Triptolide In Rats Research Articles

Healing Effects of Single-Dose Triptolide in Rats with Severe Acute Pancreatitis

Aim: Severe acute pancreatitis (SAP) carries high morbidity and mortality risk. If the proinflammatory response phase of SAP cannot be controlled, it may result in multiorgan failure (MOF). Nuclear factor-kappa B (NF-κB) activation plays an important role in the development of MOF. In this study, it was aimed to investigate the healing effects of triptolide, an anti-inflammatory and immunosuppressive agent in rats with SAP.Material and Methods: A total of 20 Wistar-Albino rats were divided into two groups as the SAP and triptolide treatment (TT) groups. SAP was induced by intraperitoneal injection of cerulean (50 mg/kg) in both groups. TT group was administered a single dose (0.2 mg/kg) triptolide 24 hour after the induction of SAP. Serum ALT, AST, GGT, Lipase, Glucose, ALP and amylase levels and pancreatic tissue samples were examined.Results: Serum glucose and amylase levels were found to be significantly lower in the TT group (p=0.011 and p=0.035, respectively). There was no significant difference between the groups in terms of other biochemical parameters. Pancreatic edema, acinar cell degeneration, fat necrosis, intrapancreatic&perivascular inflammation, inflammation in the peripancreatic fat tissue were common histopathological findings in both groups. There was no significant difference between the groups in terms of histopathologic changes.Conclusion: Cerulein-induced pancreatitis is a successful method for experimental SAP. The healing effects of single-dose triptolide treatment are not evident in the early phase of SAP. The therapeutic effects of triptolide on inflammatory and oxidative stress were not significantly approved by histopathological and biochemical parameters by the pancreatic tissue.

Influence of astragaloside IV on pharmacokinetics of triptolide in rats and its potential mechanism

Context It is common to combine two or more drugs in clinics in China. Triptolide (TP) has been used primarily for the treatment of inflammatory and autoimmune diseases. Astragaloside IV (AS-IV) has been applied with many other drugs, due to its various pharmacological effects. AS-IV and TP can be used together for the treatment of diseases in clinics in China. Objective This study investigates the effects of astragaloside IV (AS-IV) on the pharmacokinetics of TP in rats and its potential mechanism. Materials and methods The pharmacokinetics of orally administered triptolide (2 mg/kg) with or without AS-IV pre-treatment (100 mg/kg/day for 7 d) were investigated. Additionally, the effects of AS-IV on the transport of triptolide were investigated using the Caco-2 cell transwell model. Results The results indicated that when the rats were pre-treated with AS-IV, the C max of triptolide decreased from 418.78 ± 29.36 to 351.31 ± 38.88 ng/mL, and the AUC0-t decreased from 358.83 ± 19.56 to 252.23 ± 15.75 μg/h/L. The Caco-2 cell transwell experiments indicated that AS-IV could increase the efflux ratio of TP from 2.37 to 2.91 through inducing the activity of P-gp. Discussion and conclusions In conclusion, AS-IV could decrease the system exposure of triptolide when they are co-administered, and it might work through decreasing the absorption of triptolide by inducing the activity of P-gp.

Dihydromyricetin affect the pharmacokinetics of triptolide in rats

1. Dihydromyricetin (DMY) has anti-tumor and hepatoprotective activities and inhibits the activity of CYP enzymes and P-gp. In this research, we explored the effect of DMY on the pharmacokinetics of triptolide (TP), an anti-tumor Chinese medicine that is mainly metabolized by CYP enzymes and is the substrate of P-gp.2. Rats were administrated TP (1.2 mg/kg) with and without DMY in different dosage regimens, then a sensitive and reliable LC–MS/MS method was developed and applied to assess the pharmacokinetics of TP. The blood samples for TP were collected from each rat up to 120 min after administration of TP.3. When co-administrated with single dose of DMY (100 mg/kg), the AUC, Cmax and T1/2 of TP were significantly enhanced by 98, 83 and 66%, respectively. The T1/2 of TP was significantly prolonged from 23.6 ± 6.4 to 70.5 ± 12.5 min with 14-doses pretreatment of DMY (500 mg/kg), conversely, the Cmax was decreased by 30% and the AUC was enhanced by 24%.4. These results hinted that administration of DMY with TP did alter the pharmacokinetics of TP, and provided the theoretical pharmacokinetic basis to study on the protective effects of DMY against acute liver injury caused by TP.

