Xyloketal B, a marine compound, acts on a network of molecular proteins and regulates the activity and expression of rat cytochrome P450 3a: a bioinformatic and animal study

Su, Junhui; Chang, Cui; Xiang, Qi; Zhou, Zhi-Wei; Luo, Rong; Yang, Lun; He, Zhi-Xu; Yang, Hongtu; Li, Jianan; Bei, Yu; Xu, Jinmei; Zhang, Minjing; Zhang, Qihao; Su, Zhijian; Huang, Yadong; Pang, Jiyan; Zhou, Shu-Feng

Midazolam is a probe substrate for CYP3A with sedative, amnesic, anxiolytic, muscle relaxant, and anticonvulsant properties in humans. It has been widely used to examine the degree of drug interaction and inhibitory effect of xenobiotics on the activity and function of CYP3A4/5 via evaluation of urinary and/or plasma levels of midazolam and its main metabolite 1′-OH-MDZ. 49, 50 In our study, plasma concentrations of midazolam and 1′-OH-MDZ were determined using a validated HPLC method with a high specificity, linearity, precision, accuracy, and recovery rate for midazolam and 1′-OH-MDZ, and the tested samples showed high stability. This indicates that the HPLC method is reliable for determining the plasma concentration of midazolam and 1′-OH-MDZ. Our present findings show that oral administration of XKB 14 kg/mg for 8 days significantly elevated the AUC 0-t and C max of midazolam, but decreased its CL/F. XKB also showed an inhibitory effect on the metabolism of midazolam similar to that seen with ketoconazole in vivo. However, there were not remarkable changes in the k a , k e , t 1/2ka , t 1/2ke , and V/F of midazolam and 1′-OH-MDZ in rats treated with XKB. Collectively, the data strongly suggest that XKB decreased Cyp3a-mediated metabolism and clearance of midazolam in rats. Notably, it has been reported that midazolam has inducing effects on expression of Cyp3a1 and Cyp2b in rat hepatocytes, 51 which in turn may affect its own metabolism and that of other Cyp3a substrate drugs. Further, we found that oral administration of XKB for 8 days significantly reduced the expression and activity of hepatic Cyp3a via unknown mechanisms, but probably due Effect of oral administration of XKB on hepatic Cyp3a activity in rat liver microsomes. Notes: Rats were treated with XKB orally at 7 or 14 mg/kg for 8 days. The rats were sacrificed, the livers were collected, and liver microsomes were prepared. Cyp3a activity was measured using a luminescent assay (P450-Glo™). The bars represent the mean ± standard deviation (n=8). KTZ (as the positive control) showed significant inhibition of Cyp3a activity by 48.79% (P0.001) compared with the normal saline-treated group. Treatment of XKB at 7 or 14 mg/kg decreased Cyp3a2 activity by 6.27% (P0.05) and 29.27% (P0.001), respectively. ***P0.001 by one-way analysis of variance. Abbreviations: CYP, cytochrome P450; XKB, Xyloketal B; KTZ, ketoconazole. with toxicity-associated targets (eg, hERG). The potential interactions between XKB and CYP3A4/Cyp3a2 may lead to unfavorable drug interactions. In addition, the short elimination half-life of XKB may negatively affect its concentration at the site of action and compromise the therapeutic effect in clinical practice. Therefore, these findings provide clues for further XKB-based drug development and clinical use, including structural modification or nanotechnology-based formulations to minimize or avoid its potential side effects and prolong its elimination half-life to achieve therapeutic concentrations at the site of action.