About dithranolanthracene derivative, antipsoriatic, keratolytic agent.mechanism of action of dithranoldithranol inhibits the cell growth and restore cell differentiation. dithranol in presence of light undergoes auto oxidation and produce inactive products, free radicals and reactive oxygen species. free radical destroys dna of cells and inactivates enzymes associated with cell proliferation and inflammation the central pathogenetic figure in psoriasis is t-lymphocyte which in turn stimulates keratinocytes proliferation and they themselves multiply releasing il, tnf alpha and ifn gamma. there is up regulation of icam and vcam and migration of leucocytes, monocytes and neutrophil to endothelial cells. proliferating keratinocytes also release il, tnf, gf and tgf resulting in inflammation. dithranol acts on all these steps resulting in inhibition of proliferation of epidermal cells in psoriasis