Scallop mantle extract inhibits insulin signaling in HepG2 cells

Characterization and Stability of a Novel Toxin in Scallop Mantle Tissue

Previous studies have shown that mice fed a diet containing 1% mantle tissue exhibited decreased food consumption and led to death. Toxic substances present in the mantle tissue have been isolated and identified. In the present study, we explored the characteristics and stability of mantle tissue toxicity. The treatment of mantle tissue with 1 mM hydrochloric acid, 1 mM sodium hydroxide, 1 mM dithiothreitol, and 1 mM hydrogen peroxide followed by heating did not significantly reduce the toxicity of mantle tissue in mice. These results suggest that mantle toxins are stable in tissues, particularly when exposed to acidic conditions and digestive enzymes. We examined whether mantle tissue exhibited acute toxicity. Mice fed a diet containing 20% mantle tissue did not show a distinct increase in toxicity compared with mice fed a diet containing 1% mantle tissue, demonstrating that feeding mantle tissue does not lead to acute toxicity. Finally, mantle tissue toxicity in the small intestine was examined. Chronic feeding of mantle tissue to mice changed the color of the small intestine. Real-time polymerase chain reaction analysis revealed that mantle tissue feeding caused changes in inflammation and endoplasmic reticulum stress markers in the small intestine. These results suggest that mantle tissue feeding causes toxicity after initial damage to the small intestinal tissue.

Hypoglycemic effect of Taraxacum officinale root extract and its synergism with Radix Astragali extract

Taraxacum officinale (dandelion) and Radix Astragali are traditional medicinal and edible plants with high nutritional value. In this study, the synergistic hypoglycemic effect of DRE and Radix Astragali extract (RAE) was evaluated. Our results showed that water extract of dandelion (DRE-w), mainly containing polysaccharides (63.92 ± 1.82 mg/g), total flavonoid (2.57 ± 0.06 mg/g), total phenolic compounds (8.93 ± 0.34 mg/g), and saponins (0.54 ± 0.05 mg/g), exhibited significantly inhibitory effect on α-glucosidase and α-amylase. DRE-w and RAE had synergistic hypoglycemic effect; we found that DRE-w and its combination with RAE could relieve the state of insulin resistance in IR-HepG2 cells. The combination could more significantly increase the glucose consumption and intracellular glycogen content, and improve the activity of hexokinase and pyruvate kinase in IR-HepG2 cells. In summary, DRE and its combination with RAE can be developed as the drugs or functional foods for diabetes prevention and treatment.

Scallop mantle toxin induces apoptosis in liver tissues of mice

We had previously shown that the intake of scallop mantle tissue resulted in the death of mice and rats. In this study, we investigated the liver injury caused by mantle tissue to clarify the mechanism behind its toxicity. Mantle toxin increased lipid peroxidation and decreased the reductive thiol content as well as the DPPH radical scavenging activity, catalase activity, and glutathione content in the liver of the mice. These results suggested that the mantle tissue diet caused oxidative stress through the decrease in antioxidants. In addition, mantle toxin increased the mRNA expression of endoplasmic reticulum (ER) stress- and inflammation-induced genes and the protein expression of caspase-3 and Bax (which induce apoptosis), suggesting that the mantle tissue diet causes apoptosis through oxidative stress, ER stress, and inflammation in the liver tissue. Such liver injury may be an essential cause of the rodent demise.