Patent ID: 8314079

Claim:
A method for treating a gastric ulcer, which comprises administering an effective amount of a fraction comprising a hyaluronic acid tetrasaccharide comprising four saccharide residues and having the physicochemical properties defined in the following (1) to (6): (1) when the fraction is analyzed by the detection methods mentioned in the following (a) and (b) using gel filtration chromatography, the fraction shows a substantially single peak in both of the methods, and the peaks have peak areas defined in the following (a) and (b): (a) when the detection is performed based on absorbance at 210 nm, a relative ratio of peak area of the tetrasaccharide to the sum of peak areas of total HA oligosaccharides in the fraction is 85% or more; (b) when the detection is performed by using a differential refractometer, a relative ratio of peak area of the tetrasaccharide to the sum of peak areas of total HA oligosaccharides in the fraction is 98% or more; (2) when the fraction is analyzed based on absorbance at 210 nm by anion exchange chromatography, the fraction shows a substantially single peak, and a relative ratio of peak area of the tetrasaccharide to the sum of peak areas of total HA oligosaccharides in the fraction is 90% or more; (3) when the tetrasaccharide in the fraction is labeled with fluorescence and then analyzed by electrophoresis, a single band is detected, and bands of HA oligosaccharides of other sizes are not detected; (4) when a theoretical value of monoisotopic molecular weight or average molecular weight of the tetrasaccharide constituting the fraction is taken as 1, an actual value of the same measured for the fraction by mass spectrometry is 0.997 to 1.003 (relative value); (5) respective differences between theoretical values (weight %) of carbon (C), hydrogen (H) and nitrogen (N) contents in the tetrasaccharide constituting the fraction and values of the same actually measured for the elements by elemental analysis of the fraction (weight %) are all in the range off ±1 (weight %); and (6) the fraction does not substantially contain proteins, DNA and endotoxins to a subject in need thereof.