Inhibitory effects of l-arginine derivatives on endothelium-dependent vasorelaxing response to acetylcholine of the rat aorta
摘要:
N-omega-nitro-L-arginine alkyl esters (A-1-A-B) and L-arginine alkyl esters (E-I-E-B) were synthesized, and the vasorelaxing effects of acetylcholine were studied in the absence or presence of these compounds in rat aortic rings with intact endothelium that was precontracted with phenylephrine. These compounds revealed that the nitro group is an essential inhibiting group of these inhibitors, and that hydrophobic functional groups can fine-tune the binding effects. Among them, A-3 is the most potent inhibitor. (C) 2004 Elsevier SAS. All rights reserved.
beta-Carboline represents a class of compounds with potent anti-tumor activity by intercalating with DNA. To further enhance the cytotoxic potency and bioavailability of beta-carboline, a series of novel beta-carboline amino acid ester conjugates were designed and synthesized, and the cytotoxic activities of these compounds were tested using a panel of human tumor cell lines. In addition, the membrane permeability of these compounds was evaluated in vitro using a Caco-2 cell monolayer model. The P-carboline amino acid ester conjugates demonstrated improved cytotoxic activity compared to the parental beta-carbolines. In particular, the Lys/Arg conjugates were the most potent analogs with an IC50 value of 4 and 1 mu M against human cervical carcinoma cells. The low interaction energy of Arg conjugate based on molecular modeling may contribute to its enhanced cytotoxicity. Taken together, this study provided new insights into structure-activity relationships in the beta-carboline amino acid ester conjugates and identified the beta-carboline Lys/Arg conjugates as promising lead compounds for further in vivo biological and molecular evaluation. (c) 2006 Elsevier Ltd. All rights reserved.