Determination of paeonol in rat plasma by high-performance liquid chromatography and its application to pharmacokinetic studies following oral administration of Moutan cortex decoction

Pharmacological effects and mechanisms of paeonol on antitumor and prevention of side effects of cancer therapy

Cancer represents one of the leading causes of mortality worldwide. Conventional clinical treatments include radiation therapy, chemotherapy, immunotherapy, and targeted therapy. However, these treatments have inherent limitations, such as multidrug resistance and the induction of short- and long-term multiple organ damage, ultimately leading to a significant decrease in cancer survivors' quality of life and life expectancy. Paeonol, a nature active compound derived from the root bark of the medicinal plant Paeonia suffruticosa, exhibits various pharmacological activities. Extensive research has demonstrated that paeonol exhibits substantial anticancer effects in various cancer, both in vitro and in vivo. Its underlying mechanisms involve the induction of apoptosis, the inhibition of cell proliferation, invasion and migration, angiogenesis, cell cycle arrest, autophagy, regulating tumor immunity and enhanced radiosensitivity, as well as the modulation of multiple signaling pathways, such as the PI3K/AKT and NF-κB signaling pathways. Additionally, paeonol can prevent adverse effects on the heart, liver, and kidneys induced by anticancer therapy. Despite numerous studies exploring paeonol's therapeutic potential in cancer, no specific reviews have been conducted. Therefore, this review provides a systematic summary and analysis of paeonol's anticancer effects, prevention of side effects, and the underlying mechanisms involved. This review aims to establish a theoretical basis for the adjunctive strategy of paeonol in cancer treatment, ultimately improving the survival rate and enhancing the quality of life for cancer patients.

Traditional uses, phytochemistry, pharmacology, and pharmacokinetics of the root bark of Paeonia x suffruticosa andrews: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Moutan Cortex (MC), commonly known as "Mu dan pi", refers to the dried root bark of Paeonia x suffruticosa Andrews and is broadly used as a traditional herbal medication in China, Japan, and Korea. For thousands of years, it has been utilized to treat female genital, extravasated blood, cardiovascular, and stagnant blood disorders.

AIM OF THE REVIEW

The purpose of this review article was to summarize information on the traditional uses, phytochemistry, pharmacology and pharmacokinetics of MC, as well as to outline the further research directions for the development of new drugs and the associations between traditional uses and pharmacological effects.

MATERIALS AND METHODS

The information involved in the study was gathered from a variety of electronic resources, including PubMed, Web of Science, ScienceDirect, SciFinder, China Knowledge Resource Integrated Database, and Google Scholar. The date was from 1992 to 2022.

RESULTS

Approximately 163 chemical compounds have been extracted and identified from MC, including monoterpenes, monoterpene glycosides, triterpenes, phenolics, flavonoids, volatile oils, alkaloids, and others. In these categories, the monoterpene glycosides and phenols being the most common. A wide variety of pharmacological effects have been described for MC crude extracts and active molecules, such as antioxidant, anti-inflammatory, antibacterial and antiviral, antitumor, antidiabetic, organ protection, and neuroprotective activities, as well as treating cardiovascular diseases. Pharmacokinetics has been also used in the study of MC, including its crude extracts or chemical constituents, in order to explore the therapeutic mechanism, direct clinically appropriate application and provide new ideas for the exploitation of innovative medicines.

CONCLUSION

Modern pharmacological research has demonstrated that MC, as a significant therapeutic resource, has the ability to heal a wide range of diseases, particularly female genital and cardiovascular problems. These researches propose therapeutic ideas for the development of novel MC medicines. Furthermore, preclinical and clinical study have verified several observed pharmacological properties related with the traditional usages of MC.

Integrating pharmacokinetics and network analysis to investigate the mechanism of Moutan Cortex in blood-heat and blood stasis syndrome

Background

Raw Moutan Cortex (RMC) has been used in China and other Asian countries for thousands of years. Its medical application is the treatment of cooling blood and promoting blood circulation. However, its therapeutic mechanism is still undefined.

