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One of the approaches to enhance bioavailability of nucleoside reverse transcriptase HIV inhibitors consists in design of their prodrugs based on 1,3-diacylglycerols, which may simulate nature lipids metabolic pathways promoting the improvement of drug delivery to the target cells. Glycerolipidic AZT conjugates with different functional phosphoric centers were synthesized by H-phosphonate technique in the present work. Study of prepared prodrugs sensibility to the chemical and enzymatic hydrolysis (in buffer solution and under the influence of pancreatic lipase) and also study of their anti-HIV activity on the T-lymphoid human MT-4 cells in regarding to virus HIV-1(899A) strain were carried out.

The antimitotic agent combretastatin A4 (CA-4) has been suggested as an antivascular agent for anticancer therapy relatively recently. To reduce systemic toxicity by means of administration in liposome formulations, in this study new lipophilic prodrugs, oleic derivatives of CA-4 and its 4-arylcoumarin analog (CA4-Ole and ArC-Ole, respectively), have been synthesized: Liposomes of 100 nm mean diameter prepared on the basis of egg phosphatidylcholine and phosphatidylinositol from bakers yeast have been shown to include completely up to 10 mol. % of CA4-Ole, or 7 mol. % of ArC-Ole. Also, prodrug bearing liposomes decorated with tetrasaccharide selectin ligand Sialyl Lewis X (SiaLe(x)) have been constructed to achieve targeting to endothelium under neovascularization. The antitumor activity in vivo was studied in the model of slowly growing mouse breast cancer. Under the used dose (22 mg/kg) as well as the regimen of treatment (four injections, one per a week, starting from the appearance of palpable tumors) cytostatic CA-4 did not reveal any anticancer effect, and oppositely even stimulated tumor growth. Liposome formulations of CA4-Ole did not show such stimulation. However, to achieve pronounced antitumor effect, number of injections of liposomes should be apparently elevated. New antimitotic agent ArC revealed cytotoxic activity of only one tenth value obtained for CA-4 in vitro in the culture of human breast carcinoma cells. Nevertheless, in vivo in the mouse model of breast cancer this compound showed antitumor effect under double CA-4 equivalent dose. The results demonstrate availability of SiaLe(x)-liposomes loaded with ArC-Ole: this preparation began to inhibit tumor growth already after the second injection. It is necessary further to choose doses and regimens of administration both for ArC and liposome formulations bearing ArC-Ole.

The methods of synthesis of the derivatives of nucleoside analogues esterified with various aliphatic, aromatic, and heteroaromatic acids and the construction from them of molecular transport systems that involve lipids, carbohydrates, peptides, and amino acids are discussed. The characteristics of the biological activity of a number of such systems are described.

The regularities of biosynthesis of 6-aminopenicillanic acid (6-APA), benzylpenicillin (BP) and phenoxymethylpenicillin (PMP) by the strains under the investigation did not significantly differ. In the absence of the precursor both the strains mainly synthesized 6-APA. Phenylacetic acid (PAA) and phenoxyacetic acid (POAA) provided directed biosynthesis: the fungus synthesized BP or PMP depending on the precursor nature. When the amount of the precursors was not sufficient, 6-APA was synthesized along with the penicillins. PAA proved to be a more active precursor than POAA. When both precursors were present in the fermentation broth, only BR was synthesized. An important distinction of strain 316A was its increased sensitivity to PAA especially in the initial period. After an increase in the PAA concentration the growth rate of strain 316A lowered to a greater extent than that of strain 284A. This was likely to determine the higher levels of penicillin production by strain 316A in the presence of POAA, a nontoxic precursor. A procedure for supplying the precursors was developed. Under the laboratory conditions it provided high levels of the penicillin production.

The review covers the principles of creation of prodrugs as a chemical system for delivering drugs to targets. It presents the strategy of prodrug design and describes the main approaches to creation of prodrugs for drugs of different classes: antibiotics, anti-inflammatory and antitumour agents, corticosteroids, agents of the central action, etc.