IDENTIFICATION AND CHARACTERIZATION OF POTENT CYP3A4 INHIBITORS IN SCHISANDRA FRUIT EXTRACT

Pharmacokinetic assessment of tacrolimus in combination with deoxyschizandrin in rats

Background

Tacrolimus (Tac) is commonly used for postoperative immunosuppressive therapy in transplant patients. However, problems, for example, low bioavailability and unstable plasma concentration, persist for a long time, Studies have reported that the deoxyschizandrin could effectively improve these problems, but the pharmacokinetic parameters (PKs) of Tac combined with deoxyschizandrin are still unknown.

Method

In this study, an UHPLC-MS/MS method has been established for simultaneous quantitation of Tac and deoxyschizandrin. The PKs of Tac influenced by different doses of deoxyschizandrin after single and multiple administrations were analyzed, and the different impact of deoxyschizandrin and Wuzhi capsule on PKs of Tac were compared.

Result

The modified UHPLC-MS/MS method could rapid quantification of Tac and deoxyschizandrin within 2 min using bifendatatum as the internal standard (IS). All items were successfully validated. The C max of deoxyschizandrin increased from 148.27 ± 23.20 to 229.13 ± 54.77 ng/mL in rats after multiple administrations for 12 days. After co-administration of 150 mg/mL deoxyschizandrin, Tac had an earlier T max and greater C max and AUC0-t, and the C max and AUC0-t of Tac increased from 14.26 ± 4.73 to 54.48 ± 14.37 ng/mL and from 95.10 ± 32.61 to 315.23 ± 92.22 h/ng/mL, respectively; this relationship was positively proportional to the dosage of deoxyschizandrin. In addition, compared with Wuzhi capsule, the same dose of deoxyschizandrin has a better effective on Tac along with more stable overall PKs.

Conclusion

An UHPLC-MS/MS method was established and validated for simultaneous detection of deoxyschizandrin and Tac. Deoxyschizandrin could improve the in vivo exposure level and stability of Tac, besides, this effect is better than Wuzhi capsule in same dose.

Protection of schisantherin A against dictamnine-induced hepatotoxicity: Pharmacokinetic insights

Dictamnine (DIC), as the most abundant furoquinoline alkaloid ingredient of the herbal medicine Cortex Dictamni (CD), can induce severe liver injury. A previous study found that DIC-induced liver injury was initiated by cytochrome P4503A (CYP3A)-mediated metabolic activation and subsequent formation of adducts with cellular proteins. Schisantherin A (SchA) is the major lignan component of the herbal medicine Schisandra chinensis (SC). SC is frequently combined with CD used in numerous Chinese medicinal formulas for the treatment of eczema and urticaria. Furthermore, SC could protect against CD-induced hepatotoxicity. The objective of the study was to investigate the protective effect of SchA on DIC-induced hepatotoxicity based on pharmacokinetic interactions. The studies found that SchA exerted a protective effect on DIC-induced hepatotoxicity in a dose-dependent manner. Pharmacokinetic studies showed that pretreatment with SchA enhanced the area under concentration-time curve (AUC) and maximal concentration (Cmax ) values of DIC in the serum and liver tissue of mice, indicating that SchA could augment the accumulation of DIC in the circulation. In vitro metabolism assays with mouse liver microsomes (MLMs) showed that SchA reduced the production of DIC-glutathione (GSH) conjugate. In addition, SchA significantly reduced the excretion of DIC-GSH conjugate in the urine of mice and relieved hepatic GSH depletion induced by DIC. These results suggested that SchA could inhibit the metabolic activation of DIC in vitro and in vivo. In summary, our findings showed that the observed pharmacokinetic interactions might be attributable to the inhibition of the metabolism of DIC by SchA, which might be responsible for the protection of SchA against DIC-induced hepatotoxicity. Therefore, the development of a standardized combination of DIC and SchA may protect patients from DIC-induced liver injury.

Safety and efficacy of a feed additive consisting of a tincture derived from the dried fruit of Schisandra chinensis (Turcz.) Baill. (omicha tincture) for poultry, horses, dogs and cats (FEFANA asbl)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of a tincture from the dried fruit of Schisandra chinensis (Turcz.) Baill. (omicha tincture), when used as a sensory additive in feed for horses, cats, dogs, and in feed and in water for drinking for poultry. The product is a water/ethanol (55:45 v/v) solution, with a dry matter content of not more than 4% (w/w) and a content of 0.01%-0.15% (w/w) for the sum of schisandrin and deoxyschisandrin. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that omicha tincture is safe at the following concentrations in complete feed: 16 mg/kg for turkeys for fattening, 12 mg/kg for chickens for fattening and other poultry for fattening or reared for laying/reproduction, 18 mg/kg for laying hens and other laying/reproductive birds, 56 mg/kg for dogs and 47 mg/kg for horses and cats. The additive is considered safe for consumers when used up to the highest safe level in feed for poultry species and horses. Omicha tincture should be considered as irritants to skin and eyes, and as dermal and respiratory sensitisers. The use of omicha tincture as a flavour in feed for poultry species and horses was not considered to be a risk to the environment. Since it was recognised that the fruit of S. chinensis can influence sensory properties of feedingstuffs, no further demonstration of efficacy was considered necessary for the tincture under assessment.

Exploring the effect of Wuzhi capsule on the pharmacokinetics of regorafenib and its main metabolites in rat plasma using liquid chromatography-tandem mass spectrometry

Regorafenib is a small-molecule tyrosine kinase inhibitor with severe hepatotoxicity. It undergoes metabolism mainly by CYP3A4 to generate active metabolites regorafenib-N-oxide (M2) and N-desmethyl-regorafenib-N-oxide (M5). Wuzhi capsule (WZC) is an herbal preparation derived from Schisandra sphenanthera and is potentially used to prevent regorafenib-induced hepatotoxicity. This study aims to explore the effect of WZC on the pharmacokinetics of regorafenib in rats. An efficient and sensitive liquid chromatography-tandem mass spectrometry method was developed to quantitatively determine regorafenib and its main metabolites in rat plasma. The proposed method was applied to the pharmacokinetic study of regorafenib in rats, with or without WZC. Coadministration of regorafenib with WZC resulted in a prolonged mean residence time (MRT) of the parent drug but had no statistically significant difference in other pharmacokinetic parameters. While for the main metabolites of regorafenib, WZC decreased the area under the curve and maximum concentration (Cmax ), delayed the time to reach Cmax , and prolonged the MRT of M2 and M5. These results indicate that WZC delayed and inhibited the metabolism of regorafenib to M2 and M5 by suppressing CYP3A4. Our study provides implications for the rational use of the WZC-regorafenib combination in clinical practice.

Evidence of the interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and Chinese herbal medicine: A scoping review

OBJECTIVES

Chinese herbal medicine (CHM) has been shown to be effective in autoimmune rheumatic diseases, but harmful herb-drug interactions might be inherent. We aim to review the evidence regarding herb-drug interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and CHM.

METHODS

We searched PubMed, EMBASE and CINAHL from inception till 30 April 2023 using keywords that encompassed 'herb-drug interactions', 'herbs' and 'immunosuppressants'. Articles were included if they contained reports about interactions between immunosuppressive drugs used in the treatment of rheumatic diseases with CHM. Level of evidence for each pair of interaction was graded using the algorithm developed by Colalto.

RESULTS

A total of 65 articles and 44 unique pairs of interactions were identified. HDIs were reported for cyclophosphamide, cyclosporine, tacrolimus, methotrexate, mycophenolic acid, glucocorticoids, sulfasalazine, tofacitinib and biologic disease-modifying antirheumatic drugs. Among these, cyclosporine (n = 27, 41.5%) and tacrolimus (n = 19, 29.2%) had the highest number of documented interactions. Hypericum perforatum had the highest level of evidence of interaction with cyclosporine and tacrolimus. Consumption reduced the bioavailability and therapeutic effects of the drugs. Schisandra sphenanthera had the highest level of evidence of interaction with tacrolimus and increased the bioavailability of the drug. Majority of the articles were animal studies.

CONCLUSION

Overall level of evidence for the included studies were low, though interactions between cyclosporine, tacrolimus, Hypericum perforatum and Schisandra sphenanthera were the most and well-documented. Healthcare professionals should actively enquire about the concurrent use of CHM in patients, especially when drugs with a narrow therapeutic index are consumed.

