Free radical induced biophysical modification of membrane lipids: a novel mechanism proposed for a haemorheological alteration induced by 4,5' 8-trimethyl psoralen.

Haemostasis is the spontaneous arrest of bleeding from damaged blood vessel. Platelet aggregation is the major event in this process. A number of drugs are known to inhibit this process of platelet aggregation. 4,5' 8-trimethyl psoralen a naturally occurring furocoumarin is used as a photochemotherapeutic agent in PUVA therapy. It shows antithrombotic action by preventing platelet aggregation induced by adenosine diphosphate in vitro. It is proposed that a free radical induces a lipid phase transition of the membrane lipids, the platelet membrane undergoes certain biophysical alteration leading to increased membrane fluidity resulting in a loss of aggregating ability.