Laser interference microscopy (LIM) is a promising label-free method for single-cell research applicable to cell viability assessment in the studies of mammalian cells. This paper describes the development of a sensitive and reproducible method for assessing cell viability using LIM. The method, based on associated signal processing techniques, has been developed as a result of real-time investigation in phase thickness fluctuations of viable and non-viable MCF-7 cells, reflecting the presence and absence of their metabolic activity. As evinced by the values of the variable v_c, this variable determines the viability of a cell only in the attached state (v_c exceeds 20 nm² for viable attached cells). The critical value of the power spectrum slope β_c of the phase thickness fluctuations equals 1.00 for attached MCF-7 cells and 0.71 for suspended cells. The slope of the phase fluctuations’ power spectrum for MCF-7 cells was determined to exceed the threshold value of β_c for a living cell, otherwise the cell is dead. The results evince the power spectrum slope as the most appropriate indicator of cell viability, while the integrated evaluation criterion (v_c and β_c values) can be used to assay the viability of attached cells.

Multidrug resistance (MDR) is a common phenomenon in clinical oncology, whereby cancer cells become resistant to chemotherapeutic drugs. A common MDR mechanism is the overexpression of ATP-binding cassette efflux transporters in cancer cells, with P-glycoprotein (P-gp) being one of them. New 3,4-seco-lupane triterpenoids, and the products of their intramolecular cyclization with the removed 4,4-gem-dimethyl group, were synthesized by the selective transformations of the A-ring of dihydrobetulin. Among the semi-synthetic derivatives, the MT-assay-enabled methyl ketone 31 (MK), exhibiting the highest cytotoxicity (0.7–16.6 µM) against nine human cancer cell lines, including P-gp overexpressing subclone HBL-100/Dox, is identified. In silico, MK has been classified as a potential P-gp-inhibitor; however, the Rhodamine 123 efflux test, and the combined use of P-gp-inhibitor verapamil with MK in vitro, showed the latter to be neither an inhibitor nor a substrate of P-gp. As the studies have shown, the cytotoxic effect of MK against HBL-100/Dox cells is, arguably, induced through the activation of the ROS-mediated mitochondrial pathway, as evidenced by the positive Annexin V-FITC staining of apoptotic cells, the cell cycle arrest in the G0/G1 phase, mitochondrial dysfunction, cytochrome c release, and the activation of caspase-9 and -3.

The epoxidation process of semi-synthetic triterpenoids 2-methyl-3-oxo-19β,28-epoxy- 18α-olean-1-ene, and its allylic alcohol derivatives were examined. 1,2α-epoxide, as the main product, was found to be formed from the starting enone exposed to m-chloroperbenzoic acid (mCPBA). In the case of hydroxy-directed mCPBA-oxidation of triterpenic allyl alcohols and their 3α-alkyl-substituted derivatives, inversion of C1 and C2 asymmetric centers with the formation of 1,2β-epoxyalcohols took place. The synthesis of 2,3α-epoxides was fulfilled from 2,3-dialkyl-substituted C(3) allyl alcohols by the action of pyridinium chlorochromate under [1,3]-oxidative rearrangement conditions. The transformations brought about enabled chiral oleanane derivatives with an oxygen-containing substituent at the C1, C2, and C3 atoms to be obtained. The study also provides information on in silico PASS prediction of pharmacological effects and in vitro evaluation of the cytotoxic activity of the synthesized compounds.

Tris(diethylamino)diallylaminophosphonium tetrafluoroborate (DAAP-BF4) and chloride (DAAP-Cl) with N-vinylpyrrolidone (VP) were developed. The reduction of silver ions into silver nanoparticles was achieved using NaBH4 as a reducing agent. UV-spectroscopy and scanning electron microscopy techniques were used to characterize the formation of silver nanoparticles in copolymers. The average silver particle size ranged from 10 to 20 nm, with the corresponding UV-vis absorption peak position at 395–405 nm. The AgNCs exhibited significant cytotoxic activity towards rhabdomyosarcoma and melanoma line cells and completely inhibited bacterial growth, including both Gram-positive and Gram-negative bacteria.

New data on the phylogenetic diversity of bacteria in the salt of the Verkhnekamskoe deposit (Perm Krai) have been obtained using molecular genetic methods. Analysis of the 16S rRNA genes of total DNA from the rock salt sample (depth intervals of 239.7-239 m) evinces the presence of bacteria belonging to the classes: Actinobacteria (closely related to the genera Rhodococcus, Demequina), Gammaproteobacteria (the genera Pseudomonas, Serratia, Shigella), Betaproteobacteria (the genus Ralstonia) and Alphaproteobacteria (the genus Phyllobacterium). In addition, we identified two phylotypes of the Alphaproteobacteria (clone 66BA (GenBank MH410136) and clone 12BA (GenBank MH410128) that show lower similarity in 16S rRNA genes (98.46%) with the closest type strains of the genus Mesorhizobium (M. alhagi CCNWXJ12-2T) and the genus Chelativorans (C. multitrophicus DSM9103T). The identified phylotypes may represent new taxonomic units.