Investigating the Contribution of Major Drug-Metabolising Enzymes to Possum-Specific Fertility Control

The potential to improve the effectiveness and efficiency of potential oestrogen-based oral contraceptives (fertility control) for possums was investigated by comparing the inhibitory potential of hepatic CYP3A and UGT2B catalytic activity using a selected compound library (CYP450 inhibitor-based compounds) in possums to that of three other species (mouse, avian, and human). The results showed higher CYP3A protein levels in possum liver microsomes compared to other test species (up to a 4-fold difference). Moreover, possum liver microsomes had significantly higher basal p-nitrophenol glucuronidation activity than other test species (up to an 8-fold difference). However, no CYP450 inhibitor-based compounds significantly decreased the catalytic activity of possum CYP3A and UGT2B below the estimated IC₅₀ and 2-fold IC₅₀ values and were therefore not considered to be potent inhibitors of these enzymes. However, compounds such as isosilybin (65%), ketoconazole (72%), and fluconazole (74%) showed reduced UGT2B glucuronidation activity in possums, mainly at 2-fold IC₅₀ values compared to the control (p < 0.05). Given the structural features of these compounds, these results could provide opportunities for future compound screening. More importantly, however, this study provided preliminary evidence that the basal activity and protein content of two major drug-metabolising enzymes differ in possums compared to other test species, suggesting that this could be further exploited to reach the ultimate goal: a potential target-specific fertility control for possums in New Zealand.

Prediction of tacrolimus and Wuzhi tablet pharmacokinetic interaction magnitude in renal transplant recipients

AIM

Wuzhi tablets are a dose-sparing agent for tacrolimus (TAC) in China and increase the bioavailability of TAC. The current study aimed to evaluate the pharmacokinetic interaction magnitude of Wuzhi and TAC and explore the potential determinants of this interaction.

METHODS

This study performed a retrospective, self-controlled study of 138 renal transplant recipients who were co-administered TAC and Wuzhi. The trough concentration (C0) of TAC at baseline and 3, 7, 14 and 21 days after Wuzhi co-therapy initiation was measured, and the CYP3A5 polymorphism was genotyped. The corresponding clinical factors were recorded. The ratio of dose-adjusted C0 (C0/D) post- and pre-combination therapy (ΔC0/D) indicates the interaction magnitude. Univariate and multivariate analyses were used to identify determinants and establish the prediction model.

RESULTS

ΔC0/D reached a steady state within 14 days. The geometrical mean ΔC0/D was 2.91 (range 1.02-9.49, IQR 2.13-3.80). ΔC0/D was blunted in CYP3A5 expressers (estimated effect: -39.8%, P = .001) and affected by hematocrit (Hct) (+24.0% per 10% increase, P = .005) and baseline C0/D (-31.9% per 1 ng·ml^-1 ·mg^-1 increase, P < .001). The prediction model was ΔC0/D = .319baseline C0/D × 1.398CYP3A5 (expressers = 0/non-expressers = 1) × 1.024Hct × 1.744, and it explained 28.1% of the variability.

CONCLUSION

Our study is the first attempt to date to give an assessment of the magnitude of pharmacokinetic interaction between TAC and Wuzhi in a cohort of renal transplant recipients, and CYP3A5 genotypes, baseline C0/D and Hct were identified as determinants of this interaction.

Tacrolimus Population Pharmacokinetic Model in Adult Chinese Patients with Nephrotic Syndrome and Dosing Regimen Identification Using Monte Carlo Simulations

BACKGROUND

The study aimed to establish a population pharmacokinetic (PPK) model of tacrolimus for Chinese patients with nephrotic syndrome using the patient's genotype and Wuzhi capsule dosage as the main test factors.

METHODS

Ninety-six adult patients with nephrotic syndrome, who were receiving tacrolimus treatment, were enrolled. A nonlinear mixed-effects model was used to determine the influencing factors of interindividual tacrolimus metabolism variation and establish a PPK model. To optimize the tacrolimus dosage, 10,000 Monte Carlo simulations were performed.

RESULTS

The 1-chamber model of first-order absorption and elimination was the most suitable model for the data in this study. The typical population tacrolimus clearance (CL/F) value was 16.9 L/h. The percent relative standard error (RSE%) of CL/F was 12%. Increased Wuzhi capsule and albumin doses both decreased the tacrolimus CL/F. In CYP3A5 homozygous mutation carriers, the CL/F was 39% lower than that of carriers of the wild-type and heterozygous mutation. The tacrolimus CL/F in patients who were coadministered glucocorticoids was 1.23-fold higher than that of the control. According to the patient genotype and combined use of glucocorticoids, 26 combinations of Wuzhi capsule and tacrolimus doses were matched. The Monte Carlo simulation identified the most suitable combination scheme.

CONCLUSIONS

An improved tacrolimus PPK model for patients with nephrotic syndrome was established, and the most suitable combination of Wuzhi capsule and tacrolimus doses was identified, thus, facilitating the selection of a more economical and safe administration regimen.

Population pharmacokinetics of tacrolimus in Chinese adult liver transplant patients

Tacrolimus is widely used in organ transplantation to prevent rejection. However, the narrow therapeutic window and the large inter-and intra-individual variability in the pharmacokinetics (PK) of tacrolimus make it difficult for individualization of dosing. This study aimed at developing a population pharmacokinetic model for estimating the oral clearance of tacrolimus in Chinese liver transplant patients, and identifying factors that contribute to the PK variability of tacrolimus. Data of 151 liver transplant patients who received tacrolimus were analyzed in this study. The population PK model was analyzed and the covariates including population demographic and biochemical characteristics, drug combination, and genetic polymorphism were explored using non-linear mixed-effects modeling approach. A single-compartment population PK model was developed, and the final model was CL/F = (14.6-2.38 × cytochrome P450 (CYP) 3A5-3.72 × WZC+1.04 × (POD/9)+2.48 × COR) × Exp(η_i ), where CYP3A5 was 1 for CYP3A5*3/*3, Wuzhi Capsule (WZC) was 1 when patients took tacrolimus combined with WZC, otherwise it was 0, corticosteroids (COR) was 1 when patients take tacrolimus combined with COR, otherwise, it was 0, POD was the post-operative day. Visual inspection and bootstrap indicated that the final model was stable and robust. In this study, we developed the first tacrolimus population PK model in Chinese adult liver transplant patients. We first determined the influence of WZC on tacrolimus in these people, which could provide useful PK information for the drug combination of tacrolimus and WZC. We also revealed the influence of genetic polymorphism of CYP3A5, POD, and a combination of COR on tacrolimus PK. Therefore, these significant factors should be taken into consideration in optimizing dosage regimens.

A Comprehensive Review of the Main Lignan Components of Schisandra chinensis (North Wu Wei Zi) and Schisandra sphenanthera (South Wu Wei Zi) and the Lignan-Induced Drug-Drug Interactions Based on the Inhibition of Cytochrome P450 and P-Glycoprotein Activities

Wu Wei Zi is the dried fruit of Schisandra chinensis (Turcz.) Baill. or Schisandra sphenanthera Rehd. et Wils. (family Magnoliaceae). As a homology of medicine and food, it has been widely used in China for thousands of years, to tonify the kidney, and ameliorate neurological, cardiovascular, liver, and gastrointestinal disorders. As its increasing health benefits and pharmacological value, many literatures have reported that the combination of Wu Wei Zi in patients has led to fluctuations in the blood level of the combined drug. Therefore, it is extremely important to evaluate its safety concern such as drug-drug interactions (DDIs) when patients are under the poly-therapeutic conditions. This review summarized the effects of Wu Wei Zi extract and its major lignan components on cytochrome P450 and P-glycoprotein activities, the change of which could induce metabolic DDIs. Our review also elaborated on the differences of the major lignan components of the two Schisandra species, as well as the absorption, distribution, metabolism, and elimination of the major lignans. In conclusion, these results would enhance our understanding of the DDI mechanisms involving Wu Wei Zi, and may potentially untangle some differing and conflicting results in the future.

Effect of hepar-protecting Wuzhi capsule on Pharmacokinetics and Dose-effect Character of Tacrolimus in Healthy Volunteers

Wuzhi capsule (WZC), a preparation of Fructus Schisandra sphenanthera extract, has been widely used for the treatment of viral and drug-induced hepatitis in China. This study aimed to determine the pharmacokinetic parameters of tacrolimus (TAC) when co-administered with WZC and its dose-effect of WZC on TAC in healthy volunteers. We assessed the effect of increased dosage of WZC (1, 2, 6, and 8 capsules once daily) on the relative oral exposure of TAC to explore the dose-response relationship between WZC and TAC using bioanalysis, pharmacokinetic, genotypical analyses. We elucidate the influence of CYP3A5 and MDR1 genetic polymorphisms on the WZC dose by maintaining C_trough of TAC in Chinese healthy volunteers. When co-administered with WZC, the T_max of TAC was increased significantly while the apparent oral clearance was decreased. The plasma TAC level in volunteers with high CYP3A5 expression was greatly lower than that in those with mutant CYP3A5. However, polymorphisms of MDR1 exon26 C3435T, exon21 G2677T/A and exon12 C1236T were not associated with plasma TAC levels. Our findings provide important information on interactions between modern medications and herbal products, thus facilitating a better usage of TAC in patients receiving WZC. This article is protected by copyright. All rights reserved.

