Solomon’s Seal Polysaccharide Targets Fatty Liver Disease in Diabetes

A natural sugar molecule purified from the rhizome of a traditional Chinese medicinal herb may offer a new way to tackle one of the most burdensome metabolic double threats in modern medicine: type 2 diabetes occurring alongside metabolic dysfunction-associated steatotic liver disease, or MASLD. In a study published in the Journal of Agriculture and Food Research, researchers from the Zhejiang Academy of Traditional Chinese Medicine report that Polysaccharide III, a fraction isolated from Polygonatum cyrtonema Hua, substantially reduced body weight gain, blood sugar, liver fat accumulation, and liver injury in mice engineered to develop both conditions. The work is notable because it maps the molecular effects of the compound across multiple biological levels, from liver gene expression to the composition of the gut microbiome.

The scale of the underlying problem is enormous. According to figures cited in the study, roughly 828 million people worldwide were living with diabetes in 2022, with type 2 diabetes accounting for 96 percent of cases. MASLD, a spectrum of liver disease ranging from simple fatty liver to inflammation, fibrosis, cirrhosis, and even liver cancer, now affects an estimated 39 percent of the global population and is increasingly diagnosed in younger people. Critically, the two diseases are frequent companions: epidemiological studies suggest that up to 65 percent of patients with type 2 diabetes also have MASLD. They share a common pathological root in disordered glucose and lipid metabolism, and each worsens the other in a self-reinforcing cycle that accelerates cardiovascular and liver complications.

Current treatment options for this comorbidity remain limited. Weight loss through lifestyle change is the foundation of therapy for both conditions, but its effects are often insufficient on their own. Hypoglycemic drugs, newer injectable agents, and bariatric surgery show promise, yet safe and effective interventions designed specifically for diabetes-associated MASLD are still lacking. This therapeutic gap motivated the research team to look toward edible-medicinal plants, a traditional source of bioactive compounds, and in particular toward Polygonatum cyrtonema Hua, a tonic herb long used in Chinese medicine for its purported benefits in diabetes and hyperlipidemia. While polysaccharides are recognized as the herb’s major active constituents, their specific effects and mechanisms in diabetes-related liver disease had remained unclear.

The team isolated and purified the polysaccharide fraction they named PCP III from dried rhizomes using ethanol pretreatment, hot-water extraction, and stepwise ethanol precipitation. Characterization revealed a molecule with distinctive physical properties: a total sugar content of 90.76 percent, a modest protein content of about 6 percent, and a remarkably low average molecular weight of approximately 2.4 kilodaltons. Chromatographic analysis of its monosaccharide building blocks showed that fructose and glucose dominate the composition, accounting for roughly 65 and 33 percent respectively, with smaller amounts of galactose, glucosamine, arabinose, and galactosamine. Infrared spectroscopy confirmed the classic polysaccharide fingerprint of hydroxyl, carbon-hydrogen, and glycosidic bond vibrations. The researchers suggest that the compound’s low molecular weight may facilitate absorption or interaction with gut epithelial cells compared with larger polysaccharides, potentially contributing to its biological activity.

To test the compound’s effects, the researchers used a well-established mouse model that mimics the progressive nature of human disease. Young male C57BL/6J mice were fed a diet deriving 60 percent of calories from fat for eight weeks and then injected with streptozotocin, a chemical that damages insulin-producing cells, to induce type 2 diabetes. Only mice with fasting blood glucose at or above 11.1 millimoles per liter and histologically confirmed fatty liver were included. The diabetic mice were then divided into groups receiving either no treatment, the diabetes drug metformin, the cholesterol-lowering drug atorvastatin, or PCP III at low or high doses of 500 or 1000 milligrams per kilogram of body weight daily for eight weeks.

The results were striking. Untreated diabetic mice gained weight steadily, developed enlarged livers and expanded fat stores, showed persistent hyperglycemia, cleared glucose poorly in tolerance tests, and displayed elevated total cholesterol, triglycerides, and LDL cholesterol along with elevated liver enzymes indicating hepatocellular damage. PCP III treatment attenuated weight gain without reducing food or water intake, lowered fasting blood glucose, improved glucose tolerance, partially corrected the lipid profile with a particularly clear reduction in LDL cholesterol at the high dose, and significantly decreased the liver injury markers gamma-glutamyl transferase, alanine aminotransferase, and aspartate aminotransferase. The compound also lowered serum levels of glycated serum protein and insulin, and reduced the abnormal elevation of both leptin and its soluble receptor, pointing to a partial restoration of leptin-related metabolic regulation.

