Cranberry extract and biologically active compounds derived therefrom

A method of preparing a plant extract having an active fraction which is active to inhibit adherence of microbes to cell surfaces, comprising:

• providing a homogenate of a plant material of a plant having a native active fraction comprising polyphenolic compounds having anti-adherence activity;
• adding a sufficient amount of a base to said homogenate to alkalinize said homogenate to a pH of greater than about pH 10 and to cause phenol groups of polyphenolic compounds to be ionized to phenoxide ions;
• and
• adding to said alkalinized homogenate, a sufficient amount of an alcohol to produce a precipitate of said polyphenolic compounds having phenoxide ions, and separating said precipitate.

A method of purifying a proanthocyanidin having a structure selected from I, II and III ##STR5## wherein x, y=1 to 3, w=0 or 1, n=0 to 18 from plant material, comprising:

• providing a homogenate of a plant material of a plant having a native active fraction comprising polyphenolic compounds having anti-adherence activity;
• adding a sufficient amount of a base to said homogenate to alkalinize said homogenate to a pH of greater than about pH 10 and to cause phenol groups of polyphenolic compounds to be ionized to phenoxide ions;
• and
• adding to said alkalinized homogenate, a sufficient amount of an alcohol to produce a precipitate of said polyphenolic compounds having phenoxide ions, and separating said precipitate.

A plant extract having an active fraction which is active to inhibit adherence of microbes to cell surfaces, obtainable by a process comprising:

• providing a homogenate of a plant material of a plant having a native active fraction comprising polyphenolic compounds having anti-adherence activity;
• adding a sufficient amount of a base to said homogenate to alkalinize said homogenate to a pH of greater than about pH 10 and to cause phenol groups of polyphenolic compounds to be ionized to phenoxide ions;
• and
• adding to said alkalinized homogenate, a sufficient amount of an organic solvent to produce a precipitate of said polyphenolic compounds having phenoxide ions, and separating said precipitate.