The Influence of Wuzhi Capsule on the Pharmacokinetics of Cyclophosphamide

BACKGROUND

Cyclophosphamide is approved for the treatment of a variety of tumors, yet the use of cyclophosphamide is limited by kidney and liver toxicity. In the clinic, the Wuzhi capsule is approved to attenuate cyclophosphamide toxicity in the kidney and liver.

OBJECTIVE

We aimed to investigate the effects of the principal ingredients of Wuzhi capsule, schisandrin A (SIA) and schisantherin A (STA), on the pharmacokinetics of cyclophosphamide.

METHODS

The essential pharmacokinetic data and physicochemical parameters of SIA, STA, and cyclophosphamide were collected. Physiologically based pharmacokinetic (PBPK) models of SIA, STA, and cyclophosphamide were built in Simcyp Simulator and verified using published clinical pharmacokinetic data. The verified PBPK models were used to predict potential herb-drug interactions (HDIs) between cyclophosphamide and SIA and STA in cancer patients.

RESULTS

The area under the plasma concentration-time curve (AUC) of cyclophosphamide was increased by 18% and 1% when co-administered with STA and SIA at a single dose, respectively, and increased by 301% and 29% when co-administered with STA and SIA at multiple doses, respectively. The maximum concentration (Cmax) of cyclophosphamide was increased by 75% and 7% when co-administered with STA and SIA at multiple doses, respectively.

CONCLUSION

The AUC and Cmax of cyclophosphamide were increased when cyclophosphamide was combined with the Wuzhi capsule, compared to cyclophosphamide alone. Our study shows that the adverse drug reactions and toxicity of cyclophosphamide should be closely monitored and an effective dosage adjustment of cyclophosphamide may need to be considered when co-administered with the Wuzhi capsule.

Cough Inhibition Activity of Schisandra chinensis in Guinea Pigs

Chronic cough is very common in respiratory clinics, and no effective drugs are available. Schisandra chinensis (Turcz.) Baill. (S. chinensis), an important traditional Chinese medicine, has been extensively prescribed for patients with a persistent cough. Preliminary research indicated that 95% ethanol extracts (EE) of S. chinensis showed remarkable antitussive activity in guinea pigs exposed to cigarette smoke (CS). To find out the antitussive ingredients of S. chinensis, EE was divided into four fractions according to the polarity: petroleum ether extract (PEE), ethyl acetate extract (ECE), n-butyl alcohol extract, and residue extract. The antitussive, antioxidant, and anti-inflammatory effects of the four fractions were evaluated in a guinea pig model of cough hypersensitivity induced by CS exposure. Eighteen main constituents of the two effective fractions, PEE and ECE, were identified using ultra-high-pressure liquid chromatography electronic spray ion time-of-flight mass spectrometry. The cough inhibition activities of compound 1, 3, 9, 10, 17 were evaluated on citric acid induced acute cough guinea pigs. The results showed that the antitussive activity of EE was almost all contained in PEE and ECE. The 16 major peaks in PEE were identified as 15 lignans (1-12 and 14-16) and 1 triterpene (compound 13), and 3 major peaks (1, 17, and 18) in ECE were also identified as lignans. Three doses of five compounds brought about a significant decrease in number of cough efforts (P < .01), and the cough inhibition rates were between 40.9% and 85.1%. Therefore, lignans are the antitussive ingredients of S. chinensis.

Insights into oral bioavailability enhancement of therapeutic herbal constituents by cytochrome P450 3A inhibition

Herbal plants typically have complex compositions and diverse mechanisms. Among them, bioactive constituents with relatively high exposure in vivo are likely to exhibit therapeutic efficacy. On the other hand, their bioavailability may be influenced by the synergistic effects of different bioactive components. Cytochrome P450 3A (CYP3A) is one of the most abundant CYP enzymes, responsible for the metabolism of 50% of approved drugs. In recent years, many therapeutic herbal constituents have been identified as CYP3A substrates. It is more evident that CYP3A inhibition derived from the herbal formula plays a critical role in improving the oral bioavailability of therapeutic constituents. CYP3A inhibition may be the mechanism of the synergism of herbal formula. In this review, we explored the multiplicity of CYP3A, summarized herbal monomers with CYP3A inhibitory effects, and evaluated herb-mediated CYP3A inhibition, thereby providing new insights into the mechanisms of CYP3A inhibition-mediated oral herb bioavailability.

Inhibitory Effects of Schisandra Lignans on Cytochrome P450s and Uridine 5'-Diphospho-Glucuronosyl Transferases in Human Liver Microsomes

Schisandra chinensis has been widely used as a traditional herbal medicine to treat chronic coughs, fatigue, night sweats, and insomnia. Numerous bioactive components including lignans have been identified in this plant. Lignans with a dibenzocyclooctadiene moiety have been known to possess anti-cancer, anti-inflammatory, and hepatoprotective activity. Fragmentary studies have reported the ability of some lignans to modulate some cytochrome P450 (P450) enzymes. Herein, we investigated the drug interaction potential of six dibenzocyclooctadiene lignans (schisandrin, gomisin A, B, C, and N, and wuweizisu C) on nine P450 enzymes (CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A) and six uridine 5'-diphosphoglucuronosyl transferase (UGT) enzymes (UGT1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) using human liver microsomes. We found that lignans with one or two methylenedioxyphenyl groups inhibited CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP2E1 activities in a time- and concentration-dependent like their CYP3A inhibition. In comparison, these lignans do not induce time-dependent inhibition of CYP1A2, CYP2A6, and CYP2D6. The time-dependent inhibition of gomisin A against CYP2C8, CYP2C19, and CYP3A4 was also elucidated using glutathione as a trapping reagent of reactive carbene metabolites given that gomisin A strongly inhibits these P450 enzymes in a time-dependent manner. A glutathione conjugate of gomisin A was generated in reactions with human recombinant CYP2C8, CYP2C19, and CYP3A4. This suggests that the time-dependent inhibition of gomisin A against CYP2C8, CYP2C9, and CYP3A4 is due to the production of carbene reactive metabolite. Six of the lignans we tested inhibited the activities of six UGT to a limited extent (IC₅₀ > 15 μM). This information may aid the prediction of possible drug interactions between Schisandra lignans and any co-administered drugs which are mainly metabolized by P450s.

Investigation of the Impact of CYP3A5 Polymorphism on Drug-Drug Interaction between Tacrolimus and Schisantherin A/Schisandrin A Based on Physiologically-Based Pharmacokinetic Modeling

Wuzhi capsule (WZC) is commonly prescribed with tacrolimus in China to ease drug-induced hepatotoxicity. Two abundant active ingredients, schisantherin A (STA) and schisandrin A (SIA) are known to inhibit CYP3A enzymes and increase tacrolimus’s exposure. Our previous study has quantitatively demonstrated the contribution of STA and SIA to tacrolimus pharmacokinetics based on physiologically-based pharmacokinetic (PBPK) modeling. In the current work, we performed reversible inhibition (RI) and time-dependent inhibition (TDI) assays with CYP3A5 genotyped human liver microsomes (HLMs), and further integrated the acquired parameters into the PBPK model to predict the drug–drug interaction (DDI) in patients with different CYP3A5 alleles. The results indicated STA was a time-dependent and reversible inhibitor of CYP3A4 while only a reversible inhibitor of CYP3A5; SIA inhibited CYP3A4 and 3A5 in a time-dependent manner but also reversibly inhibited CYP3A5. The predicted fold-increases of tacrolimus exposure were 2.70 and 2.41, respectively, after the multidose simulations of STA. SIA also increased tacrolimus’s exposure but to a smaller extent compared to STA. An optimized physiologically-based pharmacokinetic (PBPK) model integrated with CYP3A5 polymorphism was successfully established, providing more insights regarding the long-term DDI between tacrolimus and Wuzhi capsules in patients with different CYP3A5 genotypes.

Co-administration of Wuzhi tablet (Schisandra sphenanthera extract) alters tacrolimus pharmacokinetics in a dose- and time-dependent manner in rats

ETHNOPHARMACOLOGY RELEVANCE

Tacrolimus is a well-known potent but expensive immunosuppressant. We previously clarified the herb-drug interaction between tacrolimus and Wuzhi tablet (WZ), a prescribed drug of ethanol extract of Schisandra sphenanthera, and showed the ideal effect of WZ on maintaining therapeutic level of tacrolimus and reducing the total drug expense. However, WZ possesses a biphasic effect on regulating CYP3A (the major metabolizing enzyme of tacrolimus), which could induce the mRNA and protein expression after long-term treatment while transiently inhibit the activity of CYP3A. In clinic, clinicians are confused about the relationship between the blood concentration of tacrolimus and the dose and the duration of pretreatment of WZ. Therefore, the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus is urgently needed to be clarified to better combine the use of WZ and tacrolimus in clinic.

AIM OF THE STUDY AND METHOD

This study aimed to investigate the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus in rats.

