Metabolite identification of triptolide by data-dependent accurate mass spectrometric analysis in combination with online hydrogen/deuterium exchange and multiple data-mining techniques

Antitumor mechanisms and future clinical applications of the natural product triptolide

Triptolide (TPL) is a compound sourced from Tripterygium wilfordii Hook. F., a traditional Chinese medicinal herb recognized for its impressive anti-inflammatory, anti-angiogenic, immunosuppressive, and antitumor qualities. Notwithstanding its favorable attributes, the precise mechanism through which TPL influences tumor cells remains enigmatic. Its toxicity and limited water solubility significantly impede the clinical application of TPL. We offer a comprehensive overview of recent research endeavors aimed at unraveling the antitumor mechanism of TPL in this review. Additionally, we briefly discuss current strategies to effectively manage the challenges associated with TPL in future clinical applications. By compiling this information, we aim to enhance the understanding of the underlying mechanisms involved in TPL and identify potential avenues for further advancement in antitumor therapy.

Metabolic Activation of the Toxic Natural Products From Herbal and Dietary Supplements Leading to Toxicities

Currently, herbal and dietary supplements have been widely applied to prevent and treat various diseases. However, the potential toxicities and adverse reactions of herbal and dietary supplements have been increasingly reported, and have gradually attracted widespread attention from clinical pharmacists and physicians. Metabolic activation of specific natural products from herbal and dietary supplements is mediated by hepatic cytochrome P450 or intestinal bacteria, and generates chemical reactive/toxic metabolites that bind to cellular reduced glutathione or macromolecules, and form reactive metabolites-glutathione/protein/DNA adducts, and these protein/DNA adducts can result in toxicities. The present review focuses on the relation between metabolic activation and toxicities of natural products, and provides updated, comprehensive and critical comment on the toxic mechanisms of reactive metabolites. The key inductive role of metabolic activation in toxicity is highlighted, and frequently toxic functional groups of toxic natural products were summarized. The biotransformation of drug cytochrome P450 or intestinal bacteria involved in metabolic activation were clarified, the reactive metabolites-protein adducts were selected as biomarkers for predicting toxicity. And finally, further perspectives between metabolic activation and toxicities of natural products from herbal and dietary supplements are discussed, to provide a reference for the reasonable and safe usage of herbal and dietary supplements.

Preclinical Pharmacokinetics of Triptolide: A Potential Antitumor Drug

Background:

Triptolide, a bioactive component in Tripterygium wilfordii extracts, possess strong antiproliferative activity on all 60-National Cancer Institute (NCI) cancer cell lines. However, the widespread use of triptolide in the clinical practice is greatly limited for its multi-organ toxicity and narrow therapeutic window. All the toxic characteristics of triptolide are associated with the pharmacokinetics especially its distribution and accumulation in the target organ.

Methods:

The literature review was done using PubMed search, SciFinder and Google Scholar databases with specific keywords such as triptolide, pharmacokinetics, drug-drug interaction, transporters, metabolism, modification to collect the related full-length articles and abstracts from 2000 to 2018.

Results:

Oral triptolide is rapidly and highly absorbed. Grapefruit juice affects oral absorption, increasing the area under the concentration-time curve (AUC) by 153 % and the maximum concentration (Cmax) by 141 %. The AUC and the Cmax are not dose proportional. Triptolide distributes into the liver, heart, spleen, lung and kidney. Biotransformation of triptolide in rats includes hydroxylation, sulfate, glucuronide, N-acetylcysteine (NAC) and Glutathione (GSH) conjugation and combinations of these pathways. Less than 4 % of triptolide was recovered from the feces, bile and urine within 24 h. After repeating dosage, triptolide was eliminated quickly without accumulation in vivo. As a substrate of P-glycoprotein (P-gp) and CYP3A4, triptolide could have clinically significant pharmacokinetic interactions with those proteins substrates/inhibitors.

Conclusion:

The findings of this review confirm the importance of pharmacokinetic character for understanding the pharmacology and toxicology of triptolide.

