Effects of caffeoyl conjugates of isoprenyl-hydroquinone glucoside and quinic acid on leukocyte function

The activity of three prenylhydroquinone glucosides (1-3) and four caffeoylquinic esters (4-7), obtained from Phagnalon rupestre, on elastase release, myeloperoxidase activity and superoxide and leukotriene B-4 production from polymorphonuclear leukocytes was determined. 4,5-Dicaffeoylquinic acid strongly inhibited elastase release with an IC50 value of 4.8 muM. Methylated caffeoylquinic derivatives were the most potent inhibitors of myeloperoxidase (IC50 near 60 muM), whereas both methylated and free carboxyl isomers inhibited superoxide production with similar potency (IC50 between 27 and 42 muM). The monocaffeoyl conjugate of prenylhydroquinone glucoside (3), the most potent inhibitor of leukotriene B-4 production (IC50 = 33 muM), possesses a mixed hydroquinone-caffeoyl character that could be considered as a potential anti-inflammatory entity. (C) 2002 Elsevier Science Inc. All rights reserved.