Preclinical Pharmacokinetics of Triptolide: A Potential Antitumor Drug.

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

MicroRNA expression, targeting, release dynamics and early-warning biomarkers in acute cardiotoxicity induced by triptolide in rats

Tripterygium wilfordii Hook. F. is a plant used in traditional Chinese medicine to treat rheumatoid arthritis, lupus erythematosus, and psoriasis in China. However, its main active substance, triptolide, has toxic effects on the heart, liver, and kidneys, which limit its clinical application. Therefore, determining the mechanism of cardiotoxicity in triptolide and identifying effective early-warning biomarkers is beneficial for preventing irreversible myocardial injury. We observed changes in microRNAs and aryl hydrocarbon receptor (AhR) as potential biomarkers in triptolide-induced acute cardiotoxicity by using techniques such as polymerase chain reaction (PCR) assay. The results revealed that triptolide increased the heart/body ratio and caused myocardial fiber breakage, cardiomyocyte hypertrophy, increased cell gaps, and nuclear dissolution in treated male rats. Real-time PCR array detection revealed a more than 2-fold increase in the expression of 108 microRNA genes in the hearts of the male rats; this not only regulated the signaling pathways of ErbB, FOXO, AMPK, Hippo, HIF-1α, mTOR, and PI3K-Akt but also participated in biological processes such as cell adhesion, cell cycling, action potential, locomotory behavior, apoptosis, and DNA binding. Moreover, triptolide reduced the circulatory and cardiac levels of AhR protein as a target of these microRNAs and the messenger RNA expression of its downstream gene CYP1 A1. However, decreases in myocardial lactate dehydrogenase, creatine kinase MB, catalase, and glutathione peroxidase activity and an increase in circulating cardiac troponin I were observed only in male rats. Moreover, plasma microRNAs exhibited dynamic change. These results revealed that circulating microRNAs and AhR protein are potentially early-warning biomarkers for triptolide-induced cardiotoxicity.

Effects of puerarin on the pharmacokinetics of triptolide in rats

Context: Puerarin and triptolide are sometimes used together for the treatment of disease in Chinese clinics; however, the drug–drug interaction between puerarin and triptolide is still unknown.Objective: This study investigates the effects of puerarin on the pharmacokinetics of triptolide in rats and clarifies its main mechanism.Materials and methods: The pharmacokinetic profiles of oral administration of triptolide (1 mg/kg) in Sprague-Dawley rats with (test group, n = 6) or without pretreatment (control group, n = 6) with puerarin (100 mg/kg/day for seven days) were investigated. The effects of puerarin on the transport and metabolic stability of triptolide were also investigated using Caco-2 cell transwell model and rat liver microsomes.Results: The results showed that puerarin could significantly increase the peak plasma concentration (from 187.25 ± 15.36 to 219.67 ± 21.52 ng/mL), and decrease its oral clearance (from 4.92 ± 0.35 to 62.46 ± 3.75 ± 0.19 L/h/kg). The Caco-2 cell transwell experiments indicated that puerarin could decrease the efflux ratio of triptolide from 2.70 to 1.33, and the intrinsic clearance rate of triptolide was decreased by the pretreatment with puerarin (38.8 ± 4.7 vs. 32.9 ± 6.5 μL/min/mg protein).Discussion and conclusions: Puerarin could significantly change the pharmacokinetic profiles of triptolide in rats, and it might exert these effects through increasing the absorption of triptolide by inhibiting the activity of P-gp, or through inhibiting the metabolism of triptolide in rat liver. The results also showed that the dose of triptolide should be decreased when these drugs were co-administered.

