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Biomedical subjects

A P Kaplun

Publications and source records attributed to A P Kaplun.

At least 19 recordsLinked to original sources
PubMed2005

Antiviral activity of liposomal preparations of antibiotic geliomycin.

A liposomal preparation with maximally possible content of incorporated geliomycin was obtained. Its cytotoxicity was studied in a culture of human embryonal diploid fibroblasts. Antiviral activity was studied on a model of cytomegaloviral infection in vitro by the capacity to plaque formation. Liposomal geliomycin was 10-fold less toxic for human cells than the solution of the antibiotic in DMSO and exhibited antiviral activity towards cytomegaloviral infection at a concentration of 0.042 microg/ml.

Antiviral Agents↗
PubMed2000

[The inhibition of complement-dependent hemolysis of liposomes containing cerebroside sulfate].

Cerebroside sulfate (CGS) was found to be capable of inhibiting complement-dependent hemolysis. The activity dependence of CGS-containing liposomes on their composition was studied. Mixtures of CGS with phosphatidylethanolamine, phosphatidylserine, sphingomyelin from cattle brain, cerebroside from cattle spinal cord (CG), and egg yolk phosphatidylcholine (ePC) were investigated. In the case of binary CGS/ePC mixtures, the antihemolytic activity varied nonlinearly with an increase in the mass part of CGS: it sharply increased with an increase in the CGS part from 0.3 to 0.5 and decreased by 20-30% of the maximum value with an increase in the CGS part from 0.9 to 1. On the basis of these experiments, the optimum distance between the charged groups of CGS was estimated to be 0.92-1.6 nm. In the ternary compositions of 4:3:3 CGS/ePC/polar lipid, only CG increased the activity of liposomes as compared to that of liposomes from the 4:6 CGS/ePC. The preliminary incubation of CGS-containing liposomes with complement decreased hemolysis more effectively than incubation with other components of the hemolytic system. This suggests that the interaction of CGS-containing liposomes with the complement proteins is responsible for their antihemolytic activity.

Animals↗
PubMed1999

[Concentrating dopamine in liposomes using transmembrane gradient of ammonium sulfate].

The active loading of liposomes from egg phosphatidylcholine and cholesterol with dopamine using an ammonium sulfate gradient was studied. Our conditions allowed the enrichment of the monolamellar liposomes with 90% dopamine added to the medium and, thus, considerably improve the dopamine/lipid ratio. Dopamine-containing liposomes with tocopherol in their lipid bilayer were shown to be stable for 3 weeks.

Ammonium Sulfate↗
PubMed1999

[Preparation and certain properties of the liposomal substance 2,4-di(1-methyl-3-hydroxybutyl)deuteroporphyrin-IX].

A liposome preparation of a porphyrin photosensitizer for photodynamic therapy of tumors (PDT) was obtained. The in vitro efficiency of the photosensitizer was enhanced 2.5-fold through the liposome formulation. The composition and some properties of the new preparation were studied. An algorithm for a complex approach to the prediction of photosensitizer efficiencies by model experiments in vitro was developed. This approach is based on the use of two models: the determination of coefficient of distribution between n-octanol and a phosphate buffer, pH 7.4, and the determination of the cytotoxic effect on the culture of CaOv ovarian adenocarcinoma cells.

Adenocarcinoma↗
PubMed1998

[Physico-chemical properties of borate derivatives of DOPA, dopamine, and their liposome forms].

To increase the solubility of L-3,4-dihydroxyphenylalanine (DOPA) and dopamine (DA) incorporated in liposomes, it was suggested to convert them into ammonium and 1-adamantylammonium borate complexes. The structure of these complexes was studied by 11B and 1H NMR, IR, and mass spectrometry and conductometry. The liposomic form of the complexes is characterized by a high active compound/lipid molar ratio (0.5). Catechols in the form of complex salts are retained better within the inner volume of liposomes.

Amantadine↗
PubMed1998

[Synthesis of betulinic acid from betulin and study of its solubilization usingliposomes].

