Growth inhibition and oxidative stress of cyanobacteria induced by sanguinarine and 6-methoxy-dihydrochelerythrine isolated from Macleaya microcarpa

摘要

To investigate the algicidal allelochemicals from Macleaya microcarpa we used the activity-guided isolation. Five solvents (petroleum ether, chloroform, acetone, ethanol and water) were employed for the extraction of M. microcarpa. Among them, only the ethanol extract was active (7d-EC50 = 95.52 mg L-1) and hence, was subjected to further isolation and purification using various chromatographic techniques. Two benzophenanthridine alkaloids with potent algicidal activity, sanguinarine and 6-methoxy-dihydrochelerythrine were isolated. The algicidal effects of these compounds were species-specific, both sanguinarine and 6-methoxy-dihydrochelerythrine were active against Microcystis aeruginosa with 3 d-EC50 values of 0.47 and 3.43 mg L-1, and the 7 d-EC50 values of 0.36 and 2.87 mg L-1, respectively. However, sanguinarine showed low inhibition on Chlorella pyrenoidosa and Scenedesmus obliquus with 3 d-EC50 values of 5.32 and 9.70 mg L-1, respectively. 6-Methoxy-dihydrochelerythrine had little effect on C. pyrenoidosa and S. obliquus. The active compounds could cause oxidative damage in M. aeruginosa based on the observed malondialdehyde (MDA) content decrease in superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC). These results indicated that M. microcarpa extract and the isolated allelochemicals may serve as new agents for controlling the growth of toxic M. aeruginosa in eutrophic water bodies.