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. 2013 Dec 30;6(1):168-79.
doi: 10.3390/toxins6010168.

Effects of the amino acid constituents of microcystin variants on cytotoxicity to primary cultured rat hepatocytes

Kumiko Shimizu  1 , Tomoharu Sano  2 , Reiji Kubota  3 , Norihiro Kobayashi  4 , Maiko Tahara  5 , Tomoko Obama  6 , Naoki Sugimoto  7 , Tetsuji Nishimura  8 , Yoshiaki Ikarashi  9
Affiliations

Effects of the amino acid constituents of microcystin variants on cytotoxicity to primary cultured rat hepatocytes

Kumiko Shimizu et al. Toxins (Basel). .

Abstract

Microcystins, which are cyclic heptapeptides produced by some cyanobacterial species from algal blooms, strongly inhibit serine/threonine protein phosphatase and are known as hepatotoxins. Microcystins have many structural variations, yet insufficient information is available on the differences in the cytotoxic potentials among the structural variants. In this study, the cytotoxicities of 16 microcystin variants at concentrations of 0.03-10 μg/mL to primary cultured rat hepatocytes were determined by measuring cellular ATP content, and subsequently determined by their 50% inhibitory concentration (IC50). Differences in the amino acid constituents were associated with differences in cytotoxic potential. [D-Asp3, Z-Dhb7] microcystin-LR exhibited the strongest cytotoxicity at IC50 of 0.053 μg/mL among the microcystin variants tested. Furthermore, [d-Asp3, Z-Dhb7] microcystin-HtyR was also highly cytotoxic. These results suggest that both D-Asp and Z-Dhb residues are important in determining the cytotoxic potential of microcystin variants.

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Figures

Figure 1
Figure 1
Structures of the MC variants. MC variants are cyclic peptides consisting of seven amino acids. The sequence position numbers of the amino acids number are denoted by a superscript.
Figure 2
Figure 2
Cytotoxicities of the MC-LR variants in primary cultured rat hepatocytes after 72-h exposure, determined by the cell viability assay. Primary cultured rat hepatocytes were exposed to purified MC-LR, [Dha7] MC-LR, [d-Asp3] MC-LR, [d-Asp3, Dha7] MC-LR, [d-Asp3, E-Dhb7] MC-LR, [d-Asp3, Z-Dhb7] MC-LR. After 72 h of exposures, cytotoxicities were determined by the cell viability assay and the values are shown as % viability. Results are presented as the mean ± SD of three independent experiments. * Significantly different from the control: p < 0.05. (Compounds No.1: MC-LR (◊); No.2: [Dha7] MC-LR (▲); No.3: [d-Asp3] MC-LR (○); No.4: [d-Asp3, Dha7] MC-LR (■); No.5: [d-Asp3, E-Dhb7] MC-LR (∆); No.6: [d-Asp3, Z-Dhb7] MC-LR (□)).
Figure 3
Figure 3
Cytotoxicities of the MC-YR variants in primary cultured rat hepatocytes after 72-h exposure, determined by the cell viability assay. Primary cultured rat hepatocytes were exposed to MC-LR, MC-YR, [Dha7] MC-YR, [d-Asp3] MC-HtyR, [d-Asp3, E-Dhb7] MC-HtyR, [d-Asp3, Z-Dhb7] MC-YR. After 72 h of exposures, cytotoxicities were determined by the cell viability assay and the values were shown as % viability. Results are presented as the mean ± SD of three independent experiments. * Significantly different from the control: p < 0.05. (Compounds No.1: MC-LR (◊); No.7: MC-YR (♦); No.8: [Dha7] MC-YR (▲); No.9: [d-Asp3] MC-HtyR (○); No.10: [d-Asp3, E-Dhb7] MC-HtyR (∆); No.11: [D-Asp3, Z-Dhb7] MC-HtyR (□)).
Figure 4
Figure 4
Cytotoxicities of the MC-RR variants in primary cultured rat hepatocytes after 72-h exposure, determined by the cell viability assay. Primary cultured rat hepatocytes were exposed to MC-LR, MC-RR, [d-Asp3] MC-RR, [Dha7] MC-RR, [d-Asp3, Dha7] MC-RR, [d-Asp3, E-Dhb7] MC-RR. After 72 h of exposures, cytotoxicities were determined by the cell viability assay and the values were shown as % viability. Results are presented as the mean ± SD of three independent experiments. * Significantly different from the control: p < 0.05. (Compounds No.1: MC-LR (◊); No.12: MC-RR (●); No.13: [d-Asp3] MC-RR (○); No.14: [Dha7] MC-RR (▲); No. 15: [d-Asp3, Dha7] MC-RR (■); No.16, [d-Asp3, E-Dhb7] MC-RR (∆)).
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References

    1. Jochimsen E.M., Carmichael W.W., An J., Cardo D.M., Cookson S.T., Holmes C.E., Antunes M.B.C., de Melo Filho D.A., Lyra T.M., Barreto V.S.T., et al. Liver failure and death after exposure to microcystins at a hemodialysis center in Brazil. N. Engl. J. Med. 1998;338:873–878. doi: 10.1056/NEJM199803263381304. - DOI - PubMed
    1. Codd G.A., Bell S.G., Kaya K., Ward C.J., Beattle K.A., Metcalf J.S. Cyanobacterial toxins, exposure routes and human health. Eur. J. Physiol. 1999;34:405–415.
    1. Krishnamurthy T., Carmichael W.W., Sarver E.W. Toxic peptides from freshwater cyanobacteria (blue-green algae). I. Isolation, purification and characterization of peptides from Microcysis aeruginosa and Anabaena flos-aquae. Toxicon. 1986;24:865–873. doi: 10.1016/0041-0101(86)90087-5. - DOI - PubMed
    1. Watanabe M.F., Oishi S., Harada K., Matsuura K., Kawai H., Suzuki M. Toxins contained in Microcystis species of cyanobacteria (blue-green algae) Toxicon. 1988;26:1017–1025. doi: 10.1016/0041-0101(88)90200-0. - DOI - PubMed
    1. Paerl H.W., Otten T.G. Harmful cyanobacterial blooms: Causes, consequences, and controls. Microb. Ecol. 2013;65:995–1010. doi: 10.1007/s00248-012-0159-y. - DOI - PubMed

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