Stability of some microginins synthesized by the cyanobacterium Woronichinia naegeliana (Unger) Elenkin

Abstract

Summary Microginins are linear oligopeptides synthesized by cyanobacteria. The literature data on their characteristics are scant. This study examined the influence of abiotic factors including pH, temperature, visible and ultraviolet radiation on the stability of the microginins FR3 (MG‐FR3), FR4 (MG‐FR4) and 757 (MG‐757) synthesized by Woronichinia naegeliana. In alkaline conditions (pH 9) only the concentration of MG‐757 was reduced significantly, by 14.3%. The tested microginins were stable at room temperature (half‐life 7–17 weeks). Boiling for one hour caused 26.1% decomposition of MG‐FR4 and 26.8% decomposition of MG‐757; MG‐FR3 was not significantly affected. Under visible radiation the initial content of MG‐FR4 declined 23.0%, but MG‐FR3 and MG‐757 proved insensitive to it. Treatment with a high dose of UV radiation (36 μmol m−2 s−1) caused the tested microginins to degrade by 13.8% to 21.4%. The study showed these microginins to be oligopeptides of high stability, the most stable of them being MG‐FR3.

Effect of abiotic factors on the stability of chosen oligopeptides isolated from the freshwater cyanobacterium Woronichinia naegeliana

“…A similar observation was made for the cyanobacterial alkaloids anatoxin-a or cylindrospermopsin (Kaminski et al 2013;Adamski et al 2016a). Data for other cyanopeptides, such as microcystin-LR or microginin FR3, indicate that they are relatively more resistance to boiling compared to the studied compounds (Harada et al 1996;Bober et al 2014).…”

“…anatoxin-a, anatoxin-a(s), cylindrospermopsin), as well as linear microginins (e.g. microginin-757), showed higher stability under acidic conditions than at alkaline pH (Matsunaga et al 1989;Harada et al 1996;Kaminski et al 2013;Bober et al 2014;Adamski et al 2016a). In contrast, acidification and alkalization of ANB-899 samples had a non-significant effect on the change in its content, which was determined to be about 30% after 12 weeks (Fig.…”

Determination of the toxicity of the freshwater cyanobacterium Woronichinia naegeliana (Unger) Elenkin

“…The difference between the LC 50 of separated fractions and that obtained for the total W. naegeliana extract might be the result of the synergic effect of all the compounds. Most of the metabolites synthesized by W. naegeliana (Bober et al 2011 , 2014 ) belong to several classes of oligopeptides, which non-ribosomal synthesis is a significant part of cell metabolism (Welker and von Döhren 2006 ). Although their ecological role has not been fully elucidated, their inhibitory activity against proteases indicates that they are able to affect other organisms, even causing cell lysis.…”