Drug interaction study of flavonoids toward CYP3A4 and their quantitative structure activity relationship (QSAR) analysis for predicting potential effects

Inhibitory interaction of flavonoids with organic anion transporter 3 and their structure-activity relationships for predicting nephroprotective effects

The organic anion transporter 3 (OAT3), an important renal uptake transporter, is associated with drug-induced acute kidney injury (AKI). Screening and identifying potent OAT3 inhibitors with little toxicity in natural products, especially flavonoids, in reducing OAT3-mediated AKI is of great value. The five strongest OAT3 inhibitors from the 97 flavonoids markedly decreased aristolochic acid I-induced cytotoxicity and alleviated methotrexate-induced nephrotoxicity. The pharmacophore model clarified hydrogen bond acceptors and hydrophobic groups are the critical pharmacophores. These findings would provide valuable information in predicting the potential risks of flavonoid-containing food/herb-drug interactions and optimizing flavonoid structure to alleviate OAT3-related AKI.

Interactions studies of CYP2D6 with quercetin and hyperoside by spectral analysis and molecular dynamics simulations

Some ingredients from herbal medicine can significantly affect the activity of CYP2D6, thus leading to serious interactions between herbs and drugs. Quercetin and hyperoside are active ingredients widely found in vegetables, fruits, and herbal medicines. Quercetin and hyperoside have many biological activities. In this work, the characteristic bindings of CYP2D6 with quercetin/hyperoside are revealed by multi-spectroscopy analysis, molecular docking, and molecular dynamics simulations. The fluorescence of CYP2D6 is statically quenched by quercetin and hyperoside. The binding constant (Ka ) values of CYP2D6-quercetin/hyperoside range from 104  L mol-1 , which indicates that these two flavonoids bind moderately to CYP2D6. Meanwhile, quercetin has a stronger quenching ability to CYP2D6 than that of hyperoside. The secondary structure of CYP2D6 is obviously changed by binding with quercetin/hyperoside. The docking results reveal that the quercetin/hyperoside enters the active site of CYP2D6 near heme and binds to CYP2D6 by hydrogen bonds and van der Waals forces. The molecular dynamics simulation results indicate that the binding of quercetin/hyperoside can stabilize the two complexes, enhance the flexibility of CYP2D6 backbone atoms, and make a more unfolded and looser structure of CYP2D6.

Inhibition Effect of Okanin Toward Human Cytochrome P450 3A4 and 2D6 with Multi-spectroscopic Studies and Molecular Docking

Okanin, a major flavonoid of a popular herb tea, Coreopsis tinctoria Nutt., showed strong inhibition on CYP3A4 and CYP2D6. The strong interaction between okanin and CYPs were determined by enzyme kinetics, multispectral technique and molecular docking. The inhibition type of two enzymes, CYP3A4 and CYP2D6, by okanin are mixed and non-competitive inhibition type, respectively. The IC50 values and the binding constant of okanin to CYP3A4 can be deduced that the interaction was stronger than that of CYP2D6. The Conformations of CYP3A4 and CYP2D6 were changed by okanin. The evidence from fluorescence measurement along with molecular docking verified that these two CYPs were bound with okanin by hydrogen bonds and hydrophobic forces. Our investigation suggested that okanin may lead to interactions between herb and drug by inhibiting CYP3A4 and CYP2D6 activities, thus its consumption should be taken with caution.

Comparative study of the interaction mechanism of astilbin, isoastilbin, and neoastilbin with CYP3A4

The interactions of human CYP3A4 with three selected isomer flavonoids, such as astilbin, isoastilbin and neoastilbin, were clarified using spectral analysis, molecular docking, and molecular dynamics simulation. During binding with the three flavonoids, the intrinsic fluorescence of CYP3A4 was statically quenched in static mode with nonradiative energy conversion. The fluorescence and ultraviolet/visible (UV/vis) data revealed that the three flavonoids had a moderate and stronger binding affinity with CYP3A4 due to the order of the Ka1 and Ka2 values ranging from 104 to 105  L·mol-1 . In addition, astilbin had the highest affinity with CYP3A4, then isoastilbin and neoastilbin, at the three experimental temperatures. Multispectral analysis confirmed that binding of the three flavonoids resulted in clear changes in the secondary structure of CYP3A4. It was found from fluorescence, UV/vis and molecular docking analyses that these three flavonoids strongly bound to CYP3A4 by means of hydrogen bonds and van der Waals forces. The key amino acids around the binding site were also elucidated. Furthermore, the stabilities of the three CYP3A4 complexes were evaluated using molecular dynamics simulation.

Construction of a QSAR Model Based on Flavonoids and Screening of Natural Pancreatic Lipase Inhibitors

Pancreatic lipase (PL) is a key hydrolase in lipid metabolism. Inhibition of PL activity can intervene in obesity, a global sub-health disease. The natural product is considered a good alternative to chemically synthesized drugs due to its advantages, such as low side effects. However, traditional experimental screening methods are labor-intensive and cost-consuming, and there is an urgent need to develop high-throughput screening methods for the discovery of anti-PL natural products. In this study, a high-throughput virtual screening process for anti-PL natural products is provided. Firstly, a predictable anti-PL natural product QSAR model (R2train = 0.9444, R2test = 0.8962) were developed using the artificial intelligence drug design software MolAIcal based on genetic algorithms and their conformational relationships. 1068 highly similar (FS > 0.8) natural products were rapidly enriched based on the structure-activity similarity principle, combined with the QSAR model and the ADMET model, for rapid prediction of a total of five potentially efficient anti-PL natural products (IC50pre < 2 μM). Subsequently, molecular docking, molecular dynamics simulation, and MMGBSA free energy calculation were performed to not only reveal the interaction of candidate novel natural products with the amino acid residues of PL but also to validate the stability of these novel natural compounds bound to PL. In conclusion, this study greatly simplifies the screening and discovery of anti-PL natural products and accelerates the development of novel anti-obesity functional foods.

