DOI: 10.5176/2251-2489_BioTech46
Authors: Sanjay Verma and Ashwin Kumar
Abstract: For hundreds of years, harmful algal blooms and Cyanotoxins have been associated with incidents of animal poisonings and outbreaks of human illness. Eutrophication has been a constant problem due to its association with the formation of cyanobacterial blooms. WHO has adopted provisional guideline values for drinking water supplies of 1μg/ml Microcystin-LR (MC-LR) based on the sub-acute toxicity of MC-LR in in-vivo models. Most of the variants of microcystins known today are specific Serine/threonine protein phosphatases inhibitors, which are potent tumour promoters with the general structure of Cyclo-(D-Ala1-X2-D-MeAsp3-Z4-Adda5-D-Glu6-Madha7). The difference in toxicity of different varients of microcystin is attributed to different functional group with varying long chains fatty acids. The present study shows the tumourogenic potential of filamentous cyanobacteria Anabaena doliolum and Nostoc spongiaeforme present in the water blooms in the Shekawati region of India. Crude Methanolic extracts of these isolates showed high level of hepatotoxicity and tumour promoting activity in in-vivo mouse bioassay model. The crude methanolic extracts (150μg of total protein/kg of body weight injected intraperitonially) showed restlessness, spasmodic leaping, fast breathing, slow movement, loss of co-ordination within 40 mins of administration. Partially purified toxins on TLC with silica gel G60 plates showed four spots with both Anabaena doliolum and Nostoc spongiaeforme extracts. One spot each from Anabaena doliolum (Ad spot-3) and Nostoc spongiaeforme (Ns spot-3) was shown to be highly toxic and was subjected for further investigation. The chronic toxicity studies of partially purified toxins at a dose of 20μg of total protein/kg of body weight have shown an increase in oxidative stress (MDA level), SGOT, SGPT, ALP, Serum LDL levels. Ad spot-3 showed a tumour promotion in colon whereas Ns spot-3 induced intestinal tumour in Swiss albino mice model. Spectral peak, Rf valve of these spots and toxicity of partially purified compounds indicate that the active fraction in these organisms belong to the family of Microcystin.
Keywords: Cyanobacteria, Cyanotoxins, Colon tumour, Intestinal tumour, Shekhawati, Water bloom, Microcystin, Eutrophicated pond, Anabaena doliolum, Nostoc spongiaeforme.
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