RESULTS AND CONCLUSIONS

After pretreated rats with WZ for 0, 0.5, 2, 6, 12 or 24 h, the area under the curve (AUC) of tacrolimus was 2.27 ± 0.59, 1.87 ± 1.14, 2.86 ± 0.64, 1.62 ± 0.70, 1.54 ± 1.06 and 1.12 ± 0.69-fold of that of the tacrolimus alone group, respectively. The ratio of AUC of tacrolimus to that of the co-administration group with 0, 62.5, 125, 250, 500 or 750 mg/kg of WZ was 1.00: 1.07: 1.44: 2.60: 2.32: 2.42, respectively. These findings suggested that WZ increased tacrolimus AUC in a pretreatment time- and dose-dependent manner. In line with the in vivo findings, WZ extract inhibited CYP3A activity in a pre-treatment time- and concentration-dependent manner in human liver microsomes. In conclusion, the pharmacokinetics of tacrolimus was significantly affected by the pretreatment time and the dose of WZ. Oral pretreatment with WZ for 0-2 h or co-dosing of 250 mg/kg of WZ most significantly increased the blood concentration of tacrolimus. These findings would be helpful for guiding the reasonable use of WZ and tacrolimus in clinic.

Mechanism-based inactivation of cytochrome P450 enzymes by natural products based on metabolic activation

Cytochrome P450 enzymes (P450 enzymes) are the most common and important phase I metabolic enzymes and are responsible for the majority of the metabolism of clinical drugs and other xenobiotics. Drug-drug interactions (DDIs) can occur when the activities of P450 enzymes are inhibited. In particular, irreversible inhibition of P450 enzymes may lead to severe adverse interactions, compared to reversible inhibition. Many natural products have been shown to be irreversible inhibitors of P450 enzymes. The risks for intake of naturally occurring irreversible P450 enzyme inhibitors have been rising due to the rapid growth of the global consumption of natural products. Irreversible inhibition is usually called mechanism-based inactivation, which is time-, concentration- and NADPH- dependent. Generally, the formation of electrophilic intermediates is fundamental for the inactivation of P450 enzymes. This review comprehensively classifies natural P450 enzyme inactivators, including terpenoids, phenylpropanoids, flavonoids, alkaloids, and quinones obtained from herbs or foods. Moreover, the structure - activity correlations according to the IC₅₀ (or K_i) values reported in the literature as well as the underlying mechanisms based on metabolic activation are highlighted in depth.

Alternative Medicine and Oncology: Erroneous Biochemical Failure Following Herbal Supplementation in Early-Stage Prostate Cancer

Prostate-specific antigen (PSA) levels are routinely surveilled after oncologic intervention in patients with prostate cancer. Occasionally, PSA levels are elevated because of factors unrelated to disease recurrence, such as herbal supplement use. False-positive PSA elevations may confound the clinical picture and subsequent decision-making processes, potentially leading to unnecessary diagnostic and therapeutic interventions. In this case report, a patient with low-risk prostate cancer who was treated with low-dose-rate interstitial brachytherapy presented several years after treatment with an erroneously elevated PSA level after taking an herbal supplement. This case highlights the importance of a holistic approach to patient care, whereby tactful assessment of the psychosocial and spiritual aspects of health led to the identification of an uncommon but potentially morbid entity.

Potential for pharmacokinetic interactions between Schisandra sphenanthera and bosutinib, but not imatinib: in vitro metabolism study combined with a physiologically-based pharmacokinetic modelling approach

AIMS

This study aimed to investigate the potential interaction between Schisandra sphenanthera, imatinib and bosutinib combining in vitro and in silico methods.

METHODS

In vitro metabolism of imatinib and bosutinib using recombinant enzymes and human liver microsomes were investigated in the presence and absence of Schisandra lignans. Physiologically-based pharmacokinetic (PBPK) models for the lignans accounting for reversible and mechanism-based inhibitions and induction of CYP3A enzymes were built in the Simcyp Simulator (version 17) and evaluated for their capability to predict interactions with midazolam and tacrolimus. Their potential effect on systemic exposures of imatinib and bosutinib were predicted using PBPK in silico simulations.

RESULTS

Schisantherin A and schisandrol B, but not schisandrin A, potently inhibited CYP3A4-mediated metabolism of imatinib and bosutinib. All three compounds showed a strong reversible inhibition on CYP2C8 enzyme with k_i of less than 0.5 μmol L^-1 . The verified PBPK models were able to describe the increase in systemic exposure of midazolam and tacrolimus due to co-administration of S. sphenanthera, consistent with the reported changes in the corresponding clinical interaction study (AUC ratio of 2.0 vs 2.1 and 2.4 vs 2.1, respectively). The PBPK simulation predicted that at recommended dosing regimens of S. sphenanthera, co-administration would result in an increase in bosutinib exposure (AUC ratio 3.0) but not in imatinib exposure.

CONCLUSION

PBPK models for Schisandra lignans were successfully developed. Interaction between imatinib and Schisandra lignans was unlikely to be of clinical importance. Conversely, S. sphenanthera at a clinically-relevant dose results in a predicted three-fold increase in bosutinib systemic exposure.

"Natural" is not synonymous with "Safe": Toxicity of natural products alone and in combination with pharmaceutical agents

During the 25 years since the US Congress passed the Dietary Supplement Health and Education Act (DSHEA), the law that transformed the US Food and Drug Administration's (FDA's) authority to regulate dietary supplements, the dietary supplement market has grown exponentially. Retail sales of herbal products, a subcategory of dietary supplements, have increased 83% from 2008 to 2018 ($4.8 to $8.8 billion USD). Although consumers often equate "natural" with "safe", it is well recognized by scientists that constituents in these natural products (NPs) can result in toxicity. Additionally, when NPs are co-consumed with pharmaceutical agents, the precipitant NP can alter drug disposition and drug delivery, thereby enhancing or reducing the therapeutic effect of the object drug(s). With the widespread use of NPs, these effects can be underappreciated. We present a summary of a symposium presented at the Annual Meeting of the Society of Toxicology 2019 (12 March 2019) that discussed potential toxicities of NPs alone and in combination with drugs.

Clinical observation on the effect of Wuzhi soft capsule on FK506 concentration in membranous nephropathy patients

The current research aimed to investigate the correlation between the effect of Wuzhi soft capsule (WZC) on FK506 concentration and CYP3A5 gene polymorphism in patients with membranous nephropathy (MN).Seventy-five patients with idiopathic MN were enrolled and divided according to the expression of CYP3A5 gene metabolic enzyme into group A (CP3A5 metabolic enzyme function expression types CYP3A5*1/*1 type and CYP3A5*1/*3 type), and group B (non-expression type CYP3A5*3/*3 type). All patients were given oral administration of tacrolimus capsule at the initial dose of 1 mg for twice a day 1 hour before breakfast and dinner. Afterwards, the oral administration of WZC was added at the dose of 0.5 g for 3 times a day within half an hour after 3 meals.The blood concentrations of FK506 in groups A and B were significantly higher than those before administration. Compared with that before administration, the FK506 blood concentration was increased by 3.051 ± 0.774 ng/ml after adding the WZC. Besides, the blood concentrations of FK506 in group A were lower than those in group B before and after administration; meanwhile, the 24 hours total urine protein and the biochemical indexes in both groups displayed no statistically significant difference. Only 1 case of diarrhea was observed, which was relieved after the reduction of tacrolimus.Wuzhi soft capsule can significantly increase the blood concentration of FK506 in MN patients. Moreover, the CYP3A5 genotyping should be considered when WZC is used to increase the blood concentration of FK506.

The Pharmacokinetic Prediction of Cyclosporin A after Coadministration with Wuzhi Capsule

We aim to describe the influence of principal ingredients of Wuzhi capsule, schisandrin A (SIA) and schisantherin A (STA), on the pharmacokinetics of cyclosporin A (CsA) and to quantify the herb-drug interactions (HDIs) between SIA, STA, and CsA. CsA is a first-line immunosuppressant for anti-rejection therapy after solid organ transplantation, while narrow therapeutic window associated with strong hepatotoxicity largely limited its use. Wuzhi capsule, a liver-protective drug, was approved for coadministration with CsA to reduce the hepatotoxicity. There are few studies exploring HDIs of CsA when coadministered with Wuzhi capsule. The essential adjusted physicochemical data and pharmacokinetic parameters of SIA, STA, and CsA were collected. Then physiologically based pharmacokinetic (PBPK) models of SIA, STA, and CsA were built and verified in healthy subjects using Simcyp respectively. The refined PBPK models were used to estimate potential HDIs between CsA and SIA, STA. The simulated plasma concentration-time curves of CsA, SIA, and STA were in good accordance with the observed profiles respectively. CsA pharmacokinetics were improved after coadministration. After a single dose and multiple doses, the area under the plasma concentration-time curve (AUC) of CsA was increased by 47% and 226% when coadministered with STA, respectively, and by 8% and 36% when coadministered with SIA, respectively. PBPK models sufficiently described the pharmacokinetics of CsA, SIA, and STA. Compared with SIA, STA inhibited CsA metabolism to a greater extent. Our result revealed the dose of CsA can be reduced to maintain similar profile when used concomitantly with Wuzhi capsule.

