In vitro metabolism of l-corydalmine, a potent analgesic drug, in human, cynomolgus monkey, beagle dog, rat and mouse liver microsomes

Metabolic characteristics of evodiamine were associated with its hepatotoxicity via PPAR/PI3K/AKT/NF-кB/tight junction pathway-mediated apoptosis in zebrafish

Evodiae Fructus (EF), an herbal medicine, possesses remarkable anti-inflammatory and analgesic properties. It exhibits insecticidal activity as a potent insecticide candidate. However, the toxic characteristics of EF and the underlying mechanisms have not been comprehensively elucidated comprehensively. Thus, we comprehensively explored the toxic components of EF and established the relationship between the therapeutic and toxic effects of EF, encouraging its therapeutic use. We found that evodiamine (EVO), one of the main ingredients of EF, can truly reflect its analgesic properties. In phenotype observation trials, low doses of EVO (< 35 ng/mL) exhibited distinct analgesic activity without any adverse effects in zebrafish. However, EVO dose-dependently led to gross morphological abnormalities in the liver, followed by pericardial edema, and increased myocardial concentrations. Furthermore, the toxic effects of EVO decreased after processing in liver microsomes but increased after administering CYP450 inhibitors in zebrafish, highlighting the prominent effect of CYP450s in EVO-mediated hepatotoxicity. EVO significantly changed the expression of genes enriched in multiple pathways and biological processes, including lipid metabolism, inflammatory response, tight junction damage, and cell apoptosis. Importantly, the PPAR/PI3K/AKT/NF-кB/tight junction-mediated apoptosis pathway was confirmed as a critical functional signaling pathway inducing EVO-mediated hepatotoxicity. This study provided a typical example of the overall systematic evaluation of traditional Chinese medicine (TCM) and its active ingredients with significant therapeutic effects and simultaneous toxicities, especially metabolic toxicities.

A critical review: traditional uses, phytochemistry, pharmacology and toxicology of Stephania tetrandra S. Moore (Fen Fang Ji)

ABSTRACT

Stephania tetrandra S. Moore (S. tetrandra) is distributed widely in tropical and subtropical regions of Asia and Africa. The root of this plant is known in Chinese as "Fen Fang Ji". It is commonly used in traditional Chinese medicine to treat arthralgia caused by rheumatism, wet beriberi, dysuria, eczema and inflamed sores. Although promising reports have been published on the various chemical constituents and activities of S. tetrandra, no review comprehensively summarizes its traditional uses, phytochemistry, pharmacology and toxicology. Therefore, the review aims to provide a critical and comprehensive evaluation of the traditional use, phytochemistry, pharmacological properties, pharmacokinetics and toxicology of S. tetrandra in China, and meaningful guidelines for future investigations.

Regio- and enantioselective O-demethylation of tetrahydroprotoberberines by cytochrome P450 enzyme system from Streptomyces griseus ATCC 13273

Tetrahydroprotoberberines (THPBs), a class of naturally occurring isoquinoline alkaloids, contain substituent methoxyl or hydroxyl groups which play a significant role in the pharmacological properties of these molecules. In this study, we report a biocatalytic strategy for selective O-demethylation of THPBs. CYP105D1, a cytochrome P450 from Streptomyces griseus ATCC 13273, exhibited markedly regioselective demethylation of nonhydroxyl-THPBs and monohydroxyl-THPBs on the D-ring. A possible binding mode of THPBs with CYP105D1 was investigated by docking analysis, and the results revealed that the D-rings of THPBs were with the minimum distance to the heme iron. Tetrahydropalmatine was used as a model substrate and enantioselective demethylation was demonstrated. (S)-Tetrahydropalmatine was only demethylated at C-10, while (R)-tetrahydropalmatine was first demethylated at C-10 and then subsequently demethylated at C-9. The kcat/Km value for demethylation of (R)-tetrahydropalmatine by CYP105D1 was 3.7 times greater than that for demethylation of (S)-tetrahydropalmatine. Furthermore, selective demethylation of (S)-tetrahydropalmatine by the CYP105D1-based whole-cell system was demonstrated for the highly efficient production of (S)-corydalmine which has distinct pharmacological applications, such as providing relief from bone cancer pain and reducing morphine tolerance. Moreover, a homologous redox partner was identified to enhance the catalytic efficiency of the CYP105D1-based whole-cell system. This is the first enzymatic characterization of a cytochrome P450 that has regio- and enantioselective demethylation activity of THPBs for application purpose. The cytochrome P450 system could be a promising strategy for selective demethylation in the pharmaceutical industry.

Studies on the metabolism and degradation of vancomycin in simulated in vitro and aquatic environment by UHPLC-Triple-TOF-MS/MS

Vancomycin is one of the most commonly used glycopeptide antiobiotics, and as such is an important emerging environmental contaminant. Pharmaceuticals and personal care products (PPCPs), such as antibiotics, are problematic since wastewater treatment processes are not completely effective at removing these chemical compounds. Since wastewater treatment processes are not completely effective, vancomycin occurs in surface water. Vancomycin and its metabolites in vivo and degradation products in aquatic environment may lead to undesirable ecological effects that threaten the environment or cause undesirable reactions that affect human health. We aimed to study vancomycin metabolism in vitro and its natural degradation in aquatic environment, as well as explore for related metabolites and degradation products. Accordingly, we established four systems, using a constant temperature oscillator at 37 °C for 10 days for vancomycin in activated rat liver microsomes (experimental system), inactivated rat liver microsomes (control system), phosphate buffer saline (PBS system) and pure water (pure water system), as well as an additional system of activated rat liver microsomes without vancomycin (blank system). The metabolism and degradation of vancomycin were studied using a high resolution and high sensitivity ultra-high performance liquid chromatography (UHPLC)-Triple-time of flight (TOF)-mass spectrometry (MS) method in positive ion mode. The compared result of activated rat liver microsomes system and inactivated rat liver microsomes system confirms that vancomycin is not metabolized in the liver. Vancomycin was degraded in the four non-blank incubation systems. The MetabolitePilot 2.0 software was used for screening the probable degradation products, as well as for establishing its associated degradation pathways. Eventually, four degradation products were identified and their chemical structures were deduced. The results of this study provide a foundation for evaluation of the effects of vancomycin and its degradation products on environmental safety and human health in the future.

