Effects of Dihydroartemisinin and Artemether on the Growth, Chlorophyll Fluorescence, and Extracellular Alkaline Phosphatase Activity of the Cyanobacterium Microcystis aeruginosa

Abstract

Increased eutrophication in the recent years has resulted in considerable research focus on identification of methods for preventing cyanobacterial blooms that are rapid and efficient. The objectives of this study were to investigate the effects of dihydroartemisinin and artemether on the growth of Microcystis aeruginosa and to elucidate its mode of action. Variations in cell density, chlorophyll a, soluble protein, malondialdehyde, extracellular alkaline phosphatase activity (APA), and chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, ETR, rapid light curves, fast chlorophyll fluorescence curves on fluorescence intensity, and relative variable fluorescence) were evaluated by lab-cultured experiments. Our results demonstrated that both dihydroartemisinin and artemether inhibited the growth of M.aeruginosa by impairing the photosynthetic center in photosystem II and reducing extracellular APA, with a higher sensitivity exhibited toward artemether. The inhibitory effects of dihydroartemisinin on M.aeruginosa increased with concentration, and the maximum growth inhibitory rate was 42.17% at 24 mg·L-1 after 120h exposure, whereas it was 55.72% at 6 mg·L-1 artemetherafter 120h exposure. Moreover, the chlorophyll fluorescence was significantly inhibited (p<0.05) after 120h exposure to 12 and 24 mg·L-1 dihydroartemisinin. Furthermore, after 120h exposure to 6 mg·L-1 artemether, Fv/Fm, ΦPSII, ETR and rETRmax showed a significant decrease (p<0.01) from initial values of 0.490, 0.516, 17.333, and 104.800, respectively, to 0. One-way analysis of variance showed that 6 mg·L-1 artemether and 24 mg·L-1 dihydroartemisinin had significant inhibitory effects on extracellular APA (p<0.01). The results of this study would be useful to further studies to validate the feasibility of dihydroartemisinin and artemether treatment to inhibit overall cyanobacterial growth in water bodies, before this can be put into practice.

Ocorrência e ecotoxicidade de antidepressivos residuais em amostras do Rio Piracicaba (SP)

“…As consequências da ocorrência dos fármacos no ambiente ainda estão sendo pesquisadas e discutidas. Estudos já apontam algumas sequelas relacionadas a presença dessas substâncias, como interferência no crescimento, alterações no metabolismo celular, interferência na fotossíntese e na estrutura da comunidade do fitoplâncton, resistência bacteriana, alteração no cloroplasto de algas, bioacumulação, biomagnificação, redução da capacidade de resposta do sistema imunológico de invertebrados, alteração na natação, alteração na reprodução e no comportamento de anfípodes e cladóceros, etc (BONNEFILLE et al, 2017(BONNEFILLE et al, , 2018BOSSUS et al, 2014;BURGOS-ACEVES;FAGGIO, 2017;CAMPOS et al, 2016;KRAEMER;RAMACHANDRAN;PERRON, 2019;LI et al, 2020;PAGANO et al, 2016;QIAO et al, 2018;ROSI-MARSHALL et al, 2013;ULLAH et al, 2019;WANG;ZHANG;GUO, 2017;WANG;XU, 2016).…”