Exploring the molecular mechanisms of Traditional Chinese Medicine components using gene expression signatures and connectivity map

BACKGROUND AND OBJECTIVE

Traditional Chinese Medicine (TCM) has been practiced over thousands of years in China and other Asian countries for treating various symptoms and diseases. However, the underlying molecular mechanisms of TCM are poorly understood, partly due to the "multi-component, multi-target" nature of TCM. To uncover the molecular mechanisms of TCM, we perform comprehensive gene expression analysis using connectivity map.

METHODS

We interrogated gene expression signatures obtained 102 TCM components using the next generation Connectivity Map (CMap) resource. We performed systematic data mining and analysis on the mechanism of action (MoA) of these TCM components based on the CMap results.

RESULTS

We clustered the 102 TCM components into four groups based on their MoAs using next generation CMap resource. We performed gene set enrichment analysis on these components to provide additional supports for explaining these molecular mechanisms. We also provided literature evidence to validate the MoAs identified through this bioinformatics analysis. Finally, we developed the Traditional Chinese Medicine Drug Repurposing Hub (TCM Hub) - a connectivity map resource to facilitate the elucidation of TCM MoA for drug repurposing research. TCMHub is freely available in http://tanlab.ucdenver.edu/TCMHub.

CONCLUSIONS

Molecular mechanisms of TCM could be uncovered by using gene expression signatures and connectivity map. Through this analysis, we identified many of the TCM components possess diverse MoAs, this may explain the applications of TCM in treating various symptoms and diseases.

Wuzhi capsule regulates chloroacetaldehyde pharmacokinetics behaviour and alleviates high-dose cyclophosphamide-induced nephrotoxicity and neurotoxicity in rats

High-dose cyclophosphamide (HD-CTX) treatment often leads to severe nephrotoxicity and neurotoxicity, which are mainly caused by one of its metabolites, chloroacetaldehyde (CAA). However, there are no effective antidotes to prevent these side effects. The objective of this study was to evaluate the effect of Wuzhi Capsule (WZC) on the pharmacokinetics of CTX and its metabolites in rats, and the attenuation of CAA induced kidney and brain injuries, which was produced at equimolar with 2-dechloroethylcyclophosphamide. Rats were treated with single- or multiple-dose of WZC when giving HD-CTX, and the plasma concentration of CTX and its metabolites were quantitated by UHPLC-MS/MS Single-dose, not multiple-dose of WZC co-administration (300 mg/kg) significantly reduced C_max and AUC_0→24 h of DC-CTX by 33.10% and 35.51%, respectively. Biochemical assay suggested oxidative stress was involved in kidney and brain injuries by HD-CTX, which were attenuated by single-dose WZC (300 mg/kg) pre-treatment, with increased glutathione, glutathione peroxidase and superoxide dismutase contents/or activities in both tissues and plasma (P < 0.05). Meanwhile, WZC pre-treatment could also significantly decrease the plasma levels of creatinine, blood urea nitrogen and malondialdehyde (P < 0.05). Additionally, WZC treatment improved the morphology and pathology condition of the kidneys and brains in rats. In conclusion, single-dose WZC co-administration decreased CAA production and exerted protective effect on CTX-induced oxidative stress in kidney and brain, whereas repetitive WZC co-administration with CTX was probably not recommended.

Shenmai-Yin decreased the clearance of nifedipine in rats: The involvement of time-dependent inhibition of nifedipine oxidation

The traditional Chinese herbal formula Shenmai-Yin (SY) and nifedipine have both been used to treat patients with cardiovascular disorders. Nifedipine is primarily oxidized by cytochrome P450 (CYP) 3A. The oxidation and pharmacokinetics of nifedipine were studied in rats in vitro and in vivo to illustrate the interaction of SY with nifedipine. Schisandrol A, schisandrin A and schisandrin B were identified as the main lignans in SY. In the study in vitro, the ethanolic extract of SY was used due to the solubility and the extract inhibited nifedipine oxidation (NFO) activity in a time-dependent manner. Among lignans, schisandrin B caused the most potent inhibition. According to the time-dependent inhibition behavior, rats were treated with SY 1 h before nifedipine administration. After oral treatment with 1.9 g/kg SY, nifedipine clearance decreased by 34% and half-life increased by 142%. SY treatment decreased hepatic NFO activity by 49%. Compared to the change caused by ketoconazole, the SY-mediated reduction of nifedipine clearance was moderate. These findings demonstrate that SY causes a time-dependent inhibition of NFO and schisandrin B contributes to the inhibition. The decreased nifedipine clearance by SY in rats warrants further human study to examine the clinical impact of this decrease.

The complete mitochondrial genome of Schisandra sphenanthera (Schisandraceae)

Schisandra sphenanthera (Austrobaileyales) is a famous traditional Chinese medicine being long-history used, is also one of early-diverging angiosperms and important links to uncover the early evolution of angiosperms. Here the complete mitochondrial genome of S. sphenanthera was obtained for the first time. It is 1,106,521 bp in length with 46.4% GC content. It contains 58 genes, including 41 protein coding genes, three ribosomal RNA genes and 14 transfer RNA genes. Phylogenetic analysis indicated that S. sphenanthera was placed in the basal angiosperm just after Amborella and Nuphar. The mitogenome of S. sphenanthera would provide a reliable genetic and evolutionary resource.

Schisandra chinensis extract decreases chloroacetaldehyde production in rats and attenuates cyclophosphamide toxicity in liver, kidney and brain

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill (S. chinensis) has been used for thousands years in China, and is usually applied in treatment of urinary tract disorders and liver injury. S. chinensis extract (SCE) has board protective effects on liver, kidney and nervous system. Schisandra lignans are generally considered as the bioactive components of SCE.

AIM OF THE STUDY

To investigate the pharmacokinetic herb-drug interactions (HDIs) between SCE and cyclophosphamide (CTX). To evaluate the protective effects of SCE against CTX induced damage in rat liver, kidney and brain.

MATERIALS AND METHODS

The pharmacokinetic HDIs between SCE and CTX were investigated by determining plasma concentrations of CTX and three metabolites, namely 4-ketocyclophosphamide (4-Keto), 2-dechloroethylcyclophosphamide (DCCTX) and carboxyphosphamide (CPM) using a previously developed UPLC-MS/MS method. To evaluate the protective effects of SCE pretreatment, toxicity and oxidation stress assessments along with histology investigations were carried out in rat liver, kidney and brain.

RESULTS

The equimolar produced metabolite DCCTX was chosen to reflect chloroacetaldehyde (CAA, a toxic metabolite of CTX) production in rats. Single-dose pretreatment of SCE significantly reduced CAA production and decreased the C_max and AUC_0-24h of DCCTX by 69% and 49% respectively (P < 0.05). After pretreated with SCE for 7 consecutive days, the C_max and AUC_0-24h of DCCTX were still decreased (-25% and -37%, P < 0.05) when compared with CTX alone group. Parallel toxicity and oxidation stress investigations showed that single-dose SCE pretreatment significantly decreased plasma BUN and Cr levels (-12% and -46%, respectively) and reduced liver AST activity (-32%). Moreover, SCE pretreatment potently increased the brain GSH content by 7.8-fold, and reduced MDA levels in rat liver, kidney and brain by 39%, 28% and 31%, respectively (compared with CTX alone group). The protective effects of SCE were also supported by histological observations.

CONCLUSION

Our experiment results suggest that S. chinensis may find use as a complementary medicine in CTX treatment.

Traditional Chinese Medicine for Refractory Nephrotic Syndrome: Strategies and Promising Treatments

Refractory nephrotic syndrome (RNS) is an immune-related kidney disease with poor clinical outcomes. Standard treatments include corticosteroids as the initial therapy and other immunosuppressants as second-line options. A substantial proportion of patients with RNS are resistant to or dependent on immunosuppressive drugs and often experience unremitting edema and proteinuria, cycles of remission and relapse, and/or serious adverse events due to long-term immunosuppression. Traditional Chinese medicine has a long history of treating complicated kidney diseases and holds great potential for providing effective treatments for RNS. This review describes the Chinese medical theories relating to the pathogenesis of RNS and discusses the strategies and treatment options using Chinese herbal medicine. Available preclinical and clinical evidence strongly supports the integration of traditional Chinese medicine and Western medicine for improving the outcome of RNS. Herbal medicine such as Astragalus membranaceus, Stephania tetrandra S. Moore, and Tripterygium wilfordii Hook F can serve as the alternative therapy when patients fail to respond to immunosuppression or as the complementary therapy to improve therapeutic efficacy and reduce side effects of immunosuppressive agents. Wuzhi capsules (Schisandra sphenanthera extract) with tacrolimus and tetrandrine with corticosteroids are two herb-drug combinations that have shown great promise and warrant further studies.