Consideration for Flavonoid-Containing Dietary Supplements to Tackle Deficiency and Optimize Health

Randomized clinical trials (RCT) and observational studies have highlighted the importance of flavonoid consumption for human health. Several studies have associated a high intake of dietary flavonoids with (a) enhanced metabolic and cardiovascular health, (b) enhanced cognitive and vascular endothelial functions, (c) an improved glycemic response in type 2 diabetes mellitus, and (d) a reduced risk of breast cancer in postmenopausal women. Since flavonoids belong to a broad and diverse family of polyphenolic plant molecules-with more than 6000 compounds interspersed in the human diet-researchers are still uncertain whether the intake of single, individual polyphenols or a large combination of them (i.e., synergistic action) can produce the greatest health benefits for humans. Furthermore, studies have reported a poor bioavailability of flavonoid compounds in humans, which presents a major challenge for determining their optimal dosage, recommended intake, and, consequently, their therapeutic value. Especially because of their scarce bioavailability from foods-along with the overall declining food quality and nutrient density in foods-the role of flavonoid supplementation may become increasingly important for human health. Although research shows that dietary supplements can be a highly useful tool to complement diets that lack sufficient amounts of important nutrients, some caution is warranted regarding possible interactions with prescription and non-prescription drugs, especially when taken concurrently. Herein, we discuss the current scientific basis for using flavonoid supplementation to improve health as well as the limitations related to high intakes of dietary flavonoids.

3D-QSAR studies on the structure-bitterness analysis of citrus flavonoids

Despite their important bioactivities, the unpleasant bitter taste of citrus derived flavonoids limits their applications in the food industry, and the structure-bitterness relationship of flavonoids is still far from clear. In this study, 26 flavonoids were characterized by their bitterness threshold and their common skeleton using sensory evaluation and molecular superposition, respectively. The quantitative conformational relationship of the structure-bitterness of flavonoids was explored using 3D-QSAR based on comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA). The results showed that increases of a hydrogen bond donor at A-5 or B-3', a bulky group at A-8, or an electron-withdrawing group at B-4' would enhance the bitterness of flavonoids. The bitterness of some flavonoids was predicted and evaluated, and the results were similar to the bitter intensity of the counterparts from the 3D-QSAR and contour plots, confirming the validation of 3D-QSAR. This study explains the theory of the structure-bitterness relationship of flavonoids, by showing potential information for understanding the bitterness in citrus flavonoids and developing a debittering process.

Effect of flavonoids and CYP3A4 variants on midostaurin metabolism

The objective of this study was to determine the effect of flavonoids on midostaurin disposition considering co-administration and metabolic enzyme gene polymorphism. Enzymatic incubation assays were performed in vitro, while in vivo experiments were conducted in Sprague-Dawley rats. The analytes were determined via UPLC-MS/MS. We found that myricetin was the most potent among the investigated 10 flavonoids in suppressing the metabolism of midostaurin, with an IC₅₀ at a low μM level. After co-administration of midostaurin and myricetin, the plasma concentration of midostaurin's primary metabolite CGP62221 was reduced corresponding to myricetin exposure. Furthermore, CYP3A4 homologous rat protein CYP3A2 was reduced significantly in the co-administration group. Thereafter, the kinetic parameters of 23 recombinant human CYP3A4 variants were determined using midostaurin. The relative intrinsic clearance varied from 269.63% in CYP3A4.29-8.95% in CYP3A4.17. In addition, the inhibitory potency of myricetin was substantially different for CYP3A4.29 and CYP3A4.17 compared with wild type, with IC₅₀ values of 9.85 ± 0.27 μM and 90.99 ± 16.13 μM, respectively. Collectively, our data demonstrated that flavonoids, particularly myricetin, can inhibit the metabolism of midostaurin. Additionally, CYP3A4 genetic polymorphism may contribute to stratification of midostaurin blood exposure.

In Vitro Investigation on the Effect of Dendrobine on the Activity of Cytochrome P450 Enzymes

Dendrobine is the major active ingredient of Dendrobium nobile, Dendrobium chrysotoxum, and Dendrobium fimbriatum, all of which are used in traditional Chinese medicine owing to their antitumor and anti-inflammation activities. Hence, investigation on the interaction of dendrobine with cytochrome P450 enzymes could provide a reference for the clinical application of Dendrobium. The effects of dendrobine on cytochrome P450 enzymes activities were investigated in the presence of 0, 2.5, 5, 10, 25, 50, and 100 µM dendrobine in pooled human liver microsomes. The specific inhibitors were employed as the positive control and the blank groups were set as the negative control. The Lineweaver-Burk plots were plotted to characterize the specific inhibition model and obtain the kinetic parameters. The study reveals that dendrobine significantly inhibited the activity of CYP3A4, 2C19, and 2D6 with IC₅₀ values of 12.72, 10.84, and 15.47 µM, respectively. Moreover, the inhibition of CYP3A4 was found to be noncompetitive (Ki = 6.41 µM) and time dependent (KI = 2.541 µM^-1, Kinact  = 0.0452 min^-1), while the inhibition of CYP2C19 and 2D6 was found to be competitive with the Ki values of 5.22 and 7.78 µM, respectively, and showed no time-dependent trends. The in vitro inhibitory effect of dendrobine implies the potential drug-drug interaction between dendrobine and CYP3A4-, 2C9-, and 2D6-metabolized drugs. Nonetheless, these findings need further in vivo validation.

