이재범 (성신여자대학교)

이재범 (성신여자대학교)

고병준 (성신)

Plasma stability is a critical property of cell-penetrating peptides (CPPs), as plasma-mediated degradation can reduce systemic exposure and limit their therapeutic potential.

In this study, the time-dependent plasma stability of CPP, a CPP candidate, was evaluated in rat plasma at 37 °C using ultra-performance liquid chromatography coupled with parallel reaction monitoring (PRM). CPP was incubated in rat plasma for up to 72 h, and aliquots collected at predetermined time points were processed by protein precipitation using bradykinin as an internal standard. Processed samples and calibration standards were analyzed within the same analytical batch by UPLC–Orbitrap PRM.

Plasma stability was assessed by calculating the peak area ratio of CPP to bradykinin based on the integrated product-ion signals and normalizing each value to the corresponding 0 h sample. CPP remained relatively stable in rat plasma for up to 24 h at 37 °C. After 24 h, the CPP/bradykinin peak area ratio gradually decreased with

increasing incubation time. The relative CPP response declined to approximately 53.5% and 23.0% of the initial (0 h) value after 48 h and 72 h of incubation, respectively. These results demonstrate that the UPLC–Orbitrap PRM workflow enables selective and reliable monitoring of time-dependent changes in CPP within a complex plasma matrix. This high-resolution MS-based approach provides a practical analytical platform for establishing the plasma stability profile of CPP candidates and may facilitate their optimization during preclinical development and pharmacokinetic evaluation.