Ultrasonic treatment for improved solution properties of a high-molecular weight exopolysaccharide produced by a medicinal fungus.

High-power ultrasound (20 kHz) was applied to modify the physicochemical properties of a high-molecular weight (MW) exopolysaccharide (EPS) from mycelial culture of a medicinal fungus. At 35 W/cm(2) or higher ultrasound power, the apparent and intrinsic viscosities of EPS solution dropped by nearly 85% within 10 min, and the water solubility was increased by more than fourfold. The ultrasonic treatment led to a notable reduction of the maximum MW and a more uniform MW distribution, but no significant change in the primary structure of the EPS molecules. In contrast, the intrinsic viscosity of EPS was reduced by only 20% in 1.0M sulfuric acid at 50 degrees C for 9h. Ultrasound was proven an effective and favorable means for improving the solution properties of high-MW bioactive polysaccharides in mild conditions.

Inhibitory effects of ethyl acetate extract of Cordyceps sinensis mycelium on various cancer cells in culture and B16 melanoma in C57BL/6 mice.

The cultivated mycelium of a Cordyceps sinensis (Cs) fungus was sequentially extracted by petroleum ether (PE), ethyl acetate (EtOAc), ethanol (EtOH) and hot water. All solvent extracts except hot water extract showed a significant and dose-dependent inhibitory effect on the proliferation of four cancer cell lines, MCF-7 breast cancer, B16 mouse melanoma, HL-60 human premyelocytic leukemia and HepG2 human hepatocellular carcinoma, with IC(50) values below 132 microg/ml. The EtOAc extract, in particular, had the most potent effect against all four cancer cell lines, with IC(50) between 12 microg/ml (on B16) and 45 microg/ml (on MCF-7). In contrast, it had much lower cytotoxicity against normal mouse bone marrow cells. The EtOAc extract contained carbohydrates, adenosine, ergosterol and trace amount of cordycepin, of which ergosterol and related compounds were identified as a major class of active constituents contributing to the in vitro cytotoxicity. In an animal test, the EtOAc extract showed significant inhibiting effect on B16-induced melanoma in C57BL/6 mice, causing about 60% decrease of tumor size over 27 days. Our results suggest that the EtOAc extract of Cs fungal mycelium has strong anti-tumor activity and is a potential source of natural anti-tumor products.