The team began by purifying GEP from dried Gastrodia elata collected in Xiaocaoba, Zhaotong City, using hot-water extraction followed by ethanol precipitation and deproteinization. Chemical characterization revealed a remarkably pure preparation: total sugar content reached 90.04 percent, while protein contamination was a mere 1.72 percent. High-performance gel permeation chromatography showed a single symmetric peak corresponding to an average molecular weight of about 314 kilodaltons, placing GEP firmly in the category of large macromolecular polysaccharides. Monosaccharide analysis identified glucose as the dominant building block, and Fourier transform infrared spectroscopy confirmed a classic α-glucopyranose architecture, with absorption peaks marking hydroxyl stretching, pyranose ring vibrations, and α-glycosidic bonds. These structural details matter because the size, composition, and linkage chemistry of a polysaccharide determine how gut bacteria ferment it and which microbial species thrive on it.

With the molecule characterized, the researchers turned to cellular models. They exposed BV2 microglial cells, the resident immune cells of the brain, to d-galactose, a sugar widely used to induce senescence in laboratory settings. After 24 hours, cell viability fell in a concentration-dependent manner, with 200 millimolar d-galactose cutting viability roughly in half. Staining for senescence-associated β-galactosidase, a standard molecular marker of aged cells, confirmed that the treatment had pushed the microglia into a senescent state. When the team co-treated the cells with graded doses of GEP, the polysaccharide reversed the viability loss and significantly reduced the fraction of senescent cells, with 40 micrograms per milliliter showing the strongest effect. Senescent microglia are considered a central driving force of brain aging because they fuel chronic neuroinflammation, so rescuing them from senescence is a meaningful therapeutic signal.

The next test was one of the most demanding in aging biology: lifespan extension in Caenorhabditis elegans. Synchronized nematodes were raised from the first larval stage on plates containing 0.25, 0.5, or 1.0 milligram per milliliter of GEP. Because many plant polysaccharides have antibacterial properties that could indirectly extend lifespan by restricting the worms’ bacterial food supply and triggering caloric restriction, the researchers used heat-inactivated Escherichia coli OP50 as a uniform food source across all groups, carefully excluding this confounding pathway. Survival was tracked daily, and Kaplan–Meier analysis showed that GEP significantly prolonged average lifespan, with the 0.5 milligram per milliliter dose performing best. The result established that the anti-senescence activity seen in cells translates into a whole-organism longevity benefit.

The centerpiece of the study, however, was a natural aging model in mice, which avoids the artificialities of chemically induced senescence. Seventy-five eighteen-month-old male C57BL/6J mice were divided into groups receiving vehicle, vitamin E as a positive control, or GEP at 100, 200, or 400 milligrams per kilogram by daily oral gavage for two months, alongside fifteen two-month-old young controls. After the treatment period, the animals faced a battery of behavioral challenges. In the Morris water maze, aging mice took significantly longer to locate a hidden platform during five days of navigation training, and in the probe trial they spent less time in the target quadrant and crossed the platform position fewer times. Medium- and high-dose GEP shortened escape latencies and restored probe performance, with the medium dose showing the most pronounced improvement. Nest building, a sensitive index of social and autonomous function, was similarly depressed in aged mice and restored by GEP. Grip strength and wire-mesh climbing endurance, both of which decline with age, also rebounded under GEP treatment.

Histology explained the behavioral rescue. Hematoxylin–eosin staining of the hippocampus revealed that aging had disordered the neurons, shrunken their nuclei, and increased the number of damaged cells, while GEP preserved normal neuronal morphology and arrangement. Immunohistochemistry showed that GEP upregulated brain-derived neurotrophic factor, or BDNF, a core factor for neuronal survival and synaptic plasticity whose expression drops in the aging hippocampus. Notably, the medium dose of 200 milligrams per kilogram outperformed both the high dose and vitamin E across behavioral, histological, and molecular endpoints, producing a consistent inverted U-shaped dose–response curve. The authors suggest that excessively high polysaccharide concentrations may mildly overstimulate innate immune signaling in the gut, partially counteracting the compound’s own antioxidant and anti-inflammatory benefits, though they acknowledge this hypothesis requires further validation.

