Mechanism-based inactivation of cytochrome P450 2B6 by isoimperatorin

Isoimperatorin alleviates lipopolysaccharide-induced periodontitis by downregulating ERK1/2 and NF-κB pathways

Chronic periodontitis is an inflammatory disease characterized by inflammation of the soft tissues of the gums. To combat this disease, more effective drugs are still needed to identify and develop. Isoimperatorin is a kind of a natural compound, which has anti-inflammatory, analgesic, antitumor, antivirus, and other pharmacological effects. However, its possible effects on the progression of chronic periodontitis are still unclear. In this study, we used human periodontal membrane fibroblasts (hPDLCs), human bone marrow-derived macrophages, and found that isoimperatorin reduced hPDLCs viability. In addition, isoimperatorin alleviated the oxidative stress of periodontal membrane cells. Isoimperatorin reduced proinflammatory factor secretion and receptor activator for nuclear factor-κB ligand-induced osteoclast differentiation in periodontal membrane cells. Further, isoimperatorin inhibited the activation of ERK1/2 and nuclear factor-κB pathways. We, therefore, thought isoimperatorin could serve as a promising drug for the treatment of this disease.

Exploring the Scientific Rationality of the Phenomenon of "Different Dosage Forms of the Same Prescription" of Chinese Proprietary Medicine Based on Biopharmaceutical Properties of Powder and Pill of Chuanxiong Chatiao Prescription

Background: The 2020 edition of the Pharmacopoeia of the People’s Republic of China (Chinese Pharmacopoeia 2020 edition) has 255 Chinese prescriptions with different dosage forms, accounting for 21.09% of the total prescriptions (1,209) in Chinese Pharmacopoeia 2020 edition. However, the scientific rationality of the phenomenon of “Different Dosage Forms of the Same Prescription” of Chinese proprietary medicine has been less explored. Based on the dosage form theory of “components in pills release slowly and take effect in slow-acting manner, while in powders release quickly and take effect in fast-acting way,” we provided the in vitro dissolution experiment and in vivo pharmacokinetics of Chuanxiong Chatiao powders and pills in order to rationalize the phenomenon of “Different Dosage Forms of the Same Prescription” of Chuanxiong Chatiao prescription.

Materials and Methods: Chuanxiong Chatiao powders and pills were prepared in the laboratory referring to the preparation methods in the Chinese Pharmacopoeia 2020 edition, and the contents of tetramethylpyrazine, ferulic acid, nodakenin, and isoimperatorin were determined by the external standard method. We measured the in vitro dissolution of four analytes of Chuanxiong Chatiao powders and pills according to the second method for dissolution determination (paddle method) in the Chinese Pharmacopoeia 2020 edition, and their corresponding contents in each sampling point were determined by LC-MS/MS. We also provided a pharmacokinetic study of Chuanxiong Chatiao powders and pills. Six female domestic rabbits were divided into two groups (powder and pill groups) and given Chuanxiong Chatiao powders and pills (9.85 g/kg) by surgical administration separately. Blood samples were collected at 5, 15, 30, 45, 60, 90, 120, 150, 180, 240, 360, 480, 720, and 1,440 min after drug administration to measure the plasma concentration of the four analytes by LC-MS/MS.

Results: The results of in vitro dissolution experiment showed that the dissolution rate of four analytes in the powder group was greater than that of the pill group. However, the solubilities of tetramethylpyrazine and isoimperatorin were very low in the powder and pill, which may be related to their low solubility properties. The results of the in vivo pharmacokinetic study of Chuanxiong Chatiao powders and pills showed that T_max (h) of ferulic acid and nodakenin in the powder group was 0.420 and 0.053 times that of the pill group and t_1/2 (h) of ferulic acid, nodakenin, and isoimperatorin of the powder group was 0.910, 0.262, and 0.661 times that of the pill group, respectively.