Predicted contributions of cytochrome P450s to drug metabolism in human liver microsomes using relative activity factor were dependent on probes

Contributions of cytochrome P450 (CYP450) isoforms to drug metabolism are often predicted using relative activity factor (RAF) method, assuming RAF values were independent of probe. We aimed to report probe-dependent characteristic of RAF values using CYP3A4 or CYP2C9 probes. Metabolism of four CYP3A4 probes (testosterone, midazolam, verapamil and atorvastatin) and three CYP2C9 probes (tolbutamide, diclofenac and S-warfarin) in human liver microsomes (HLM) and cDNA-expressed recombinant CYP450 (Rec-CYP450) systems were characterized and RAF_CL value was estimated as ratio of probe intrinsic clearance in HLM to that in Rec-CYP450. CYP450i contributions to metabolic reaction of a probe were predicted using other probes and compared with data from specific inhibitions. Contributions of CYP3A4 and CYP2C9 to metabolism of deoxypodophyllotoxin and nateglinide were also predicted. RAF values were dependent on probes, leading to probe-dependently predicted contributions. Predicted contributions of CYP3A4 to formations of 6β-hydroxytestosterone, 1'-hydroxymidazolam, norverapamil, ortho-hydroxyatorvastatin and para-hydroxyatorvastatin using other probes were 47.46-219.46%, 21.62-98.87%, 186.49-462.44%, 21.87-101.15% and 53.62-247.97%, respectively. Predicted contributions of CYP3A4 and CYP2C9 to nateglinide metabolism were 8.18-37.84% and 36.08-94.04%, separately. In conclusion, CYP450i contribution to drug metabolism in HLM estimated using RAF approach were probe-dependent. Therefore, contribution of each isoform must be confirmed by multiple probes.

Stereoselective in vitro metabolism of rhynchophylline and isorhynchophylline epimers of Uncaria rhynchophylla in rat liver microsomes

1. The objective was to investigate the underlying mechanism of the stereoselectivity in the metabolism of rhynchophylline (RIN) and isorhynchophylline (IRN) epimers in rat liver microsomes (RLM). 2. After incubation, eight metabolites of RIN (M1-5) and IRN (M6-8) reacted at A- and C-ring were identified using LC-Q-TOF/MS. Metabolic pathways included oxidation, hydroxylation, N-oxidation and dehydrogenation. In addition, hydroxylation at A-ring was the major metabolic pathway for RIN whereas the oxidation at C-ring was the major one for IRN. 3. Enzyme kinetics showed that the intrinsic clearance (CL_int) for IRN elimination was 1.9-fold higher than RIN and the degradation half-life (T_1/2) of RIN was 4.7-fold higher than that of IRN, indicating IRN was more favorable to be metabolized than RIN in RLM. 4. Data from chemical inhibition study demonstrated CYP3A was the predominant isoform involved in the metabolic elimination of both epimers, as well as the formation of M1-8. 5. In conclusion, data revealed that due to the spatial configurations at C-7 position, RIN and IRN epimers possessed different hepatic metabolic pathways and elimination rates which were mainly mediated by CYP3A.

Metabolic profiling of five flavonoids from Dragon's Blood in human liver microsomes using high-performance liquid chromatography coupled with high resolution mass spectrometry

Although much is known about the pharmacological activities of Dragon's Blood (DB, a traditional Chinese herb), its metabolism in human liver microsomes (HLMs) and the cytochrome P450 (CYP) enzymes has not been studied. This study aims to identify the metabolic profile of five flavonoids (loureirin A, loureirin B, loureirin C, 7,4'-dihydroxyflavone and 5,7,4'-trihydroxyflavanone) from DB in HLMs as well as the CYP enzymes that are involved in the metabolism of them. High-resolution mass spectrometry was used to characterize the structures of their metabolites and 10 cDNA-expressed CYP enzymes (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) were used to verify which isozymes mediate in the metabolism of the metabolites. Totally, 29 metabolites including 10 metabolites of loureirin A, 10 metabolites of loureirin B, 4 metabolites of loureirin C, 2 metabolites of 7,4'-dihydroxyflavone and 3 metabolites of 5,7,4'-trihydroxyflavanone were elucidated and identified on the basis of the high-resolution MSⁿ data. The metabolic profile of the five flavonoids in HLMs involved hydroxylation, oxidation and demethylation. Among them, hydroxylation was the predominant biotransformation of the five flavonoids in HLMs, occurring in combination with other metabolic reactions. Assay with recombinant P450s revealed that CYP2C9 and CYP2C19 played an important role in the hydroxylation of flavonoids in HLMs. To the best of our knowledge, this is the first in vitro evaluation of the metabolic profile of loureirin A, loureirin B, loureirin C, 7,4'-dihydroxyflavone and 5,7,4'-trihydroxyflavanone in HLMs.