Abstract: A new composition of matter is provided comprising negatively charged polysaccharides which can be derived from Aloe vera and a process to prepare that composition of matter by sub fractionation of an extract of Aloe vera, passing the formed subfraction over a positively charged column and eluting the same with a salt solution. Optionally the Aloe vera is pre purified over a Sephadex G-25 column. This composition of matter and also the extract comprising the same which is formed after pre purification or ultra filtration of an Aloe vera extract is useful as a food supplement or in dietary foods, for use in personal care and in cosmetics, especially to prevent an infection with the bacteria Helicobacter pylori, Pseudomonas aeruginosa, Streptococcus mutans or Streptococcus sanguis.