Comparison of various methods for validity evaluation of QSAR models

BACKGROUND

Quantitative structure-activity relationship (QSAR) modeling is one of the most important computational tools employed in drug discovery and development. The external validation of QSAR models is the main point to check the reliability of developed models for the prediction activity of not yet synthesized compounds. It was performed by different criteria in the literature.

METHODS

In this study, 44 reported QSAR models for biologically active compounds reported in scientific papers were collected. Various statistical parameters of external validation of a QSAR model were calculated, and the results were discussed.

RESULTS

The findings revealed that employing the coefficient of determination (r²) alone could not indicate the validity of a QSAR model. The established criteria for external validation have some advantages and disadvantages which should be considered in QSAR studies.

CONCLUSION

This study showed that these methods alone are not only enough to indicate the validity/invalidity of a QSAR model.

Computer-Aided (In Silico) Modeling of Cytochrome P450-Mediated Food–Drug Interactions (FDI)

Modifications of the activity of Cytochrome 450 (CYP) enzymes by compounds in food might impair medical treatments. These CYP-mediated food–drug interactions (FDI) play a major role in drug clearance in the intestine and liver. Inter-individual variation in both CYP expression and structure is an important determinant of FDI. Traditional targeted approaches have highlighted a limited number of dietary inhibitors and single-nucleotide variations (SNVs), each determining personal CYP activity and inhibition. These approaches are costly in time, money and labor. Here, we review computational tools and databases that are already available and are relevant to predicting CYP-mediated FDIs. Computer-aided approaches such as protein–ligand interaction modeling and the virtual screening of big data narrow down hundreds of thousands of items in databanks to a few putative targets, to which the research resources could be further directed. Structure-based methods are used to explore the structural nature of the interaction between compounds and CYP enzymes. However, while collections of chemical, biochemical and genetic data are available today and call for the implementation of big-data approaches, ligand-based machine-learning approaches for virtual screening are still scarcely used for FDI studies. This review of CYP-mediated FDIs promises to attract scientists and the general public.

Endoplasmic Reticulum-Targeting Near-Infrared Fluorescent Probe for CYP2J2 Activity and Its Imaging Application in Endoplasmic Reticulum Stress and Tumor

CYP2J2 as an endoplasmic reticulum (ER)-expressed vital cytochrome P450 isoform participates in the metabolism of endogenous polyunsaturated fatty acids. Its abnormal expression and function are closely related to the progress of cancer and cardiovascular diseases. Herein, an ER-targeting near-infrared (NIR) fluorescent probe ER-BnXPI was developed for monitoring CYP2J2 activity, which possessed a high selectivity and sensitivity toward CYP2J2 among various CYP450 isoforms and exhibited excellent subcellular localization for ER. Then, the CYP2J2 variation behavior under the ER stress model was imaged by ER-BnXPI in living cells and successfully used for the in vivo imaging in different tumors that well distinguished tumor tissues from para-cancerous tissues. All these findings fully demonstrated that ER-BnXPI could be used as a promising tool for exploring the physiological function of CYP2J2 and provided some novel approach for the diagnosis and therapy of CYP2J2-related vascular inflammation and cancer.

Metabolic Behaviors of Aconitum Alkaloids in Different Concentrations of Aconiti Lateralis Radix Praeparata and Effects of Aconitine in Healthy Human and Long QT Syndrome Cardiomyocytes

Aconiti Lateralis Radix Praeparata (Fu Zi) is the processed lateral root of Aconitum carmichaelii Debx, which is widely used in emergency clinics. Poisoning incidents and adverse reactions occur with the improper intake of Fu Zi. Metabolic characteristics of aconitum alkaloids of Fu Zi may vary, and the effects of Fu Zi in healthy and Long QT syndrome (LQTS) patients is unknown. In this experiment, 24 Sprague Dawley rats were randomly divided into three groups: 2.0, 1.0, and 0.5 g/kg dose groups, and blood samples were collected after the oral administration of Fu Zi extract. We used an ultra-high performance liquid chromatography-tandem mass spectrometry system to detect the concentrations of six aconitum alkaloids. Cell toxicity, calcium imaging, and patch-clamp recordings of human induced pluripotent stem cells-cardiomyocytes (hiPSC-CMs) of aconitine in healthy and LQTS were observed. We found that the AUC(0–48h), Cmax, and t1/2 of the six compounds increased with the multiplicative dosages; those in the high group were significantly higher than those in the low group. Aconitine concentration-dependently decreased the amplitude, which has no significant effect on the cell index of normal hiPSC-CMs. Aconitine at 5.0 μM decreased the cell index between 5–30 min for LQTS hiPSC-CMs. Meanwhile, aconitine significantly increased the frequency of calcium transients in LQTS at 5 μM. Aconitine significantly shortened the action potential duration of human cardiomyocytes in both normal and LQTS groups. These results show metabolic behaviors of aconitum alkaloids in different concentrations of Fu Zi and effects of aconitine in healthy and LQTS patients.

