by Jenna Mallon (’18)
In recent years, cyclic peptides have emerged as leaders in therapeutic drugs due to their in vivo stability and bioavailability. A class of specific cyclic peptides known as Cyclosporins has been effective in preventing rejection and infection in the body after organ transplants. The different analogs of Cyclosporin are very structurally similar, making separation extremely difficult. For this reason Yuefei Shao, of Bristol-Myers Squibb, and a team of researchers set out to find a supercritical fluid chromatography (SFC) method that would easily separate the analogs.
The team obtained five naturally occurring Cyclosporin analogs and tested the separation under various SFC environments, while changing a different variable each time. The researchers tested the effect of different stationary phases and mobile phase modifiers; they discovered that a bare silica stationary phase with an ethanol modified carbon dioxide mobile phase resulted in the best separation. Next the researchers tested the effect that column temperature and back pressure had on the separation. They found that both variables played an important role in the sample resolution. Additionally, conditions of 80°C and 300 bar were the most ideal. The researchers concluded that using the aforementioned conditions would result in a clear separation and would save time and materials that have been previously wasted because of inefficient techniques.
This study was only conducted on natural Cyclosporin analogs, so future research would will work to expand to synthetic analogs as well as study other types of cyclic peptides.
- Y. Shao, et al., Rapid separation of five cyclosporine analogs by supercritical fluid chromatography. Journal of Analytical Sciences, Methods and Instrumentation 6, 23-32 (2016). doi: 10.4236/jasmi.2016.62004.