The molecular analysis traced the benefits to two canonical signaling axes. In serum and brain tissue, aging mice showed elevated malondialdehyde, a lipid peroxidation marker of oxidative damage, alongside reduced activities of the antioxidant enzymes superoxide dismutase and catalase. GEP reversed all three indicators. Western blotting revealed the mechanism: aging increased the expression of Keap1, the cytosolic protein that tags the transcription factor Nrf2 for degradation, and suppressed the downstream antioxidant enzymes HO-1 and NQO1. GEP downregulated Keap1 and restored HO-1 and NQO1, reactivating the Nrf2/Keap1 antioxidant defense system. Total Nrf2 protein levels were unchanged across groups, which the authors note is consistent with the pathway’s canonical regulation, since Nrf2 activation depends on nuclear translocation rather than increased total abundance, and the robust rise in downstream enzymes provides functional proof of pathway activation.

On the inflammatory side, the researchers measured the cytokines IL-1β, IL-6, and TNF-α by enzyme-linked immunosorbent assay and found them significantly elevated in both serum and brain of aged mice, the systemic fingerprint of inflammaging. The TLR4/NF-κB pathway, which drives this inflammatory transcription program, was correspondingly overactive, with increased TLR4 expression and heightened phosphorylation of the NF-κB subunit P65. GEP treatment suppressed TLR4 and reduced P65 phosphorylation, cutting the release of pro-inflammatory cytokines and breaking the vicious cycle in which oxidative stress fuels inflammation and inflammation in turn generates more reactive oxygen species.

The gut microbiota data tied the whole story together. Sixteen S ribosomal RNA sequencing of fecal samples showed that aging significantly reduced α-diversity and shifted the overall microbial composition away from that of young mice, as confirmed by principal coordinate analysis. At the phylum level, aging increased Bacteroidota and Pseudomonadota while depleting Bacillota and Verrucomicrobiota; at the genus level, beneficial taxa such as Lactobacillus and Dubosiella fell sharply, Akkermansia declined modestly, and Blautia was abnormally enriched. GEP reversed each of these shifts, restoring diversity and pushing the microbial profile of aged mice back toward the young control pattern. Critically, immunofluorescence of colon tissue showed that aging depleted the tight junction proteins ZO-1 and Occludin, the molecular seals of the intestinal barrier, and GEP restored both, outperforming vitamin E. This barrier repair is central to the proposed mechanism: a leaky aging gut allows lipopolysaccharide to enter the bloodstream, cross the blood–brain barrier, and activate TLR4/NF-κB signaling in microglia, driving neuroinflammation and cognitive decline. By resealing the gut, GEP may block this endotoxin traffic at its source.

The authors are candid about the implications and the limitations. Because GEP’s 314-kilodalton size prevents it from crossing an intact blood–brain barrier, its primary target must be the gastrointestinal tract, with brain protection arriving indirectly through the gut–brain axis, possibly via short-chain fatty acids and other microbial metabolites that the study did not measure directly. The work also lacked glycosidic linkage analysis by methylation and two-dimensional NMR, which would clarify how the polysaccharide’s structure governs its fermentability by taxa like Akkermansia, and the findings rest on mice aged twenty months, leaving older cohorts untested. Even so, the convergence of evidence across worms, cells, and mice, spanning behavior, histology, redox biochemistry, inflammatory signaling, microbiome sequencing, and barrier integrity, makes a compelling case that a single natural polysaccharide can coordinate oxidative stress, inflammation, and gut ecology simultaneously. As populations worldwide age and the search for safe multi-target interventions intensifies, GEP’s demonstration that a large, indigestible sugar molecule can protect the brain by way of the gut may prove to be the study’s most enduring insight.

Subject of Research: Anti-aging effects of Gastrodia elata polysaccharide via oxidative stress, inflammation, and gut microbiota modulation

Article Title: Gastrodia elata Polysaccharide Attenuates Aging by Modulating Oxidative Stress, Inflammation, and Gut Microbiota

Article References: Shi, H., Yang, S., Chen, Y., Shaog, B., Gong, R., & Li, Z. (2026). Gastrodia elata Polysaccharide Attenuates Aging by Modulating Oxidative Stress, Inflammation, and Gut Microbiota. Food Science & Nutrition, 14(10), Article e72413. https://doi.org/10.1002/fsn3.72413

Image Credits: AI Generated

DOI: 10.1002/fsn3.72413

Keywords: Gastrodia elata, polysaccharide, aging, oxidative stress, Nrf2/Keap1, TLR4/NF-κB, gut microbiota, intestinal barrier, BDNF, Caenorhabditis elegans, inflammaging, gut-brain axis