Effects of Natural Flavonoids on Photosynthetic Activity and Cell Integrity in Microcystis aeruginosa

Abstract

Flavonoids are natural polyphenolic compounds produced by many aquatic plants and released in their environments. In this study, the effects of several aquatic flavonoids on cyanobacterial Microcystis aeruginosa, especially in relation to the cell growth, photosynthetic activity, cell morphology, and cell membrane integrity, were investigated. Significant growth inhibition was observed when the cyanobacteria were exposed to three flavonoids, namely, 5,4'-dihydroxyflavone (DHF), apigenin, and luteolin. Luteolin reduced the effective quantum yield, photosynthetic efficiency, and maximal electron transport rate by 70%, 59% and 44%, respectively, whereas 5,4'-DHF and apigenin slightly affected these parameters, which implies that luteolin disrupts the photosynthetic system. Moreover, 5,4'-DHF and apigenin compromised the membrane integrity, and induced membrane depolarization in 52% and 38%, and permeabilization in 30% and 44% of the cells, respectively. The 5,4'-DHF and apigenin showed more pronounced effects on M. aeruginosa morphology and membrane integrity, compared to the luteolin. These results suggest that flavonoids could have significant effects on growth and physiological functions in cyanobacterial species.

Biocatalytic hydrogenation of the C=C bond in the enone unit of hydroxylated chalcones—process arising from cyanobacterial adaptations

“…The presence of flavonoids, such as 4′,5-dihydroxyflavone, apigenin, and luteolin, also suppressed the growth of M . aeruginosa significantly, and this effect increased with the concentration of these compounds (Huang et al 2015 ). Importantly, in the case of our study, the position of the substitution of the hydroxyl group is likely responsible for this effect, suggesting that this aspect is crucial for understanding the mechanism of interactions between chalcones and cyanobacterial species.…”

New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates

“…ovata . Previous studies have reported important degradations in intracellular contents, membrane disruption, and cell shrinkage of microalgal cells exposed to the allelopathic compounds of macrophytes [ 29 , 45 , 74 ]. Potential allelochemicals also seem to have genotoxic properties, as a DNA damage was observed for O .…”

“…noltei is also characterized by the presence of flavonoids [ 101 ]. Like other polyphenols, these compounds have the capacity to act as antioxidants and can also affect growth and important metabolic functions of harmful microalgal species, including cyanobacteria and dinoflagellates [ 74 ].…”

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

“…Known examples are related to the presence of flavonoids in the cells and culture media of cyanobacteria [ 44 – 46 ]; cyanobacterial cells growing in different culture media can accumulate flavonoids to near-millimolar levels [ 47 ]. Additionally, evidence was found for the influence of flavonoids on gene expression of cyanobacteria [ 48 , 49 ] and the ability to inhibit the growth of cyanobacteria by plants containing flavonoids [ 50 – 52 ]. Nevertheless, the interactions between chalcones, the initial precursors of flavonoid biosynthesis, and cyanobacteria still remain poorly understood, especially due to unknown mechanisms(s) of metabolic adaptations of these microorganisms.…”