Synthesis and biological activity of tuftsin, its analogue and conjugates containing muramyl dipeptides or...

Several conjugates of muramyl dipeptide (MDP) or nor-muramyl dipeptide (nor-MDP) with tuftsin were synthesized. Conjugates 8a-f were prepared by acylation of protected tuftsin with the isoglutamine carboxyl group of MDP or nor-MDP 2a-f. Also tuftsin analogue 6 (H-Thr-Lys-Pro-Arg(NO2)-OH) was obtained. All synthesized compounds were investigated at the Medical University of Gdansk. The biological activity of the examined compounds was estimated using in vitro cultures of human monocytes and lymphocytes. The substances displayed cytotoxic effects, as was revealed in the viability tests performed. The effects were most probably mediated by the induction of an oxidative burst in monocytes and the stimulation of redox enzymes in lymphocytes. In addition, the analogues turned out to be efficient stimulators of TNFalpha and IL6 secretion by monocytes and lymphocytes. Nevertheless, the secretion of cytokines did not affect the viability of the leukocyte population used in the experiments.The beneficial properties of the compounds examined (mainly 6, 3, 8a and 8c), which implies their usefulness as potential therapeutic agents, are connected with their rapid start of action and more efficient effects compared with tuftsin alone. An in vivo assay on animal models will be performed.