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.

Time- and NADPH-Dependent Inhibition on CYP3A by Gomisin A and the Pharmacokinetic Interactions between Gomisin A and Cyclophosphamide in Rats

The traditional Chinese medicine Schisandra chinensis has remarkable protective effects against chemical-induced toxicity. Cyclophosphamide (CTX), in spite advances in chemotherapy and immunosuppressive regimes, is prone to cause severe toxicity due to its chloroacetaldehyde (CAA) metabolite produced by CYP3A. Our previous study identified that S. chinensis extract (SCE) co-administration potently decreased CAA production and attenuated liver, kidney and brain injuries in CTX-treated rats. Gomisin A (Gom A) is proved to be one of the most abundant bioactive lignans in S. chinensis with a significant CYP3A inhibitory effect. To find out whether and how Gom A participated in the chemoprevention of SCE against CTX toxicity, the Gom A-caused CYP3A inhibition in vitro as well as the pharmacokinetic interactions between Gom A and CTX in vivo were examined in this study. Using human liver microsomes, a reversible inhibition assay revealed that Gom A was a competitive inhibitor with a K_I value of 1.10 µM, and the time- and NADPH-dependent CYP3A inhibition of Gom A was observed in a time-dependent inhibition assay (K_I = 0.35 µM, k_inact = 1.96 min⁻¹). Hepatic CYP3A mRNA expression experienced a significant increase in our rat model with Gom A administration. This explained why CAA production decreased in the 0.5 h- and 6 h-pretreatment rat groups while it increased in the 24 h- and 72 h-pretreatment groups, indicating a bidirectional effect of Gom A on CYP3A-mediated CTX metabolism. The present study suggested that Gom A participates like SCE in the pharmacokinetic intervention of CTX by blocking CYP3A-mediated metabolism and reducing CAA production, and thus plays an important role in the chemopreventive activity of S. chinensis against CTX toxicity, in addition to the previously recognized protective effects. Also, the combined use of S. chinensis preparation or other drugs containing Gom A as the main component with CTX needed to be addressed for better clinical intervention.

Metabolic profiling of dehydrodiisoeugenol using xenobiotic metabolomics

Dehydrodiisoeugenol (DDIE), a representative and major benzofuran-type neolignan in Myristica fragrans Houtt., shows anti-inflammatory and anti-bacterial actions. In order to better understand its pharmacological properties, xenobiotic metabolomics was used to determine the metabolic map of DDIE and its influence on endogenous metabolites. Total thirteen metabolites of DDIE were identified through in vivo and in vitro metabolism, and seven of them were reported for the first time in the present study. The identity of DDIE metabolites was achieved by comparison of the MS/MS fragmentation pattern with DDIE using ultra-performance chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI- QTOFMS). Demethylation and ring-opening reaction were the major metabolic pathways for in vivo metabolism of DDIE. Recombinant cytochrome P450s (CYPs) screening revealed that CYP1A1 is a primary enzyme contributing to the formation of metabolites D1-D4. More importantly, the levels of two endogenous metabolites 2,8-dihydroxyquinoline and its glucuronide were significantly elevated in mouse urine after DDIE exposure, which explains in part its modulatory effects on gut microbiota. Taken together, these data contribute to the understanding of the disposition and pharmacological activities of DDIE in vivo.

Inhibition of human CYP3A4 and CYP3A5 enzymes by gomisin C and gomisin G, two lignan analogs derived from Schisandra chinensis

Gomisin C (GC) and gomisin G (GG) are two lignan analogs isolated from the Traditional Chinese Medicine Schisandra chinensis which possesses multiple pharmacological activities. However, the potential herb-drug interactions (HDI) between these lignans and other drugs through inhibiting human cytochrome P450 3A4 (CYP3A4) and CYP3A5 remains unclear. In the present study, the inhibitory action of GC and GG on CYP3A4 and CYP3A5 were investigated. The results demonstrated that both GC and GG strongly inhibited CYP3A-mediated midazolam 1'-hydroxylation, nifedipine oxidation and testosterone 6β-hydroxylation. Notably, the inhibitory intensity of GC towards CYP3A4 was stronger than CYP3A5 when using midazolam and nifedipine as substrates. While inhibition of GC towards CYP3A5 was weaker than CYP3A4 when using testosterone as substrate. In contrast, GG showed a stronger inhibitory activity on CYP3A5 than CYP3A4 without substrate-dependent behavior. In addition, docking simulations indicated that the π-π interaction between CYP3A4 and GC, and hydrogen-bond interaction between CYP3A5 and GG might result in their different inhibitory actions. Furthermore, the AUC of drugs metabolized by CYP3A was estimated to increase by 8%-321% and 2%-3190% in the presence of GC and GG, respectively. These findings strongly suggested that GC and GG showed high HDI potentials, and the position of methylenedioxy group determined their different inhibitory effect towards CYP3A4 and CYP3A5, which are of significance for the application of Schisandra chinensis-containing herbs.

Mechanistic understanding of the effect of Dengzhan Shengmai capsule on the pharmacokinetics of clopidogrel in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The Dengzhan Shengmai capsule (DZSM) is known in China for its remarkable curative effect as a treatment of cardiovascular diseases, such as coronary heart disease and ischemic stroke. DZSM is a Chinese herbal compound preparation that consists of four ingredients, including Erigeron breviscapus (Vaniot) Hand.-Mazz., Panax ginseng C.A. Mey, Ophiopogon japonicas (Thunb.) Ker-Gawl. and Schisandra chinensis (Turcz.) Baill., and was indexed in the Chinese Pharmacopoeia 2010. DZSM and clopidogrel are often co-prescribed in the clinic to prevent the recurrence of stroke or other cardiovascular and cerebrovascular diseases. However, the effect of DZSM on the pharmacokinetics of clopidogrel remains unclear.

AIM OF THE STUDY

The purpose of the study is to explore the pharmacokinetics and potential interaction between DZSM and clopidogrel and the underlying mechanism.

MATERIALS AND METHODS

Rats were used to investigate the effect of DZSM on the pharmacokinetics of clopidogrel and its active metabolite in vivo. The plasma concentrations were simultaneously determined using LC-MS/MS. The effects of DZSM on the P-gp-mediated efflux transport and CYP450-mediated metabolism of clopidogrel were investigated using MDCKII-MDR1 cells and rat liver microsomes, respectively.

RESULTS

After pretreatment with DZSM, the C_max and AUC_0-∞ of clopidogrel increased from 0.4±0.1 to 1.7±0.6ng/mL and 0.9±0.4 to 2.0±0.2ng/mLh, respectively. The C_max and AUC_0-∞ of the derivatized active metabolite of clopidogrel decreased from 8.2±1.2 to 2.8±0.5ng/mL and 18.2±5.6 to 6.4±3.7ngh/mL, respectively. In MDCKII-MDR1 cells, the P-gp-mediated efflux transport of clopidogrel was significantly inhibited by the DZSM extract. In rat liver microsomes, DZSM inhibited clopidogrel metabolism with an IC₅₀ of 0.02mg/mL.

CONCLUSIONS

DZSM significantly affects the pharmacokinetics of clopidogrel and its active metabolite by inhibiting the P-gp-mediated efflux transport and CYP450-mediated metabolism of clopidogrel. Thus, caution is needed when DZSM is co-administered with clopidogrel in the clinic because the interaction of these drugs may result in altered plasma concentrations of clopidogrel and its active metabolite.

In Vitro Effects of Concomitant Use of Herbal Preparations on Cytochrome P450s Involved in Clozapine Metabolism

Herbal supplements are increasingly used in psychiatric practice. Our epidemiological study has identified several herbal preparations associated with adverse outcomes of antipsychotic therapy. In this study, we evaluated the in vitro effects of four herbal preparations—Radix Rehmanniae (RR), Fructus Schisandrae (FS), Radix Bupleuri (RB) and Fructus Gardeniae (FG)—on cytochrome P450s (CYPs) involved in the metabolism of clozapine in human liver microsomes (HLMs) and recombinant human cytochrome P450 enzymes (rCYPs). N-desmethylclozapine and clozapine N-oxide, two major metabolites of clozapine, were measured using high-performance liquid chromatography (HPLC). FG, RR and RB showed negligible inhibitory effects in both in vitro systems, with estimated half-maximal inhibitory concentrations (IC₅₀) and apparent inhibitory constant values (K_i) greater than 1 mg/mL (raw material), suggesting that minimal metabolic interaction occurs when these preparations are used concomitantly with clozapine. The FS extract affected CYP activity with varying potency; its effect on CYP 3A4-catalyzed clozapine oxidation was relatively strong (K_i: 0.11 mg/mL). Overall, the weak-to-moderate inhibitory effect of FS on in vitro clozapine metabolism indicated its potential role in herb-drug interaction in practice.