A method for betulinic acid synthesis from betulin was developed. Betulin was oxidized with chromium oxide (VI) into betulonic acid, which was reduced with sodium borohydride to yield a mixture of 3-hydroxy epimers containing 85% of the natural beta-epimer. Studying changes in light scattering by dispersions of liposomes with different contents of betulinic acid revealed that up to 10 mol % of this compound may be entrapped in liposomes. The dependence of the efficiency of the betulinic acid entrapment on liposome composition was studied. The presence of polyvinylpyrrolidone or Proxanol increased the resistance of betulinic acid-containing liposomes to aggregation. These polymers solubilized betulinic acid with the same efficiency as liposomes.

Light↗
PubMed1997

[Oxidation in liposomes from egg phosphatidylcholine loaded with L-3,4-dihydroxyphenylalanine (DOPA) and dopamine: mutual effect of components].

Oxidation of egg phosphatidylcholine and catechols (L-3,4-dihydroxyphenylalanine or dopamine) in liposome dispersions was studied. These catechols, encapsulated in liposomes, were shown to decrease the rate of phosphatidylcholine oxidation by factors of 4.9 and 2.6, respectively, at storage in darkness at 4 degrees C. After 40 min of Fe(II)-ascorbate-induced oxidation, the level of malonaldehyde in such liposomes remained constant, while in the empty liposomes, it increased 3,4-fold. Egg phosphatidylcholine protected catechols encapsulated into liposomes from oxidation, and the rate of this oxidation was shown to be substantially lower than that in micellar solutions under the same conditions. Evidently, this can be due to the barrier function of a lipid bilayer.

Dopamine↗
PubMed1988

[Studies of complex lipids. Synthesis of ionophore derivatives of diphosphatidylglycerol (cardiolipin)].

Synthesis of cardiolipin analogues containing an ionophore residue in the fatty acid moiety is described. The ionophore, dibenzo-18-crown-6, has been incorporated into second position of the glycerol residue by acylating mono- and dilysocardiolipin with a modified fatty acid anhydride. Lyso-derivatives of cardiolipin have been prepared by enzymatic hydrolysis of beef heart cardiolipin by snake venom phospholipase A2 (Naja naja oxiana).

Acylation↗
PubMed1983

[Effect of neurotropic compounds on the transmembrane potential of synaptosomes].

Using the potential-sensitive dye (3,3-dipropylthiodicarbocyanine) [dis-C3-(5)] it has been shown that synaptosomes isolated from the rat brain cortex by the method of Hajôs retain their transmembrane potential (TMP) close to the K+-diffusional one. In the Krebs-Ringer medium containing 5 mM KCl the TMP of the synaptosomes was equal to 70-80 mV. The cytostatics cytochalazine B and colchicine and the peptides leu- and met-enkephalins and tuftcin in concentrations up to 10(-3) and 10(-4) M did not affect the TMP of the synaptosomes. Cytochalazine B in a concentration of 4 X 10(-4) M and over caused synaptosomal aggregation. The neuroleptics aminazine, trifluoroperazine, haloperidol, the antidepressant imipramine in concentrations about 10(-4) M as well as the tranquilizers diazepam and phenazepam in concentrations about 10(-3) M completely depolarized synaptosomal membranes.

Animals↗
PubMed1983

[Semisynthetic cerebrosides].

Psychosine prepared from bovine brain cerebroside was used for synthesis of galactosphingolipids with DL-, D-, or L-2-hydroxyhexadecanoic acids and 6-(2'-anthroyl) hexanoic acid. Psychosine was N-acetyl with p-nitrophenyl 2-acetoxyhexadecanoates in the presence of hydroxybenzotriazole to give cerebrosides. The 6-(2'-anthroyl)hexanoic acid reaction with psychosine was effected via its acyl chloride.

Animals↗
PubMedDate not supplied

[Synthesis and antitumor activity of cyclopropane derivatives of betulinic and betulonic acids].

