Development of an LC-MS/MS-based method for quantification and pharmacokinetics study on SCID mice of a dehydroabietylamine-adamantylamine conjugate, a promising inhibitor of the DNA repair enzyme.

Earlier, it was found that the agent KS-389, a conjugate of dehydroabietylamine and 1-aminoadamantane, possess inhibiting activity with regard to Tdp1. It this study, LC-MS/MS-based methods of quantification of KS-389 in mice blood and several organs (brain, liver and kidney) were developed and validated. Validation of the methods was performed according to the guidelines of U.S. Food and Drug Administration and European Medicines Agency in terms of selectivity, linearity, accuracy, precision, recovery, matrix effect, stability and carry-over. Dried blood spots (DBS) method was used for blood sample preparation. HPLC separation was performed on a reversed-phase column; the total analysis time was 12 min. Mass spectral detection was performed on a 6500 QTRAP mass spectrometer in multiple reaction monitoring mode. Transitions 463.5→135.1/107.2 and 336.2→332.2/176.2 were scanned for KS-389 and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole used as the internal standard, respectively. Pharmacokinetics of the compound as well as its distribution in the organs were studied on SCID mice after intraperitoneal administration of the substance at a dose of 5 mg/kg, and it was found that its maximum concentration in blood is reached in 1-1.5 h and was 80 ng/mL. The maximum concentration in all organs is reached after the same time and is approximately 1500 ng/g and 1100 ng/g in liver and kidney, respectively. This is the first report on the pharmacokinetics of Tdp1 inhibitor based on dehydroabietylamine and 1-aminoadamantane after a single administration to mice. Also, the substance was found to be able to penetrate the blood-brain barrier which is important for, and its maximum concentration was c.a. 25-30 ng/g. These results are important for glioma treatment and make it promising for this purpose.

Synthesis and Antiviral Properties of Camphor-Derived Iminothiazolidine-4-Ones and 2,3-Dihydrothiazoles.

A set of heterocyclic products was synthesized from natural (+)-camphor and semi-synthetic (-)-camphor. Then, 2-Imino-4-thiazolidinones and 2,3-dihydrothiazoles were obtained using a three-step procedure. For the synthesized compounds, their antiviral activity against the vaccinia virus and Marburg virus was studied. New promising agents active against both viruses were found among the tested compounds.

Design, Synthesis, and Biological Evaluation of (+)-Camphor- and (-)-Fenchone-Based Derivatives as Potent Orthopoxvirus Inhibitors.

In this work, a library of (+)-camphor and (-)-fenchone based N-acylhydrazones, amides, and esters, including para-substituted aromatic/hetaromatic/cyclohexane ring was synthesized, with potent orthopoxvirus inhibitors identified among them. Investigations of the structure-activity relationship revealed the significance of the substituent at the para-position of the aromatic ring. Also, the nature of the linker between a hydrophobic moiety and aromatic ring was clarified. Derivatives with p-Cl, p-Br, p-CF3, and p-NO2 substituted aromatic ring and derivatives with cyclohexane ring showed the highest antiviral activity against vaccinia virus, cowpox, and ectromelia virus. The hydrazone and the amide group were more favourable as a linker for antiviral activity than the ester group. Compounds 3 b and 7 e with high antiviral activity were examined using the time-of-addition assay and molecular docking study. The results revealed the tested compounds to inhibit the late processes of the orthopoxvirus replication cycle and the p37 viral protein to be a possible biological target.

Discovery of New Ginsenol-Like Compounds with High Antiviral Activity.

A number of framework amides with a ginsenol backbone have been synthesized using the Ritter reaction. We named the acetamide as Ginsamide. A method was developed for the synthesis of the corresponding amine and thioacetamide. The new compounds revealed a high activity against H1N1 influenza, which was confirmed using an animal model. Biological experiments were performed to determine the mechanism of action of the new agents, a ginsamide-resistant strain of influenza virus was obtained, and the pathogenicity of the resistant strain and the control strain was studied. It was shown that the emergence of resistance to Ginsamide was accompanied by a reduction in the pathogenicity of the influenza virus.

Design, Synthesis, and Molecular Docking Study of New Tyrosyl-DNA Phosphodiesterase 1 (TDP1) Inhibitors Combining Resin Acids and Adamantane Moieties.

In this paper, a series of novel abietyl and dehydroabietyl ureas, thioureas, amides, and thioamides bearing adamantane moieties were designed, synthesized, and evaluated for their inhibitory activities against tyrosil-DNA-phosphodiesterase 1 (TDP1). The synthesized compounds were able to inhibit TDP1 at micromolar concentrations (0.19-2.3 µM) and demonstrated low cytotoxicity in the T98G glioma cell line. The effect of the terpene fragment, the linker structure, and the adamantane residue on the biological properties of the new compounds was investigated. Based on molecular docking results, we suppose that adamantane derivatives of resin acids bind to the TDP1 covalent intermediate, forming a hydrogen bond with Ser463 and hydrophobic contacts with the Phe259 and Trp590 residues and the oligonucleotide fragment of the substrate.

New class of hantaan virus inhibitors based on conjugation of the isoindole fragment to (+)-camphor or (-)-fenchone hydrazonesv.

