†These authors contributed equally.
Academic Editors: Jiang Pi, Anguo Wu and Deyu Kong
Background: The theory of free radical oxidative stress (ROS) is one of the leading theories of ageing, and antioxidants play an important role in antiaging. Dendrobium has always been popular as a natural antioxidant. Methods: This study investigated the effects of various polarity fractions of ethanol extracts from Dendrobium nobile Lindl. (D. nobile) on D-galactose-induced aging mice. D. nobile stems were extracted by ethanol to form the crude extract (EA), which was sequentially extracted by trichloromethane, ethyl acetate, and n-butanol to yield the secondary extracts, named TCM, EAC, and NBA, respectively. EA, TCM, EAC and NBA were intragastrically administered at a dose of 200 mg/kg b.w. to the aging mice induced by D-galactose for 8 weeks. Results: Compared with the aging control group (AC), D. nobile extracts reduced body weight and lipid accumulation and enhanced endurance and immunity by increasing the index of the spleens and thymus. Meanwhile, D. nobile extracts showed antioxidant properties by lowering Malondialdehyde (MDA) levels and increasing the activities of superoxide dismutase (SOD), catalase (CAT), and Glutathione peroxidase (GSH-Px) in the skin, blood, liver, and brain. Furthermore, D. nobile extracts had a good protective effect on the cell structure and function against lesions of the skin, liver, brain, kidney, and ovary of aging mice. In particular, EA and EAC had better antioxidant and antiaging effects, suggesting that the most effective components were flavonoids and polyphenols that existed in EAC. Both EA and EAC downregulated the expression of aging-related genes such as Il1a, Il1b, Il1rn, Ccl3, Ccl4, Fos and Gck in the brain at the transcriptome level. Both EA and EAC reversed the increase in the Firmicutes/Bacteroidota ratio in aging mice, increased the abundance of probiotic bacteria Lactobacillus and Muribaculum, and decreased the abundance of pathogenic bacteria such as Staphylococcus, Corynebacterium and Brevibacterium. Conclusions: The EA and EAC extracts of D. nobile have better effects on immunity improvement, antioxidation and antiaging by remodelling the intestinal microecosystem and downregulating the expression of age-promoting genes in the brain. D. nobile, especially EA and EAC extracts, could be used as an antiaging drug or functional food.