New cyclopropane derivatives of betulin were synthesized by attachment of dichlorocarbenes or dibromocarbenes to the double bond of betulin diacetate, followed by the deprotection of hydroxyl groups. The betulin cyclopropane derivative was obtained from 20,29-dihydro-20,29-dichloromethylenebetulin by treatment with lithium in tert-butanol. These compounds were converted into the corresponding derivatives of betulonic acid by oxidation with chromium trioxide. The reduction of oxo group with sodium borohydride led to the corresponding derivatives of betulinic acid. 20,29-Dihydro-20,29-dichloromethylenebetulinic acid proved to be the most cytotoxic toward human melanoma of the Colo 38 and Bro lines and human ovarian carcinoma of the CaOv line (IC50 10 microM). 20,29-Dihydro-20,29-dibromomethylenebetulinic acid inhibited the growth of the Bro melanoma cell line and the CaOv carcinoma cell line practically by 50% at a concentration of 10 microM. The other derivatives of betulinic and betulonic acids were active toward all of the three cancer cell lines at concentrations higher than 10 microM. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

Antineoplastic Agents↗
PubMedDate not supplied

[Epimerization of hydroxyl group in the lupan series of triterpenes].

Two methods of obtaining of 3 alpha-betulinic acid and related compounds from their 3 beta-epimers were studied: the reaction of bimolecular substitution and the stereoselective reduction of 3-ketoderivatives. The substitution of acyloxy by formyloxy group in 3-O-tosyllupeol or of the betulin hydroxyl by benzoyloxy group resulted only in delta 2, 3-elimination products, with none of the expected products of bimolecular substitution being found. The catalytic hydrogenation of betulonic acid over Raney nickel resulted only in reduction of the isopropenyl double bond, whereas the use of 5% Ru/C gave a 60:40 mixture of epimers of dihydrobetulinic acid. Practically the same mixture of betulinic acid epimers was obtained when reducing betulonic acid with L-Selectride. The cytotoxic activity of 3 alpha-betulinic acid increased toward melanoma Bro cells and decreased toward melanoma MS cells.

Antineoplastic Agents↗
PubMedDate not supplied

[The mechanism of inhibition of the activation of the complement first component by polyanions and polycations ].

Polyethyleneimine (PEI, 50 kDa) and polymethacrylic acid (PMA, 200 kDa) were shown to inhibit the lysis of sheep erythrocytes induced by the guinea pig complement. They twofold suppress the hemolysis at the concentrations of 0.47 and 0.89 microgram/ml, respectively. The inhibitory effect on the binding of the C1q subunit of human complement to the sensitized sheep erythrocytes (EA) was found to depend on the component of the reaction with which the inhibitors were preliminarily incubated. When an inhibitor, C1q, and EA were simultaneously incubated, the inhibition constants for PEI and PMA were 17 +/- 6 and 8.1 +/- 0.1 micrograms/ml, respectively. The preincubation of EA with PEI and the subsequent washing out of the inhibitor resulted in the inhibition constant of 22 +/- 3 micrograms/ml. No inhibitory effect was observed after a similar preincubation of EA with PMA. No inhibition was also detected when the inhibitors were added after the formation of the C1q complex with antibodies. These observations suggest that the binding of antibodies to cationic PEI prevents the C1q-antibody complex formation, while the binding of anionic PMA to the active site of C1q impedes the interaction of this subunit with immunoglobulins. Moreover, within the range of concentrations studied, the studied inhibitors did not affect the subsequent C1q binding to the C1r and C1s enzymes.

Animals↗
PubMedDate not supplied

[Liposomes and other nanoparticles as drug delivery systems].

The basic principles of designing of nanoparticle drug delivery systems are considered. The special attention is paid to liposomes, because the greatest success has been achieved in this area. The modern condition in such intensively developing areas as antitumor and, antibacterials drugs, gene therapy, vaccines is reviewed.

Animals↗