Diorganotin(IV) Derivatives of Dipeptides Containing at Least One Essential Amino Acid Residue: Synthesis, Characteristic Spectral Data, Cardiovascular, and Anti‐inflammatory Activities

Abstract

New diphenyltin(IV) derivatives of the formula Ph₂SnL, where L is the dianion of glycyltryptophan (Gly‐Trp), glycylphenylalanine (Gly‐Phe), valylvaline (Val‐Val), alanylvaline (Ala‐Val), and leucylalanine (Leu‐Ala), have been synthesized by the reaction of Ph₂SnCl₂ and the disodium salt of the respective dipeptides. The bonding and coordination behaviour in these derivatives are discussed on the basis of IR, multinuclear ¹H, ¹³C, and ¹¹⁹Sn NMR and ¹¹⁹Sn Mössbauer spectroscopic studies. These investigations suggest that all the dipeptides in Ph₂SnL act as dianionic tridentate ligands coordinating through the COO⁻, NH₂, and N_peptide groups. The ¹¹⁹Sn Mössbauer studies, together with the NMR data, suggest a trigonal‐bipyramidal geometry around tin in Ph₂SnL with the phenyl groups and N_peptide in the equatorial positions, whereas a carboxylic oxygen and the amino nitrogen atom occupy the axial positions. The anti‐inflammatory and cardiovascular activities, and toxicity of all the synthesized diphenyltin(IV) derivatives of dipeptides and of n‐dibutyltin(IV) derivatives of dipeptides (synthesized and characterized earlier) viz. Gly‐Trp, Val‐Val, Ala‐Val, glycyltyrosine (Gly‐Tyr), leucyltyrosine (Leu‐Tyr), and leucylleucine (Leu‐Leu) are discussed. The n‐dibutyltin(IV) derivatives exhibit better cardiovascular and anti‐inflammatory activities than the diphenyltin(IV) analogues.

Keywords:

• Spectral studies
• Diphenyltin(IV) derivative
• Dipeptides
• Anti‐inflammatory activity

Acknowledgments

This work was a part of a major research project sponsored by the Department of Science and Technology (DST) (Grant No. SP/S1/F‐07/2000), New Delhi, India. M. Nath is thankful to the DST, New Delhi, India. Financial support for the Mössbauer work from the National Institute of Health, Minority Biomedical Research Support Programs MBRS/SCORE, GM08005, is gratefully acknowledged. Thanks are also due to the Head, Regional Sophisticated Instrumentation Centre, Central Drug Research Institute, Lucknow, India, for elemental analyses and NMR spectral measurements, and to the Head, Department of Chemistry, Indian Institute of Technology, Delhi, India, for ¹¹⁹Sn NMR spectral studies. One of the authors (S. Pokharia) is thankful to the Council for Scientific and Industrial Research, New Delhi, for a Senior Research fellowship during the period of writing this manuscript.