A series of nucleoterpenoids in which uridine is attached to diterpenoid isosteviol (16-oxo-ent-beyeran-19-oic acid) by means of an alkyl or 1,2,3-triazolylalkyl linker has been synthesized. Screening of their in vitro cytotoxicity against 7 cancer cell lines revealed three lead compounds. This is nucleoterpenoid 13c in which the uridine moiety is attached by the octyl linker to the amide group of isosteviol. Compound 13c caused the death of MCF-7 and PANC-1 cancer cells at an IC50 concentration of 11 µM. Nucleoterpenoid 15b, in which the uridine moiety with protected hydroxyl groups is attached by the 1,2,3-triazolylbutyl linker to the C-16(S) position of isosteviol, caused the death of cancer cells M-HeLa, MCF-7, PANC-1, PC-3, A 549, and HuTu 80 at IC50 values in the range 10.4-16.8 µM. Its derivative, nucleoterpenoid 15d with free hydroxyl groups, caused the death of cancer cells MCF-7, PANC-1, PC-3, and A 549 at IC50 values in the range 11.7-19.5 µM.

A series of 1,2,3-triazole nucleoside analogues containing an N-acetyl-D-glucosamine residue was synthesized via copper-catalyzed azide-alkyne cycloaddition of 3,4,6-tri-O-acetyl-2-deoxy-2-acetamido-β-D-glucopyranosyl azide with N-propargyl derivatives of phenothiazine, carbazole, isatin, phthalimide, and imidazolin-2-one. The synthesized compounds demonstrated moderate in vitro cytotoxicity against human cancer cell lines M-HeLa, MCF-7, PANC-1, PC-3, T 98G, A 549, and HuTu 80.

Triphenylphosphonium (TPP) conjugates of nucleoterpenoids were synthesized for the first time, and these were nucleoterpenoids consisting of the diterpenoid isosteviol (16-oxo-ent-beyran-19-oic acid) and uracil. In these conjugates, the TPP cation was attached by a polymethylene linker to the N3 atom of the uracil moiety. In turn, the N1 atom of the uracil moiety was bound by a 1,2,3-triazole-4-yl-alkyl (methyl or n-butyl) linker to the 16(S)-position of the isosteviol moiety. The screening of in vitro cytotoxicity of the synthesized TPP-conjugates revealed their high activity (IC50 = 0.4–15.5 µM) against cancer cells M-HeLa, MCF-7, PANK-1, PC-3, T 98G, A 549, and HuTu 80. The mechanism of the in vitro cytotoxic effect of the lead compound [(1′-1′′-[19-(ethyloxycarbonyl)-ent-beyeran-16(S)-yl]-1H-1,2,3-triazol-4′′-yl-butyl-1H,3H-pyrimidine-2,4-dione-3′-yl)decyl]triphenylphosphonium bromide, in which the TPP cation is attached to the nucleoterpenoid fragment by a decyl linker, against M-HeLa cancer cells, was studied by flow cytofluorometry. The results obtained indicated that [(1′-1′′-[19-(ethyloxycarbonyl)-ent-beyeran-16(S)-yl]-1H-1,2,3-triazol-4′′-yl-butyl-1H,3H-pyrimidine-2,4-dione-3′-yl)decyl]triphenylphosphonium bromide reduced the mitochondrial membrane potential, induced apoptosis along the mitochondrial pathway and delayed the cell cycle at an early stage G1.

A series of triphenylphosphonium (TPP) conjugates of 1,2,3-triazolyl analogues of pyrimidine nucleosides was synthesized. In these compounds a TPP cation was attached via a decamethylene linker to the atom N-3 of the nucleic base (uracil, thymine) or its analog (6-methyluracil), and the N-acetyl-β-D-glucosamine residue with protected (or unprotected) hydroxyl groups was attached via a 1,2,3-triazolylmethyl or 1,2,3-triazolylbutyl linker to the atom N-1 of the listed pyrimidine derivatives. All synthesized TPP-conjugates caused the death of MCF-7 cancer cells within the range IC50 = 1.9-27 µM and PC-3 cancer cells within the range IC50 = 2.6-19.4 µM. Bacteriostatic and bactericidal activity against Gram-positive bacteria Staphylococcus aureus, Bacillus cereus, and methicillin-resistant strains of S. aureus MRSA-1 and MRSA-2 was detected for several TPP-conjugates within the concentration range (MIC and MBC) from 7.8 to 15.6 µM.