Conclusion: The in vitro dissolution rate and in vivo pharmacokinetic parameters of four analytes in CXCTF could partly explain the scientific rationality of the classic theory of “丸者缓也, 散者散也” as in Chinese, which is helpful for providing a basis for the comparison of subsequent dosage forms. The results of our studies also suggest the complexity of the design of dosage forms of Chinese proprietary medicines and imply that we should pay more attention to the scientific rationality of the phenomenon of “Different Dosage Forms of the Same Prescription.”

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.

Inhibition of cytochrome P450 2B6 by Astragalus extract mixture HT042

Astragalus extract mixture (AEM) HT042 is a functional food approved by the MFDS (Korean FDA) for increasing height. It comprises a mixture of three standardized extracts from Astragalus membranaceus root, Eleutherococcus senticosus stem, and Phlomis umbrosa root. In this study, drug-functional food interaction was analyzed using six major human cytochrome P450 enzymes. The inhibitory effect of AEM HT042 on P450 activities was studied using a P450-NADPH P450 reductase reconstitution system. Among the six P450 enzymes (1A2, 2A6, 2B6, 2D6, 2C9, and 3A4), only P450 2B6 activity was markedly decreased by AEM HT042 addition. The bupropion hydroxylation activity of P450 2B6 was analyzed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A calculated IC₅₀ value of 10.62 µg/ml was obtained. To identify the inhibitory compounds in the mixture, four active compounds in AEM HT042 were analyzed. Shanzhiside methylester exhibited inhibitory effects on P450 2B6, whereas formononetin, eleutheroside E, and sesamoside did not affect P450 2B6 activity at all. Our results suggest that shanzhiside methylester in AEM HT042 is responsible for the inhibitory effect on P450 2B6 metabolism. Characterization of the inhibitory effect on P450 can help determine the safe administration of functional foods along with many clinical drugs that are metabolized by P450.

Chinese Herbal Medicine Hepatotoxicity: The Evaluation and Recognization Based on Large-scale Evidence Database

Background:

Due to the special nature of Chinese Herbal medicine and the complexity of its clinical use, it is difficult to identify and evaluate its toxicity and resulting herb induced liver injury (HILI).

Methods:

First, the database would provide full profile of HILI from the basic ingredients to clinical out-comes by the most advanced algorithms of artificial intelligence, and it is also possible that we can predict possibilities of HILI after patients taking Chinese herbs by individual patient evaluation and prediction. Second, the database would solve the chaos and lack of the relevant data faced by the current basic re-search and clinical practice of Chinese Herbal Medicine. Third, we can also screen the susceptible patients from the database and thus prevent the accidents of HILI from the very beginning.

Results:

The Roussel Uclaf Causality Assessment Method (RUCAM) is the most accepted method to evalu-ate DILI, but at present before using the RUCAM evaluation method, data resource collection and analysis are yet to be perfected. Based on existing research on drug-metabolizing enzymes mediating reactive me-tabolites (RMs), the aim of this study is to explore the possibilities and methods of building multidimen-sional hierarchical database composing of RMs evidence library, Chinese herbal evidence library, and indi-vidualized reports evidence library of herb induced liver injury HILI.

Conclusion:

The potential benefits lie in its ability to organize, use vast amounts of evidence and use big data mining techniques at the center for Chinese herbal medicine liver toxicity research, which is the most difficult key point of scientific research to be investigated in the next few years.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

High hepatic exposure of furanocoumarins in Radix Angelica dahuricae is associated with transporter mediated active uptake

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Angelica dahuricae (RAD), the roots of Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav, is a well-known traditional Chinese medicine (TCM) and has been used for centuries to treat headaches, toothaches, nose congestion, abscesses, furunculoses, and acne. This herb is also one of frequently reported TCMs showing the herb-drug interaction potential. Furanocoumarins are main bioactive components of RAD.

AIM OF THE STUDY

This study is designed to characterize the tissue distribution profiles of furanocoumarins after oral administration of RAD extract in rats and to explore the mechanism underlying the high hepatic exposure of the major furanocoumarins.

