Safe botanical drug for treatment and prevention of influenza and increasing immune function

A process for producing polysaccharides from Isatis tinctora L., Isatis indigotica Fort or Baphica cusia Bremek comprising:

• a) extracting the dried powder of the plant with hot water;
• b) filtering the extract;
• c) dialyzing the filtrate against running water though cellulose;
• d) concentrating the filtrate;
• e) adding ethanol to the concentrated filtrate to obtain a first precipitate;
• f) extracting said first precipitate with aqueous 0.4% sodium borate;
• g) collecting the residue of said extraction by centrifugation and dissolving the residue in water;
• h) acidifying the solution with acetic acid, dialyzing the solution against running water, and lyophilizing the solution to produce a first fraction;
• i) adding ethanol to the first fraction and collecting a second precipitate by centrifugation;
• j) dissolving said second precipitate in water and chromatographing said solution in a column of sepharose;
• k) eluting said column with water to produce a second and third fraction;
• l) adding ethanol to said second and third fractions to produce a third precipitate and collecting said third precipitate by centrifugation;
• m) drying said third precipitate by washing it with acetone followed by ether and further drying said third precipitate in a vacuum to produce the polysaccharides.

A process for producing Isatin B comprising:

• a) extracting the dried powder of a plant containing Isatin B with hot water;
• b) filtering the extract;
• c) dialyzing said filtrate against running water through cellulose;
• d) concentrating said filtrate;
• e) adding ethanol to said concentrated filtrate to obtain a first precipitate;
• f) extracting said first precipitate with aqueous 0.4% sodium borate;
• g) collecting the residue of said extraction by centrifugation and dissolving said residue in water;
• h) acidifying said solution with acetic acid, dialyzing said solution against running water and lyophilizing said solution to obtain a first fraction;
• i) adding ethanol to said first fraction to obtain a second precipitate and collecting said second precipitate by centrifugation;
• j) dissolving said second precipitate in water and chromatographing said solution in a column of sepharose;
• k) eluting said column with water to obtain a second and third fraction;
• l) precipitating said second and third fraction with ethanol to obtain a third precipitate and collecting said third precipitate by centrifugation;
• m) drying said third precipitate by washing with acetone followed by ether and further drying said third precipitate by vacuum to produce Isatin B.

A process for producing Isatin B comprising:

• a) extracting the dried powder of a plant containing Isatin B with hot water;
• b) filtering the extract;
• c) extracting said filtrate with methanol;
• d) obtaining a residue by recovering said methanol under reduced pressure;
• e) extracting said residue with chloroform;
• f) chromatographing said extract on silica gel using chloroform as the eluent;
• g) concentrating said eluate and rechromatographing said eluate on silica gel G using chloroform as the eluent;
• h) crystallizing lsatin B from said chloroform;
• i) recrystalizing Isatin B and drying Isatin B under vacuum.