Acylhydrazide and Isatin Schiff Bases as Alternate UV-Laser Desorption Ionization (LDI) Matrices for Low Molecular Weight (LMW) Peptides Analysis

Abstract

Matrix-assisted laser desorption/ionization (MALDI) is a preferred and widely used mass spectrometric technique for the analysis of macromolecules. Limited UV-LDI matrices are available for the analysis of biomolecules due to the restricted structural features to serve in the laser desorption/ionization mechanism with a problem of background signals appearing in the low mass region. This paper describes the application of Schiff base derivatives of acylhydrazide and isatin as alternate UV-LDI matrices for the analysis of peptides with significantly low background signals. Thirty one compounds have been successfully employed as matrices for the analysis of low molecular weight (LMW) peptides (<2000 Da) including bradykinin and renin substrate tetra-decapeptide. Bovine serum albumin (BSA)-digest was also analyzed and identified through database search against Swiss-Prot by using MASCOT. The MS measurements were recorded by using dried droplet sample preparation procedures by mixing the matrix solution with analyte at a volume ratio of 1:2. Finally, LMW organic compounds (<500 Da) were also analyzed by the synthesized matrix materials which showed better S/N ratios and minimal background signals for low mass range in comparison to the comparable results with α-Cyano-4-hydroxycinnamic acid (HCCA), a preferred choice for peptide analysis.

(E)-2,4-Dimethyl-N′-(2-methylbenzylidene)benzohydrazide

“…For the applications and biological activity of Schiff bases, see: Musharraf et al (2012); Khan et al (2012). For the crystal structures of related compounds, see: Taha et al (2012a,b); Naz et al (2012).…”

Synthesis of novel derivatives of oxindole, their urease inhibition and molecular docking studies

“…The (E)-4-((6-chloro-2-oxoindolin-3-ylidene)methyl)benzohydrazide was treated with different acetophenones and aryl aldehydes in the presence of acetic acid to give desired products (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) Scheme-2. …”

4-[5-(2-Methoxyphenyl)-1,3,4-oxadiazol-2-yl]benzohydrazide

“…Benzohydrazides are easily converted into hydrazones by treating with aldehyde or ketone [4]. Benzohydrazones are applicable in mass spectrometry as alternate UV-LDI matrices for the analysis of peptides with significantly low background signals [5]. Recent studies on benzohydrazones also showed that they are potent antileishmanial [6] antioxidant [7,8] antidiabetic [9,10] antibacterial [3] and antifungal [11] agents.…”