This work presents the design and synthesis of camphor, fenchone, and norcamphor N-acylhydrazone derivatives as a new class of inhibitors of the Hantaan virus, which causes haemorrhagic fever with renal syndrome (HFRS). A cytopathic model was developed for testing chemotherapeutics against the Hantaan virus, strain 76-118. In addition, a study of the antiviral activity was carried out using a pseudoviral system. It was found that the hit compound possesses significant activity (IC50 = 7.6 ± 2 µM) along with low toxicity (CC50 > 1000 µM). Using molecular docking procedures, the binding with Hantavirus nucleoprotein was evaluated and the correlation between the structure of the synthesised compounds and the antiviral activity was established.

(+)-Camphor and (-)-borneol derivatives as potential anti-orthopoxvirus agents.

Although the World Health Organisation had announced that smallpox was eradicated over 40 years ago, the disease and other related pathogenic poxviruses such as monkeypox remain potential bioterrorist weapons and could also re-emerge as natural infections. We have previously reported (+)-camphor and (-)-borneol derivatives with an antiviral activity against the vaccinia virus. This virus is similar to the variola virus (VARV), the causative agent of smallpox, but can be studied at BSL-2 facilities. In the present study, we evaluated the antiviral activity of the most potent compounds against VARV, cowpox virus, and ectromelia virus (ECTV). Among the compounds tested, 4-bromo-N'-((1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)benzohydrazide 18 is the most effective compound against various orthopoxviruses, including VARV, with an EC50 value of 13.9 µM and a selectivity index of 206. Also, (+)-camphor thiosemicarbazone 9 was found to be active against VARV and ECTV.

Dehydroabietylamine-based thiazolidin-4-ones and 2-thioxoimidazolidin-4-ones as novel tyrosyl-DNA phosphodiesterase 1 inhibitors.

Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a DNA repair enzyme that plays a key role in repairing damage caused by various antitumor drugs. It is a promising target in medicinal chemistry for the creation of cancer adjuvant therapy. Inhibition of this enzyme together with the use of anticancer chemotherapy enhances the effect of the latter. The natural mutant of TDP1, TDP1(H493R), causes severe neurodegenerative disease spinocerebellar ataxia syndrome with axonal neuropathy (SCAN1). Inhibition of TDP1(H493R) appears to be useful in containment the progression of the disease. A library of compounds was synthesized starting from dehydroabietylamine including heterocyclic pharmacophore groups in the core. To obtain the desired products, the starting dehydroabietylamine was introduced sequentially in reaction with isothiocyanate and ethyl bromoacetate. Different classes of heterocyclic derivatives-2-iminothiazolidin-4-ons and 2-thioxoimidazolidin-4-ones-were obtained depending on the addition order of reagents. 2-Iminothiazolidin-4-thiones were obtained from 2-iminothiazolidin-4-ones under the action of the Lawesson's reagent. Effective TDP1 inhibitors were found among the obtained compounds that work in submicromolar concentrations. The inhibitor of TDP1(H493R) was also detected.

Zhurkov's Stress-Driven Fracture as a Driving Force of the Microcrystalline Cellulose Formation.

Microcrystalline cellulose (MCC) is a chemically pure product of cellulose mechano-chemical conversion. It is a white powder composed of the short fragments of the plant cells widely used in the modern food industry and pharmaceutics. The acid hydrolysis of the bleached lignin-free cellulose raw is the main and necessary stage of MCC production. For this reason, the acid hydrolysis is generally accepted to be the driving force of the fragmentation of the initial cellulose fibers into MCC particles. However, the low sensibility of the MCC properties to repeating the hydrolysis forces doubting this point of view. The sharp, cleave-looking edges of the MCC particles suggesting the initial cellulose fibers were fractured; hence the hydrolysis made them brittle. Zhurkov showed that mechanical stress decreases the activation energy of the polymer fracture, which correlates with the elevated enthalpy of the MCC thermal destruction compared to the initial cellulose.

Dehydroabietylamine Ureas and Thioureas as Tyrosyl-DNA Phosphodiesterase 1 Inhibitors That Enhance the Antitumor Effect of Temozolomide on Glioblastoma Cells.

A new class of tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors was found among resin acid derivatives. Several novel ureas and thioureas derived from dehydroabietylamine were synthesized and tested for TDP1 inhibition. The synthesized compounds showed IC50 values in the range of 0.1 to 3.7 µM and demonstrated low cytotoxicity against the human tumor cell lines U-937, U-87MG, MDA-MB, SK-Mel8, A-549, MCF7, T98G, and SNB19. Several compounds showed enhancement of the cytotoxic activity of the alkylating agent temozolomide, which is used as a first line therapy against glioblastoma (GBM), in the GBM cell lines U-87MG and SNB19.

Synthesis of d-(+)-camphor-based N-acylhydrazones and their antiviral activity.

The design and synthesis of a series of novel d-(+)-camphor N-acylhydrazones exhibiting inhibitory activity against vaccinia and influenza viruses are presented. An easy pathway to camphor-based N-acylhydrazones containing in their structure aliphatic, aromatic, and heterocyclic pharmacophore scaffolds has been developed. The conformation and configuration of the synthesized hydrazones were thoroughly characterized by a complete set of spectral characterization techniques, including 2D NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. In vitro screening for activity against vaccinia virus (VV) and influenza H1N1 virus was carried out for the obtained compounds. It was revealed that the derived N-acylhydrazones exhibited significant antiviral activity with a selectivity index >280 against VV for the most promising compound.