Identification of hepatotoxic and nephrotoxic potential markers of triptolide in mice with delayed-type hypersensitivity

Triptolide (TP) is the crucial active ingredient of Tripterygium glycoside tablets and has been shown to have a significant therapeutic effect on delayed-type hypersensitivity (DTH)-related diseases. However, due to its potential hepatotoxicity and nephrotoxicity, adverse reactions have often been observed in long-term treatment regimens. Therefore, it is meaningful to find metabolic markers for toxicity for early diagnosis. In this study, a feasible strategy using HPLC-HRMS method combined with multivariate statistical analysis to discover toxic potential markers of TP was developed. TP was used to treat a DTH mouse model at a therapeutic dose (45μg/kg) and toxic dose (900 μg/kg). The metabolic profiles of the liver, kidney and plasma were characterized by HPLC-Q/TOF MS. Significant differences in the metabolite profiles of the liver, kidney and plasma existed between the toxic and therapeutically dosed mice. Forty-six metabolites were identified and 27 of them may be related to toxicity based on a structure-toxicity prediction model. Using OPLS-DA analysis, the metabolite profiles between the two dose groups could be well distinguished. It was found that 18, 4 and 4 metabolic markers were altered in the liver, kidney and plasma, respectively; 15, 4 and 3 of these metabolic markers were predicted to be toxic. Two toxic markers detected both in mouse plasma and human liver microsomes following incubation with TP showed great potential as early diagnosis markers for TP hepatotoxicity and nephrotoxicity.

Effects of triptolide on the expression of MHC II in microglia in kainic acid‑induced epilepsy

The purpose of the present study was to determine whether triptolide (T10) had any effect on major histocompatibility complex class II (MHC II) expression in kainic acid (KA)‑activated microglia, and to investigate the underlying molecular mechanism. BV‑2 microglia were pretreated with T10 prior to activation with KA. The expression level of MHC II and class II transactivator (CIITA) mRNA was determined via reverse transcription‑polymerase chain reaction. The expression of MHC II, CIITA and the phosphorylation level of c‑Jun and proto‑oncogene c‑Fos (c‑Fos) was determined by western blotting. The protein expression level of MHC II was determined by immunocytochemistry. It was observed that the mRNA and protein levels of MHC II and CIITA were increased in KA‑activated BV‑2 microglia, and that this increase was almost completely eliminated by T10. AP‑1 is a family of homodimers or heterodimers, composed of Jun family and Fos family proteins. Sequence analysis revealed an AP‑1 DNA binding site in the promoter of CIITA. The phosphorylation of c‑Jun and c‑Fos was increased in KA‑activated microglia, while T10 was able to suppress the phosphorylation of c‑Jun and c‑Fos in KA‑activated microglia. These data suggested that T10 may exert suppressive effects on MHC II expression in KA‑activated microglia, and that the mechanism may involve the regulation of AP‑1 activity.

Detection and characterization of the metabolites of rutaecarpine in rats based on ultra-high-performance liquid chromatography with linear ion trap-Orbitrap mass spectrometer

CONTEXT

Rutaecarpine is an active indoloquinazoline alkaloid ingredient originating from Evodia rutaecarpa (Wu-zhu-yu in Chinese), which possesses a variety of effects. However, its metabolism has not been investigated thoroughly yet.

OBJECTIVE

This study develops a highly sensitive and effective method for detection and characterization of the metabolites of rutaecarpine in Sprague-Dawley (SD) rats.

MATERIALS AND METHODS

In this study, an efficient method was developed using ultra-high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometer (UHPLC-LTQ-Orbitrap MS) to detect the metabolism profile of rutaecarpine in rat plasma. First, a blood sample (1 mL) was withdrawn 2 h after oral administration of rutaecarpine in SD rats (50 mg/kg). Second, the blood was centrifuged at 4000 rpm for 10 min and pretreated by solid-phase extraction method. Third, 2 μL of the plasma was injected into UHPLC-LTQ-Orbitrap MS for analysis. Finally, the metabolites of rutaecarpine were tentatively identified based on accurate mass measurements, fragmentation patterns and chromatographic retention times.

