Characterization of human metabolism and disposition of levo-tetrahydropalmatine: Qualitative and quantitative determination of oxidative and conjugated metabolites

A Comprehensive Review on the Chemical Properties, Plant Sources, Pharmacological Activities, Pharmacokinetic and Toxicological Characteristics of Tetrahydropalmatine

Tetrahydropalmatine (THP), a tetrahydroproberine isoquinoline alkaloid, is widely present in some botanical drugs, such as Stephania epigaea H.S. Lo (Menispermaceae; Radix stephaniae epigaeae), Corydalis yanhusuo (Y.H.Chou & Chun C.Hsu) W.T. Wang ex Z.Y. Su and C.Y. Wu (Papaveraceae; Corydalis rhizoma), and Phellodendron chinense C.K.Schneid (Berberidaceae; Phellodendri chinensis cortex). THP has attracted considerable attention because of its diverse pharmacological activities. In this review, the chemical properties, plant sources, pharmacological activities, pharmacokinetic and toxicological characteristics of THP were systematically summarized for the first time. The results indicated that THP mainly existed in Papaveraceae and Menispermaceae families. Its pharmacological activities include anti-addiction, anti-inflammatory, analgesic, neuroprotective, and antitumor effects. Pharmacokinetic studies showed that THP was inadequately absorbed in the intestine and had rapid clearance and low bioavailability in vivo, as well as self-microemulsifying drug delivery systems, which could increase the absorption level and absorption rate of THP and improve its bioavailability. In addition, THP may have potential cardiac and neurological toxicity, but toxicity studies of THP are limited, especially its long-duration and acute toxicity tests. In summary, THP, as a natural alkaloid, has application prospects and potential development value, which is promising to be a novel drug for the treatment of pain, inflammation, and other related diseases. Further research on its potential target, molecular mechanism, toxicity, and oral utilization should need to be strengthened in the future.

Role of Levo-tetrahydropalmatine and its metabolites for management of chronic pain and opioid use disorders

BACKGROUND

Opioids have been prescribed to reduce suffering from pain and to enhance quality of life. Due to the addictive potential and the lack of other effective alternatives to treat severe acute and chronic pains, opioids remain a serious public health issue. While, opioids directly influence the drug-seeking behavior, tolerance and withdrawal processes, through neuroadaptation, the brain's endogenous opioid system also adapts in the presence of chronic pain and could contribute to the difficulty of treatment. Despite the seemingly obvious interaction between the presence of pain and opioid-abuse, little is known about the underlying mechanisms in the brain.

PURPOSE

To review the current understanding of the interaction mechanisms of neurotransmitter circuitries in pain modulation and reward in the brain and the effects of L-tetrahydropalmatine (L-THP) and its metabolites in pain management and opioid use disorder and gain a better insight on the pharmacological profile and in vivo effects of L-THP and its metabolites.

METHOD

A detailed literature search on available (preclinical and clinical) studies about the effects of L-THP and its metabolites against drug addiction and chronic pain has been performed. The data was collected using various search engines such as PubMed, ScienceDirect, Google scholar and articles in English up to December 2020 were included in this review.

RESULTS

L-THP and its metabolites demonstrated analgesic and anti-addiction effects. Due to their dual pharmacological properties (D1 partial agonist and D2 antagonist) these compounds could be used as molecular tools to provide a better understanding of the interactions between pain and addiction.

CONCLUSION

The available data confirms the potential of L-THP and its metabolites to treat both chronic pain and drug addiction. However, further clinical trials are needed to establish safety and efficacy.

Metabolic profiles of Jin-hong tablets in rats by ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry

Jin-hong tablets (JHTs), a well-known traditional Chinese patent medicine (TCPM), have been effectively used for the treatment of chronic superficial gastritis (CSG). The metabolic profile of TCPMs is performed to determine their bioactive components. In this study, a five-step strategy based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and metabolynx™ software combined with mass defect filter technique was developed to delineate the metabolic profile of JHT in vivo. As a result, a total of 163 JHT-related xenobiotics (38 prototypes and 125 metabolites) were identified or tentatively characterized in rat biological samples, and the phase I and II metabolism processes mainly included demethylation, hydroxylation, sulfation, and glucuronidation. In addition, after oral administration of JHT, a large amount of alkaloid-related ingredients was detected in rat plasma samples, indicating that alkaloids may play an important role in the treatment of CSG with JHT. This study is beneficial for understanding the JHT's in vivo metabolic profiles and characteristics, which helps to reveal its in vivo effective components and provides a solid basis for further studies on its functional mechanism.

