Abstract:Western blotting was used to study the impact of d-borneol on the expression of ABC transporter proteins ABCB1, ABCC1, and ABCG2 in the cell membrane. Furthermore, flow cytometry was used to examine the impact of d-borneol on the membrane permeability of HepG2 cells, and a possible physical model for the action of d-borneol was investigated. The results showed that d-borneol significantly downregulated the expression levels of the transport proteins ABCB1, ABCC1, and ABCG2, and increased HepG2 cell membrane permeability, thus improving the absorption of curcuminoids. When HepG2 cells were pretreated with 20 μg/mL d-borneol for 12 h, followed by 24-h treatment using 20 μM curcumin (Cur), 40 μM demethoxycurcumin (DCur), and 40 μM bisdemethoxycurcumin (BDCur), respectively, the expression levels of ABCB1 in cells reduced from 0.7, 0.9, and 0.7 to 0.4, 0.6, and 0.5, respectively. When HepG2 cells were pretreated with 20 μg/mL d-borneol for 12 h, followed by 24-h treatment using 40 μM BDCur, the expression levels of ABCC1 and ABCG2 in the cells were reduced from 1.0 to 0.7 and from 0.5 to 0.3, respectively. Further flow cytometric analysis indicated that d-borneol could improve the membrane permeability of the HepG2 cell. When HepG2 cells were pretreated with 20 μg/mL d-borneol for 12 h, the fluorescence intensity of YO-PRO-1 in the cells increased from 20.79 (control group) to 45.51, and the fluorescence intensity was positively correlated with the concentration of d-borneol.
