In order to reduce the side effects and to improve pharmacokinetics of the studied drugs, cyclodextrin complexation has been proposed. This studyis dedicated to characterization, by means of infrared spectrometry, of amantadine and rimantadine products with βcyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD) at the presence of a hydrosoluble polymer - polyvinylpyrrolidone (PVP). The corresponding ternary products were obtained using two main methods: kneading and coevaporation. In the result of this study we concluded that, as well as in the spectra of binary products studied before, the stretching vibrations of cyclodextrin glycosidic bonds and hydroxyl groups have significantly changed their frequencies in the spectra of AM-βCD-PVP and RIM-βCD-PVP products. At the same time these vibrations retained their frequencies unchanged in the spectra of AM-HPβCD-PVP and RIM-HPβCD-PVP products. Supposedly, the inclusion complexformation took place in the case of βCD-containing products, while the HPβCD-containing products remained uncomplexed.