Methods

In this study, the pharmacokinetics strategy that integrated network analysis was employed to explore the mechanism of RMC in blood-heat and blood stasis syndrome (BHS) model rats. Firstly, Ultra-High performance Liquid Chromatography coupled with Diode Array Detector (UHPLC-DAD) method was developed to determine nine absorbed compounds in rat serum in BHS and normal rats after oral administration of RMC extract respectively. Then the pharmacology network was established based on the relationship between nine compounds absorbed into the blood and BHS targets. Finally, the predicted hub targets were validated experimentally in human umbilical vein endothelial cells (HUVECs).

Results

Pharmacokinetic study showed that the pharmacokinetic parameters of nine absorbed compounds had significant differences between BHS and normal groups (p < 0.05). Network analysis showed that 8 target genes, namely, F2, F10, F7, PLAU, MAPK14, MAPK10, AKT1, and NOS3 may be the primary targets regulated by RMC for the treatment of BHS. Among them, targets (F2, F10, F7 and MAPK14, MAPK10, AKT) and 4 active ingredients (paeonol, paeoniflorin, quercetin and oxypaeoniflorin) were selected for evaluating the reliability in vitro experiments, which revealed that the mechanism of RMC against BHS syndrome may inhibit inflammatory pathways and regulate coagulation cascades pathway for cooling and promoting blood circulation.

Conclusion

The proposed pharmacokinetics study integrated network analysis strategy provides a combination method to explore the therapeutic mechanism of RMC on BHS.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00657-w.

Paeonol protects against doxorubicin-induced cardiotoxicity by promoting Mfn2-mediated mitochondrial fusion through activating the PKCε-Stat3 pathway

INTRODUCTION

The anti-cancer medication doxorubicin (Dox) is largely restricted in clinical usage due to its significant cardiotoxicity. The only medication approved by the FDA for Dox-induced cardiotoxicity is dexrazoxane, while it may reduce the sensitivity of cancer cells to chemotherapy and is restricted for use. There is an urgent need for the development of safe and effective medicines to alleviate Dox-induced cardiotoxicity.

OBJECTIVES

The objective of this study was to determine whether Paeonol (Pae) has the ability to protect against Dox-induced cardiotoxicity and if so, what are the underlying mechanisms involved.

METHODS

Sprague-Dawley rats and primary cardiomyocytes were used to create Dox-induced cardiotoxicity models. Pae's effects on myocardial damage, mitochondrial function, mitochondrial dynamics and signaling pathways were studied using a range of experimental methods.

RESULTS

Pae enhanced Mfn2-mediated mitochondrial fusion, restored mitochondrial function and cardiac performance both in vivo and in vitro under the Dox conditions. The protective properties of Pae were blunted when Mfn2 was knocked down or knocked out in Dox-induced cardiomyocytes and hearts respectively. Mechanistically, Pae promoted Mfn2-mediated mitochondria fusion by activating the transcription factor Stat3, which bound to the Mfn2 promoter in a direct manner and up-regulated its transcriptional expression. Furthermore, molecular docking, surface plasmon resonance and co-immunoprecipitation studies showed that Pae's direct target was PKCε, which interacted with Stat3 and enabled its phosphorylation and activation. Pae-induced Stat3 phosphorylation and Mfn2-mediated mitochondrial fusion were inhibited when PKCε was knocked down. Furthermore, Pae did not interfere with Dox's antitumor efficacy in several tumor cells.

CONCLUSION

Pae protects the heart against Dox-induced damage by stimulating mitochondrial fusion via the PKCε-Stat3-Mfn2 pathway, indicating that Pae might be a promising therapeutic therapy for Dox-induced cardiotoxicity while maintaining Dox's anticancer activity.