Assessment of the CYP1A2 Inhibition-Mediated Drug Interaction Potential for Pinocembrin Using In Silico, In Vitro, and In Vivo Approaches

Pinocembrin, a bioflavonoid, is extensively used in complementary/alternative medicine. It turns out as a promising candidate against neurodegenerative diseases because of its multifaceted pharmacological action toward neuroprotection. However, literature evidence is still lacking for its inhibitory action on CYP1A2, which is responsible for xenobiotic metabolism leading to the generation of toxic metabolites and bioactivation of procarcinogens. In the present study, our aim was to evaluate the CYP1A2 inhibitory potential of pinocembrin via in silico, in vitro, and in vivo investigations. From the results of in vitro studies, pinocembrin is found to be a potent and competitive inhibitor of CYP1A2. In vitro-in vivo extrapolation results indicate the potential of pinocembrin to interact with CYP1A2 substrate drugs clinically. Molecular docking-based in silico studies demonstrate the strong interaction of pinocembrin with human CYP1A2. In in vivo investigations using a rat model, pinocembrin displayed a marked alteration in the plasma exposure of CYP1A2 substrate drugs, namely, caffeine and tacrine. In conclusion, pinocembrin has a potent CYP1A2 inhibitory action to cause drug interactions, and further confirmatory study is warranted at the clinical level.

Interaction study of engeletin toward cytochrome P450 3A4 and 2D6 by multi-spectroscopy and molecular docking

The inhibitory effects of engeletin on the activities of human cytochrome P450 3A4 and 2D6 (CYP3A4 and CYP2D6) were investigated by enzyme kinetics, multi-spectroscopy and molecular docking. Engeletin was found to strongly inhibit CYP3A4 and CYP2D6, with the IC₅₀ of 1.32 μM and 2.87 μM, respectively. The inhibition modes of engeletin against CYP3A4 and CYP2D6 were a competitive type and a mixed type, respectively. The fluorescence of the two CYPs was quenched statically by engeletin, which was bound to CYP3A4 stronger than to CYP2D6 at the same temperature. Circular dichroism spectroscopy, three-dimensional fluorescence, ultraviolet-visible spectroscopy and synchronous fluorescence confirmed that the conformation and micro-environment of the two CYPs protein were changed after binding with engeletin. Molecular docking, ultraviolet-visible spectroscopy and the fluorescence data revealed that engeletin had strong binding affinity to the two CYPs through hydrogen and van der Waals forces. The findings here suggested that engeletin may cause the herb-drug interactions for its inhibition of CYP3A4 and CYP2D6 activities.

Targeting multidrug resistance-associated protein 1 (MRP1)-expressing cancers: Beyond pharmacological inhibition

Resistance to chemotherapy remains one of the most significant obstacles to successful cancer treatment. While inhibiting drug efflux mediated by ATP-binding cassette (ABC) transporters is a seemingly attractive and logical approach to combat multidrug resistance (MDR), small molecule inhibition of ABC transporters has so far failed to confer clinical benefit, despite considerable efforts by medicinal chemists, biologists, and clinicians. The long-sought treatment to eradicate cancers displaying ABC transporter overexpression may therefore lie within alternative targeting strategies. When aberrantly expressed, the ABC transporter multidrug resistance-associated protein 1 (MRP1, ABCC1) confers MDR, but can also shift cellular redox balance, leaving the cell vulnerable to select agents. Here, we explore the physiological roles of MRP1, the rational for targeting this transporter in cancer, the development of small molecule MRP1 inhibitors, and the most recent developments in alternative therapeutic approaches for targeting cancers with MRP1 overexpression. We discuss approaches that extend beyond simple MRP1 inhibition by exploiting the collateral sensitivity to glutathione depletion and ferroptosis, the rationale for targeting the shared transcriptional regulators of both MRP1 and glutathione biosynthesis, advances in gene silencing, and new molecules that modulate transporter activity to the detriment of the cancer cell. These strategies illustrate promising new approaches to address multidrug resistant disease that extend beyond the simple reversal of MDR and offer exciting routes for further research.

Herb-drug interactions and toxicity: Underscoring potential mechanisms and forecasting clinically relevant interactions induced by common phytoconstituents via data mining and computational approaches

Herbals in the form of medicine are employed extensively around the world. Herbal and conventional medicine combination is a potentially dangerous practice mainly in comorbid, hepato insufficient and frail patients leading to perilous herb-drug interactions (HDI) and toxicity. This study features potential HDI of 15 globally famous plant species through data mining and computational methods. Several plant species were found to mimic warfarin. Phytochemicals from M. charantia induced hypoglycemica. M. chamomila and G. biloba possessed anticoagulant activities. S. hispanica reduces postprandial glycemia. R. officinalis has been reported to inhibit the efflux of anticancer substrates while A. sativum can boost the clearance of anticancer agents. P. ginseng can alter blood coagulation. A cross link of the biological and in silico data revealed that a plethora of herbal metabolites such as ursolic and rosmarinic acid among others are possible/probable inhibitors of specific CYP450 enzymes. Consequently, plant species/metabolites with a given pharmacological property/metabolizing enzyme should not be mixed with drugs having the same pharmacological property/metabolizing enzyme. Even if combined with drugs, herbal medicines must be used at low doses for a short period of time and under the supervision of a healthcare professional to avoid potential adverse and toxic effects.

