Rutin-rich extract and method of making same

A method of obtaining a rutin-rich extract from a plant, the method comprising,

• dissolving a rutin-containing plant extract in methanol or ethanol to obtain a crude rutin extract solution, the rutin-containing plant extract containing 90% to 95% rutin by weight and 100 to 300 ppm iron;
• reducing the volume of the crude rutin extract solution to obtain a concentrate;
• obtaining a mixture by adding to the concentrate an acid at 1-15% by weight of the rutin-containing plant extract, and optionally a C1-C4 alcohol, water, or both, wherein the rutin-containing plant extract constitutes 8% to 30% (w/v) of the mixture and the acid is selected from the group consisting of ascorbic acid, citric acid, tartaric acid, gallic acid, and malic acid;
• allowing the mixture to stand for formation of a precipitate;
• and
• isolating the precipitate, thereby obtaining a rutin-rich extract that contains less than 20 ppm iron.