Chicoric acid is a caffeic acid derivative, belonging to the group of polypfenols. Chicoric acid is the most active compound in Echinacea pupurea. Chicoric acid is very stable in dry conditions but can be broken down by enzymes, which are found in the Echinacea, in moist conditions.

Chicoric acid makes our immune cells more efficient in attacking intruders. In vivo en vitro studies have shown that chicoric acid promotes phagocytosis. This is the process whereby white blood cells and lymphocytes attack and destroy pathogens. Chicoric acid stimulates T-cell activation, stimulates healing of wounds and reduces the inflammation in arthritis. Chicoric acid increases the production of interferon, immunoglobulin and other chemicals important for the immune system.
Studies have indicated that chicoric acid can inhibit the penetration of viruses in cells.
Chicoric acid also acts as an antioxidant by preventing the oxidation of collagen and cells.

References:

1. 1,Preparative separation of cichoric acid from Echinacea Purpurea by pH-zone-refining counter-current chromatography.  Journal of Chromatography A Volume 1103, Issue 1,2006, Pages 166-169
2. Chicoric acid analogues as HIV-1 integrase inhibitors.   J Med Chem. 1999 Apr 22;42(8):1401-14.
3. HPLC Determination of Chicoric Acid in Leaves of Posidonia oceanica.  Pharmaceutical Biology, Volume 45, Issue 10 December 2007 , pages 745-748