The development of novel cytochrome P450 2J2 (CYP2J2) inhibitor and the underlying interaction between inhibitor and CYP2J2

Human Cytochrome P450 2J2 (CYP2J2) as an important metabolic enzyme, plays a crucial role in metabolism of polyunsaturated fatty acids (PUFAs). Elevated levels of CYP2J2 have been associated with various types of cancer, and therefore it serves as a potential drug target. Herein, using a high-throughput screening approach based on enzymic activity of CYP2J2, we rapidly and effectively identified a novel natural inhibitor (Piperine, 9a) with IC₅₀ value of 0.44 μM from 108 common herbal medicines. Next, a series of its derivatives were designed and synthesised based on the underlying interactions of Piperine with CYP2J2. As expected, the much stronger inhibitors 9k and 9l were developed and their inhibition activities increased about 10 folds than Piperine with the IC₅₀ values of 40 and 50 nM, respectively. Additionally, the inhibition kinetics illustrated the competitive inhibition types of 9k and 9l towards CYP2J2, and K_i were calculated to be 0.11 and 0.074 μM, respectively. Furthermore, the detailed interaction mechanism towards CYP2J2 was explicated by docking and molecular dynamics, and our results revealed the residue Thr114 and Thr 315 of CYP2J2 were the critical sites of action, moreover the spatial distance between the carbon atom of ligand methylene and Fe atom of iron porphyrin coenzyme was the vital interaction factor towards human CYP2J2.

Designer benzodiazepines versus prescription benzodiazepines: can structural relation predict the next step?

Designer benzodiazepines are a part of the recently discovered abuse synthetic drugs called Novel Psychoactive Substances (NPS) which need to be controlled due to their constantly growing market. Most of them are derived from the medically approved benzodiazepines used nowadays yet, may possess stronger effects, more toxicity, and longer durations of action. Some differences have also been observed in their detection and characteristics, in addition to the variations discovered in postmortem redistribution and drug stability. All these major alterations in features can result from only minor structural modifications. For example, a classic benzodiazepine (BZD) like diazepam only lacks one fluorine atom which exists in its derivatized designer drug, diclazepam, making substantial differences in activity. For this reason, it is essential to study the designer drugs in order to identify their dangers and distinguish them thus rule out their abuse and control the spread of such drugs. This review would highlight the distinct characteristics of some of the most commonly abused designer benzodiazepine analogies in relation to their original prescription BZD compounds.

Pharmacokinetics and Pharmacodynamic Herb-Drug Interaction of Piperine with Atorvastatin in Rats

Herbals that are widely consumed as therapeutic alternatives to conventional drugs for cardiovascular diseases, may lead to herb-drug interactions (HDIs). Atorvastatin (ATR) is drug of choice for hyperlipidemia and is extensively metabolized through CYP3A4 enzyme. Thus, we postulate that concomitant administration of ATR with piperine (PIP, potent inhibitor of CYP3A4 enzyme)/ridayarishta (RID, cardiotonic herbal formulations containing PIP) may lead to potential HDI. A simple, accurate, sensitive high-performance liquid chromatography-photodiode array detection method using Kromasil-100 C18 column, mobile phase acetonitrile: 30 mM phosphate buffer (55:45 v/v) pH 4.5 with flow rate gradient programming was developed to study the potential HDI in rats. Method was found to be linear (2-100 ng/mL) with Lower Limit of Detection (LLOD) 2 ng/mL. The precision (%CV < 15%), accuracy (-1.0 to -10% R.E) with recoveries above 90% from rat plasma of ATR and IS were obtained. The pharmacokinetic (PK) interactions studies on co-administration of ATR (8.4 mg/kg, p.o.) with PIP (35 mg/kg, p.o.), demonstrated a threefold increase in Cmax of ATR (P < 0.01) with significant increase in AUC0-t/AUC0-∞ compared to ATR alone indicating potential PK-HDI. However co-administration of RID (4.2 mL/kg, p.o.) showed less significant changes (P > 0.05) indicating low HDI. The pharmacodynamic effects/interactions study (TritonX-100 induced hyperlipidemic model in rats) suggested no significant alterations in the lipid profile on co-administration of PIP/RID with ATR, indicating that there may be no significant pharmacodynamic interactions.

Effects of naringenin on the pharmacokinetics of tofacitinib in rats

Context: Naringenin and tofacitinib are often used together for treatment of rheumatoid arthritis in Chinese clinics.Objective: This experiment investigates the effect of naringenin on the pharmacokinetics of tofacitinib in rats.Materials and methods: Twelve Sprague-Dawley rats were randomly divided into two groups (experimental group and control group). The experimental group was pre-treated with naringenin (150 mg/kg/day) for two weeks before dosing tofacitinib, and equal amounts of CMC-Na solution in the control group. After a single oral administration of 5 mg/kg of tofacitinib, 50 μL blood samples were directly collected into 1.5 mL heparinized tubes via the caudal vein at 0.083, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 and 24 h. The plasma concentration of tofacitinib was quantified by UPLC/MS-MS.Results: Results indicated that naringenin could significantly affect the pharmacokinetics of tofacitinib. The AUC_0-24 of tofacitinib was increased from 1222.81 ± 222.07 to 2016.27 ± 481.62 ng/mL/h, and the difference was significant (p < 0.05). Compared with the control group, the T_max was increased from 0.75 ± 0.29 to 3.00 ± 0.00 h (p < 0.05), and the MRT_(0-24) was increased from 4.90 ± 0.51 to 6.57 ± 0.66 h (p < 0.05), but the clearance was obviously decreased from 4.10 ± 0.72 to 2.42 ± 0.70 L/h/kg (p < 0.05) in experimental group. Although the C_max and t_1/2 of tofacitinib were increased, there were no significant differences (p > 0.05).Conclusions: This research demonstrated a drug-drug interaction between naringenin and tofacitinib possibly when preadministered with naringenin; thus, we should pay attention to this possibility in the clinic.