A sensitive LC–MS/MS method for the determination of triptolide and its application to pharmacokinetic research in rats

Triptolide is one of the main active ingredients of Tripterygium wilfordii Hook. F. In this study, a sensitive LC-MS/MS method was established and validated to determine the concentration of triptolide in rat plasma. Triptolide and an internal standard [(5R)-5-hydroxytriptolide] were extracted from 100 μL of rat plasma with acetonitrile, and the dried residue was then reconstituted and reacted with benzylamine to produce benzylamine triptolide and benzylamine (5R)-5-hydroxytriptolide. Derivatization increased the sensitivity of triptolide detection by ~100-fold. Quantification was performed using a QTRAP 5500 tandem mass spectrometer with positive electrospray ionization in multiple reaction monitoring mode with an ion transition m/z 468.5 → 192.0 for benzylamine triptolide and m/z 484.3 → 192.1 for benzylamine (5R)-5-hydroxytriptolide. Good linearity was observed in the range of 0.030-100 ng/mL with a lower limit of quantitation of 0.030 ng/mL. The intra- and inter-day precision was <6.5%, and the accuracy ranged from -11.7 to -4.4%. The recovery remained consistent and was reproducible at different concentrations. This method was successfully applied to the study of triptolide drug-drug interactions in Sprague-Dawley rats. With the use of itraconazole (40 mg/kg, p.o.) as a CYP3A inhibitor, the plasma exposure of triptolide in rats was increased by 36%.

Influence of grapefruit juice on pharmacokinetics of triptolide in rats grapefruit juice on the effects of triptolide

1. Triptolide, a major pharmacological component isolated from Tripterygium wilfordii Hook F (TWHF), is a substrate of both CYP3A4 and P-glycoprotein (P-gp).2. This study investigates the effects of GFJ on the pharmacokinetics of triptolide in rats.3. The pharmacokinetics of orally administered triptolide with or without GFJ pretreatment were investigated. A mechanistic study was also undertaken using the Caco-2 cell transwell model and rat liver microsomes incubation systems to support the in vivo pharmacokinetic data.4. The results indicated that coadministration of GFJ could increase the systemic exposure of triptolide significantly, including area under the curve (828.58 ± 79.72 versus 541.53 ± 45.23 ng·h/mL) and maximum plasma concentration (273.58 ± 27.98 versus 193.67 ± 10.08 ng/mL). The apparent permeability of triptolide across the Caco-2 cell transwell model increased significantly with the pretreatment of GFJ (from 1.62 ± 0.25 × 10−6 to 2.51 ± 0.41 × 10−6 cm/s), and the metabolic stability of triptolide was also increased from 32.6 ± 5.1 to 52.5 ± 7.8 min with the pretreatment of GFJ, and the difference was significant (p < 0.05).5. In conclusion, GFJ could increase the systemic exposure of triptolide in rats, when GFJ and triptolide was coadministered, and it might work mainly through increasing the absorption of triptolide by inhibiting P-gp, or through slowing down the metabolism of triptolide in rat liver by inhibiting the activity of CYP3A4.

Sex-Related Differences of Lipid Metabolism Induced by Triptolide: The Possible Role of the LXRα/SREBP-1 Signaling Pathway.

Triptolide, a diterpenoid isolated from the plant Tripterygium wilfordii Hook. f., exerts a unique bioactive spectrum of anti-inflammatory and anticancer activities. However, triptolide’s clinical applications are limited due to its severe toxicities. Fatty liver toxicity occurs in response to triptolide, and this toxic response significantly differs between males and females. This report investigated the pathogenesis underlying the sex-related differences in the dyslipidosis induced by triptolide in rats. Wistar rats were administered 0, 150, 300, or 450 μg triptolide/kg/day by gavage for 28 days. Ultrastructural examination revealed that more lipid droplets were present in female triptolide-treated rats than in male triptolide-treated rats. Furthermore, liver triglyceride, total bile acid and free fatty acid levels were significantly increased in female rats in the 300 and 450 μg/kg dose groups. The expression of liver X receptor α (LXRα) and its target genes, cholesterol 7α-hydroxylase (CYP7A1) and Sterol regulatory element-binding transcription factor 1(SREBP-1), increased following triptolide treatment in both male and female rats; however, the female rats were more sensitive to triptolide than the male rats. In addition, the expression of acetyl-CoA carboxylase 1(ACC1), a target gene of SREBP-1, increased in the female rats treated with 450 μg triptolide/kg/day, and ACC1 expression contributed to the sex-related differences in the triptolide-induced dysfunction of lipid metabolism. Our results demonstrate that the sex-related differences in LXR/SREBP-1-mediated regulation of gene expression in rats are responsible for the sex-related differences in lipid metabolism induced by triptolide, which likely underlie the sex-related differences in triptolide hepatotoxicity. This study will be important for predicting sex-related effects on the pharmacokinetics and toxicity of triptolide and for improving its safety.