Twenty triphenylphosphonium (TPP) conjugates in which 1-alkynyl-substituted nucleic bases (uracil, thymine) and their analogues (6-methyluracil, quinazoline-2,4-dione) were connected to the TPP cation via an octyl or decyl linker were synthesized. In vitro evaluation of their antibacterial activity against five Gram-positive bacteria, two Gram-negative bacteria and fungus C. albicans revealed six lead compounds which exhibited high bacteriostatic activity (MIC 0.2–0.9 μM) against Gram-positive bacteria S. aureus, B. cereus, E. faecalis, as well as MRSA strains. These lead compounds are TPP-conjugates in which 1-alkynylquinazoline-2,4-dione moiety is bound to the TPP cation via the decyl (4 d, 4 f) or octyl (4e) linker and biscationic TPP-conjugates in which two TPP cations are attached to the N-1 and N-3 atoms of 5-alkynylquinazoline-2,4-dione moiety via the decyl (5 d, 5 f) or octyl (5e) linkers. Biscations 5 d and 5e showed high in vitro bacteriostatic and bactericidal activity (MIC/MBC 0.2–7.8 μM) against Gram-negative bacteria E. coli and P. aeruginosa. In addition, biscations 5 d and 5 f exhibited noticeable in vitro fungistatic and fungicidal activity against fungus C. albicans. Using colorimetric and fluorimetric methods, it was found that all lead compounds at concentrations corresponding to the MIC and MBC values caused cytoplasmic membrane damage and depolarization, without violating the integrity of the S. aureus cell wall. In addition, all lead compounds inhibited the formation of S. aureus biofilm by 80-100

In this work, we designed and synthesized 12 triphenylphosphonium (TPP) conjugates of acetylenated nucleic bases (uracil, thymine) and their analogues (6-methyluracil, quinazoline-2,4-dione) and evaluated their in vitro cytotoxicity against 9 human cancer cell lines M-HeLa, HuTu 80, MCF-7, T 98 G, A 549, DU-145, SK-OV-3, PC-3, A-375 and two lines of normal human cells RPMI 1788 and WI-38. All synthesized TPP-conjugates showed high cytotoxicity (IC50 values in the range of 0.1–7.3 µM) against all used human cancer cell lines. The mechanisms of cytotoxic action were studied for the lead compounds 2c,d, 4c,d which exhibited very high cytotoxicity (IC50 = 0.2–0.3 μM) against PC-3 cancer cells. The flow cytometry method using Annexin V and propidium iodide (PI) has shown that the lead compounds cause apoptosis of PC-3 cells. With the help of flow cytometry using cationic carbocyanine dye JC-1, it was found that the lead compounds cause a significant dose-dependent decrease in the mitochondrial membrane potential of PC-3 cancer cells, that induces apoptosis along the mitochondrial pathway. Significant ROS production in PC-3 cells after their treatment with the lead compounds 2c,d was detected by flow cytometry using CellROX® Deep Red fluorogenic probe. Enzyme-linked immunosorbent assay (ELISA) found that the lead compounds activated apoptosis-initiating caspase-9 and blocked anti-apoptotic Bcl-2 protein in PC-3 cancer cells. This experimental fact was explained by molecular docking.

A series of conjugates of diterpenoid isosteviol (16-oxo-ent-beyran-19-oic acid) and uracil (nucleoterpenoids) was synthesized and examined for their in vitro cytotoxicity against 9 human cancer cell lines. Nucleoterpenoids 13c,f,15 exhibited the best in vitro cytotoxic activity against cancer cell lines M-HeLa, MCF-7, and PC3 (IC50 = 12.7-21.3 µM) among the synthesized compounds. The mechanisms of the in vitro cytotoxic effect of nucleoterpenoids 13f and 15 against M-HeLa cancer cell line (cervical carcinoma) were studied using flow cytofluorometry and enzyme-linked immunosorbent assay (ELISA). The results obtained indicated that 13f and 15 by acting on M-HeLa cancer cells reduced the mitochondrial membrane potential, caused oxidative stress, blocked anti-apoptotic protein Bcl-2, activated apoptosis-initiating caspase-9, thus inducing apoptosis occurring along the mitochondrial pathway. It should be emphasized that although isosteviol and uracil do not have cytotoxicity against human cancer cells, nucleoterpenoids 13c,f, and 15 containing isosteviol and uracil as fragments exhibited good cytotoxicity against M-HeLa, MCF-7, and PC3 cancer cells. Thus, it can be considered that conjugation of diterpenoid isosteviol and nucleic bases is a promising way to search for new cytotoxic agents of unusual structure.