RESULTS

A total of 16 metabolites (four new metabolites, viz., dihydroxylation and sulphate conjugation products of rutaecarpine (M8-M11)) as well as parent drug itself, including three phase I and 12 phase II metabolites were detected and identified in rat plasma. Hydroxylation, sulphate conjugation and glucuronidation were confirmed as the primary metabolic pathways for rutaecarpine in rat plasma.

DISCUSSION AND CONCLUSION

These results provide an insight into the metabolism of rutaecarpine and also can give strong indications on the effective forms of rutaecarpine in vivo.

Critical Role of Hepatic Cyp450s in the Testis-Specific Toxicity of (5R)-5-Hydroxytriptolide in C57BL/6 Mice

Low solubility, tissue accumulation, and toxicity are chief obstacles to developing triptolide derivatives, so a better understanding of the pharmacokinetics and toxicity of triptolide derivatives will help with these limitations. To address this, we studied pharmacokinetics and toxicity of (5R)-5-hydroxytriptolide (LLDT-8), a novel triptolide derivative immunosuppressant in a conditional knockout (KO) mouse model with liver-specific deletion of CYP450 reductase. Compared to wild type (WT) mice, after LLDT-8 treatment, KO mice suffered severe testicular toxicity (decreased testicular weight, spermatocytes apoptosis) unlike WT mice. Moreover, KO mice had greater LLDT-8 exposure as confirmed with elevated AUC and Cmax, increased drug half-life, and greater tissue distribution. γ-H2AX, a marker of meiosis process, its localization and protein level in testis showed a distinct meiosis block induced by LLDT-8. RNA polymerase II (Pol II), an essential factor for RNA storage and synapsis in spermatogenesis, decreased in testes of KO mice after LLDT-8 treatment. Germ-cell line based assays confirmed that LLDT-8 selectively inhibited Pol II in spermatocyte-like cells. Importantly, the analysis of androgen receptor (AR) related genes showed that LLDT-8 did not change AR-related signaling in testes. Thus, hepatic CYP450s were responsible for in vivo metabolism and clearance of LLDT-8 and aggravated testicular injury may be due to increased LLDT-8 exposure in testis and subsequent Pol II reduction.

Development of a modified QuEChERS method for the determination of veterinary antibiotics in swine manure by liquid chromatography tandem mass spectrometry

A QuEChERS (quick, easy, cheap, effective, rugged and safe) based methodology was developed for the rapid, simultaneous quantification and identification of 26 veterinary drugs in swine manure by liquid chromatography tandem mass spectrometry. The selected antibiotics included tetracyclines, sulfonamides, macrolides, fluoroquinolones, lincosamides and pleuromutilins. This is the first study to determine pleuromutilin levels in manure. The QuEChERS process involved two simple steps. First, sample extraction with methanol: acetonitrile: 0.1M EDTA-McIlvaine buffer followed by phase separation with MgSO4: NaCl addition. The supernatant was then extracted and cleaned by dispersive solid-phase extraction using a primary-secondary amine (PSA) and octadecylsilane (C18) support. The proposed method provides a linearity in the range of 1-500ngmL-1 and linear regression coefficients (r) were greater than 0.996. MDL and MQL ranged between 0.01-1.86μgkg(-1) and 0.05-5.91μgkg(-1), respectively. Recoveries ranged from 61.39 to 105.65% with the exception of sulfaquinoxaline (55.7-56.8%) and valnemulin (33.7-37.7%). This method resulted in good precision (repeatability and reproducibility) and relative standard deviations less than 17% within the same day, and lower than 20% between days. The method was then applied to study the swine manure samples collected from Guangdong, China. Chlortetracycline, tetracycline, doxycycline, sulfadimidine and tilmicosin were detected in all samples indicating high residuals in manure. In fact tilmicosin was detected at 14400μgkg(-1) suggesting that prudent treatment of manure should be conducted to prevent environmental contamination. In conclusion, this workflow can provide a simpler and more cost-effective alternative to conventional methods and is compatible with processing large sample numbers over a short time period.