MATERIALS AND METHODS

The tissue distribution of nine furanocoumarins was determined in rats after an oral dose of 0.46g/kg RAD extract using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Unbound fractions (ƒ_u) of major furanocoumarins, including imperatorin (IM), isoimperatorin (IIM), bergapten (BER) and oxypeucedanin hydrate (OXYH), were measured in rat plasma and selected tissue homogenates (liver, kidney, lung and brain) with Rapid Equilibrium Dialysis (RED) method. The temperature dependent hepatic uptake of IM, IIM, BER and OXYH were evaluated in suspended rat primary hepatocytes at 4°C or 37°C by the oil-spin method. The uptake kinetics was conducted in the cells over a wide concentration range. The furanocoumarins were co-incubated with a panel of transporter inhibitors to investigate the involvement of uptake transporters in the hepatic uptake. The transcellular transport characteristics of IM, IIM, BER and OXYH were further assessed using Caco-2 cell monolayer model.

RESULTS

IM, IIM, BER and OXYH were found to be the major bioactive furanocoumarins in rat plasma and tissues, representing more than 90% exposure for all the detected furanocoumarins. The most concentrative organ of major furanocoumarins was the liver, with liver-to-plasma exposure ratio (K_p,_AUC) of 5.1, 6.5 and 4.7 for IM, IIM and BER, and 2.3 for OXYH, respectively. IM, IIM and BER also showed higher concentrations in the kidney with K_p above 2.2. The higher protein binding of the furanocoumarins partially contributed to their higher tissue exposure. In suspended rat primary hepatocyte, the hepatic uptake of IM, IIM, BER and OXYH was temperature-dependent, with considerably higher uptake at 37°C than at 4°C. Uptake kinetics indicated that the hepatic uptake of IM, IIM, BER and OXYH involved both active transport and passive diffusion processes. For IM, IIM and BER, the contribution of the active transport was greater than the passive process, with the CL_active/CL_uptake > 72%. Ritonavir (RTN) and cyclosporine A (CsA), the known inhibitors of organic anion transporting polypeptide (Oatp) significantly inhibited the hepatic uptake of IM and BER, while the inhibitor of the organic anion transporters (Oat) probenecid (PBC) remarkably reduced IIM uptake. In the Caco-2 cell model, the furanocoumarins were highly permeable in the apical to basolateral direction without notable active efflux.

CONCLUSION

The furanocoumarins rapidly and widely distributed into various tissues after oral dose of the RAD extract. IM, IIM, BER and OXYH were the major components detected in both plasma and tissues. Liver was the most distributed tissue of the total and free furanocoumarins. Non-specific protein binding contributed partially to the higher tissue exposures of these bioactive components. The Oatp and Oat mediated active uptake played the primal role in the high hepatic exposure of the furanocoumarins.

Coordination Mechanism and Bio-Evidence: Reactive γ-Ketoenal Intermediated Hepatotoxicity of Psoralen and Isopsoralen Based on Computer Approach and Bioassay

Psoralen and isopsoralen are secondary plant metabolites found in many fruits, vegetables, and medicinal herbs. Psoralen-containing plants (Psoralea corylifolia L.) have been reported to cause hepatotoxicity. Herein, we found that psoralen and isopsoralen were oxidized by CYP450s to reactive furanoepoxide or γ-ketoenal intermediates, causing a mechanism-based inhibition of CYP3A4. Furthermore, in GSH-depleted mice, the hepatotoxicity of these reactive metabolites has been demonstrated by pre-treatment with a well-known GSH synthesis inhibitor, L-buthionine-S, Rsulfoxinine (BSO). Moreover, a molecular docking simulation of the present study was undertaken to understand the coordination reaction that plays a significant role in the combination of unstable intermediates and CYP3A4. These results suggested that psoralen and isopsoralen are modest hepatotoxic agents, as their reactive metabolites could be deactivated by H₂O and GSH in the liver, which partly contributes to the ingestion of psoralen-containing fruits and vegetables being safe.