Supramolecular systems based on amphiphilic triphenylphosphonium (TPP) conjugates of the diterpenoid isosteviol in which the diterpenoid skeleton and the TPP cation are linked by a polymethylene linker of varying length (n = 3, 6 or 8) have been fabricated. Elongation of this linker from 3 to 8 methylene units, allows for an 8-fold decrease in the amphiphile aggregation thresholds in aqueous solutions. These systems exhibit tunable self-assembly behavior, with the formation of both small aggregates (with a hydrodynamic diameter of ~5-10nm), as well as large vesicle-like structures (with a diameter of ~50-100nm), depending on the amphiphile concentration and length of the spacer fragment. The biotechnological potential of these amphiphiles has been demonstrated on the example of its membranotropic properties toward liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Significant capacity for integration into lipid bilayer has been revealed in these amphiphiles, which could be increased by extending the length of the polymethylene linker. Cationic liposome formulations have been prepared on the basis of these amphiphiles and DPPC by a noncovalent modification approach. Sustainability of its DH and zeta potential during longtime storage has been demonstrated. The studied systems exhibit a selective cytotoxic effect on M-HeLa cancer cell line and are a less toxic to normal Chang liver cells. The mechanism of the cytotoxic action of the liposomes is associated with the induction of apoptosis through mitochondrial pathway. The obtained formulations have successfully been applied for metronidazole encapsulation, characterized by high encapsulation efficiency and loading capacity, as well as prolonged time of drug release.

A series of new dimers of pyrimidine nucleoside analogues have been synthesized. The dimers are composed of two uracil or thymine fragments linked at N3 through a polymethylene bridge and bearing a β-D-ribofuranose residue linked to N1 of the nucleobase through a 1,2,3-triazolylalkyl spacer. Biological screening revealed that some of the synthesized dimers are active against influenza A (H1N1) virus and coxsackievirus B3 with IC50 values of 13 and 4.5 μM, respectively.

Based on the fact that a search for influenza antivirals among nucleoside analogues has drawn very little attention of chemists, the present study reports the synthesis of a series of 1,2,3-triazolyl nucleoside analogues in which a pyrimidine fragment is attached to the ribofuranosyl-1,2,3-triazol-4-yl moiety by a polymethylene linker of variable length. Target compounds were prepared by the Cu alkyne-azide cycloaddition (CuAAC) reaction. Derivatives of uracil, 6-methyluracil, 3,6-dimethyluracil, thymine and quinazolin-2,4-dione with ω-alkyne substituent at the N1 (or N5) atom and azido 2,3,5-tri-O-acetyl-D-β-ribofuranoside were used as components of the CuAAC reaction. All compounds synthesized were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1) and coxsackievirus B3. The best values of IC50 (inhibiting concentration) and SI (selectivity index) were demonstrated by the lead compound 4i in which the 1,2,3-triazolylribofuranosyl fragment is attached to the N1 atom of the quinazoline-2,4-dione moiety via a butylene linker (IC50 = 30 μM, SI = 24) and compound 8n in which the 1,2,3-triazolylribofuranosyl fragment is attached directly to the N5 atom of the 6-methyluracil moiety (IC50 = 15 μM, SI = 5). According to theoretical calculations, the antiviral activity of the 1,2,3-triazolyl nucleoside analogues 4i and 8n against H1N1 (A/PR/8/34) influenza virus can be explained by their influence on the functioning of the polymerase acidic protein (PA) of RNA-dependent RNA polymerase (RdRP).

Conjugates of the diterpenoid isosteviol with uracil and 6-methyluracil (nucleoterpenoids) were synthesized and showed moderate in vitro cytotoxicity (IC50 values in the range 11.6–51.0 μM) against M-HeLa, HuTu 80, and MCF-7 human cancer cells.

•Acetylenation of nucleobases gave them moderate cytotoxicity against cancer cells.•TPP-conjugates of acetylenated nucleobases exhibited IC50 values of 0.1–0.2 µM.•The selectivity index values reached 120–150.•Induction of apoptosis proceeding along the mitochondrial pathway.•The arrest of the cell cycle in the G0/G1 phase.