Inhibitory effects of astilbin, neoastilbin and isoastilbin on human cytochrome CYP3A4 and 2D6 activities

Astilbin, neoastilbin and isoastilbin are three flavonoid isomers from Smilacis glabrae Roxb. (S. glabrae). Several studies have shown that consumption of flavonoids can increase the risk of food/drug-drug interaction by affecting the activities of human cytochrome CYP3A4 and 2D6. In the present study, an ultrahigh-performance liquid chromatography and triple quadrupole mass spectrometry method was developed for the determination of the interaction between three flavonoid isomers and two CYPs. Under the optimized reaction conditions, the K_m values were 18.9 and 36.4 μM and the V_max values were 0.02 and 0.20 μM/min for CYP3A4 and 2D6 in vitro, respectively. Astilbin showed the strongest inhibition on CYP3A4, followed by isoastilbin and neoastilbin with IC₅₀ values of 2.63, 3.03 and 6.51 μM. Neoastilbin showed the strongest inhibition on CYP2D6, followed by isoastilbin and astilbin, with IC₅₀ values of 1.48, 11.87 and 14.16 μM, respectively. The three isomers showed reversible inhibition on both enzymes. Neoastilbin and astilbin were noncompetitive type for CYP3A4 and 2D6, isoastilbin was a mixture and noncompetitive type for CYP3A4 and 2D6, respectively. Our study suggests that the three isomers may increase the risk of food/drug-drug interactions by affecting the activities of CYP3A4 and 2D6.

A Review: The Anti-inflammatory, Anticancer and Antibacterial Properties of Four Kinds of Licorice Flavonoids Isolated from Licorice

Plants have always been an important source of medicines for humans, and licorice is a very significant herb in the development of humans. As a traditional herb, it is widely cultivated in China, Japan, Russia, Spain and India. With the development of organic chemistry and biochemistry, various chemical ingredients extracted from licorice have been studied and identified. Among them, many chemical components were considered to have strong pharmacological activities, such as anti-inflammatory, anti-ulcer, antibacterial, anticancer and so on. Based on those reports, licorice has attracted the attention of many researchers in recent years, and they are devoted to discovering the active ingredients and mechanism of action of active compounds. Licorice flavonoids are one of the main extracts of licorice root and stem and have many potential biological properties. This paper aims to summarize the four kinds of licorice flavonoids, including liquiritigenin, isoliquiritigenin, licochalcone (including licochalcone A and licochalcone B) and glabridin, about their biological activities of anti-inflammatory, anticancer, antibacterial.

Lack of Correlation between In Vitro and In Vivo Studies on the Inhibitory Effects of (‒)-Sophoranone on CYP2C9 is Attributable to Low Oral Absorption and Extensive Plasma Protein Binding of (‒)-Sophoranone

(‒)-Sophoranone (SPN) is a bioactive component of Sophora tonkinensis with various pharmacological activities. This study aims to evaluate its in vitro and in vivo inhibitory potential against the nine major CYP enzymes. Of the nine tested CYPs, it exerted the strongest inhibitory effect on CYP2C9-mediated tolbutamide 4-hydroxylation with the lowest IC₅₀ (K_i) value of 0.966 ± 0.149 μM (0.503 ± 0.0383 μM), in a competitive manner. Additionally, it strongly inhibited other CYP2C9-catalyzed diclofenac 4′-hydroxylation and losartan oxidation activities. Upon 30 min pre-incubation of human liver microsomes with SPN in the presence of NADPH, no obvious shift in IC₅₀ was observed, suggesting that SPN is not a time-dependent inactivator of the nine CYPs. However, oral co-administration of SPN had no significant effect on the pharmacokinetics of diclofenac and 4′-hydroxydiclofenac in rats. Overall, SPN is a potent inhibitor of CYP2C9 in vitro but not in vivo. The very low permeability of SPN in Caco-2 cells (P_app value of 0.115 × 10⁻⁶ cm/s), which suggests poor absorption in vivo, and its high degree of plasma protein binding (>99.9%) may lead to the lack of in vitro–in vivo correlation. These findings will be helpful for the safe and effective clinical use of SPN.

