Chrysanthemum stems and leaves as promising by-products with high application potential: Phytochemical characterization and bioactivity evaluation

Chrysanthemum morifolium Ramat. is widely used as a medicinal and industrial crop, possessing notable medicinal, economic and cultural value. Chrysanthemum stems and leaves, accounting for 70–80% of the total plant biomass, are underutilized and often discarded as agricultural waste, resulting in environmental pollution and waste of resources. Hence, exploring the potential value of such waste materials may generate environmental, social and economic benefits. Accordingly, this study aims to evaluate the potential therapeutic effects of Chrysanthemum stems and leaves extract (CSLE) on fish subjected to long-term heat stress, in order to realize the value in aquaculture. The results indicated that Chrysanthemum stems and leaves were rich in various potential bioactive compounds. Dietary supplementation with CSLE (10–20 g/kg) ameliorated heat stress-induced growth inhibition by modulating multiple physiological pathways. CSLE restored intestinal homeostasis by suppressing harmful bacteria ( Plesiomonas and Acinetobacter ), elevating short-chain fatty acids and reducing lipopolysaccharide levels. It enhanced heat shock protein (HSP70/90) expression, improved intestinal barrier function via tight junction proteins and attenuated oxidative stress through the Keap1a/Nrf2/HO-1 pathway. Additionally, CSLE reduced apoptosis and inflammation in intestine and gills, alleviated gill immune suppression and ammonia accumulation, and improved muscle metabolism by modulating amino acids and lowering lactate. Systemic cortisol levels were decreased, confirming reduced overall stress. This study thus reveals Chrysanthemum stems and leaves are potential raw materials in veterinary pharmaceutical industry. The valorization not only facilitates the utilization of waste resources but also provides safe and effective drug choices for aquaculture, which demonstrates multiple benefits in resource utilization, environmental protection and industrial development.