Purification of cyanobacterial toxin, microcystins, by DEAE and Strata-X SPE chromatography

Abstract

The lyophilized cells (20 grams) of cyanobacterial bloom from Bueng Nong Khot, Khon Kaen province was extracted and purified and a mixture of microcystins (MCs) were identified. The toxins were purified with DEAE and Strata-X SPE cartridge chromatography and identified by reversed-phase HPLC with photodiode-array UV detection (UVD) and liquid chromatography-tandem mass spectrometry (LC-MS). Chemical characterization of the lyophilized cells revealed three variants of MCs, including MC-RR; MC-FR and [Dha⁷]MC-LR) of which [Dha⁷]MC-LR was the major variant extracted with a purity of 93% and yield of 25.38 mg. [Dha⁷]MC-LR is MC-LR which is the loss of a methyl group which occurs at the amino acid, Mdha, resulting in [Dha⁷]MC-LR The main variant appears to be [Dha⁷]MC-LR not MC-LR as seen in lakes overseas. These toxins have been implicated in animal deaths and human illness. They are extremely stable and may persist in water bodies for several weeks. Knowledge of the MC-variants present in the water bodies will help in further investigations in eliminating them.