Inhibitory effect of ketoconazole, quinidine and 1-aminobenzotriazole on pharmacokinetics of l-tetrahydropalmatine and its metabolite in rats

l-tetrahydropalmatine (l-THP) is mainly metabolised by CYP450 enzymes.This study was to investigate the possible effect of co-administered CYP inhibitors on the pharmacokinetics of l-THP and its metabolites in rats.An established LC-MS/MS method has been applied for the evaluation of drug-drug interaction between l-THP and CYP inhibitors. Following the administration of CYP inhibitors, a single dose of l-THP (9 mg/kg) was orally administrated.With regard to l-THP, the AUC_0-48 were significantly increased by 4.3, 3.79, and 11.39 folds, and C_max were increased by 4.74, 3.64, and 2.76 folds in the ketoconazole group (KET), quinidine group (QD), and 1-aminobenzotriazole group (ABT), respectively. KET and QD both significantly increased the AUC_0-48 of 2-DM and 2-DM-Glu by 1.38 ∼ 2.43 times, while C_max was significantly decreased by 41.3 and 78.0% in the ABT group, respectively. The C_max of 3-DM was reduced by 51.38, 48.02, and 63.31% after pre-treatment with KET, QD, and ABT, respectively, and C_max of 3-DM-Glu decreased correspondingly by 29.6, 22.1, and 58.0%.Results indicated that CYP inhibitors could markedly influence the systemic level of l-THP and its metabolites. To guarantee the safe use of l-THP, attention should be paid when l-THP was co-administered with CYP inhibitors, particularly with CYP3A4 and 2D6 inhibitors.

Corydalis Rhizoma as a model for herb-derived trace metabolites exploration: A cross-mapping strategy involving multiple doses and samples

Deciphering the metabolites of multiple components in herbal medicine has far-reaching significance for revealing pharmacodynamic ingredients. However, most chemical components of herbal medicine are secondary metabolites with low content whose in vivo metabolites are close to trace amounts, making it difficult to achieve comprehensive detection and identification. In this paper, an efficient strategy was proposed: herb-derived metabolites were predicted according to the structural characteristics and metabolic reactions of chemical constituents in Corydalis Rhizoma and chemical structure screening tables for metabolites were conducted. The fragmentation patterns were summarized from representative standards combining with specific cleavage behaviors to deduce structures of metabolites. Ion abundance plays an important role in compound identification, and high ion abundance can improve identification accuracy. The types of metabolites in different biological samples were very similar, but their ion abundance might be different. Therefore, for trace metabolites in biological samples, we used the following two methods to process: metabolites of high dose herbal extract were analyzed to characterize those of clinical dose herbal extracts in the same biological samples; cross-mapping of different biological samples was applied to identify trace metabolites based on the fact that a metabolite has different ion abundance in different biological samples. Compared with not using this strategy, 44 more metabolites of clinical dose herbal extract were detected. This study improved the depth, breadth, and accuracy of current methods for herb-derived metabolites characterization.

Tetrahydroprotoberberines: A Novel Source of Pharmacotherapies for Substance Use Disorders?

Tetrahydroprotoberberines (THPBs) are a class of compounds that target both dopamine D1 and D2 families of receptors, making them attractive candidates for treating substance use disorder (SUD). The binding of some THPBs to serotonin and adrenergic receptors, in addition to dopamine receptors, gives rise to complex pharmacological profiles. Significant progress has been made over the last decade in examining these compounds for their therapeutic potential. Here, we evaluate recent discoveries relating to the neural mechanism and therapeutic effects of THPBs, focusing on compounds that have shown promise in animal models of SUD and preliminary clinical studies. Advancements in structure-activity relationship studies and in silico modeling of THPB binding to dopamine receptors have facilitated the synthesis of novel THPBs with enhanced therapeutic properties and provide insights regarding use of the THPB scaffold to serve as a template for innovative drug designs.

Characterization of in vitro metabolism of focal adhesion kinase inhibitors by LC/MS/MS

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, is critically involved in cell migration, spreading and proliferation at the early step of various cancers. Small molecule inhibitors of FAK are effective to inhibit its activation in the process of tumor formation in cell. To better understand biotransformation of FAK inhibitors, this work has investigated in vitro phase I metabolism of inhibitors (namely PF-573228, PF-562271 and PF-03814735) by rat liver microsomes model. Using liquid chromatography - quadrupole time of flight mass spectrometry and tandem mass spectrometry (LC/Q-TOF/MS and MS/MS), three metabolites of PF-573228 and PF-562271 were observed and characterized, respectively. These in vitro metabolites were reported for the first time. The structures and fragmentation patterns of these metabolites were elucidated, and phase I metabolic pathways for FAK inhibitors were proposed. The main metabolic pathways of PF-573228 were hydroxylation, dehydrogenation and N-dealkylation. For PF-562271, they were hydroxylation and dehydrogenation. Hydroxylation was observed as the primary metabolism for PF-0381473.

