Neuroprotection and Enhanced Learning and Memory Abilities of Steamed American Ginseng (Panax quinquefolium L.) Based on Zebrafish

American ginseng (Panax quinquefolius L.) exhibits multiple pharmacological properties, including anti-inflammatory, antioxidant, and neuroprotective effects. In 2023, it was officially approved as a dual-purpose substance for both medicinal and food applications, establishing it as a scientifically validated ingredient for functional foods and health supplements. We extracted total saponins (AGTS0-AGTS9) from American ginseng subjected to different steaming-drying cycles to explore how the steaming process affects saponin composition and neuroprotective activity. Using ultra-high-performance liquid chromatography coupled with quadrupole Orbitrap mass spectrometry (UHPLC-Q-Orbitrap/MS) technology, 35 types of ginsenosides were identified from AGTS0-AGTS9. With increasing steaming cycles, the original ginsenoside content decreased, while the rare ginsenoside content gradually increased. During steaming, ginsenosides undergo deglycosylation, hydrolysis, and acetylation, transforming into rare ginsenosides. We employed two models–neuronal injury in transgenic zebrafish larvae and cognitive impairment in wild-type AB adults, both induced by AlCl₃–to assess the neuroprotective effects of AGTS0-AGTS9 and the memory-enhancing potential of AGTS5, respectively. Results showed that AGTS4, AGTS5, and AGTS6 markedly increased the neuronal fluorescence area and intensity in larvae, reduced acetylcholinesterase (AChE), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels in larval tissues, while elevating acetylcholine (ACh), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities. AGTS5 exhibited the most potent neuroprotective activity. In adult zebrafish, AGTS5 significantly improved locomotor performance in the Novel Tank Test (NTT) and T-maze, increased Nissl body counts in the brain, reduced AChE activity and MDA/TNF-α/IL-6 levels, and enhanced ACh, SOD, GSH-Px, and CAT content. These findings demonstrate that AGTS5 holds promise as a functional food or nutritional supplement for neuroprotection and cognitive enhancement.