Journal of Marine Biology

The present study investigated the effects of hydroalcoholic extract of Malva sylvestris on blood glucose levels, liver enzymes, and the expression of selected genes in zebrafish (Danio rerio). Adult three-and-a-half-month-old zebrafish were randomly assigned to five treatments, each with three replicates. Fish in treatment 1 (control) were fed only a commercial diet without Malva sylvestris extract. Fish in treatment 2 were fed a combination of commercial diet and Artemia nauplii without Malva sylvestris extract. Fish in treatments 3, 4, and 5 were fed a combination of commercial diet and Artemia nauplii supplemented with 0.1, 0.5, and 1% Malva sylvestris extract, respectively. Artemia nauplii were provided to the respective treatments 20 minutes after commercial feeding. To induce hyperglycemia, glucose monohydrate was added to the aquarium water according to the experimental protocol and at predetermined concentrations. Blood glucose levels and liver enzyme activities were measured at the beginning and end of the experiment. The expression of the FOXO, INFγ, interleukin, SREBF1, TNF-α, and PPARα genes was also evaluated. The results showed that increasing the dietary level of Malva sylvestris extract significantly reduced blood glucose levels (P < 0.05). The use of Artemia increased liver enzyme levels compared with the basal commercial diet; however, Malva sylvestris extract reduced liver enzyme levels, and increasing the extract dosage resulted in a significant decrease in liver enzymes (P < 0.05). The expression of the studied genes also showed a significant decrease with increasing levels of Malva sylvestris extract in zebrafish, while the highest expression levels were observed in fish fed the Artemia diet containing 0.1% Malva sylvestris extract (P < 0.05). Overall, the hydroalcoholic extract of Malva sylvestris appeared to be effective in controlling increases in blood glucose and liver enzyme levels without causing adverse effects on the liver.