Hitendra Singh

New diorganotin(IV) derivatives of dipeptides: Synthesis and characteristic spectral studies

Some new diorganotin(IV) derivatives of the formulae, R2SnL, where R=Me, n-Bu, Ph, and n-Oct, and L is the dianion of histidinylalanine (H2L-1) and histidinylleucine (H2L-2) have been synthesized by the reaction of R2SnCl2 and the preformed sodium salt of the respective dipeptides. The bonding and coordination behaviour in these derivatives are discussed on the basis of FT-IR, multinuclear 1H, 13C and 119Sn NMR and 119Sn Mössbauer spectroscopic studies. These investigations suggest that dipeptides in R2SnL act as dianionic tridentate 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 R2SnL with the alkyl/aryl groups and Npeptide in the equatorial positions, while a carboxylic oxygen and the amino nitrogen atom occupy the axial positions.

Synthesis, Structure–Activity Relationship of Some New Triorganotin(IV) Derivatives of Dipeptides as Anti-Inflammatory Agents

Abstract New triorganotin(IV) derivatives of dipeptides with general formulae, R3Sn(HL), where R = Me and Ph, and HL is the monoanion of histidinylalanine and histidinylleucine, have been synthesized and characterized on the basis of infrared (IR), multinuclear NMR (1H, 13C, and 119Sn), and 119Sn Mössbauer spectroscopic studies. These derivatives exhibit distorted trigonal-bipyramidal geometry around tin in which dipeptide anion acts as bidentate ligand coordinating through carboxyl oxygen and amino nitrogen. Ph3Sn(HHis-Ala), Ph3Sn(HHis-Leu), and previously reported Ph2Sn(His-Ala), Me2Sn(His-Ala), n-Oct2Sn(His-Ala), Me2Sn(His-Leu), n-Oct2Sn(His-Leu), Ph3Sn(HTyr-Phe), Ph2Sn(Tyr-Phe), Bu2Sn-(Tyr-Phe), and n-Oct2Sn(Tyr-Phe) along with standard drugs, viz. phenyl butazone and indomethacin were screened for in vivo anti-inflammatory activity and acute toxicity (LD50). Diorganotin(IV) derivatives are more active than triorganotin(IV) derivatives. Me2Sn(His-Leu) shows the highest activity. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Interaction of 5′-Guanosine Monophosphate with Organotin(IV) Moieties: Synthesis, Structural Characterization, and Anti-Inflammatory Activity

Reaction(s) of 5′-guanosine monophosphate (5′GMP) with di- and triorganotin(IV) chloride(s) led to formation of organotin(IV) derivatives of general formulae, [R2Sn(5′-GMP)·H2O]n and [(R′3Sn)2(5′-GMP)·H2O]n, where R = Me, n-Bu, and Ph; R′ = Me, i-Pr, n-Bu, and Ph; (5′-GMP)2− = 5′-guanosine monophosphate. An attempt has been made to prove the structures of the resulting derivatives on the basis of FT-IR, multinuclear 1H, 13C, and 119Sn NMR and 119Sn Mössbauer spectroscopic studies. These investigations suggest that both di- and triorganotin(IV)-5′-guanosine monophosphates are polymeric in which (5′-GMP)2− is bonded through phosphate group resulting in a distorted trigonal bipyramidal geometry around tin. The ribose conformation in all of the derivatives is C3′-endo, except diphenyltin(IV) and tri-i-propyltin(IV) derivatives where it is C2′-endo. All of the studied derivatives exhibited mild-to-moderate anti-inflammatory activity (~15.64–20.63% inhibition) at 40 mg kg−1 dose and LD50 values > 400 mg kg−1 in albino rats.