Organotin(IV) tryptophanylglycinates: potential non‐steroidal antiinflammatory agents; crystal structure of dibutyltin(IV) tryptophanylglycinate

Abstract

AbstractDiorganotin(IV) derivatives of tryptophanylglycine (H2Trp–Gly) with general formula R2Sn(Trp–Gly), where R = Me,n‐Bu, Ph andn‐Oct, and triorganotin(IV) derivatives R′3Sn(HTrp–Gly) where R′ = Me,n‐Bu and Ph, have been synthesized and structurally characterized in the ‘solid state as well as in solution on the basis of various spectroscopic techniques, viz. FT‐IR, multinuclear1H,13C and119Sn NMR,119Sn Mössbauer and single crystal X‐ray diffraction. These investigations suggest that tryptophanylglycine in R2Sn(Trp–Gly) acts as dianionic tridentate coordinating through carboxylate oxygen [C(O)O−], amino nitrogen (NH2) and N−peptide, while in the case of R′3Sn(HTrp–Gly), the ligand acts as monoanionic bidentate coordinating through C(O)O−and NH2. This is further confirmed by the single‐crystal X‐ray structure ofn‐Bu2Sn(Trp–Gly) which shows that two butyl groups and peptide nitrogen (N−peptide) are in the equatorial positions, while the two axial positions are occupied by the carboxylic oxygen [C(O)O−] and the amino nitrogen (NH2) atom from the same ligand molecule in the distorted trigonal–bipyramidal geometry around tin. The anti‐inflammatory (using the carrageenan‐induced paw edema bioassay in rats), cardiovascular activities and acute toxicity (LD50) of some of these compounds have been examined. All of the studied R2Sn(Trp–Gly) and Ph3Sn(HTrp–Gly) exhibit very high anti‐inflammatory activities comparable to that of phenylbutazone along with high safety margin (LD50> 400 mg kg−1) with no side effects on the cardiovascular system. Copyright © 2009 John Wiley & Sons, Ltd.