Studies on the metabolites difference of psoralen/isopsoralen in human and six mammalian liver microsomes in vitro by UHPLC-MS/MS

Psoralen and isopsoralen are found in many fruits, vegetables and traditional Chinese medicines (TCM), such as Ficus carica L., Celery, Fructus Psoraleae etc. Modern pharmacological studies found that psoralen and isopsoralen can show estrogen-like activity, antitumor, and antibacterial activities etc. However, some research results also show some liver damage associated with the use of psoralen/isopsoralen or related medicines in human. Many studies focus on the pharmacological activities of psoralen/isopsoralen, while it is important to choose the suitable pharmacological models which are relevant to human in drug metabolism and pharmacokinetic process. The aim of this study is to identify the metabolites of psoralen/isopsoralen by human and six mammalian liver microsomes, and compare the metabolites difference of different species. Psoralen/isopsoralen are metabolized by liver microsomes of different animals to form five and seven metabolites, respectively. The metabolism of psoralen/isopsoralen undergoes hydroxylation, hydrogenation and hydrolysis, and oxidation of the furan ring to generate a furanoepoxide or γ-ketoenal intermediate. Furanoepoxide then forms a dihydrodiol, while γ-ketoenal forms 6-(7-hydroxycoumaryl)-acetic acid (in psoralen)/8-(7-hydroxycoumaryl)-acetic acid (in isopsoralen). By comparing the types of metabolites in the seven liver microsomes, it shows that the metabolic behaviors of psoralen by Beagle dog is most relevant to human, while the metabolic behaviors of isopsoralen by Sprague-Dawley rat is most similar to human. By comparing the relative amounts of the main metabolites, it shows that the metabolic capabilities of Sprague-Dawley rat and Rhesus monkey for psoralen are most similar to human, while the metabolic capabilities of Mouse, Dunkin-Hartley guinea pig, Sprague-Dawley rat, and human for isopsoralen are similar. Furthermore, the results show that the metabolic capability of human for psoralen and isopsoralen are weaker than other mammal species. The results of this work are useful for studying the metabolism mechanism of psoralen/isopsolaren, and choosing the most relevant animal species for investigation of psoralen/isopsolaren from experimental animals to human.

Cytochrome P450 and P-Glycoprotein-Mediated Interactions Involving African Herbs Indicated for Common Noncommunicable Diseases

Herbal remedies are regularly used to complement conventional therapies in the treatment of various illnesses in Africa. This may be because they are relatively cheap and easily accessible and are believed by many to be safe, cause fewer side effects, and are less likely to cause dependency. On the contrary, many herbs have been shown to alter the pharmacokinetics of coadministered allopathic medicines and can either synergize or antagonize therapeutic effects as well as altering the toxicity profiles of these drugs. Current disease burden data point towards epidemiological transitions characterised by increasing urbanization and changing lifestyles, risk factors for chronic diseases like hypertension, diabetes, and cancer which often present as multimorbidities. As a result, we highlight African herb-drug interactions (HDIs) modulated via cytochrome P450 enzyme family (CYP) and P-glycoprotein (P-gp) and the consequences thereof in relation to antihypertensive, antidiabetic, and anticancer drugs. CYPs are enzymes which account for to up to 70% of drug metabolism while P-gp is an efflux pump that extrudes drug substrates out of cells. Consequently, regulation of the relative activity of both CYP and P-gp by African herbs influences the effective drug concentration at the site of action and modifies therapeutic outcomes.

A Molecular Aspect in the Regulation of Drug Metabolism: Does PXR-Induced Enzyme Expression Always Lead to Functional Changes in Drug Metabolism?

Pregnane X receptor (PXR, NR112) is a xenobiotic receptor whose primary function is to regulate the expression of drug-metabolizing enzymes (DMEs) and drug transporters. Drug-induced PXR activation and subsequent enzyme and transporter induction has been proposed to be an important mechanism for the drug-drug interactions. In addition to activating PXR, many pharmaceutical chemicals can also function as reversible or irreversible inhibitors of DMEs, which may also impact the pharmacokinetics and pharmacodynamics (PK/PD) of drugs. Therefore, we cannot simply conclude that the PXR-induced alteration in enzyme expression always reflects functional changes. We should consider both PXR activation and DMEs inhibition to improve drug safety in the clinic.

