Synthesis of modified RGD based peptides and their in vitro.

RGD peptides represent the most outstanding recognition motif involved in cell adhesion and binds to αvβ3 integrin that has been targeted for cancer therapy. Various RGD-containing peptides and peptidomimetics have been designed and synthesized to selectively inhibit this integrin.In this study, the synthesis of RGD based peptides through the incorporation of the short bioactive peptide FAKLF at the C- and N- terminus of RGD has been achieved using solid phase peptide synthesis approach. The peptides were purified using preparative RP-HPLC and their structures were confirmed using HR-MS (ESI). The MTT assay study displayed that RGD (Peptide 1) and FAKLF (Peptide 2) inhibited the proliferation of HUVECs in a dose-dependent manner, with the IC50 values of 3000 ng/mL and 500 ng/mL, respectively. Interestingly, a drastic improvement was observed in the antiproliferative activity of FAKLFRGD (Peptide 3) and RGDFAKLF (Peptide 4) combined structures, leading to the IC50 values of 200 and 136.7 ng/mL, respectively. Meanwhile, based on the apoptosis results, the potential of peptides for induction of apoptosis, in accordance with their antiproliferative activity, indicated that RGD (Peptide 1) and FAKLF (Peptide 2) peptides and the peptides synthesized based on their combinations induced cell apoptosis in a dose-dependent manner followed by inhibition of proliferation of endothelial cells. Moreover, the incorporation of D-Leucine increased the apoptosis induction by these peptides.