Abstract
Clarified the binding mechanism of drugs with plasma proteins could provide fresh insights into the drug development. Caffeoylquinic acids (CQAs) are a kind of phenolic acid compounds which has extensive biological effects. This study investigated the binding mechanism of three CQAs, including chlorogenic acid, neochlorogenic acid, and cryptochlorogenic acid, with bovine serum albumin (BSA) by using multi-spectroscopic techniques, including fluorescence, UV-Vis, Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy, LC-MSn, molecular docking and antioxidant activity assessment. In addition, the influences of PBS buffer, Tris-HCl buffer and water as solvents on the characteristics of CQAs and BSA interaction were also investigated. The results showed that intrinsic fluorescence of BSA was quenched by CQAs and the interaction was static quenching with the formation of a non-fluorescent complex. The binding of CQAs and BSA was spontaneous, and Van der Waals forces and hydrogen-bond interaction occupied crucial roles in the binding. All the three CQAs could bind to Site I in Domain IIA. The weakest interaction between neochlorogenic acid and BSA may due to its larger polarity. The results also indicated that the binding affinity of CQAs had a descending order of Tris-HCl > H2O > PBS. This study firstly clarified the binding mechanism of CQAs with BSA and changes of the binding in different solvents, and provided fresh insights into this drug transportation and metabolism.
Highlights
Phenolic acid compounds are a series of dietary antioxidants which are belong to secondary metabolism of many plants
For Caffeoylquinic acids (CQAs)-bovine serum albumin (BSA) system, the red shifts could be observed in PBS buffer and H2O, but blue shifts happened in Tris-HCl buffer
This study investigated the binding mechanism of CQAs and BSA in PBS buffer, Tris-HCl buffer and H2O by multi-spectroscopic method, antioxidant activity assessment and docking
Summary
Phenolic acid compounds are a series of dietary antioxidants which are belong to secondary metabolism of many plants. Due to their multiple active phenolic groups, phenolic acid compounds have good antioxidant, anti-microbial and anti-cancerogenic effects (Cui et al, 2002; Kacem et al, 2015; Zhao et al, 2015). As the only CGA commercially available, 5-CQA has multiple functions such as anti-oxidative, anti-bacterial, anti-inflammatory, anti-hypertensive, cardiovascular protection and regulation of glycolipid metabolism activities (Upadhyay and Mohan Rao, 2013). As two monoacyl isomers of 5-CQA, 3-CQA and 4-CQA show the highly similar chemical structures and strong anti-oxidative activity like 5-CQA (Bajko et al, 2016)
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