Dietary Flavonoids Interaction with CREB-BDNF Pathway: An Unconventional Approach for Comprehensive Management of Epilepsy

cAMP response element binding protein (CREB) is a key transcriptional regulator that regulates the transcription of genes related with neuronal differentiation, synaptic plasticity, learning and memory. Brain derived neurotrophic factor (BDNF), is a CREB dependent gene which plays a pivotal role in the pathogenesis of epilepsy and central comorbid conditions associated with epilepsy. However, the beneficial or detrimental consequences of CREB-BDNF activation on the induction and/or progression of seizures depend specifically on the region of brain involved and the time of activation. The bioactive molecules that alter the activity of CREB in a way to have specialized effects in different brain regions and neural circuits involved could potentially be utilized for therapeutic purposes. Flavonoids are the polyphenolic compounds which lead to phosphorylation of CREB in the hippocampus, followed by increase in extracellular signal regulated kinase (ERK) and BDNF. Several members of flavonoid family have also showed suppression of epileptic seizures via interaction with CREB/BDNF pathway. Moreover, epilepsy is often accompanied by a number of behavioural and psychological comorbid conditions that further gets aggravated by the use of conventional antiepileptic drug therapy. Multiple studies have also supported the beneficial effects of flavonoids in cognitive and memory impairments by upregulation of CREB-BDNF pathway. The current review is an attempt to collate the available preclinical and clinical studies to establish the therapeutic potential of various dietary flavonoids in comprehensive management of epilepsy with relation to CREB-BDNF pathway.

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.

A Single Dose of Baicalin Has No Clinically Significant Effect on the Pharmacokinetics of Cyclosporine A in Healthy Chinese Volunteers

Despite its narrow therapeutic window and large interindividual variability, cyclosporine A (CsA) is the first-line therapy following organ transplantation. Metabolized mainly by CYP3A and being a substrate of P-glycoprotein (P-gp), CsA is susceptible to drug–drug interactions. Baicalin (BG) is a drug used for adjuvant therapy of hepatitis in traditional Chinese medicine. Since its aglycone baicalein (B) inhibits CYP3A and P-gP, co-administration might affect CsA pharmacokinetics. This study investigated the effect of BG on CsA pharmacokinetics. In a two-period study, 16 healthy volunteers received a single 200 mg oral CsA dose alone (reference period) or in combination with 500 mg BG (test period). Pharmacokinetic evaluation of CsA was carried out using non-compartmental analysis (NCA) and population pharmacokinetics (popPK). Treatments were compared using the standard bioequivalence method. Based on NCA, 90% CIs of AUC and C_max test-to-reference ratios were within bioequivalence boundaries. In the popPK analysis, a two-compartment model (clearance/F 62.8 L/h, central and peripheral volume of distribution/F 254 L and 388 L) with transit compartments for absorption appropriately described CsA concentrations. No clinically relevant effect of 500 mg BG co-administration on CsA pharmacokinetics was identified and both treatments were well tolerated.

Machine learning prediction of nanoparticle in vitro toxicity: A comparative study of classifiers and ensemble-classifiers using the Copeland Index

Nano-Particles (NPs) are well established as important components across a broad range of products from cosmetics to electronics. Their utilization is increasing with their significant economic and societal potential yet to be fully realized. Inroads have been made in our understanding of the risks posed to human health and the environment by NPs but this area will require continuous research and monitoring. In recent years Machine Learning (ML) techniques have exploited large datasets and computation power to create breakthroughs in diverse fields from facial recognition to genomics. More recently, ML techniques have been applied to nanotoxicology with very encouraging results. In this study, categories of ML classifiers (rules, trees, lazy, functions and bayes) were compared using datasets from the Safe and Sustainable Nanotechnology (S2NANO) database to investigate their performance in predicting NPs in vitro toxicity. Physicochemical properties, toxicological and quantum-mechanical attributes and in vitro experimental conditions were used as input variables to predict the toxicity of NPs based on cell viability. Voting, an ensemble meta-classifier, was used to combine base models to optimize the classification prediction of toxicity. To facilitate inter-comparison, a Copeland Index was applied that ranks the classifiers according to their performance and suggested the optimal classifier. Neural Network (NN) and Random forest (RF) showed the best performance in the majority of the datasets used in this study. However, the combination of classifiers demonstrated an improved prediction resulting meta-classifier to have higher indices. This proposed Copeland Index can now be used by researchers to identify and clearly prioritize classifiers in order to achieve more accurate classification predictions for NP toxicity for a given dataset.

Tenacigenin B ester derivatives from Marsdenia tenacissima actively inhibited CYP3A4 and enhanced in vivo antitumor activity of paclitaxel

ETHNOPHARMACOLOGICAL RELEVANCE

Marsdenia tenacissima (Roxb.) Wight et Arn is a vine distributed in southwest area of China and used in folk medicine for treatment of tumors. Recent decades of studies on this plant reveal its synergistic effects with certain anticancer drugs in cancer therapy. In our previous study, an extract ETA which contains total aglycones made from M. tenacissima significantly enhanced antitumor activity of paclitaxel in tumor-bearing mice. However, the effective constituents in ETA and the underlying mechanisms remain unclear.

AIM OF THE STUDY

Reveal the active components in ETA as well as the molecular mechanism in enhancing antitumor efficacy of paclitaxel.

MATERIAL AND METHODS

Main constituents in ETA were purified by chemical methods. Effects of the purified constituents on metabolic activity of CYP450 enzymes were evaluated in human liver microsomes. Ability of the constituents to enhance antitumor activity of paclitaxel were investigated in nude mice bearing HeLa tumors. Pharmacokinetic study was performed in SD rats. Molecular docking was carried out for investigation of drug-protein interactions.

