Abstract
Effects of quercetin on the green hydra, Hydra viridissima Pallas, and its endosymbiotic alga were studied under laboratory conditions. Quercetin is the most studied flavonoid known for its ability to act as an antioxidant, but it can also show a pro-oxidative effect. Green hydras were treated with four concentrations of quercetin (0.12 g/L, 0.2 g/L, 0.25 g/L and 0.3 g/L) for three days and compared to the control group of animals. Through the use of light microscopy, morphometry and macroscopic observations the results showed morphological changes in the hydra body as well as behavioral changes: depigmentation, migration, deformation, disordered locomotion, diminished reactions to mechanical stimuli and mortality. Further, different histopathological changes in the hydra body were detected. Different changes were monitored in the endosymbiotic alga: cell viability, division, shape and size of cells and chloroplasts, the level of damage and intensity of green color. Based on our results, the most important conclusion is that quercetin has a possible pro-oxidative effect on the green hydra.
Highlights
Quercetin (3,3',4',5,7-pentahydroxyflavone) is a unique bioflavonoid that has been extensively studied over the past 30 years
Through the use of light microscopy, morphometry and macroscopic observations the results showed morphological changes in the hydra body as well as behavioral changes: depigmentation, migration, deformation, disordered locomotion, diminished reactions to mechanical stimuli and mortality
Higher migration rate occurred during the treatment where individuals of the green hydra migrated to the surface and showed more inhibited reactions to the mechanical stimuli, as a result of unfavorable and deleterious micro-environmental conditions (Kovačević, Želježić, Kalafatić, & Horvatin, 2007)
Summary
Quercetin (3,3',4',5,7-pentahydroxyflavone) is a unique bioflavonoid that has been extensively studied over the past 30 years. Flavonoids belong to a group of organic compounds with phenolic structure. They are natural compounds that are found in different fruits and vegetables, cereals, flowers, tea and wine. The best-described property of quercetin is its ability to act as antioxidant. Lower concentrations of quercetin can stimulate proliferation of some cancer cells that depend on estrogen receptors. Higher concentrations of quercetin may have cytotoxic effect on the same cells (Maggiolini et al, 2001). Quercetin can be antioxidant or pro-oxidant, depending on the concentration and source of free radicals in a cell (Lee, Kim, Park, Chung, & Jang, 2003)
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