Effect of treatment with certain flavonoids on Mengo virus-induced encephalitis in mice.

Among the four flavonoids tested quercetin and morin proved to be significantly effective against lethal Mengo virus-induced encephalitis in mice when the drugs were adminsitered orally (p.o.). With subcutaneous (s.c.) administration all four drugs failed to prevent mortality in the infected mice. Quercetin produced maximum protective response in intraperitoneally (i.p.) or intranasally (i.nas.) infected mice when administered twice daily at doses of 20 mg/kg for a period of not less than four days. Single injections of the full daily dose of drug failed to prevent deaths in mice. Treatment must be begun at the time of, or prior to, virus inoculation. Delayed initiation of treatment was ineffective in preventing mortality.