RESULTS

Three main C₂₁ steroidal aglycones, 11α-O-tigloyl-12β-O-acetyl-tenacigenin B (MT1), 11α-O-2-methylbutanoyl-12β-O-tigloyl-tenacigenin B (MT2) and 11α-O-2-methylbutanoyl-12β-O-acetyl-tenacigenin B (MT3), together with tenacigenin B (MT4) was prepared from ETA. Among them, MT1, MT2 and MT3 strongly inhibit the metabolic activity of CYP3A4. MT2 also showed inhibitory effects on CYP2C8, CYP2B6 and CYP2C19. In HeLa tumor xenografts, MT1, MT2 and MT3 (30 mg/kg) did not affect tumor growth themselves, but significantly enhanced paclitaxel-induced growth inhibition. In addition, coadministration of MT2 with paclitaxel resulted in significant reduction of liver CYP2C8. In pharmacokinetic study, MT2 significantly increased the blood concentration of paclitaxel with increased AUC value by 2.2-5.3 folds. Molecular docking analysis suggested hydrophobic interaction modes of tenacigenin B derivatives with CYP3A4, and also the essential roles of the C-11 and C-12 ester groups for effective interaction with CYP3A4.

CONCLUSION

Our study proves that, 11α-O-tigloyl-12β-O-acetyl-tenacigenin B, 11α-O-2-methylbutanoyl-12β-O-tigloyl-tenacigenin B and 11α-O-2-methylbutanoyl-12β-O-acetyl-tenacigenin B, which are the main constituents of ETA, are active inhibitors of CYP3A4 with potential to increase therapeutic efficacy of anticancer drugs that are substrates of CYP3A4. Tenacigenin B derivatives with C-11 and C-12 ester group substitutions, or at least a large part of them, are active components in ETA and M. tenacissima to enhance in vivo antitumor efficacies of paclitaxel.

Flavonoids as human carboxylesterase 2 inhibitors: Inhibition potentials and molecular docking simulations

In our search for natural human carboxylesterase 2 (hCE 2) inhibitors from natural products, we investigated inhibitory effects and mechanisms of flavonoids (1-16) against hCE 2. The results demonstrated that kurarinone (1), baicalein (2), 2-[(2'-(1-hydroxy-1-methylethyl)-7'-(3-methyl-2-butenyl)-2',3'-dihydrobenzofuran)-5-yl]-7-hydroxy-8-(3-methyl-2-butenyl)chroman-4-one (5), luteolin (6), kushenol X (9), and kushenol C (11) displayed significantly inhibitory effects against hCE 2 with IC₅₀ values of 1.46 ± 0.43, 5.22 ± 0.89, 1.13 ± 0.19, 9.78 ± 0.98, 3.05 ± 0.46, and 2.61 ± 0.52 μM, respectively. Compounds 1, 5, 6, 9, and 11 were all uncompetitive inhibitors with Ki values of 1.73, 1.59, 16.89, 1.72, and 0.79 μM, respectively, and their Km values ranged from 2.08 μM to 5.41 μM. Furthermore, molecular docking was conducted for investigating mechanisms of compounds 1, 5, 6, 9, and 11 with hCE 2. These results suggested that compounds 1, 5, 6, 9, and 11 could be served as lead compounds for the development of novel hCE 2 inhibitors.

Simultaneous Evaluation of the Influence of Panax ginseng on the Pharmacokinetics of Three Diester Alkaloids after Oral Administration of Aconiti Lateralis Radix in Rats Using UHPLC/QQQ-MS/MS

Objectives

To investigate whether Panax ginseng (P. ginseng) could affect the metabolism of Diester Alkaloids (DAs) derived from Aconiti Lateralis Radix in vivo.

Methods and Results

24 male Sprague-Dawley rats were randomized for 7-day treatment with P. ginseng (low, middle, and high), or vehicle. Aconiti Lateralis Radix was administered orally to each group on the 8th day. Plasma samples were collected, and Xevo TQ-S was used to detect the concentration of aconitine, mesaconitine, and hypaconitine in plasma. We describe a fast and reproducible method to detect the concentration of aconitine, mesaconitine, and hypaconitine in plasma. Compared to the control group, the AUC_(0-t) of three DAs increased in both the middle and high dosing groups. The Vz/F of three DAs in these groups as well as the CLz/F of aconitine in all P. ginseng groups and the CLz/F of mesaconitine and hypaconitine in P. ginseng middle and high groups were decreased compared to the control group.

Conclusion

Orally administrated P. ginseng potentially inhibits the metabolism of DAs from Aconiti Lateralis Radix in rats.

The Inhibitory Effect of Flavonoid Aglycones on the Metabolic Activity of CYP3A4 Enzyme

Flavonoids are natural compounds that have been extensively studied due to their positive effects on human health. There are over 4000 flavonoids found in higher plants and their beneficial effects have been shown in vitro as well as in vivo. However, data on their pharmacokinetics and influence on metabolic enzymes is scarce. The aim of this study was to focus on possible interactions between the 30 most commonly encountered flavonoid aglycones on the metabolic activity of CYP3A4 enzyme. 6β-hydroxylation of testosterone was used as marker reaction of CYP3A4 activity. Generated product was determined by HPLC coupled with diode array detector. Metabolism and time dependence, as well as direct inhibition, were tested to determine if inhibition was reversible and/or irreversible. Out of the 30 flavonoids tested, 7 significantly inhibited CYP3A4, most prominent being acacetin that inhibited 95% of enzyme activity at 1 µM concentration. Apigenin showed reversible inhibition, acacetin, and chrysin showed combined irreversible and reversible inhibition while chrysin dimethylether, isorhamnetin, pinocembrin, and tangeretin showed pure irreversible inhibition. These results alert on possible flavonoid–drug interactions on the level of CYP3A4.