Pilot Study of Gallic Acid Cream as a Potential Treatment for Plaque Psoriasis

Gallic acid, a catechin polyphenol in tea, completely inhibited angiogenesis in assays of human tissue at 10^-3 M. Psoriasis is a skin disease caused by excessive secretion of angiogenenic factors by keratinocytes and stromal skin cells. In a double-blind pilot study, six subjects with bilateral plaque psoriasis were treated with 10^-2 M gallic acid in a cream base or with a cream base placebo over 8 weeks, four times a day, and treatments were randomly assigned to either the left or the right side. The gallic acid cream was well tolerated, but it did not reduce the psoriasis more than the placebo. One subject wanted to extend treatment for an additional 8 weeks. At the end of 16 weeks, the subject had complete resolution of the psoriatic plaque treated with gallic acid cream. In contrast, the plaque treated with placebo cream was not reduced and stayed equivalent to week six. Gallic acid is inexpensive and does not cause side effects. A longer trial evaluating 10^-2 M gallic acid cream for the treatment of psoriasis seems indicated.