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1.
Structure optimisation of biopigment prodigiosin from Serratia marcescens ATCC 27117 and antimicrobial and anticancer properties of novel halogenated derivatives
Jelena Lazić, 2022, doctoral dissertation

Abstract: Prodigiosins (PGs) are a class of bacterial secondary metabolites with remarkable biological activities and colour. In this study, optimised fermentative production of prodigiosin (PG) using waste processed meat as a substrate has been achieved to levels of 83.1 ± 3.0 mg/L from a commercially available Serratia marcescens ATCC 27117 strain within 12 h. Methods were established for the reliable PG extraction from both the bacterial cell pellet and the culture supernatant, while gravitation column chromatography was used to obtain pure bacterial PG. The structure of the isolated PG was optimised by environmentally acceptable oxidative bromination reactions, obtaining mono- and dibrominated derivatives (PG-Br and PG-Br2). Chemical structures were confirmed by structural characterisation using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), showing that PG-Br is a mixture of two monobrominated isomers in approximately equal ratios, while PG-Br2 was afforded as a pure derivative. PG and its brominated derivatives (Br-derivatives) showed anticancer potential with half-maximal inhibitory concentration (IC50) values ranging from 0.62 to 17.00 μg/mL on four tested cancer cell lines (A549 lung, A375 skin, MDA-MB-231 breast, HCT116 colon) and an induction of early apoptosis, but low selectivity against healthy cell lines (MRC-5 lung fibroblasts and HaCaT skin keratinocytes). All three PG, PG-Br and PG-Br2 compounds did not affect roundworms (Caenorhabditis elegans) at concentrations up to 50 μg/mL. However, an improved toxicity profile of Br-derivatives in comparison to the parent PG was observed in vivo using zebrafish (Danio rerio) model system, when 10 μg/mL applied at 6 h post fertilisation caused death rate of 100, 30 and 0% by PG, PG-Br and PG-Br2, respectively, which is a significant finding for further structural optimisations of bacterial PGs.
Keywords: prodigiosin, Serratia marcescens, meat waste, halogenation, novel derivatives, anticancer activity, apoptosis, zebrafish embryotoxicity
Published in RUNG: 21.10.2022; Views: 1495; Downloads: 31
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2.
Chitosan and their derivatives: Antibiofilm drugs against pathogenic bacteria
Fazlurrahman Khan, Dong Pham, Sandra Oloketuyi, Panchanathan Manivasagan, Junghwan Oh, Young-Mog Kim, 2020, review article

Abstract: Biofilm formed by several pathogenic bacteria results in the development of resistance against antimicrobial compounds. The polymeric materials present in the biofilm architecture hinder the entry of antimicrobial compounds through the surface of bacterial cells which are embedded as well as enclosed beneath the biofilm matrix. Recent and past studies explored the alternative approaches to inhibit the formation of biofilm by different agents isolated from plants, animals, and microbes. Among these agents, chitosan and its derivatives have got more attention due to their properties such as biodegradability, biocompatibility, non-allergenic and non-toxicity. Recent researches have focused on employing chitosan and its derivatives as effective agents to inhibit biofilm formation and attenuate virulence properties by various pathogenic bacteria. Such antibiofilm activity of chitosan and its derivatives can be further enhanced by conjugation with a wide range of bioactive compounds. The present review describes the antibiofilm properties of chitosan and its derivatives against the pathogenic bacteria. This review also summarizes the mechanisms of biofilm inhibition exhibited by these molecules. The knowledge of the antibiofilm activities of chitosan and its derivatives as well as their underlying mechanisms provides essential insights for widening their applications in the future.
Keywords: Antibiofilm, Biofilm inhibition, Chitosan, Chitosan derivatives, Pathogenic bacteria
Published in RUNG: 14.01.2021; Views: 2341; Downloads: 0
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