Triptolide Attenuates Inflammatory Response in Membranous Glomerulo-Nephritis Rat via Downregulation of NF-κB Signaling Pathway

Background/Aims: Triptolide (TPL), a main active ingredient of Tripterygium wilfordii has been shown to exert anti-inflammatory effect. The role of TPL on glomerular diseases remains unclear. Methods: This study aims to investigate the potential anti-inflammatory effect of TPL in rats with membranous glomerulonephritis (MGN). Results: Our data showed that the pathological kidney damage was significantly alleviated by TPL treatment in MGN rats. We also found that MGN rats exhibited significantly higher (p < 0.01) level of inflammatory cytokines (TNF-α, IL-1β and MCP-1) than those in normal group, while these inflammatory cytokines levels were significantly reduced in TPL treatment group compared with model group. Additionally, we found that TPL treatment could significantly decrease the malondialdehyde (MDA) level while enhanced superoxide dismutase (SOD) activity. Meanwhile, we also found that IκB kinase inhibitor (IMD-0354) could significantly reduce the accumulation of inflammation damage and oxidative lesions. Furthermore, we observed that both TPL and IMD-0354 treatment could block IκBα degradation and suppress mRNA and protein level of nuclear factor (NF) -κB p65. Conclusion: Together, all above results suggest that inflammatory response could be attenuated by TPL and this is partly due to the inhibition of NF- κB signaling pathway.

Triptolide Attenuates Myocardial Ischemia/Reperfusion Injuries in Rats by Inducing the Activation of Nrf2/HO-1 Defense Pathway.

Triptolide is a bioactive component of Chinese herbal plant Tripterygium wilfordii Hook F that has recently been noted to attenuate hepatic and cerebral ischemia/reperfusion (I/R) injuries in rodents. To investigate whether triptolide could protect against myocardial I/R injuries, triptolide (25, 50 or 100μg/kg) was administrated in Wistar rats that underwent left anterior descending coronary artery ligation in this study. Our data showed that triptolide pretreatment could attenuate myocardial infarction, increase the fractional shortening and left ventricular systolic pressure and decrease the left ventricular end-diastolic pressure in ischemic rats. Also, triptolide was noted to inhibit the activities of lactate dehydrogenase and creatine kinase in I/R rats. Moreover, triptolide administration suppressed macrophage infiltration, inhibited the overproduction of tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and malondialdehyde (MDA) in reperfused myocardium tissues and upregulated the activities of antioxidative superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GPx). In addition, nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the activity of its downstream target Heme oxygenase-1 (HO-1) in ischemic myocardium tissues were enhanced by triptolide pretreatment. In addition, the HO-1 inhibitor, zinc protoporphyrin-IX, abrograted the cardiac protection mediated by triptolide. Our study reveals a novel cardioprotective effect of triptolide in rats with I/R injuries, wherein the activation of Nrf2/HO-1 signaling was involved.

Gender Differences in the Toxicokinetics of Triptolide after Single- and Multiple-dose Administration in Rats.

Triptolide is a natural compound extracted from the traditional Chinese medicine Tripterygium wilfordii Hook F with distinguishing pharmacological activities and evident toxicities. We reported previously that 28 continuous days of oral administration of triptolide in rats resulted in gender dimorphic profiles in toxicities. To better understand this issue, the toxicokinetics of triptolide was observed in this study. Rats of both sexes were administered 400 μg/kg triptolide either as a single dose or multiple doses for 28 days. Triptolide concentrations in rat plasma were determined using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The plasma concentration-time curve and toxicokinetic parameters revealed gender differences after single and repeated triptolide administration, including significantly higher area under the plasma concentration-time curve (AUC0-∞) and peak plasma concentration (Cmax), lower clearance rate (CL) and longer terminal elimination half-life (t1/2) of triptolide in females, and lower drug exposure levels and greater CL in males. The gender differential disposition of triptolide may be the cause of increased toxicity in females. Moreover, auto-inhibition of metabolism and the resulting increase in drug exposure were observed after repeated dosing. The AUC0-∞ of triptolide was increased 6-fold in females and 2-fold in males, while the CL of triptolide was significantly decreased by 84% in females and 55% in males. These results indicated that gender-related differences existed in the toxicokinetics of triptolide and long-term oral administration of triptolide resulted in drug accumulation, which might account for the gender differences in the toxicities of triptolide.

