INFLUENZA VIRUS-INHIBITORY EFFECTS OF INTRAPERITONEALLY AND AEROSOL-ADMINISTERED SP-303, A PLANT FLAVONOID

The phenolic biopolymer SP-303 was evaluated against experimentally in duced influenza A (H1N1) virus infections in mice in a series of exper iments. When 30, 10 or 3 mg/kg/day of SP-303 were administered intrape ritoneally once daily for 8 days beginning either 48 h before or 4 h a fter virus exposure, only lung consolidation was significantly reduced ; extended (p<0.01) mean day to death was also seen in the late-therap y groups. The high dosage was lethally toxic in this experiment. A sma ll-particle aerosol (SPA) of 10, 5 and 2.5 mg/ml of SP-303, administer ed for 1 h three times daily for 5 days beginning 4 h after virus expo sure, exerted a similar antiviral effect. Twice-daily 1-hour SPA treat ments for 3 days beginning 24 h before virus exposure using 4.3 mg/ml of SP-303 resulted in significant increases in mean day to death and r eductions of lung consolidation but no inhibition of lung virus titer. Declines in influenza-induced arterial oxygen saturation, as determin ed by pulse oximetry, were less in all animals treated with SP-303 by SPA, but this reduced decline was significant (p < 0.01) only in the l ast experiment. Mice receiving SP-303 by SPA exhibited consistent but reversible hypothermia immediately after termination of treatment.