Antiviral, embryo toxic and cytotoxic activities of Astragalus membranaceus root extracts.

Antiviral activity of Astragalus membranaceus aqueous and methanol root extracts was determined against Avian influenza H9 virus. Toxicity profile of extracts was evaluated using chicken embryos and BHK-21 cell line. Different concentrations (400, 200, 100, 50, 25. 12.5, 6.25 and 3.12µg/mL) of both aqueous and methanol extracts were mixed with standard virus inoculum (4HAunits) and incubated for 30minutes at 37°C prior to inject the chicken embryos. Chorioallantoic fluid harvested 72 hours post inoculation and evaluated for virus growth using hemagglutination assay. Same concentrations of both extracts without virus were injected in chicken embryos to evaluate embryo toxic activity as well. The cytotoxic activity of aqueous and methanol extracts was determined by MTT colorimetric assay using BHK-21 cells. Three concentrations (400, 200 and 100µg/mL) of aqueous and five concentrations (400, 200, 100, 50 and 25µg/mL) of methanol extract showed antiviral activity. None of the tested concentrations of aqueous and methanol A. membranaceus root extracts caused chicken embryo mortality. Cell survival percentage of aqueous extract was higher than 50 at all of the tested concentrations except 400µg/mL. Two concentrations (400 and 200µg/mL) of methanol extract showed cytotoxicity. It was concluded that aqueous and methanol roots extracts of A. membranaceus have antiviral activity and concentrations which were safe may be used for treatment of Avian influenza H9 virus infections.

Subchronic toxicity studies of Radix Astragali extract in rats and dogs.

Radix Astragali extract (RAE) is obtained from Astragalus membranaceus. It consists of Astragalus polysaccharide and Astragalus membranaceus saponins. In the study, we observed the subchronic toxicity of RAE in Sprague-Dawley rats and beagle dogs to evaluate the safety dosage range in clinical application. These subjects were daily administered of RAE by intra-peritoneum or vein for three consecutive months. General index were observed such as food-intake, behavior, body weight, hematological parameters, etc. Body weight, the weight of principal organ and hematology index are normal in experimental groups and control groups. The hematological biochemistry examination and histopathology examination of experimental groups are similar to control groups. In conclusion, our studies clearly demonstrated that RAE was safe without any distinct toxicity and side effects, the safety dosage range is 5.7-39.9g/kg for rats and 2.85-19.95g/kg for beagle dogs, which is equal to 70 or 35 times of that of human (0.57g/kg, say, average BW 70kg), respectively.