The hepatoprotective effect of the combination use of Fructus Schisandrae with statin--A preclinical evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Schisandrae is traditionally used as a liver-toning Chinese herb. Recent studies suggested Fructus Schisandrae could prevent high-fat diet-induced hepatic steatosis as well as improving anti-oxidative status within the liver, which is a proposed mechanism against statin-induced liver toxicity.

AIM

The aim of the present study was to determine if the combination use of Atorvastatin (AS) and Fructus Schisandrae aqueous extract (FSE) could (a) exert potent therapeutic effects not only on high-fat diet-induced hyperlipidemia, but also on hepatomegaly (enlarge of liver size) and hepatic steatosis (fatty liver); and (b) reduce side effects caused by intake of statin alone including increased incidence of elevated liver enzymes and liver toxicity in Sprague Dawley rats.

MATERIALS AND METHODS

We studied 5 groups of Sprague Dawley rats that were given the following treatment for 8 weeks: (i) Normal-chow diet; (ii) High-fat diet (contains 21% fat and 0.15% cholesterol); (iii) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.3% Atorvastatin; (iv) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.45% FSE; (v) High-fat diet (contains 21% fat and 0.15% cholesterol)+0.3% Atorvastatin+0.45% FSE. After 8 weeks of treatment, body weight, adipose tissue and liver mass were measured, and liver and plasma lipid levels were determined to evaluate to effect of FSE with or without AS treatment on diet-induced obesity, hyperlipidemia and hepatic steatosis. Liver enzyme activities, anti-oxidative status and membrane permeability transition were also assessed to determine if FSE could reduce the side effects induced by AS.

RESULTS

From the results, FSE treatment alone resulted in significant inhibitory effect on diet-induced increase in: (a) body weight; (b) fat pad mass (epididymal, perirenal and inguinal fat); (c) liver weight; (d) total liver lipid; (e) liver triglyceride and cholesterol levels; and (f) plasma lipid levels, suggesting FSE has a potential preventive beneficial effect on weight control and lipid metabolism in Sprague Dawley rats with diet-induced obesity. However, FSE supplementation exerted no further beneficial effect on diet-induced metabolic syndrome when it is combined with AS treatment, compared with rats given AS-treatment alone. At the dose of 0.45%, dietary FSE supplementation resulted in: (a) reduced liver enzymes (ALT and AST) levels; (b) reduced macrophage infiltration (CD68); (c) improved liver glutathione levels (anti-oxidative status); (d) reduced liver reactive oxidative species; (e) a trend to reduce calcium-induced membrane permeability transition within the liver. Most importantly, these improvements induced by FSE treatment were not only observed in the livers of rats given high-fat-diet, but also in high-fat-fed rats with atorvastatin-induced hepatotoxicity.

CONCLUSIONS

Taken together, these data suggested FSE has a potential beneficial effect on weight control and lipid metabolism in Sprague Dawley rats with diet-induced obesity, and the combination use of FSE with AS could significantly prevent liver toxicity and anti-oxidative status induced by AS alone.

Validation of an LC-MS/MS method for quantitative analysis of the 5 bioactive components of Wuzhi capsule in human plasma samples

BACKGROUND

Wuzhi capsule (WZC) is an ethanol extract from the ripe fruit of Schisandra sphenanthera in traditional Chinese medicine that has long been used to treat viral and drug-induced hepatitis in China. The principal active components in WZC are Schisandra lignans. The clinical pharmacokinetics of these components in the form of an oral WZC preparation is unknown. To optimize the WZC dosage and develop WZC-related combination therapies, it is necessary to conduct a comprehensive pharmacokinetic study of the Schisandra lignans.

METHODS

A method was developed for simultaneous quantification of multiple bioactive lignans in WZC in human plasma through liquid-liquid extraction followed by multiple reaction monitoring liquid chromatography/tandem mass spectrometry with positive-mode electrospray ionization. The 5 bioactive constituents were separated by isocratic elution using a mobile phase consisting of acetonitrile, methanol, and 0.1% aqueous formic acid at a flow rate of 0.3 mL/min. The total run time was 3.5 minutes.

RESULTS

All analytes showed good linearity over a wide concentration range with a lower limit of quantification at 0.5 ng/mL. Using this method, we determined the 5 bioactive lignans in WZC from human plasma simultaneously and performed a pharmacokinetic study on the Schisandra lignans in healthy volunteers.

CONCLUSIONS

Owing to simplicity, quickness, high sensitivity, and selectivity, and a sufficient lower limit of detection of the new liquid chromatography/tandem mass spectrometry method, it may be used as a routine technique for clinical monitoring of WZC, and for understanding interactions between herbal and conventional drug therapies.

Inhibition of UDP-Glucuronosyltransferases (UGTs) Activity by constituents of Schisandra chinensis

Structure-activity relationship for the inhibition of Schisandra chinensis's ingredients toward (Uridine-Diphosphate) UDP-glucuronosyltransferases (UGTs) activity was performed in the present study. In vitro incubation system was employed to screen the inhibition capability of S. chinensis's ingredients, and in silico molecular docking method was carried out to explain possible mechanisms. At 100 μM of compounds, the activity of UGTs was inhibited by less than 90% by schisandrol A, schisandrol B, schisandrin, schisandrin C, schisantherin A, gomisin D, and gomisin G. Schisandrin A exerted strong inhibition toward UGT1A1 and UGT1A3, with the residual activity to be 7.9% and 0% of control activity. Schisanhenol exhibited strong inhibition toward UGT2B7, with the residual activity to be 7.9% of control activity. Gomisin J of 100 μM inhibited 91.8% and 93.1% of activity of UGT1A1 and UGT1A9, respectively. Molecular docking prediction indicated different hydrogen bonds interaction resulted in the different inhibition potential induced by subtle structure alteration among schisandrin A, schisandrin, and schisandrin C toward UGT1A1 and UGT1A3: schisandrin A > schisandrin > schisandrin C. The detailed inhibition kinetic evaluation showed the strong inhibition of gomisin J toward UGT1A9 with the inhibition kinetic parameter (Ki ) to be 0.7 μM. Based on the concentrations of gomisin J in the plasma of the rats given with S. chinensis, high herb-drug interaction existed between S. chinensis and drugs mainly undergoing UGT1A9-mediated metabolism. In conclusion, in silico-in vitro method was used to give the inhibition information and possible inhibition mechanism for S. chinensis's components toward UGTs, which guide the clinical application of S. chinensis.

Interactions between CYP3A4 and Dietary Polyphenols

The human cytochrome P450 enzymes (P450s) catalyze oxidative reactions of a broad spectrum of substrates and play a critical role in the metabolism of xenobiotics, such as drugs and dietary compounds. CYP3A4 is known to be the main enzyme involved in the metabolism of drugs and most other xenobiotics. Dietary compounds, of which polyphenolics are the most studied, have been shown to interact with CYP3A4 and alter its expression and activity. Traditionally, the liver was considered the prime site of CYP3A-mediated first-pass metabolic extraction, but in vitro and in vivo studies now suggest that the small intestine can be of equal or even greater importance for the metabolism of polyphenolics and drugs. Recent studies have pointed to the role of gut microbiota in the metabolic fate of polyphenolics in human, suggesting their involvement in the complex interactions between dietary polyphenols and CYP3A4. Last but not least, all the above suggests that coadministration of drugs and foods that are rich in polyphenols is expected to stimulate undesirable clinical consequences. This review focuses on interactions between dietary polyphenols and CYP3A4 as they relate to structural considerations, food-drug interactions, and potential negative consequences of interactions between CYP3A4 and polyphenols.

The Effect of Oxidation on Berberine-Mediated CYP1 Inhibition: Oxidation Behavior and Metabolite-Mediated Inhibition

The protoberberine alkaloid berberine carries methylenedioxy moiety and exerts a variety of pharmacological effects, such as anti-inflammation and lipid-lowering effects. Berberine causes potent CYP1B1 inhibition, whereas CYP1A2 shows resistance to the inhibition. To reveal the influence of oxidative metabolism on CYP1 inhibition by berberine, berberine oxidation and the metabolite-mediated inhibition were determined. After NADPH-fortified preincubation of berberine with P450, the inhibition of CYP1A1 and CYP1B1 variants (CYP1B1.1, CYP1B1.3, and CYP1B1.4) by berberine was not enhanced, and CYP1A2 remained resistant. Demethyleneberberine was identified as the most abundant metabolite of CYP1A1- and CYP1B1-catalyzed oxidations, and thalifendine was generated at a relatively low rate. CYP1A1-catalyzed berberine oxidation had the highest maximal velocity (V max) and exhibited positive cooperativity, suggesting the assistance of substrate binding when the first substrate was present. In contrast, the demethylenation by CYP1B1 showed the property of substrate inhibition. CYP1B1-catalyzed berberine oxidation had low K m values, but it had V max values less than 8% of those of CYP1A1. The dissociation constants generated from the binding spectrum and fluorescence quenching suggested that the low K m values of CYP1B1-catalyzed oxidation might include more than the rate constants describing berberine binding. The natural protoberberine/berberine fmetabolites with methylenedioxy ring-opening (palmatine, jatrorrhizine, and demethyleneberberine) and the demethylation (thalifendine and berberrubine) caused weak CYP1 inhibition. These results demonstrated that berberine was not efficiently oxidized by CYP1B1, and metabolism-dependent irreversible inactivation was minimal. Metabolites of berberine caused a relatively weak inhibition of CYP1.

