AUTHOR=Peng Huan , Yang Xiangrong , Fang Huanle , Zhang Zhongqi , Zhao Jinli , Zhao Te , Liu Jianli , Li Yan 

TITLE=Simultaneous effect of different chromatographic conditions on the chromatographic retention of pentapeptide derivatives (HGRFG and NPNPT)

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1171824

DOI=10.3389/fchem.2023.1171824

ISSN=2296-2646

ABSTRACT=<p><bold>Introduction:</bold> Oligopeptides exhibit great prospects for clinical application and its separation is of great importance in new drug development.</p><p><bold>Methods:</bold> To accurately predict the retention of pentapeptides with analogous structures in chromatography, the retention times of 57 pentapeptide derivatives in seven buffers at three temperatures and four mobile phase compositions were measured via reversed-phase high-performance liquid chromatography. The parameters (<inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mrow><mml:mi>H</mml:mi><mml:mi>A</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula>, <inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>k</mml:mi><mml:mi>A</mml:mi></mml:msub></mml:mrow></mml:math></inline-formula>, and <inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mi>K</mml:mi><mml:mi>a</mml:mi></mml:mrow></mml:math></inline-formula>) of the acid–base equilibrium were obtained by fitting the data corresponding to a sigmoidal function. We then studied the dependence of these parameters on the temperature (T), organic modifier composition (φ, methanol volume fraction), and polarity (<inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>P</mml:mi><mml:mi>m</mml:mi><mml:mi>N</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> parameter). Finally, we proposed two six-parameter models with (1) pH and T and (2) pH and φ or <inline-formula id="inf10"><mml:math id="m10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>P</mml:mi><mml:mi>m</mml:mi><mml:mi>N</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> as the independent variables. These models were validated for their prediction capacities by linearly fitting the predicted retention factor k-value and the experimental k-value.</p><p><bold>Results:</bold> The results showed that <inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="italic">log</mml:mi><mml:msub><mml:mi>k</mml:mi><mml:mrow><mml:mi>H</mml:mi><mml:mi>A</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula> and <inline-formula id="inf6"><mml:math id="m6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="italic">log</mml:mi><mml:msub><mml:mi>k</mml:mi><mml:mi>A</mml:mi></mml:msub></mml:mrow></mml:math></inline-formula> exhibited linear relationships with <inline-formula id="inf7"><mml:math id="m7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mi>T</mml:mi></mml:mrow></mml:math></inline-formula>, φ or <inline-formula id="inf8"><mml:math id="m8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>P</mml:mi><mml:mi>m</mml:mi><mml:mi>N</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> for all pentapeptides, especially for the acid pentapeptides. In the model of pH and T, the correlation coefficient (R<sup>2</sup>) of the acid pentapeptides was 0.8603, suggesting a certain prediction capability of chromatographic retention. Moreover, in the model of pH and φ or <inline-formula id="inf11"><mml:math id="m11" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>P</mml:mi><mml:mi>m</mml:mi><mml:mi>N</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula>, the R<sup>2</sup> values of the acid and neutral pentapeptides were greater than 0.93, and the average root mean squared error was approximately 0.3, indicating that the k-values could be effectively predicted.</p><p><bold>Discussion:</bold> In summary, the two six-parameter models were appropriate to characterize the chromatographic retention of amphoteric compounds, especially the acid or neutral pentapeptides, and could predict the chromatographic retention of pentapeptide compounds.</p>