Fig. 3.

The water extract is devoid of antiviral activity after depletion of glycyrrhizic acid by acid precipitation; whereas the precipitant has improved antiviral activity. The pH of the water extract of Glycyrrhiza uralensis was lowered with dilute H₂SO₄ to precipitate glycyrrhizic acid using a standard protocol. The precipitant was collected by filtration. After neutralizing the pH of the supernatant devoid of glycyrrhizic acid, the antiviral activity against CVA16 (A) and EV71 (B) of this supernatant (Sup), the precipitant (PPT), and the water extract of Glycyrrhiza uralensis (Extract) was assayed on Vero cells. Acid precipitation removes glycyrrhizic acid from the water extract of Glycyrrhiza uralensis, resulting in loss of antiviral activity of the supernatant. As expected, the antiviral activity was enriched in the precipitant. Data are presented as mean±standard errors of triplicate samples from three independent experiments.