Effects of Aloe-emodin on growth performance, biochemical parameters, and histopathology of goldfish (Carassius auratus)

Abstract

Aloe-emodin (AE) (1,8-dihydroxy-3-hydroxymethyl-anthraquinone) is an anthraquinone derived from some natural plants. This study aimed to evaluate the safety and potential benefits of its application in fish, through studying the effects of AE on growth performance, serum biochemical parameters, hepatic antioxidant capacity and histopathological aspects of goldfish (Carassius auratus). Fish were fed diets supplemented with AE at four concentrations (0‰, 0.08‰, 0.8‰, and 8‰). After the feeding trial of 30 days, the visceral index decreased significantly (p < 0.05), and the content of plasma triglycerides (TG) and cholesterol (CHO) in the treatment groups also showed a downward trend as the AE content increased from 0 to 8‰, indicating that AE has hypolipidemic effects on goldfish. The hypolipidemic effects were further verified by the observed decline of lipid droplets in liver tissues using Oil Red O staining. Furthermore, the activities of hepatic superoxide dismutase in the 8‰ supplementation group and glutathione peroxidase in the 0.8–8‰ supplementation groups increased significantly (p < 0.05) compared to the control group, showing the increased hepatic antioxidant capacity of AE. However, some abnormalities and lesions in histopathological sections and a significant increase in malondialdehyde (MDA) index were observed when the AE content reached 8‰, indicating that the 8‰ AE supplementation diet would negatively affect goldfish. Our present study is the first to report that oral administration of AE can decrease blood lipid parameters (TG and CHO) in fish. In conclusion, the AE supplementation diet has the potential to reduce blood lipids and enhance the hepatic antioxidant capacity, but an appropriate concentration needs to be administered.