New Biocides Based on N4-Alkylcytidines: Effects on Microorganisms and Application for the Protection of Cultural Heritage Objects of Painting.

The rapid increase in the antibiotic resistance of microorganisms, capable of causing diseases in humans as destroying cultural heritage sites, is a great challenge for modern science. In this regard, it is necessary to develop fundamentally novel and highly active compounds. In this study, a series of N4-alkylcytidines, including 5- and 6-methylcytidine derivatives, with extended alkyl substituents, were obtained in order to develop a new generation of antibacterial and antifungal biocides based on nucleoside derivatives. It has been shown that N4-alkyl 5- or 6-methylcytidines effectively inhibit the growth of molds, isolated from the paintings in the halls of the Ancient Russian Paintings of the State Tretyakov Gallery, Russia, Moscow. The novel compounds showed activity similar to antiseptics commonly used to protect works of art, such as benzalkonium chloride, to which a number of microorganisms have acquired resistance. It was also shown that the activity of N4-alkylcytidines is comparable to that of some antibiotics used in medicine to fight Gram-positive bacteria, including resistant strains of Staphylococcus aureus and Mycobacterium smegmatis. N4-dodecyl-5- and 6-methylcytidines turned out to be the best. This compound seems promising for expanding the palette of antiseptics used in painting, since quite often the destruction of painting materials is caused by joint fungi and bacteria infection.

Versatile synthesis of oxime-containing acyclic nucleoside phosphonates--synthetic solutions and antiviral activity.

New oxime-containing acyclic nucleoside phosphonates 9-{2-[(phosphonomethyl)oximino]ethyl}adenine (1), -guanine (2) and 9-{2-[(phosphonomethyl)oximino]propyl}adenine (3) with wide spectrum activity against different types of viruses were synthesized. The key intermediate, diethyl aminooxymethylphosphonate, was obtained by the Mitsunobu reaction. Modified conditions for the by-product separation (without chromatography and distillation) allowed us to obtain 85% yield of the aminooxy intermediate. The impact of DBU and Cs2CO3 on the N(9)/N(7) product ratio for adenine and guanine alkylation was studied. A convenient procedure for aminooxy group detection was found. The synthesized phosphonates were tested and they appeared to display moderate activity against different types of viruses (HIV, herpes viruses in cell cultures, and hepatitis C virus in the replicon system) without toxicity up to 1000 µM.

Crystal structure of ammonium 3'-azido-3'-de-oxy-thymidine-5'-amino-carbonyl-phospho-nate hemi-hydrate: an anti-HIV agent.

The asymmetric unit of the title compound, NH4 (+)·C11H14N6O7P(-)·0.5H2O, contains one 3'-azido-3'-de-oxy-thymidine-5'amino-carbonyl-phospho-nate (ACP-AZT) anion, half of an NH4 (+) cation lying on a twofold rotation axis and in another position, occupied with equal probabilities of 0.5, an NH4 (+) cation and a water mol-ecule. The amide group of the ACP-AZT anion is disordered (occupancy ratio 0.5:0.5), with one part forming an N-H⋯O (involving C=O⋯H4N(+)) hydrogen bond and the other an O-H⋯N (involving C-NH2⋯OH2) hydrogen bond with the components of the split NH4 (+)/H2O position. The pseudorotation parameters of ACP-AZT set it apart from previously studied AZT and thymidine. In the crystal, the various components are linked by N-H⋯O, O-H⋯O, N-H⋯N, C-H⋯O and C-H⋯N hydrogen bonds, forming a three-dimensional framework.

5-Substituted Uridines with Activity against Gram-Positive Bacteria.

The emergence of drug-resistant strains of pathogenic microorganisms necessitates the creation of new drugs. A series of uridine derivatives containing an extended substituent at the C-5 position as well as C-5 alkyloxymethyl, alkylthiomethyl, alkyltriazolylmethyl, alkylsulfinylmethyl and alkylsulfonylmethyl uridines were obtained in order to explore their antimicrobial properties and solubility. It has been shown that new ribonucleoside derivatives have an order of magnitude better solubility in water compared to their 2'-deoxy analogues and effectively inhibit the growth of a number of Gram-positive bacteria, including resistant strains of Mycobacterium smegmatis (MIC=15-200 µg/mL) and Staphylococcus aureus (MIC=25-100 µg/mL). Their activity is comparable to that of some antibiotics used in medicine.

Phosphoramidate derivatives of acyclovir: synthesis and antiviral activity in HIV-1 and HSV-1 models in vitro.

The antiviral activity against HIV and HSV and the chemical stability of ACV phosphoramidate derivatives were studied. The phosphoramidates of ACV demonstrated moderate activity. The best compound appeared to be 9-(2-hydroxymethyl)guanine phosphoromonomorpholidate (7), which inhibited virus replication in pseudo-HIV-1 particles by 50% at 50 µM. It also inhibited replication of wild-type HSV-1 (9.7 µM) as well as an acyclovir-resistant strain (25 µM). None of the synthesised compounds showed any cytotoxicity.

