A variety of oxazolones (3-18) with structural variation at C-2 and C-4 were synthesized and evaluated as chymotrypsin inhibitors. The synthesized compounds showed varying degree of chymotrypsin inhibitory activity ranging IC 50 values from 12.62 ± 1.32 -126.57 ± 1.06 μM, if compared to standard chymostatin (IC 50 = 7.01 ± 0.1 μM). Compounds 3,9,10,13,14, and 15 have IC 50 values 17.03 ± 0.78, 69.05 ± 1.48, 12.62 ± 1.32, 17.29 ± 0.93, 126.57 ± 1.06, and 31.55 ± 1.31 μM, respectively. This study reveals that the substitution of functional group (s) at C-2 and C-4 positions plays a vital role in the activity of this series of compounds. The size and electron donating or withdrawing effects of substituents influenced the activity.
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.
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