A bioassay of the toxic effects of aluminum chloride and aluminum sulfate using Auloforus (Dero furcata)

The analysis of the toxicity of aluminum salts is determined by the fact that aluminum cation is contained in drinking water, artificial dyes and additives, medicines, vaccines, aerosols, and there is also a correlation between the concentration of aluminum ion in brain tissues and clinical manifestations of Alzheimer’s disease. The article presents the results of biotesting the toxic effects of aluminum chloride and sulfate using Aulophorus (Dero furcata). Currently, the methods of bioassay do not have a generally recognized and standardized system of biological analysis, there are no unambiguous requirements that an indicator system should meet. These worms are a biotest object, because its reaction to the environment can be traced by its creation of conglomerates. The behavior of Auloforus in the experiment depends on the concentration, the time spent in aluminum solutions, as well as on the specific salt. When comparing the dynamics of the behavior of Auloforus in experimental samples of aluminum solutions, we established toxic concentrations. It was found that aluminum chloride salts have a less toxic effect than aluminum sulfate.

ASSESSMENT OF THE DEGREE OF POLLUTION OF BOTTOM SEDIMENTS IN SMALL RIVERS OF ROSTOV REGION

Purpose: to study the degree of pollution of bottom sediments of small rivers of the Rostov region. Materials and Methods: the research was carried out in 2019–2020 according to the decree of the Government of Rostov region of 25.09.2013 no. 595 and in accordance with the orders of the Ministry of Natural Resources and Environment no. 432 of 08.10.2014 and no. 112 of 24.02.2014. The work on monitoring the pollution of bottom sediments carried out by the authors included: samples selection, description, conservation, delivery and preparation; conducting an integral assessment of toxicity. The studies were carried out on microalgae according to the biotesting method for inhibiting the growth of unicellular algae Chlorella vulgaris Beijer and ciliates Paramecium caudatum. A sample was considered toxic if the value of the toxic effect was 50 % or more. In case of detecting high toxicity, the repeated sampling to determine the prevailing priority and specific pollutants was carried out. Results: according to the approved research program, 70 samples (33 in 2019, 37 in 2020) at 21 water bodies were selected. As a result of an integrated assessment of the toxicity of bottom sediments of water bodies, an excess was revealed only in two samples taken in 2019 at the site of the river Temernik. Conclusions: the results of biotesting did not reveal an excess of the permissible toxicity values in all areas of water bodies, except for the river Temernik, where a slight excess was revealed (55 %). In this case, when forming a program for the environmental protection measures implementation, more attention should be paid to a number of other environmental problems of water bodies in the region, among which a special place is taken by low water associated with both climate change and excessive water consumption for the needs of economic activities, land plowing to the water's edge, washing out dams and other blocking structures, including due to improper functioning of culverts.

Conjugate of podophyllotoxin with chlorambucil: synthesis, biological testing and molecular modeling

In the present work we have studied a novel conjugate of the DNA alkylating agent chlorambucil with podophyllotoxin, a ligand of the colchicine binding site in tubulin. The target compound was obtained by Steglich esterification of podophyllotoxin with the percentage yield of 41%. Results of biotesting carried out on the carcinoma A549 cell line revealed that at a concentration of 2 μM the conjugate caused full depolymerization of microtubules without any other effect on free tubulin. The conjugate inhibited proliferation (IC50=135±30 nM) and growth (EC50=240±30 nM) of A549 cells. The data of computer molecular docking of the novel compound into the 3D model of the colchicine binding site in α,β-tubulin and molecular dynamics modelling allowed to explain the observed difference in effects of chlorambucil-podophyllotoxin and chlorambucil-colchicine conjugates on microtubules.

Podophyllotoxin analogue with bicyclo[3.2.1]octane moiety annelated with indole: synthesis, molecular modeling, and biological testing

C4-Ester derivatives of the anticancer agent podophyllotoxin with bridged moieties can either inhibit polymerization of alpha,beta-tubulin with the formation of microtubules (analogously to the parent molecule) or cause an unusual effect of “curling and shortening” of the microtubules (MT). In order to predict the effect of bridged podophyllotoxin derivatives on the MT network using computer molecular modeling it is desirable to enhance the structural diversity of their bridged substituents. In the present work we synthesized novel podophyllotoxin ester with bicyclo[3.2.1]octane moiety annelated with indole core. The target compound was obtained by Steglich esterification of podophyllotoxin by rac-exo-(indolo[2,3-b])bicyclo[3.2.1]oct-2-ene-6-carboxylic acid as diastereomeric (6RS,8SR,9RS) mixture, which could not be separated by thin layer or preparative column chromatography on silica gel. Results of biotesting of 4-O-{(6R,8S,9R)-5,6,7,8,9,10-hexahydro-6,9-methanocyclohepto[b]indol-8-ylcarbonyl}-Lpodophyllotoxin on the carcinoma A549 cells proved its ability to cause full depolymerization of microtubules without curling effect at a concentration 10 μM. Cytotoxicity value of the compound estimated in MTT test was in a high nanomolar concentration interval (EC50=710±30 nM). Computer molecular docking of both isomers of novel compound and earlier synthesized podophyllotoxin esters with bridged moieties into the 3D model of the colchicine domain in alpha,beta-tubulin revealed the difference in positions of the bridge moieties of new compound and MT-curling ligands and allowed to hypothesize that the atypical action on MT might be caused by positioning of their bridge groups near the GTP binding site in alpha-tubulin.

Zooplankton of Mokraya Sura River

Structural and functional characteristics of zooplankton as well as the results of biotesting were researched to indicate the ecological status of Mokraya Sura river sites. Zooplankton sampling was performed at the sites of Mokraya Sura river in autumn 2014 and in spring 2015. Species composition and abundance of zooplankton showed that zooplankton is most depressed at the upper sites of the river due to joint effect of slime accumulation eutrophication and industrial sewage. Biotesting results estimated water quality of the site near aeration plant sewage emergency discharge as most polluted of the river sites where large abundance and biomass of zooplankton were created mostly by planktonic rotifers. Large figures of filter-seeding crustaceans as well as low saprobity index indicate improvement in water quality at the sites 3 km and 2 km upstream from the river mouth.