Triptolide Attenuates Podocyte Injury by Regulating Expression of miRNA-344b-3p and miRNA-30b-3p in Rats with Adriamycin-Induced Nephropathy.

Objectives. We investigated the action of triptolide in rats with adriamycin-induced nephropathy and evaluated the possible mechanisms underlying its protective effect against podocyte injury. Methods. In total, 30 healthy male Sprague-Dawley rats were randomized into three groups (normal group, model group, and triptolide group). On days 7, 28, 42, and 56, 24 h urine samples were collected. All rats were sacrificed on day 56, and their blood and renal tissues were collected for determination of biochemical and molecular biological parameters. Expression of miRNAs in the renal cortex was analyzed by a biochip assay and RT-PCR was used to confirm observed differences in miRNA levels. Results. Triptolide decreased proteinuria, improved renal function without apparent adverse effects on the liver, and alleviated renal pathological lesions. Triptolide also elevated the nephrin protein level. Furthermore, levels of miR-344b-3p and miR-30b-3p were elevated in rats with adriamycin-induced nephropathy, while triptolide treatment reversed the increase in the expression of these two miRNAs. Conclusions. These results suggest that triptolide may attenuate podocyte injury in rats with adriamycin-induced nephropathy by regulating expression of miRNA-344b-3p and miRNA-30b-3p.

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.

Prediction of the Pharmacokinetic Parameters of Triptolide in Rats Based on Endogenous Molecules in Pre-Dose Baseline Serum

BackgroundIndividual variances usually affect drug metabolism and disposition, and hence result in either ineffectiveness or toxicity of a drug. In addition to genetic polymorphism, the multiple confounding factors of lifestyles, such as dietary preferences, contribute partially to individual variances. However, the difficulty of quantifying individual diversity greatly challenges the realization of individualized drug therapy. This study aims at quantitative evaluating the association between individual variances and the pharmacokinetics.Methodology/Principal FindingsMolecules in pre-dose baseline serum were profiled using gas chromatography mass spectrometry to represent the individual variances of the model rats provided with high fat diets (HFD), routine chows and calorie restricted (CR) chows. Triptolide and its metabolites were determined using high performance liquid chromatography mass spectrometry. Metabonomic and pharmacokinetic data revealed that rats treated with the varied diets had distinctly different metabolic patterns and showed differential Cmax values, AUC and drug metabolism after oral administration of triptolide. Rats with fatty chows had the lowest Cmax and AUC values and the highest percentage of triptolide metabolic transformation, while rats with CR chows had the highest Cmax and AUC values and the least percentage of triptolide transformation. Multivariate linear regression revealed that in baseline serum, the concentrations of creatinine and glutamic acid, which is the precursor of GSH, were linearly negatively correlated to Cmax and AUC values. The glutamic acid and creatinine in baseline serum were suggested as the potential markers to represent individual diversity and as predictors of the disposal and pharmacokinetics of triptolide.Conclusions/SignificanceThese results highlight the robust potential of metabonomics in characterizing individual variances and identifying relevant markers that have the potential to facilitate individualized drug therapy.

Comparison of toxicokinetic and tissue distribution of triptolide-loaded solid lipid nanoparticles vs free triptolide in rats

