FIELD : medicine; pharmaceuticals.SUBSTANCE : invention relates to an antiviral derivative of general formula (I), pharmaceutical compositions based thereon, a method for production thereof, which can be used in the pharmaceutical and medical industry : , where R1=CnH2n+1, R2=CnH2n+1, R3=H or R1-R2=-CH2-, R3=CnH2n+1; n=1–30. Disclosed method comprises mixing forsythia leaves with water, heating with boiling and extraction to obtain water extract of forsythia; separating water extract of forsythia on a column with macroporous resin; chromatography of eluate from forsythia obtained on column with macroporous resin, on column with silica gel, collection of eluate and its drying.EFFECT : disclosed are a novel derivative of phillygenin and glucuronic acid, a novel effective method for production thereof, pharmaceutical compositions based thereon for preparing drugs effective for preventing and treating influenza.10 cl, 3 ex, 9 tbl