Acta Pharmacologica Sinica (2009) 30: 1573–1576; doi: 10.1038/aps.2009.148

Aim: To investigate noncovalent interactions between borneol and human serum albumin (HSA) under near-physiological conditions.

Methods: A 65-µm polydimethylsiloxane (PDMS) fiber was selected for sampling.  The extraction temperature was kept at 37 ºC, and the extraction time was optimized at 10 min.  Borneol solutions of different concentrations were equilibrated in 600 µmol/L HSA and 67 mmol/L phosphate buffer solution (pH 7.4, 37 ºC) for 24 h prior to solid phase microextraction (SPME) using headspace mode.  The binding properties were obtained based on the calculation of extracted borneol amount using gas chromatography (GC) determination.

Results: The headspace SPME extraction method avoided disturbance from the HSA binding matrix.  The recovery showed good linearity for the borneol concentrations over the range of 0.4–16.3 µmol/L with a regression coefficient (R²) of 0.9998.  The limit of detection and lower limit of quantitation were determined to be 0.01 µmol/L and 0.4 µmol/L, respectively.  The binding constant and the percentage binding rate were estimated to be 2.4×10³ (mol/L)^-1 and 59.5%, respectively.

Conclusion: Headspace SPME coupled to GC is a simple, sensitive and rapid method for the study of borneol binding to HSA.  The method may be applied in the determination of other protein binding properties in human plasma.

Keywords: borneol; human serum albumin; binding; gas chromatography; headspace; solid phase microextraction