Prediction of oral hepatotoxic dose of natural products derived from traditional Chinese medicines based on SVM classifier and PBPK modeling.

The risk of drug-induced liver injury (DILI) poses a major challenge for development of natural products derived from traditional Chinese medicines (NP-TCMs). It is urgent to find a new method for the safety assessment of the NP-TCMs. Recent study has reported an in vitro/in silico method to estimate the acceptable daily intake of hepatotoxic compounds using support vector machine (SVM) classifier and physiologically based pharmacokinetic (PBPK) modeling. However, this method is not suitable for estimating the dosing schedule of compounds which are administered in multiple daily doses. Thus, in this study, the method mentioned above was in particular optimized, and used to estimate the hepatotoxic plasma concentrations of 17 NP-TCMs. Additionally, the oral dosing schedules of the triptolide, emodin, matrine and oxymatrine were also predicted by the SVM classifier and PBPK modeling. The optimization included that: (1) in vitro cytotoxicity data of 28 training set compounds was optimized using benchmark concentrations (BMC) modeling; (2) AUC of the training set compound was used as the in vivo metric instead of Cmax to better reflect the total daily exposure of compounds which are administered in multiple daily doses; (3) using the mean AUC in plasma as in vivo metric and BMC value as in vitro metric could achieve the better toxicity separation index (0.962 vs. 0.938); (4) The TSI for Cmax and BMC values was 0.985 calculated in this study, and the results indicated that BMC modeling improved the separation performance. This optimized in vitro-in vivo extrapolation (IVIVE) workflow could extrapolate in vitro BMC to blood concentrations and the oral dosing schedule which are corresponding to certain risk of hepatotoxicity. The estimated safe dosing schedule of oxymatrine by this optimized method was close to the clinical recommended dosing regimen. The results indicate that the optimized method could be used to predict the dosing schedule of compounds administered in multiple daily doses, and our optimized workflow could be helpful for the safety assessment as well as the research and development on NP-TCMs.

Prediction of Drug-Drug Interaction between Tacrolimus and Principal Ingredients of Wuzhi Capsule in Chinese Healthy Volunteers Using Physiologically-Based Pharmacokinetic Modelling.

Schisantherin A and schisandrin A, the most abundant active ingredients of Wuzhi capsule, are known to inhibit tacrolimus metabolism by inhibiting CYP3A4/5. We aimed to predict the contribution of schisantherin A and schisandrin A to drug-drug interaction (DDI) between Wuzhi capsule and tacrolimus using physiologically-based pharmacokinetic (PBPK) modelling. Firstly, the inhibition mechanism of schisantherin A and schisandrin A on CYP3A4/5 was investigated. Thereafter, PBPK models of schisantherin A, schisandrin A and tacrolimus were established. Finally, tacrolimus pharmacokinetics were evaluated after the combined use with schisantherin A or schisandrin A. The blood area under the curve (AUC) of tacrolimus increased 1.77- and 2.61-fold after a single dose and multiple doses of schisantherin A, respectively. Meanwhile, schisandrin A inhibited tacrolimus metabolism to a smaller extent. Also, it showed that mechanism-based inhibition (MBI) played a more important role in DDI than reversible inhibition after long-term administration, while reversible inhibition was comparable to MBI after single-dose administration. In conclusion, we utilized PBPK modelling to quantify the contribution of schisantherin A and schisandrin A to DDI between tacrolimus and Wuzhi capsule. This may provide more insights for the rational use of this drug combination.

Curcumol induces apoptosis in SPC-A-1 human lung adenocarcinoma cells and displays anti-neoplastic effects in tumor bearing mice.

Curcumol is a sesquiterpene originally isolated from curcuma rhizomes, a component of herbal remedies commonly used in oriental medicine. Its beneficial pharmacological activities have attract significant interest recently. In this study, anti-cancer activity of curcumol was examined with both in vitro and in vivo models. It was found that curcumol exhibited time- and concentration-dependent anti-proliferative effects in SPC-A-1 human lung adenocarcinoma cells with cell cycle arrest in the G0/G1 phase while apoptosis-induction was also confirmed with flow cytometry and morphological analyses. Interestingly, curcumol did not display growth inhibition in MRC-5 human embryonic lung fibroblasts, suggesting the anti-proliferative effects of curcumol were specific to cancer cells. Anti-neoplastic effects of curcumol were also confirmed in tumor bearing mice. Curcumol (60 mg/kg daily) significantly reduced tumor size without causing notable toxicity. In conclusion, curcumol appears a favorable anti-cancer candidate for further development.

Quantification of the resveratrol analogs trans-2,3-dimethoxy-stilbene and trans-3,4-dimethoxystilbene in rat plasma: application to pre-clinical pharmacokinetic studies.

