In this study, a water-soluble metal-free phthalocyanine (SPC) containing sodium 2-mercaptoethanesulfonate substituents at the peripheral positions was used to investigate the algaecidal properties and oxidative effects on the growth of two microalgal species, Arthrospira platensis and Chlorella vulgaris. Although OD at 560 nm and chlorophyll-a content were decreased in Arthrospira platensis during 7 days depending on dose and time, increases in both OD at 750 and chlorophyll-a content at 8 ppb (parts per billion) concentration on the 7th day were observed in Chlorella vulgaris. However, total SOD (superoxide dismutase) and GR (glutathione reductase) enzyme activity of A. platensis cultures did not display any alteration in all concentrations, SOD activity displayed an increase significantly at 2 ppb concentration, and GR activity showed increases at 1, 2, and 4 ppb concentrations in C. vulgaris application. In A. platensis application, APX (ascorbate peroxidase) activity decreased at 0.50 ppb, 1 ppb, and 1.5 ppb concentrations. In addition, C. vulgaris application showed decreases at all concentrations. When MDA content increased at all concentrations, the H2O2 content increased only at significatly 0.125 ppb concentration in A. platensis cultures. Both MDA (malondialdehyde) and H2O2 (hydrogen peroxide) content of C. vulgaris cultures showed a statistically significant decrease at all concentrations compared to control. Free proline decreased at 0.25 ppb, 0.50 ppb, 1 ppb, and 1.5 ppb concentrations in A. platensis application, and it decreased at all the concentrations of C. vulgaris application. It concluded that this compound has inhibition effects on A. platensis, but it supports growth in C. vulgaris. Therefore, this synthesized phthalocyanine compound (SPC) should be consumed carefully, and the contamination to aquatic ecosystems should be prevented.
Keywords: Microalgae; antioxidant; growth rate; oxidative stress; sulfonated phthalocyanine.
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