Investigation of the active components in Tripterygium wilfordii leading to its acute hepatotoxicty and nephrotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional herbal medicine Tripterygium wilfordii Hook. f. (TW) has been widely used for the treatment of rheumatoid arthritis and autoimmune disease in the clinic. However, adverse reactions of TW including hepatotoxicity and nephrotoxicity have been frequently reported. Terpenes and alkaloids are among the most important active components in TW. Triptolide (TP), a major terpene in TW, has been found to induce toxicity, and metabolic pathways could lead to detoxification of TP. In this study, whether other major terpenes or alkaloids in TW contribute to its toxicity was investigated. The role of metabolic eliminations in their potential detoxification process was also evaluated.

MATERIALS AND METHODS

The toxicity of TW and its five major active components (one terpene and four alkaloids) in mice was evaluated in terms of mortality and blood biochemical levels (ALT, AST, BUN and CREA). TP was used as a positive control. Metabolic pathways leading to potential detoxification of TW or its two representative components (triptonide and wilforgine) were evaluated in glutathione (GSH)-depleted (treated with L-buthionine-S,R-sulfoxinine, BSO) and aminobenzotriazole (ABT; a nonspecific inhibitor for P450s)-treated mice.

RESULTS

In normal mice, the major metabolic pathways for the terpene compounds TP and triptonide (TN) were hydroxylation and cysteine conjugation, and the alkaloid wilforgine (WG) mainly underwent oxidative metabolism and hydrolysis. In ABT/BSO-treated mice, the hydroxylated metabolites of TP, TN and WG were found at a lower level than normal mice, and the level of cysteine conjugates of TN increased probably due to the stress response. Compared with normal mice, mortality and levels of ALT (but not BUN) were significantly higher (P<0.01) in TW (or TP)-treated mice (1.2 mg kg(-1)), indicating the acute toxicity (may not nephrotoxicity) of TW and its active component TP. Pretreatment with ABT and/or BSO increased the acute toxicity (including hepatotoxicity and nephrotoxicity) caused by TW or TP. No significant toxicity was found for TN or four alkaloids in normal mice or ABT/BSO-treated mice.

CONCLUSIONS

TP was probably the main contributor to the toxicity of TW, and the terpene TN and alkaloids in TW may be of no toxicological concern at dosage levels up to 20-fold of the therapeutic dose. Metabolic eliminations to less reactive metabolites implied a high potential for detoxification of TW, and caution should be taken for TW clinical use during co-administration with other CYP inhibitors or GSH-depleting agents.

Metabolite profiling and identification of triptolide in rats

The purpose of the current study was to investigate the metabolite profile of [(3)H]triptolide in rats. The separation and characterisation techniques used to identify the major metabolites were high-performance liquid chromatography-online radiodetector, ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and nuclear magnetic resonance. In all, 33 major metabolites were detected. The major components found in the rat plasma included the parent drug and its monohydroxy- and dihydroxy-metabolites. Reference standards for the monohydroxy-metabolites were obtained either by the incubation of the parent drug with rat liver microsomes or by microbial transformation with Cunninghamella blakesleana. The metabolites' structures were identified as 17-hydroxytriptolide, 16-hydroxytriptolide, tripdiolide, and 15-hydroxytriptolide. The major metabolites found in male rat urine included the monohydroxy-, dihydroxy-, and trihydroxy-metabolites. The major metabolites in female rat urine were the monohydroxy- and dihydroxy-metabolites, as well as sulphates of the monohydroxy-metabolites. A glutathione adduct, multiple hydroxy-metabolites, and a number of unidentified metabolites were detected in the bile and faeces of male rats. Sulphates of monohydroxy-metabolites were detected in the bile and faeces of female rats.

