Substance found in cotton plant could help treat psoriasis

A substance found in the cotton plant could help treat the common skin disease psoriasis, according to new research from the Pharmacy School at Sunderland University launched at the British Pharmaceutical Conference in Manchester.

Gossypol is a natural toxin that is thought to protect the cotton plant from insect damage. In the past it has been investigated as a male contraceptive but no product was ever marketed. Dr Kalliopi Dodou from Sunderland University reports that, since discovery of gossypol's antifertility activity in the 1960s, studies had indicated that it might also have anti-proliferative and anti-inflammatory activity.

"Such activity suggested possible therapeutic use in psoriasis, since the disease is associated with skin inflammation and hyper-proliferation of cells (keratinocytes) in the outer skin layers," she says. "It is this hyper-proliferation that leads to the characteristic scaly skin patches in patients with psoriasis."

Dr Dodou tested the efficacy of gossypol and synthetic derivatives in treating the human papillomavirus (HPV). HPV infection is associated with benign hyper-proliferation. The tested compounds were found to inhibit keratinocyte proliferation, with gossypol itself being the most active.

In further studies gossypol was also shown to have anti-oxidant activity. Dr Dodou explains that this is also potentially useful in treating psoriasis: "One of the theories of the pathogenesis of psoriasis is that the condition is related to imbalance in the body's anti-oxidant system. Some studies have shown people with psoriasis to have high levels of oxidative metabolites. Gossypol might therefore stop oxidation of the fatty acids in the skin."

Dr Dodou is to tell the conference that gossypol appears to dampen down inflammation and hyper-proliferation and is a good candidate for the topical treatment of psoriasis. She said that subsequent work showed that formulating gossypol into a cream would be feasible.