Joint effects and mechanisms of luteolin and kaempferol on toxigenic Microcystis growth-Comprehensive analysis on two isomers interaction in binary mixture
Joint effects and mechanisms of luteolin and kaempferol on toxigenic Microcystis growth-Comprehensive analysis on two isomers interaction in binary mixture
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木犀草素和山奈酚对产毒微囊藻生长的联合作用及机制——二元混合物中两种异构体相互作用的综合分析
DOI：
10.1016/j.jenvman.2022.114904
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发表时间：
2022-03-25
影响因子：
8.7
通讯作者：
Guo, Zhonghui
中科院分区：
文献类型：
--
作者：
Li, Jieming;Cao, Linrong;Guo, Zhonghui
化感物质被广泛认为是缓解微囊藻主导的蓝藻水华(MCBs)的有前途的除藻剂。木犀草素或山奈酚对微囊藻的化感杀藻作用已得到证实，但其联合作用尚不清楚。本研究对木犀草素和山奈酚在14天内对微囊藻生长的时间依赖性联合作用及其机制进行了全面的研究。在等毒比例下，木犀草素和山奈酚的半数抑制阈值(IC_(50))在第8天和第14天分别为4.872 mg/L和5.211 mg/L，在当量比例下分别为5.167 mg/L和4.487 mg/L。利用毒性单位、等线图和预测模型，结果表明，木犀草素和山奈酚按等量比例在低、中、高剂量下存在相加作用，而在中剂量和更高剂量下具有协同作用，说明它们的等毒混合物对微囊藻具有较好的杀藻效果。不同剂量的等毒混合物同时降低了水样和总微囊藻毒素(MCs)的含量。因此，木犀草素和山奈酚可以作为高效、生态安全的除藻剂联合使用，降低MC污染风险。随着混合剂用量的增加，后期细胞MCs保留力减弱，细胞光合色素含量受到抑制，水样MCs含量降低，共同解释了随着混合剂用量的增加，细胞生长抑制率增加的原因。然而，在每种混合剂量下，由于早期刺激的抗氧化防御，细胞损伤逐渐修复，因此细胞损伤可能不是混合胁迫下抑制生长的主要原因。本研究为联合应用木犀草素和卡米菲酚减轻MCB和降低MCs污染风险提供了新的见解和指导。
Allelochemicals are widely accepted as promising algaecide to mitigate Microcystis-dominated cyanobacterial blooms (MCBs). Allelopathic algicidal effect of single luteolin or kaempferol against Microcystis had been confirmed, but their joint effect against Microcystis was unclear. This study comprehensively explored timedependent joint effect and mechanisms of luteolin and kaempferol on Microcystis growth during 14 day-test. The 50%-inhibitory threshold of their mixture (IC50 mix) was verified as 4.872 and 5.211 mg/L at equitoxic ratio, and 5.167 and 4.487 mg/L at equivalent ratio, respectively, on day 8 and 14. Using toxicity unit, isobologram and predictive models, results revealed that luteolin and kaempferol at equivalent ratio interacted additively at lower, median and higher dosages, while at equitoxic ratio interacted additively at lower dosage but synergistically at median and higher dosages in Microcystis on day 8 and 14, implying that their equitoxic mixture posed better algicidal effect against Microcystis. Various dosages of equitoxic mixture concurrently decreased aqueous and total microcystins (MCs) contents along test. Thus, luteolin and kaempferol could be jointly applied as high-efficacy and eco-safe algaecide with declined MCs pollution risks. As mixture dosage elevated, more strongly weakened cellular MCs retention and inhibited cellular photosynthetic pigments content during late stage, as well as decreased aqueous MCs content long test, jointly explained increasing growth inhibition ratio with rising mixture dosage. Yet, cell damage was gradually repaired due to early stimulated antioxidant defense at each mixture dosage, thus cell damage might not be a major reason for inhibited growth under mixture stress. This study provided novel insights and guidance to coupled application of luteolin and kamepferol for mitigating MCBs and decreasing MCs pollution risks.