The traditional Chinese medicine Tripterygium wilfordii Hook F (TWHF) is used clinically to treat some autoimmune and inflammatory disorders including rheumatoid arthritis, systemic lupus erythematosus, and skin diseases. However TWHF has a high potential for toxicity, so its clinical use is limited. Solid lipid nanoparticle (SLN) delivery systems are reported to have remarkable advantages over conventional formulations of bioactive plant extracts, such as enhancing solubility and bioavailability, offering protection from toxicity, and enhancing pharmacological activity. We reported previously that a tripterygium glycoside (TG) solid lipid nanoparticle (TG-SLN) delivery system had a protective effect against TG-induced male reproductive toxicity. To better understand this issue, we used triptolide (TP) as a model drug in a comparative study of the toxicokinetic and tissue distribution of TP-SLN and free TP in rats, allowing us to observing the in vivo behavior of this nanoformulation and to assess mechanisms of SLN-related toxicity. A fast and sensitive HPLC–APCI–MS/MS method was developed for the determination of triptolide in rat plasma. Fourteen rats were divided randomly into two groups of 7 rats each for toxicokinetic analysis, with one group receiving free TP (450μg/kg) and the other receiving the TP-SLN formulation (450μg/kg). Blood was obtained before dosing and 0.083, 0.17, 0.25, 0.33, 0.5, 0.75, 1, 1.5, 2, 3 and 4h after drug administration. Thirty-six rats were divided randomly into six equal groups for a tissue-distribution study. Half of the rats received intragastric administration of TP (450μg/kg) and the other half received TP-SLN (450μg/kg). At 15, 45, and 90min after dosing, samples of blood, liver, kidney, spleen, lung, and testicular tissue were taken. TP concentration in the samples was determined by LC–APCI–MS–MS. The toxicokinetic results for the nanoformulation showed a significant increase the area under the curve (AUC) (P<0.05), significantly longer Tmax and mean retention times (MRTs) (0–t) (P<0.05), significantly decreased Cmax (P<0.05). The nanoformulation promoted absorption with a slow release character, indicating that toxicokinetic changes may be the most important mechanism for the enhanced efficacy of nanoformulations. Tissue-distribution results suggest a tendency for TP concentrations in the lung and spleen to increase, while TP concentrations in plasma, liver, kidney, and testes tended to decrease in the TP-SLN group. At multiple time points, testicular tissue TP concentrations were lower in the TP-SLN group than in free TP group. This provides an important clue for the decreased reproductive toxicity observed with TP-SLN.

Sex differences in subacute toxicity and hepatic microsomal metabolism of triptolide in rats

Triptolide, a major active component of Tripterygium wilfordii Hook F (TWHF), has multiple pharmacological activities. However, its clinical use is often limited by its severe toxicity. In the present study, we evaluated the oral toxicity of triptolide in Sprague–Dawley rats for 28 days at the dosages of 0, 200 and 400 μg/kg/day, respectively. Significant difference in the toxicity of triptolide at 400 μg/kg was found between different sexes. The triptolide-treated female rats showed many abnormalities, including anorexia, diarrhea, leanness, suppression of weight gain and food intake, fatty liver, splenomegaly and atrophy of ovaries. In contrast, no such abnormalities were observed in male rats except for the significant reproductive toxicity. Furthermore, the metabolism of triptolide in liver microsomes from both sexes was investigated by HPLC. A greater rate of triptolide metabolism was observed in male rat hepatic microsomes, suggesting that one of the cytochrome P450s (CYPs) responsible for triptolide metabolism is male-specific or predominant at least. The inhibition experiments with CYP inhibitors showed that CYP3A and CYP2B were mainly involved in the metabolism of triptolide. In addition, since CYP3A2 is a male-predominant form in rats, significant sex difference in the metabolism of triptolide disappeared in vitro after anti-rat CYP3A2 antibody pretreatment. Results suggested that CYP3A2 made an important contribution to the sex-related metabolism of triptolide, which may result in the sex differences in triptolide toxicity.

Pharmacokinetic Study of Triptolide, a Constituent of Immunosuppressive Chinese Herb Medicine, in Rats

Triptolide is a potential anti-immune agent, and has shown multi-organic toxicity, however its toxic mechanism remained undiscovered. This paper aimed at characterizing the pharmacokinetic profiles of triptolide in rats to provide the clue to approach the toxic mechanism. The absorption, distribution, metabolism and excretion of triptolide were investigated in male Sprague-Dawley rats after single doses of oral and i.v. administration. After oral administration of 0.6, 1.2 and 2.4 mg/kg, the concentration of triptolide in plasma reached the maximum within 15 min, and declined rapidly with an elimination half-life from 16.81 to 21.70 min. The triptolide kinetics was fitted into one-compartment model after i.v. administration. Oral absolute bioavailability was 72.08% at the dose of 0.6 mg/kg. Triptolide was also rapidly distributed and eliminated in all selected tissues. Less than 1% triptolide of the dose was recovered from the bile, urine or feces as parent drug within 48 h. While triptolide could not be detected in tissues and plasma at 4 h post dose, rats in the group C (oral: 1.2 mg/kg) and D (oral: 2.4 mg/kg) showed obvious toxic response to triptolide and some of rats even died out. It was indicated that triptolide was metabolized extensively, eliminated rapidly, and also showed that the toxicity produced by the triptolide was lag behind the exposure concentration.