A series of the first conjugates of N -acetyl- D -glucosamine with alpha-aminophosphonates was synthesized using the Kabachnik-Fields reaction, the Pudovik reaction, a copper(I)-catalyzed azide-alkyne cycloaddition reaction (CuAAC) and evaluated for the in vitro cytotoxicity against human cancer cell lines M - HeLa, HuTu-80, A549, PANC-1, MCF-7, T98G and normal lung fibroblast cells WI -38. The tested conjugates, with exception of compound 21b , considered as a lead compound, were either inactive against the used cancer cells or showed moderate cytotoxicity in the range of IC 50 values 33-80 mu M. The lead compound 21b , being non cytotoxic against normal human cells WI -38 (IC 50 = 90 mu M), demonstrated good activity (IC 50 = 17 mu M) against breast adenocarcinoma cells (MCF-7) which to be 1.5 times higher than the activity of the used reference anticancer drug tamoxifen (IC 50 = 25.0 mu M). A flexible receptor molecular docking simulation showed that the cytotoxicity of the synthesized conjugates of N -acetyl- D -glucosamine with alpha-aminophosphonates against breast adenocarcinoma MCF-7 cell line is due to their ability to inhibit EGFR kinase domain. In addition, it was found that conjugates 22a and 22b demonstrated antioxidant activity that was not typical for alpha-aminophosphonates.

By covalent binding of 1,2,3-triazolyl nucleoside analogues by a polymethylene chain at the N3 atoms, a series of homodimers was synthesized, in which nucleic bases are replaced by quinazoline-2,4-dione moieties connected to the β-D-ribofuranose residues by 1,2,3-triazolylbutyl linkers. Screening of in vitro antiviral activity against influenza A (H1N1) and Coxsackie B3 viruses revealed a lead compound that showed high antiviral activity (IC50 = 11.6 μM) against influenza A/Puerto Rico/8/34 (H1N1) virus and a lead compound that exhibited high antiviral activity (IC50 = 12.2 μM) against enterovirus Coxsackie B3.

Two macrocyclic 1,2,3-triazolyl uridine analogues were obtained for the first time by a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. A 29-membered macrocycle consisted of one uracil molecule, two D-ribofuranose molecules and four 1,2,3-triazole molecules. A 58-membered macrocycle consisted of two uracil mol-ecules, four D-ribofuranose molecules and eight 1,2,3-triazole molecules. Both macro cycles demonstrated moderate cytotoxicity against eight human cancer cell lines and normal cell line WI-38.

A comparative analysis of in vitro antiviral activity (in terms of the concentration of semi-maximal inhibition, IC50) against influenza virus A/PR/8/34 (H1N1) of a large series of parent 1,2,3-triazolyl nucleoside analogues (with uracil, thymine, 6-methyluracil, quinazoline-2,4-dione moieties as nucleic bases) and their prodrug forms with masked 5ʹ-phosphate groups (diethyl phosphate, diphenyl phosphate, phosphoramidate) and negatively charged H-phosphonate and monophosphate groups was carried out. Obtained structure-activity relationships were interpreted based on the assumption that the synthesized parent 1,2,3-triazolyl nucleoside analogues and their prodrug forms, by analogy with the literature data, are metabolized by cellular kinases to their active 5ʹ-triphosphate forms that inhibit the activity of viral RNA-dependent RNA polymerase (RdRp). A correlation was found between the experimental values of IC50 and the theoretical values of the binding energies of 5ʹ-triphosphate derivatives of the parent 1,2,3-triazolyl nucleoside analogues in the active site of RdRp.

A series of 1,2,3-triazolyl nucleoside analogues bearing N-acetyl-D-glucosamine residue was synthesized by the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction of N1-omega-alkynyl derivatives of uracil, 6-methyluracil, thymine and 3,4,6-tri-O-acetyl-2-deoxy-2-acetamido-beta-D-glucopyranosyl azide. Antiviral assays revealed the lead compound 3f which showed both the same activity against the influenza virus A H1N1 (IC50=70.7 mu M) as the antiviral drug Rimantadine in control (IC50=77 mu M) and good activity against Coxsackievirus B3 (IC50=13.9 mu M) which was one and a half times higher than the activity of the antiviral drug Pleconaril in control (IC50=21.6 mu M). According to molecular docking simulations, the antiviral activity of the lead compound 3f against Coxsackie B3 virus can be explained by its binding to a key fragment of the capsid surface of this virus.