Separation and simultaneous quantification of nine furanocoumarins from Radix Angelicae dahuricae using liquid chromatography with tandem mass spectrometry for bioavailability determination in rats

Radix Angelicae dahuricae is a well-known medicinal herb in a number of herb preparations for medical uses. In this study, a rapid and selective method using liquid chromatography with tandem mass spectrometry was developed for the separation and simultaneous quantitation of nine furanocoumarins from Radix A. dahuricae, namely imperatorin, isoimperatorin, oxypeucedanin hydrate, bergapten, oxypeucedanin, xanthotoxol, xanthotoxin, isopimpinellin, and psoralen. Chromatographic separation was achieved on a CAPCELL PAK MG II C18 analytical column. Detection was performed using positive electrospray ion source in the multiple reaction monitoring mode. The method was fully validated for analyzing these principles in rat plasma with a lower limit of quantification from 0.5 to 5 ng/mL. The intra- and interbatch precisions were less than 10%, and the accuracies ranged from -7.5 to 8.0%. The extraction recovery of the analytes was above 70% without a significant matrix effect. The method was used to determine the oral and intravenous pharmacokinetic profiles of these furanocoumarins after dosing with Radix A. dahurica extract. The bioavailability of these furanocoumarins ranged from 10.1 to 82.8%. These data provide critical information for a better understanding of the pharmacological mechanisms and herb-drug interaction potential of Radix A. dahurica.

Mechanism-based inactivation of cytochrome P450 2B6 by isopsoralen

1. Isopsoralen (IPRN) is a major component in many traditional medicinal herbs widely used in Asian countries. The objective of the present study was to investigate the inhibitory effect of IPRN on cytochrome P450 2B6 (CYP2B6) and the mechanism involved in the enzyme inactivation. 2. Pre-incubation of CYP2B6 with IPRN resulted in a time- and concentration-dependent enzyme activity loss. The values of K(I) and k(inact) were found to be 7.89 μM and 0.067 min(-1), respectively. Ticlopidine exhibited protective effect on the IPRN-induced enzyme inactivation. The estimated partition ratio of the inactivation was 122. The GSH trapping experiments indicate that an epoxide and/or γ-ketoenal intermediate were/was generated in IPRN-fortified microsomal incubations. The synthetic work verified the formation of the reactive intermediate(s). Additionally, CYPs2E1, 2C19, 2B6 and 1A2 were found to be the major enzymes participating in the bioactivation of IPRN. 3. IPRN was characterized as a mechanism-based inactivator of CYP2B6. An IPRN-derived furanoepoxide and/or γ-ketoenal intermediate(s) were/was generated and may be responsible for the inactivation of CYP2B6.

Mechanism-based inactivation of CYP2C9 by linderane

1. Linderane (LDR), a furan-containing sesquiterpenoid, is found in Lindera aggregata (Sims) Kosterm, a common traditional Chinese herbal medicine. We thoroughly studied the irreversible inhibitory effect of LDR on cytochrome P450 2C9 (CYP2C9). 2. LDR caused a time- and concentration-dependent inactivation of CYP2C9. In addition, the inactivation of CYP2C9 by LDR was NADPH-dependent and irreversible. More than 50% of CYP2C9 activity was lost after its incubation with LDR at the concentration of 10 μM for 15 min at 30 °C. The maximal rate constant for inactivation (kinact) was found to be 0.0419 min(-1), and the concentration required for half-maximal inactivation (KI) was 1.26 μM, respectively. Glutathione (GSH), catalase, and superoxide dismutase (SOD) failed to protect CYP2C9 against inactivation by LDR. Diclofenac, a substrate of CYP2C9, prevented the enzyme from inactivation produced by LDR. The estimated partition ratio of the inactivation was approximately 227. 3. Two reactive intermediates, including furanoepoxide and γ-ketoenal, might be responsible for the observed enzyme inactivation. The formation of the intermediates was verified by chemical synthesis. Multiple P450 enzymes, including CYPs 1A2, 2B6, 2C9, 2C19, 2D6, 3A4, and 3A5, were found to be involved in the metabolic activation of LDR. In conclusion, LDR was characterized as a mechanism-based inactivator of CYP2C9.