Metabolic pathways leading to detoxification of triptolide, a major active component of the herbal medicine Tripterygium wilfordii

Triptolide (TP) shows promising anti-inflammatory and antitumor activity but with severe toxicity. TP is a natural reactive electrophile containing three epoxide groups, which are usually linked to hepatotoxicity via their ability to covalently bind to cellular macromolecules. In this study, metabolic pathways leading to detoxification of TP were evaluated in glutathione (GSH)-depleted (treated with L-buthionine-S,R-sulfoxinine, BSO) and aminobenzotriazole (ABT; a non-specific inhibitor for P450s)-treated mice. The toxicity of TP in mice was evaluated in terms of mortality and levels of serum alanine transaminase (ALT). In incubates with NADPH- and GSH-supplemented liver microsomes, seven GSH conjugates derived from TP were detected. In mice, these hydrolytically unstable GSH conjugates underwent γ-glutamyltranspeptidase/dipeptidases-mediated hydrolysis leading to two major cysteinylglycine conjugates, which underwent further hydrolysis by dipeptidases to form two cysteine conjugates of TP. In ABT-treated mice, the hydroxylated metabolites of TP were found at a lower level than normal mice, and their subsequent conjugated metabolites were not found. The level of cysteinylglycine and cysteine conjugates derived from NADPH-independent metabolism increased in mice treated with both TP and BSO (or ABT), which could be the stress response to toxicity of TP. Compared with normal mice, mortality and ALT levels were significantly higher in TP-treated mice, indicating the toxicity of TP. Pretreatment of ABT increased the toxicity caused by TP, whereas the mortality decreased in GSH-depleted mice. Metabolism by cytochrome P450 enzymes to less reactive metabolites implied a high potential for detoxification of TP. The GSH conjugation pathway also contributed to TP's detoxification in mice.

Exploring the utility of high-resolution MS with post-acquisition data mining for simultaneous exogenous and endogenous metabolite profiling

Background: The utility of high-resolution MS (HRMS) with post-acquisition data mining in DMPK goes much further than the now established approach to simultaneously acquire quantitative and qualitative information for lead compounds at the discovery stage. Indeed, HRMS has promise for addressing multiple complex drug-development applications in a single experiment. In the present study, one HRMS dataset acquired for in vitro incubations of the model compound dasatinib was mined post-acquisition to address four different issues: stability, metabolite profiling, glutathione conjugate analysis, and endogenous lipid profiling. Results & Conclusion: The derived results demonstrated that HRMS has potential for generating high information content datasets that can be stored and mined as needed to answer numerous complex development-stage questions without the need for additional sample generation or analysis.

Detection and characterization of ticlopidine conjugates in rat bile using high-resolution mass spectrometry: applications of various data acquisition and processing tools

Ticlopidine, an antiplatelet drug, undergoes extensive oxidative metabolism to form S-oxide, N-oxide, hydroxylated and dealkylated metabolites. However, metabolism of ticlopidine via conjugation has not been thoroughly investigated. In this study, multiple data acquisition and processing tools were applied to the detection and characterization of ticlopidine conjugates in rat bile. Accurate full-scan mass spectrometry (MS) and collision-induced dissociation (CID) MS/MS data sets were recorded using isotope pattern-dependent acquisition on an LTQ/Orbitrap system. In addition, mass spectral data from online H/D exchanging and high collision energy dissociation (HCD) were recorded. Data processes were carried out using extracted ion chromatography (EIC), mass defect filter (MDF) and isotope pattern filter (IPF). The total ion chromatogram displayed a few major conjugated metabolites and many endogenous components. Profiles from EIC and IPF processes exhibited multiple conjugates with no or minimal false positives. However, ticlopidine conjugates that were not predictable or lost a chorine atom were not found by EIC or IPF, respectively. MDF was able to detect almost all of ticlopidine conjugates although it led to a few more false positives. In addition to CID spectra, data from HCD, H/D exchanging experiments and isotope pattern simulation facilitated structural characterization of unknown conjugates. Consequently, 20 significant ticlopidine conjugates, including glucuronide, glutathione, cysteinylglycine, cysteine and N-acetylcysteine conjugates, were identified in rat bile, a majority of which are associated with bioactivation and not previously reported. This study demonstrates the utility and limitation of various high-resolution MS-based data acquisition and processing techniques in detection and characterization of conjugated metabolites.