Metabolic profiling analysis of corilagin in vivo and in vitro using high-performance liquid chromatography quadrupole time-of-flight mass spectrometry

Corilagin is an Ellagitannin with favorable pharmacological activities. But there was no report regarding the metabolism of corilagin in vitro or in vivo. In this study, the metabolic profile of corilagin in rats as well as in rat intestinal bacteria and liver microsomes incubation system in vitro were investigated comprehensively for the first time. Consequently, with the aid of sensitive HPLC-Q-TOF-MS/MS, corilagin and its twenty-four metabolites (fourteen phase II conjugate metabolites of corilagin, three hydrolyzed metabolites EA, GA, M3 and their seven derived metabolites) were absolutely or tentatively identified in rat biological samples (urine, feces, plasma and tissues) after oral administration of corilagin. In vitro, the three hydrolyzed metabolites were identified in rat intestinal microflora and liver microsomes. These results demonstrated that corilagin itself not only could underwent extensive phase II metabolism in rats, but also could underwent hydrolysis reaction in rats as well as in rat intestinal bacteria and liver microsomes in vitro. This study is first report to identify phase II conjugate metabolites (except mono-methylate conjugated metabolites) of pure Ellagitannin and distribution of these metabolites in vivo. In addition, clear, detailed metabolic pathways of corilagin were shown to involve hydrolysis, methylation, glycosylation, reduction, glucuronidation and sulfation.

Selective blockade of spinal D2DR by levo-corydalmine attenuates morphine tolerance via suppressing PI3K/Akt-MAPK signaling in a MOR-dependent manner

Morphine tolerance remains a challenge in the management of chronic pain in the clinic. As shown in our previous study, the dopamine D2 receptor (D2DR) expressed in spinal cord neurons might be involved in morphine tolerance, but the underlying mechanisms remain to be elucidated. In the present study, selective spinal D2DR blockade attenuated morphine tolerance in mice by inhibiting phosphatidylinositol 3 kinase (PI3K)/serine–threonine kinase (Akt)-mitogen activated protein kinase (MAPK) signaling in a μ opioid receptor (MOR)-dependent manner. Levo-corydalmine (l-CDL), which exhibited micromolar affinity for D2DR in D2/CHO-K1 cell lines in this report and effectively alleviated bone cancer pain in our previous study, attenuated morphine tolerance in rats with chronic bone cancer pain at nonanalgesic doses. Furthermore, the intrathecal administration of l-CDL obviously attenuated morphine tolerance, and the effect was reversed by a D2DR agonist in mice. Spinal D2DR inhibition and l-CDL also inhibited tolerance induced by the MOR agonist DAMGO. l-CDL and a D2DR small interfering RNA (siRNA) decreased the increase in levels of phosphorylated Akt and MAPK in the spinal cord; these changes were abolished by a PI3K inhibitor. In addition, the activated Akt and MAPK proteins in mice exhibiting morphine tolerance were inhibited by a MOR antagonist. Intrathecal administration of a PI3K inhibitor also attenuated DAMGO-induced tolerance. Based on these results, l-CDL antagonized spinal D2DR to attenuate morphine tolerance by inhibiting PI3K/Akt-dependent MAPK phosphorylation through MOR. These findings provide insights into a more versatile treatment for morphine tolerance.

By blocking dopamine receptors located in the spinal cord, a compound found in a traditional Chinese herbal medicine may help mitigate tolerance to morphine, a common problem among cancer patients who regularly take the opioid painkiller. A team led by Ji-Hua Liu and Bo-Yang Yu from China Pharmaceutical University in Nanjing had previously showed that inhibiting dopamine D2 receptors in spinal neurons prevented mice from developing morphine tolerance, but it wasn’t clear why. They have now demonstrated that blocking D2 receptors prevents the relay of cellular signals from morphine-binding “μ-opioid” receptors to mediators of drug tolerance. Levo-corydalmine, a compound isolated from the Asian Corydalis plant, binds and inhibits D2 receptors. When administered directly into the spinal cords of mice and rats, it blocked downstream signaling, reducing morphine tolerance.

Metabolic profiles of corydaline in rats by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

1. Corydaline, an isoquinoline alkaloid obtained from the rhizomes of Corydalis yanhusuo, exhibits anti-acetylcholinesterase, anti-angiogenic, anti-allergic and gastric-emptying activities. In this study, a rapid and reliable ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS) method was developed and employed for the comprehensive study of the metabolites of corydaline in rats. 2. Altogether, 43 metabolites were identified in the plasma (11), bile (9), urine (34) and feces (21) of rats after oral administration of corydaline at a dose of 4.5mg/kg. 3. It was demonstrated that demethylation, hydroxylation, sulfation and glucuronidation were the major metabolic transformation pathways. Among these, two metabolites were identified as tetrahydropalmatine and isocorybulbine, and 33 phase I and phase II products were inferred to be new metabolites arising from the in vivo metabolism of corydaline. 4. Importantly, this research provides scientific and reliable support for full understanding of the metabolic profiles of corydaline and the results could help to elucidate its safety and efficacy.

The electrochemical behaviors of tetrahydropalmatine at a nickel nanoparticles/sulfonated graphene sheets modified glassy carbon electrode

A novel electrochemical sensor was fabricated to determine THP under optimum conditions, with a considerable repeatability, stability and sensitivity. This method has a similar recovery and RSD compared with HPLC.