Discovery of novel N4-alkylcytidines as promising antimicrobial agents.

The emergence of drug-resistant strains of pathogenic microorganisms necessitates the creation of new drugs. In order to find new compounds that effectively inhibit the growth of pathogenic bacteria and fungi, we synthesized a set of N4-derivatives of cytidine, 2'-deoxycytidine and 5-metyl-2'-deoxycytidine bearing extended N4-alkyl and N4-phenylalkyl groups. The derivatives demonstrate activity against a number of Gram-positive bacteria, including Mycobacterium smegmatis (MIC = 24-200 µM) and Staphylococcus aureus (MIC = 50-200 µM), comparable with the activities of some antibiotics in medical use. The most promising compound appeared to be N4-dodecyl-5-metyl-2'-deoxycytidine 4h with activities of 24 and 48 µM against M. smegmatis and S. aureus, respectively, and high inhibitory activity of 0.5 mM against filamentous fungi that can, among other things, damage works of art, such as tempera painting. Noteworthy, some of other synthesized compounds are active against fungal growth with the inhibitory concentration in the range of 0.5-3 mM.

Synthesis of water-soluble prodrugs of 5-modified 2'-deoxyuridines and their antibacterial activity.

Recently we have synthesized a set of pyrimidine nucleoside derivatives bearing extended alkyltriazolylmethyl substituents at position 5 of the nucleic base, and showed their significant activity against Mycobacterium tuberculosis virulent laboratory strain H37Rv as well as drug-resistant MS-115 strain. The presence of a lengthy hydrophobic substituent leads to the reduction of nucleoside water solubility making their antibacterial activity troublesome to study. A series of water-soluble forms of 5-modified 2'-deoxyuridines 4a-c and 8a-c were synthesized. They appeared at least two orders more soluble compared with the parent compounds 1a and 1b. Their half-hydrolysis time was 5-12 h, which can be considered optimal for prodrugs used in clinics. Obtained compounds showed moderate activity (MIC 48-95 µg·ml-1) against some Gram-positive bacteria including resistant strains of Staphylococcus aureus and Mycobacterium smegmatis and were low cytotoxic for human cell lines (CD50 >> 100 µg·ml-1).

5'-aminocarbonyl phosphonates as new zidovudine depot forms: antiviral properties, intracellular transformations, and pharmacokinetic parameters.

The main disadvantages of 3'-azido-3'-deoxythymidine (zidovudine, AZT), the most common anti-HIV drug, are toxicity and a short half-life in the organism. The introduction of an H-phosphonate group into the AZT 5' position resulted in significant improvement of its therapeutic properties and allowed a new anti-HIV drug, Nikavir (AZT H-phosphonate). In this work, we described a new group of AZT derivatives, namely, AZT 5'-aminocarbonylphosphonates. The synthesized compounds displayed antiviral properties in cell cultures infected with HIV-1 and the capacity to release the active nucleoside in animals (rabbits and dogs) in a dose-dependent manner. The compounds were less toxic in MT-4 and HL-60 cell cultures and experimental animals compared with AZT. Major metabolites found in MT-4 cells after their incubation with AZT 5'-aminocarbonylphosphonate 1 were AZT and AZT 5'-phosphate (25 and 55%, respectively). Among the tested compounds, phosphonate 1 was the most effective AZT donor, and its longest t(1/2) and T(max) values in the line phosphonate 1--AZT H-phosphonate--AZT imply that compound 1 is an extended depot form of AZT. Although bioavailability of AZT after oral administration of phosphonate 1 was lower than those of AZT H-phosphonate and AZT (8 against 14 and 49%), we expect that this reduction would not cause essential decrease of antiviral activity but noticeably decrease toxicity as a result of gradual accumulation of AZT in blood and the absence of sharp difference between C(max) and C(min). Such a combination of properties makes the compounds of this group promising for further studies as extended-release forms of AZT.

Uncharged AZT and D4T derivatives of phosphonoformic and phosphonoacetic acids as anti-HIV pronucleosides.

Two series of new lipophilic phosphonoformate and phosphonoacetate derivatives of AZT and d4T were synthesized and evaluated as anti-HIV agents. The efficacy of some of the synthesized compounds in cell cultures infected with HIV-1 was higher than that of the parent nucleosides and only slightly correlated to their stability in the phosphate buffer and human blood serum. The synthesized phosphonates are most probably prodrug forms of the corresponding nucleosides.

Synthesis and antiherpetic activity of acyclovir phosphonates.

Phosphonate derivatives of acyclovir containing phosphorous acid and ethoxycarbonylphosphonic acid residues as well as their isopropyl esters were prepared. They selectively inhibited the herpes simplex virus 1 reproduction in Vero cell culture, the efficacy of esters being 3-4 times higher than that of ACV. The hydrolysis of the synthesized compounds was studied in the PBS buffer and human blood serum.