Cyanobacterial inhibitory compound

While protein kinases are responsible for the phosphorylation of their substrates, protein phosphatases perform the opposite duty, removing phosphate groups from their substrates, thus countering the functional impact of the kinases. The two major types of protein phosphatases are the serine/threonine phosphatases and tyrosine phosphatases. Several natural compounds with potent serine/threonine phosphatase inhibitory activity have been identified, including the cyanobacterial metabolite microcystin [105,106]. This compound labels its targets via a Michael addition of a noncatalytic active site cysteine residue with an acceptor in the macrocyclic peptide backbone [107]. A fluorescent probe based on microcystin was synthesized by Shreder et al., and its use in Jurkat lysates identified two previously undescribed phosphatase targets of microcystin, PP-4 and PP-5 [108]. Whereas serine/threonine... 

Phenylpropanoid-type compounds have been isolated as the algal inhibitory constituents from the aquatic plant Acorus gramineus [92] using a filter paper-dish bioassay. It was noted that 1,2-dimethoxy-4-(E-3 -methyloxiranyl) benzene (10), l,2,4-trimethoxy-5-(Z-l -propenyl)benzene (11), l,2,4-trimethoxy-5-(E-3 methyloxiranyl)benzene (12), the three most abundant phenylpropanes isolated, were either inhibitory or not in each of the cyanobacterial strains tested which included Anabaena flos-aquae, Nostoc commune, and Synechococcus leopoliensis. 

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