English

Waqar Ahmad

doi:10.5897/jcreo2013.0102

Abstract

Naturally isolated cyclic pentapeptide Longicalycinin A, which showed cytotoxicity to Hep G2 cancer cell line with an IC50 value 13.52 μg/mL, has been successfully synthesized by solid-phase methodology with Fmoc/t-Bu protecting schemes via solution-phase macrocyclization. 2-chlorotrityl chloride resin was used as solid support. Solution phase macrocyclization of linear pentapeptide precursor was carried out by two different routes with mild and severe acidic conditions correspondingly and found that percentage yield of Longicalycinin A under mild acidic condition (33%) was better than severe acidic conditions (13.7%). In addition, the cytotoxicity against Dalton’s lymphoma ascites (DLA) and Ehrlich’s ascites carcinoma (EAC) cell lines with CTC50 values were found to be 2.62 and 6.17 µM respectively.   Key words: Longicalycinin A, solid phase synthesis, 2-chlorotrityl chloride, solution-phase macrocyclization, cytotoxicity.

Highlights

The researchers have paid special attention to the cyclic peptides due to their unique structures and wide spread pharmacological profile, which may solve the problem of wide spread increase of confrontation towards conventional drugs (Poteau and Trinquier, 2005; Tan and Zhou, 2006; Morel et al, 2002; Jennings et al, 2001)
Trityl linker is commonly used in solidphase peptide synthesis which allows the “protected” compound to be subjected to various chemical manipulations and to afford pure compounds without numerous purification steps (Park et al, 2004; Olsen et al, 2004; Lundquist et al, 2006; Crestey et al, 2008)
The trityl linker is readily cleaved under mild acidic condition (1% Trifluoroacetic acid (TFA) in dichloromethane) owing to the high stability of trityl cations (Rothman et al, 2003)

Summary

Introduction

The researchers have paid special attention to the cyclic peptides due to their unique structures and wide spread pharmacological profile, which may solve the problem of wide spread increase of confrontation towards conventional drugs (Poteau and Trinquier, 2005; Tan and Zhou, 2006; Morel et al, 2002; Jennings et al, 2001). Solid phase synthesis has many advantages over the classical peptide extraction like the automation of the reaction and the problems of purification and solubilization of the peptide no longer exist since it remains attached to the solid matrix. Trityl linker is commonly used in solidphase peptide synthesis which allows the “protected” compound to be subjected to various chemical manipulations and to afford pure compounds without numerous purification steps (Park et al, 2004; Olsen et al, 2004; Lundquist et al, 2006; Crestey et al, 2008). The trityl linker is readily cleaved under mild acidic condition (1% TFA in dichloromethane) owing to the high stability of trityl cations (Rothman et al, 2003)

Methods

Results

Conclusion