Hemolysis of human red blood cells by combination of ribof lavin and aminophylline Iyad Ali, Imrana Naseem* Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India Received 29 May 2001; accepted 1 October 2001 Abstract The effect of aminophylline on human red blood cells (RBC) has been studied. Under in vitro condition, aminophylline alone does not hemolyse RBC. However, in the presence of riboflavin and visible light, aminophylline causes hemolysis of RBC. This hemolysis depends on the concentration of both riboflavin and aminophylline. Using different free radical scavengers we show that RBC hemolysis is caused by reactive oxygen species. Studies using bovine serum albumin show that riboflavin–aminophylline combination can also cause protein degradation in vitro. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Riboflavin; Aminophylline; Oxygen radicals; RBC; Hemolysis Introduction There is a growing body of evidence that prooxidant species can contribute to lung injury in a variety of pulmonary diseases including asthma [1,2]. Enhanced production of free radicals has been reported particularly in asthmatic patients. This oxidant load has been found to correlate with the clinical severity of the disease and the entity of the airway obstructions [2,3]. Theophylline, and its more soluble form, aminophylline, are bronchodilator drugs commonly used for the treatment of asthma [4,5]. Both these drugs are administered 0024-3205/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII:S0024-3205(01)01540-5 * Corresponding author. Fax: +91-571-401-089. E-mail address: iyad74@lycos.com (I. Naseem). Life Sciences 70 (2002) 2013 – 2022