Biological activities of violacein, a new antitumoral indole derivative, in an inclusion complex with β-cyclodextrin

Violacein is a poorly water-soluble antitumoral and antibacterial drug. The solubility can be enhanced by complexation with beta-cyclodextrin. The inclusion complex was prepared by the co-precipitation method in molar ratios of 1 : 1 and 1 : 2 of violacein/beta-cyclodextrin, respectively. The acute toxicity (E. coli strain) of violacein did not change up to 400 mu M, either in the presence or absence of cyclodextrin. Cytotoxicity (V-79 cell culture) through DNA and MTT assays was significantly decreased in the presence of the 1 : 2 molar ratio complex. Studies on erythrocyte lipid peroxidation by the thiobarbituric acid (TBA) method showed that violacein and violacein/beta-CD (1 : 2) at 100 mu M cause 50% and 80% inhibition, respectively. At 500 mu M the violacein/beta-CD complex inhibited lipid peroxidation completely; however, with free violacein only 65% inhibition was reached at that concentration.