trans-2,3-Dimethoxystilbene (2,3-DMS) and trans-3,4-dimethoxystilbene (3,4-DMS) are two synthetic resveratrol (trans-3,5,4'-trihydroxystilbene) analogs. In this study, a simple HPLC method was developed and validated to determine 2,3-DMS and 3,4-DMS in rat plasma. Chromatographic separation was obtained with a reversed-phase HPLC column through a 12.5-min gradient delivery of a mixture of acetonitrile and water at the flow rate of 1.5 mL/min at 50 °C. The lower limit of quantification was 10 ng/mL. After successful validation, the pharmacokinetic profiles of 2,3-DMS and 3,4-DMS were subsequently studied in Sprague-Dawley rats. Upon single intravenous administration (4 mg/kg), 2,3-DMS had a medium volume of distribution of the central compartment (Vc = 2.71 ± 0.51 L/kg), quite rapid clearance (Cl = 52.0 ± 7.0 mL/min/kg), moderate mean transit time (MTT0→last = 131.0 ± 4.5 min) but a fairly long terminal elimination half-life (t1/2 λZ = 288.9 ± 92.9 min). Interestingly, 3,4-DMS displayed a pharmacokinetic profile apparently distinct from 2,3-DMS and it had more extensive distribution (Vc = 5.58 ± 1.73 L/kg), faster clearance (Cl = 143.4 ± 40.5 mL/min/kg) and shorter residence (MTT0→last = 61.4 ± 27.1 min). Following single oral administration (10 mg/kg), 2,3-DMS had low and erratic plasma exposure (Cmax = 37.5 ± 23.7 ng/mL) and poor oral bioavailability (2.22% ± 2.13%) while the oral bioavailability of 3,4-DMS was even poorer than 2,3-DMS. Clearly, the location of the methoxy groups had a significant impact on the pharmacokinetics of resveratrol analogs. This study provided useful information for the design of resveratrol derivatives in future study.

Quantification of α- and ß-amyrin in rat plasma by gas chromatography-mass spectrometry: application to preclinical pharmacokinetic study.

α- and ß-Amyrins are naturally occurring triterpenes with a wide range of biological activities. In this study, a reliable GC-MS method was developed and validated for the quantification of α- and ß-amyrins in rat plasma. The calibration curves were linear (R(2) > 0.996) with a limit of quantification of 1.0 ng ml(-1) for both α- and ß-amyrins. The precision and repeatability of this method was good as the relative standard deviation were 12% or less. The absolute recovery ranged from 71% to 89%, while the analytical recovery ranged from 95% to 99%. The pharmacokinetic profiles of α- and ß-amyrins in rats were subsequently investigated in Sprague-Dawley rats. ß-Amyrin was administered intravenously and also orally in two forms, namely, as a suspension of the pure compound and the crude plant extract. α-Amyrin was administered orally as a suspension of the crude plant extract. ß-Amyrin had a very long terminal elimination half-life (t(1/2λz) = 610 ± 179 min) and extremely slow clearance (Cl = 2.04 ± 0.24 ml min(-1) kg(-1)). The absolute oral bioavailability of ß-amyrin in the crude plant extract was about fourfold higher than that in the suspension of pure form (3.83% vs 0.86%). When given in crude plant extract, both α- and ß-amyrins had a similar dose normalized C(max). This reliable GC-MS method will enable further pharmacokinetic investigations of α- and ß-amyrins.

Quantification of oxyresveratrol analog trans-2,4,3',5'-tetramethoxystilbene in rat plasma by a rapid HPLC method: application in a pre-clinical pharmacokinetic study.

A rapid HPLC method was developed and validated for the quantification of oxyresveratrol analog trans-2,4,3',5'-tetramethoxystilbene (oxyresveratrol tetramethyl ether, OTE) in rat plasma. Chromatographic separation was achieved on an RP-HPLC column, which was protected by a guard column through a 12 min gradient delivery of a mixture of acetonitrile-water at 50°C. The UV absorbance at 325 nm was recorded. The retention time of OTE and trans-stilbene (internal standard) was about 7.7 and 8.4 min, respectively. The calibration curves were linear (R(2) ≥ 0.9986) with a lower limit of quantification of 15 ng/mL. The intra- and inter-day variations, in terms of RSD, were all lower than 9.8% while the intra-day and inter-day bias ranged from -8.3 to +9.2%. The pharmacokinetics of OTE was assessed in rats using 2-hydroxypropyl-ß-cyclodextrin as a dosing vehicle. After intravenous administration, OTE possessed a long terminal elimination half-life (t(1/2) (λz) = 481 ± 137 min) and slow clearance (Cl = 29.1 ± 3.7 mL/min/kg). Upon oral administration, OTE was rapidly absorbed. However, it only displayed minimal plasma exposure and its absolute oral bioavailability (F) was as low as 4.5 ± 3.2%. Fortunately, the levels of OTE after single oral administration were sufficient to inhibit human cytochrome P450 1B1.

A simple and sensitive HPLC-UV method for the quantification of piceatannol analog trans-3,5,3',4'-tetramethoxystilbene in rat plasma and its application for a pre-clinical pharmacokinetic study.

A simple and sensitive HPLC-UV method was developed and validated for the quantification of piceatannol analog trans-3,5,3',4'-tetramethoxystilbene (M-PIC) in rat plasma. Following protein precipitation with three volumes of acetonitrile, the analytes were separated on a RP-HPLC column, which was protected by a guard column through gradient delivery of a mixture of acetonitrile-water at 40 degrees C. The UV absorbance at 325nm was recorded to quantify M-PIC. The retention time of M-PIC and trans-3,5-dimethoxystilbene (internal standard) was 7.4 and 8.4min, respectively. The calibration curves were linear (R(2)>0.9989) with a lower limit of quantification of 15ng/ml. The intra- and inter-day precisions, in terms of RSD, were all lower than 7.5%. The average analytical recovery ranged from 97.0 to 104.3% while the average absolute recovery ranged from 101.8 to 105.0%. This reliable HPLC method was subsequently applied to assess the pharmacokinetic profile of M-PIC in Sprague-Dawley rats using 2-hydroxypropyl-beta-cyclodextrin as a dosing vehicle. The terminal elimination half-life (t(1/2lambdaz)) and clearance (Cl) of M-PIC were 313+/-20min and 33.1+/-3.9ml/min/kg, respectively; and its absolute oral bioavailability was as high as 50.7+/-15.0%. M-PIC appeared to have a favorable pharmacokinetic profile and further pharmacological investigation on this phyto-stilbene was warranted.