Vladimir Kataev explores the bonds and rifts that shaped the course of Chekhov’s writing, providing overviews of his acquaintance with prominent figures of his time, including Pablo de Sarasate, Nikolai Leskov, Leo Tolstoy, and Pyotr Tchaikovsky; and exploring his closer, more complex friendships with such figures as Vladimir Korolenko, Ivan Leontiev-Shcheglov, Vladimir Nemirovich-Danchenko, and Alexei Suvorin.

A series of 5′-phosphorylated (dialkyl phosphates, diaryl phosphates, phosphoramidates, H-phosphonates, phosphates) 1,2,3-triazolyl nucleoside analogues in which the 1,2,3-triazole-4-yl-β-D-ribofuranose fragment is attached via a methylene group or a butylene chain to the N-1 atom of the heterocycle moiety (uracil or quinazoline-2,4-dione) was synthesized. All compounds were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1). Antiviral assays revealed three compounds, 13b, 14b, and 17a, which showed moderate activity against influenza virus A (H1N1) with IC50 values of 17.9 μM, 51 μM, and 25 μM, respectively. In the first two compounds, the quinazoline-2,4-dione moiety is attached via a methylene or a butylene linker, respectively, to the 1,2,3-triazole-4-yl-β-D-ribofuranosyl fragment possessing a 5′-diphenyl phosphate substituent. In compound 17a, the uracil moiety is attached via the methylene unit to the 1,2,3-triazole-4-yl-β-D-ribofuranosyl fragment possessing a 5′-(phenyl methoxy-L-alaninyl)phosphate substituent. The remaining compounds appeared to be inactive against influenza virus A/PR/8/34/(H1N1). The results of molecular docking simulations indirectly confirmed the literature data that the inhibition of viral replication is carried out not by nucleoside analogues themselves, but by their 5′-triphosphate derivatives.

A series of 1,2,3-triazolyl nucleoside analogues in which 1,2,3-triazol-4-yl-β-d-ribofuranosyl fragments are attached via polymethylene linkers to both nitrogen atoms of the heterocycle moiety (uracil, 6-methyluracil, thymine, quinazoline-2,4-dione, alloxazine) or to the C-5 and N-3 atoms of the 6-methyluracil moiety was synthesized. All compounds synthesized were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1) and coxsackievirus B3. Antiviral assays revealed three compounds, 2i, 5i, 11c, which showed moderate activity against influenza virus A H1N1 with IC50 values of 57.5 µM, 24.3 µM, and 29.2 µM, respectively. In the first two nucleoside analogues, 1,2,3-triazol-4-yl-β-d-ribofuranosyl fragments are attached via butylene linkers to N-1 and N-3 atoms of the heterocycle moiety (6-methyluracil and alloxazine, respectively). In nucleoside analogue 11c, two 1,2,3-triazol-4-yl-2′,3′,5′-tri-O-acetyl-β-d-ribofuranose fragments are attached via propylene linkers to the C-5 and N-3 atoms of the 6-methyluracil moiety. Almost all synthesized 1,2,3-triazolyl nucleoside analogues showed no antiviral activity against the coxsackie B3 virus. Two exceptions are 1,2,3-triazolyl nucleoside analogs 2f and 5f, in which 1,2,3-triazol-4-yl-2′,3′,5′-tri-O-acetyl-β-d-ribofuranose fragments are attached to the C-5 and N-3 atoms of the heterocycle moiety (6-methyluracil and alloxazine respectively). These compounds exhibited high antiviral potency against the coxsackie B3 virus with IC50 values of 12.4 and 11.3 µM, respectively, although both were inactive against influenza virus A H1N1. According to theoretical calculations, the antiviral activity of the 1,2,3-triazolyl nucleoside analogues 2i, 5i, and 11c against the H1N1 (A/PR/8/34) influenza virus can be explained by their influence on the functioning of the polymerase acidic protein (PA) of RNA-dependent RNA polymerase (RdRp). As to the antiviral activity of nucleoside analogs 2f and 5f against coxsackievirus B3, it can be explained by their interaction with the coat proteins VP1 and VP2.