Direct examination of liver tissue reinforced the biochemical findings. Livers from untreated model mice were visibly enlarged, pale, and greasy, and microscopy revealed swollen hepatocytes crowded with lipid vacuoles and disordered hepatic cords. Oil Red O staining confirmed abundant fat droplet deposition, and ultrasound imaging showed the characteristic brightened liver echo texture, blurred vessel walls, and deep echo attenuation of hepatic steatosis. After PCP III treatment, particularly at the high dose, liver appearance normalized, histological fat accumulation fell, and ultrasonographic abnormalities improved. The compound also rebalanced hepatic oxidative stress, restoring the activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase and reducing the lipid peroxidation product malondialdehyde, all of which had been deranged by the disease process.

The mechanistic core of the study came from liver transcriptome sequencing combined with validation experiments. Untreated model mice showed 237 differentially expressed genes relative to healthy controls, whereas PCP III intervention altered 1599 genes, revealing an extensive remodeling of the hepatic transcriptional network. Forty-two genes changed in common across comparisons, and pathway analysis pointed squarely at the peroxisome proliferator-activated receptor, or PPAR, signaling pathway, alongside oxidative phosphorylation and steroid biosynthesis. Quantitative PCR and Western blotting confirmed that the compound increased expression of PPAR alpha and its downstream targets involved in fatty acid transport and oxidation, including the transporter Slc27a1 and the bile acid synthesis enzyme CYP7A1, while suppressing PPAR gamma, the lipid droplet protein PLIN2, and the fatty acid binding protein FABP2, which were abnormally elevated in disease. In essence, PCP III appeared to shift the liver away from fat storage and toward fat burning and cholesterol-to-bile-acid conversion.

The gut microbiota emerged as a second, complementary target. Sequencing of bacterial 16S rRNA genes from intestinal contents showed that diseased mice had altered community structure and depleted populations of several beneficial taxa, including members of Muribaculaceae, Clostridia UCG-014, and Dubosiella, while an opportunistic group within Erysipelotrichaceae expanded. High-dose PCP III partially reversed these shifts, restoring the beneficial genera toward the profile seen in healthy mice. Correlation analysis revealed that Clostridia UCG-014 abundance tracked positively with hepatic antioxidant enzyme levels and negatively with serum insulin, leptin, and LDL cholesterol, while Dubosiella was inversely associated with liver injury markers. Gas chromatography-mass spectrometry of cecal contents showed that PCP III also reshaped short-chain fatty acids, raising isohexanoic acid and lowering valeric, isobutyric, isovaleric, and acetic acids. Because short-chain fatty acids absorbed through the portal vein can activate hepatic PPAR alpha and strengthen the gut barrier, the authors propose that microbial remodeling and PPAR modulation form a linked, multi-target network underlying the compound’s benefit.

The authors are careful to note the study’s limitations. No pharmacological antagonist or genetic knockout was used to prove that PPAR signaling is causally required for the effects, so the mechanism remains associative; microbiota and metabolite analyses were limited to the high-dose group; only male mice were studied; the HFD and streptozotocin model does not fully recapitulate human disease; and the fine structural features of the polysaccharide, such as its glycosidic linkages and branching, remain unresolved. Even so, the convergence of phenotypic, histological, transcriptomic, protein-level, microbiological, and metabolomic evidence makes PCP III a compelling candidate for development as a functional food ingredient or nutritional supplement aimed at the metabolic comorbidity of type 2 diabetes and MASLD. Future work validating the findings in clinical cohorts and pinpointing the specific microbial metabolites involved will determine whether a sugar molecule from a humble medicinal rhizome can one day help break the vicious cycle that links two of the world’s fastest-growing chronic diseases.

Subject of Research: A purified polysaccharide from Polygonatum cyrtonema Hua that alleviates type 2 diabetes-associated fatty liver disease by regulating the PPAR pathway and gut microbiota.

Article Title: Polysaccharide III from Polygonatum cyrtonema Hua alleviates diabetes-associated MASLD via PPAR pathway-mediated regulation of lipid metabolism and gut microbiota modulation

Article References: Chen, S., Ren, Z., Guo, Z., Mei, X., Chen, X., Tong, Y., Fan, X., & Dai, G. (2026). Polysaccharide III from Polygonatum cyrtonema Hua alleviates diabetes-associated MASLD via PPAR pathway-mediated regulation of lipid metabolism and gut microbiota modulation. Journal of Agriculture and Food Research, 31, Article 103254. https://doi.org/10.1016/j.jafr.2026.103254

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103254

Keywords: Polygonatum cyrtonema, polysaccharide, MASLD, type 2 diabetes, PPAR signaling, gut microbiota, hepatic steatosis, short-chain fatty acids, insulin resistance, lipid metabolism, functional foods, mouse model