Hepato-protective effects of six schisandra lignans on acetaminophen-induced liver injury are partially associated with the inhibition of CYP-mediated bioactivation

Acetaminophen (APAP) overdose is the most frequent cause of drug-induced acute liver failure. Schisandra fructus is widely-used traditional Chinese medicine which possesses hepato-protective potential. Schisandrin A (SinA), Schisandrin B (SinB), Schisandrin C (SinC), Schisandrol A (SolA), Schisandrol B (SolB), and Schisantherin A (SthA) are the major bioactive lignans. Most recently, we found SolB exerts significant hepato-protection against APAP-induced liver injury. In this study, the protective effects of the other five schisandra lignans against APAP-induced acute hepatotoxicity in mice were investigated and compared with that of SolB. The results of morphological and biochemical assessment clearly demonstrated significant protective effects of SinA, SinB, SinC, SolA, SolB, and SthA against APAP-induced liver injury. Among these schisandra lignans, SinC and SolB exerted the strongest hepato-protective effects against APAP-induced hepatotoxicity. Six lignans pretreatment before APAP dosing could prevent the depletions of total liver glutathione (GSH) and mitochondrial GSH caused by APAP. Additionally, the lignans treatment inhibited the enzymatic activities of three CYP450 isoforms (CYP2E1, CYP1A2, and CYP3A11) related to APAP bioactivation, and further decreased the formation of APAP toxic intermediate N-acetyl-p-benzoquinone imine (NAPQI) in mouse microsomal incubation system. This study demonstrated that SinA, SinB, SinC, SolA, SolB and SthA exhibited significant protective actions toward APAP-induced liver injury, which was partially associated with the inhibition of CYP-mediated APAP bioactivation.

Constituents of Indonesian Medicinal Plant Averrhoa bilimbi and Their Cytochrome P450 3A4 and 2D6 Inhibitory Activities

As constituents of Averrhoa bilimbi leaves we identified three new compounds (1-3) together with 12 known ones (4-15); their inhibitory activities on cytochrome P450 3A4 (CYP3A4) and 2D6 (CYP2D6) were examined. Among the isolated compounds, the mixture of 1 and 2, and compounds 4 and 9 showed strong inhibition on CYP3A4, but mild or no inhibition on CYP2D6. These compounds revealed the characteristics of 1) time- and concentration-dependent inhibition, 2) requirement of NADPH for the inhibition, 3) no protection by nucleophiles, and 4) suppression of the inhibition by competitive inhibitor. Thus, they are suggested to be mechanism-based inactivators of CYP3A4 and CYP2D6. The kinetic parameters for the inactivation (kinact and KI) were 0.19 min–1 and 36.7 μM for the mixture of 1 and 2, 0.126 min–1 and 10.5 μM for 4, and 0.29 min–1 and 23.4 μM for 9.

Schisandrol B protects against acetaminophen-induced hepatotoxicity by inhibition of CYP-mediated bioactivation and regulation of liver regeneration

Acetaminophen (APAP) overdose is the most frequent cause of drug-induced acute liver failure. Schisandra sphenanthera is a traditional hepato-protective Chinese medicine and Schisandrol B (SolB) is one of its major active constituents. In this study, the protective effect of SolB against APAP-induced acute hepatotoxicity in mice and the involved mechanisms were investigated. Morphological and biochemical assessments clearly demonstrated a protective effect of SolB against APAP-induced liver injury. SolB pretreatment significantly attenuated the increases in alanine aminotransferase and aspartate aminotransferase activity, and prevented elevated hepatic malondialdehyde formation and the depletion of mitochondrial glutathione (GSH) in a dose-dependent manner. SolB also dramatically altered APAP metabolic activation by inhibiting the activities of CYP2E1 and CYP3A11, which was evidenced by significant inhibition of the formation of the oxidized APAP metabolite NAPQI-GSH. A molecular docking model also predicted that SolB had potential to interact with the CYP2E1 and CYP3A4 active sites. In addition, SolB abrogated APAP-induced activation of p53 and p21, and increased expression of liver regeneration and antiapoptotic-related proteins such as cyclin D1 (CCND1), PCNA, and BCL-2. This study demonstrated that SolB exhibited a significant protective effect toward APAP-induced liver injury, potentially through inhibition of CYP-mediated APAP bioactivation and regulation of the p53, p21, CCND1, PCNA, and BCL-2 to promote liver regeneration.

Multifaceted interaction of the traditional Chinese medicinal herb Schisandra chinensis with cytochrome P450-mediated drug metabolism in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (SC), officially listed as a sedative and tonic in the Chinese Pharmacopoeia, has been used as a common component in various prescriptions in Traditional Chinese Medicine (TCM) and more recently in western medicine for its antihepatotoxic effect. To assess the possible herb-drug interaction, effects of SC extracts on hepatic cytochrome P450 (P450, CYP) enzymes were studied.

MATERIAL AND METHODS

Effects of SC extracts on rat hepatic CYP450 enzymes in vitro and in vivo were investigated by probe substrates method, real-time RT-PCR assay and Western blotting analysis. Furthermore, the effects of SC alcoholic extract on the PK of four SC lignans and the drugs possibly co-administrated in vivo were studied in male Sprague-Dawley rat.

RESULTS

SC aqueous extract and alcoholic extract showed significant inhibitory effect on the activities of rat liver microsomal CYP1A2, 2C6, 2C11, 2D2, 2E1 and 3A1/2 in vitro. Multiple administrations of SC aqueous extract (1.5g/kg, qd×7d) and alcoholic extract (1.5g/kg, qd×7d) increased the activities, mRNA and protein expressions of CYP2E1 and CYP3A1/2, and meanwhile, inhibited the activities and mRNA expression of CYP2D2 in vivo. The in vivo metabolism of four SC lignans, such as schisandrin, schisantherin A, deoxyshisandrin and γ-schisandrin, and chlorzoxazone was significantly accelerated, exhibited by the reduced AUC and increased CLz/F, by 7-day pretreatment with SC alcoholic extract. However, both single and multiple dosing treatments of SC alcoholic extract remarkably decreased the in vivo metabolism of tacrolimus indicated by the enhanced AUC (7-12 fold) and elevated Cmax (10 fold).

CONCLUSION

These results revealed that the SC extracts exhibited multifaceted effects on rat hepatic CYP450 enzymes. Herb-drug interaction should be paid intense attention between SC components and drugs metabolized by different CYP450 enzymes.

Wuzhi tablet (Schisandra Sphenanthera extract) protects against acetaminophen-induced hepatotoxicity by inhibition of CYP-mediated bioactivation and regulation of NRF2-ARE and p53/p21 pathways

Schisandra sphenanthera is widely used as a tonic and restorative in many countries to enhance the function of liver and other organs. Wuzhi tablet (WZ) is a preparation of an ethanol extract of Schisandra sphenanthera. Our previous study demonstrated that WZ exerted a protective effect toward acetaminophen (APAP)-induced hepatotoxicity. However, the molecular mechanisms of this protection remain unclear. This study aimed to determine what molecular pathways contributed to the hepatoprotective effects of WZ against APAP toxicity. Administration of WZ 3 days before APAP treatment significantly attenuated APAP hepatotoxicity in a dose-dependent manner and reduced APAP-induced JNK activation. Treatment with WZ resulted in potent inhibition of CYP2E1, CYP3A11, and CYP1A2 activities and then caused significant inhibition of the formation of the oxidized APAP metabolite N-acetyl-p-benzoquinone imine-reduced glutathione. The expression of NRF2 was increased after APAP and/or WZ treatment, whereas KEAP1 levels were decreased. The protein expression of NRF2 target genes including Gclc, Gclm, Ho-1, and Nqo1 was significantly increased by WZ treatment. Furthermore, APAP increased the levels of p53 and its downstream gene p21 to trigger cell cycle arrest and apoptosis, whereas WZ pretreatment could inhibit p53/p21 signaling to induce cell proliferation-associated proteins including cyclin D1, CDK4, PCNA, and ALR to promote hepatocyte proliferation. This study demonstrated that WZ prevented APAP-induced liver injury by inhibition of cytochrome P450-mediated APAP bioactivation, activation of the NRF2-antioxidant response element pathway to induce detoxification and antioxidation, and regulation of the p53, p21, cyclin D1, CDK4, PCNA, and ALR to facilitate liver regeneration after APAP-induced liver injury.