RGD(F/S/V)-Dex: towards the development of novel, effective, and safe glucocorticoids

Abstract

Dexamethasone (Dex) is an effective glucocorticoid in treating inflammation and preventing rejection reaction. However, the side effects limit its clinical application. To improve its druggable profile, the conjugates of RGD-peptide-modified Dex were presented and their enhanced anti-inflammation activity, minimized osteoporotic action, and nanoscaled assembly were explored. (RGD stands for Arg-Gly-Asp. Standard single letter biochemical abbreviations for amino acids have been used throughout this paper.) In respect of the rejection reaction, the survival time of the implanted myocardium of the mice treated with 1.43 µmol/kg/d of the conjugates for 15 consecutive days was significantly longer than that of the mice treated with 2.5 µmol/kg/d of Dex, and the conjugates, but not Dex, exhibited no toxic action. At a single dose of 14.3 µmol/kg (100 times minimal effective dose, 0.143 µmol/kg), the conjugates induced no liver, kidney, or systemic toxicity. At the dose of 1.43 µmol/kg, the conjugates, but not Dex, prolonged the bleeding time of the mice, and inhibited the thrombosis of the rats. In water and rat plasma, the conjugates formed nanoparticles of 14–250 and 101–166 nm in diameter, respectively. Since the nanoparticles of ~100 nm in size cannot be entrapped by macrophages in the circulation, RGDF-Dex would particularly be worthy of development, since its nanoparticle diameter is 101 nm.

Keywords:

• Dexamethasone
• immunosuppression
• coagulation
• thrombus
• acute toxicity
• nanomedicine
• development

Supplementary materials

Optical spectra

Figure S1 ¹HNMR of RGDV-Dex.

Abbreviations: ¹HNMR, proton nuclear magnetic resonance; RGDV, Arg-Gly-Asp-Val; Dex, dexamethasone.

Figure S2 ¹³C NMR of RGDV-Dex.

Abbreviations: ¹³C NMR, carbon-13 nuclear magnetic resonance; RGDV, Arg-Gly-Asp-Val; Dex, dexamethasone.

Figure S3 ¹H NMR of RGDS-Dex.

Abbreviations: ¹H NMR, proton nuclear magnetic resonance; RGDS, Arg-Gly-Asp-Ser; Dex, dexamethasone.

Figure S4 ¹³C NMR of RGDS-Dex.

Abbreviations: ¹³C NMR, carbon-13 nuclear magnetic resonance; RGDS, Arg-Gly-Asp-Ser; Dex, dexamethasone.

Figure S5 ¹H NMR of RGDF-Dex.

Abbreviations: ¹H NMR, proton nuclear magnetic resonance; RGDF, Arg-Gly-Asp-Phe; Dex, dexamethasone.

Figure S6 ¹³C NMR of RGDF-Dex.

Abbreviations: ¹³C NMR, carbon-13 nuclear magnetic resonance; RGDF, Arg-Gly-Asp-Phe; Dex, dexamethasone.

Figure S7 HPLC chromatogram of RGDF-Dex.

Note: Mobile phase: CH₃OH: Water=15%:85%.
Abbreviations: HPLC, high performance liquid chromatography; RGDF, Arg-Gly-Asp-Phe; Dex, dexamethasone.

Figure S8 HPLC chromatogram of RGDV-Dex.

Note: Mobile phase: CH₃OH: Water=15%:85%.
Abbreviations: HPLC, high performance liquid chromatography; RGDV, Arg-Gly-Asp-Val; Dex, dexamethasone.

Figure S9 HPLC chromatogram of RGDS-Dex.

Note: Mobile phase: CH₃OH: Water=85%:15%
Abbreviations: HPLC, high performance liquid chromatography; RGDS, Arg-Gly-Asp-Ser; Dex, dexamethasone.

Acknowledgments

This work was supported by Beijing Municipal Science & Technology Commission (Z141100002114049), the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality, the NSFC (81172930, 81273379, 81373265, 81202412, 81373264), 863 program (2015AA020902), Beijing Talent Program (2014000026833ZK23) and Joint Research and Development of protective agents for low dose radiation injury (2014DFR30930).

Disclosure.

The authors report no conflicts of interest in this work.