Ameliorative effect of propolis and nanopropolis supplementation against oxidative stress induced by Microcystis aeruginosa in Oreochromis niloticus

The present study was planned to evaluate whether dietary supplementation with propolis or its nanoparticles was able to reduce the hepatic oxidative damage of the Nile tilapia, Oreochromis niloticus, feeding M. aeruginosa cells mixed with their food. Fish used in the current study were collected from the National Institute of Oceanography and Fisheries (NIOF) Serw farm and transferred to the Wet Lab of NIOF. Six groups of fish; each of three replicate, received diet twice daily at a rate of 3% of the body weight, for 4 weeks (28 days) according to the type of the treatment as follow: First Group was left as a control; the second one fed on fish meal (basal diet) plus propolis. In the third group, fish were fed on fish meal plus nanopropolis, while in the fourth group, fish were fed on fish meal plus toxic cells of M. aeruginosa, and in the fifth group, fish fed on fish meal plus toxic cells of M. aeruginosa plus propolis. The sixth group fed on fish meal plus toxic cells of M. aeruginosa. plus nanopropolis. Samples from liver were taken from all fish groups for assessing hepatic antioxidant enzymes activities  and gene expressions of the Nile tilapia. The results showed that levels of malondialdehyde (MDA) and reduced glutathione (GSH) conc. as well as (SOD) and catalase (CAT) activities decreased significantly due to dietary M. aeruginosa cells compared to the control group. Also significant reductions in the mRNA relative expressions of Superoxide dismutase (SOD), (CAT) and glutathione peroxidase (Gpx) in the liver of O. niloticus. It was noticed that propolis and nanopropolis co-administration reduced all alterations elicited by diet mixed with M. aeruginosa cells and the analyzed variables and they were nearly relative to control groups. Nano form of propolis is more effective on competing for toxicity of M. aeruginosa and as an antioxidant agent. In summary, this supplementation can be an intriguing approach in preventing M. aeruginosa induced liver damage.