Paeonol promotes Opa1-mediated mitochondrial fusion via activating the CK2α-Stat3 pathway in diabetic cardiomyopathy

Diabetes disrupts mitochondrial function and often results in diabetic cardiomyopathy (DCM). Paeonol is a bioactive compound that has been reported to have pharmacological potential for cardiac and mitochondrial protection. This study aims to explore the effects of paeonol on mitochondrial disorderes in DCM and the underlying mechanisms. We showed that paeonol promoted Opa1-mediated mitochondrial fusion, inhibited mitochondrial oxidative stress, and preserved mitochondrial respiratory capacity and cardiac performance in DCM in vivo and in vitro. Knockdown of Opa1 blunted the above protective effects of paeonol in both diabetic hearts and high glucose-treated cardiomyocytes. Mechanistically, inhibitor screening, siRNA knockdown and chromatin immunoprecipitation experiments showed that paeonol-promoted Opa1-mediated mitochondrial fusion required the activation of Stat3, which directly bound to the promoter of Opa1 to upregulate its transcriptional expression. Moreover, pharmmapper screening and molecular docking studies revealed that CK2α served as a direct target of paeonol that interacted with Jak2 and induced the phosphorylation and activation of Jak2-Stat3. Knockdown of CK2α blunted the promoting effect of paeonol on Jak2-Stat3 phosphorylation and Opa1-mediated mitochondrial fusion. Collectively, we have demonstrated for the first time that paeonol is a novel mitochondrial fusion promoter in protecting against hyperglycemia-induced mitochondrial oxidative injury and DCM at least partially via an Opa1-mediated mechanism, a process in which paeonol interacts with CK2α and restores its kinase activity that subsequently increasing Jak2-Stat3 phosphorylation and enhancing the transcriptional level of Opa1. These findings suggest that paeonol or the promotion of mitochondrial fusion might be a promising strategy for the treatment of DCM.

Nine absorbed components pharmacokinetic of raw and processed Moutan Cortex in normal and blood-heat and hemorrhage syndrome model rats

Raw Moutan Cortex (RMC) and Processed Moutan Cortex (PMC) have a long history of use in China and other Asian countries. In this study, a rapid and accurate ultra-high-pressure liquid chromatography coupled with diode array detector (UHPLC-DAD) method was developed and validated for the simultaneous determination of nine absorbed compounds of RMC/PMC. After extraction by protein precipitation with methanol from plasma, the analytes were separated on an Acquity UPLC® BEH Shield RP₁₈ column (2.1 × 100 mm, 1.7 μm, Waters, USA). Acetonitrile (A) and 0.1% (v/v) formic acid in water (B) were selected as the mobile phase to perform gradient elution. The linearity of nine analytes was >0.9915. The intra- and inter-assay precision (RSD) values were within 11.18%, and accuracy ranged from 91.32 to 101.29%. Suitable stability, matrix effect and extraction recoveries were also obtained. The validated method was applied to compare the pharmacokinetics of RMC and PMC in Blood-Heat and Hemorrhage Syndrome Model and normal rats. The results revealed that processing and the pathological state could influence the pharmacokinetic characteristics of compounds in RMC/PMC. The study willbe useful for further studies on pharmacokinetics and clinical application of raw and processed Moutan Cortex.

Paeonol, an Ingredient of Kamishoyosan, Reduces Intracellular Lipid Accumulation by Inhibiting Glucocorticoid Receptor Activity in 3T3-L1 Cells

Excessive triglyceride accumulation in lipid-metabolizing tissues is associated with an increased risk of a variety of metabolic diseases. Kamishoyosan (KSS) is a Kampo composed of 10 constituent herbs, and contains moutan cortex (MC) and paeonol (PN) as the major ingredient of MC. Here, we demonstrate the molecular mechanism underlying the effect of KSS on the differentiation of mouse preadipocytes (3T3-L1 cells). KSS inhibited the accumulation of triglycerides in a dose-dependent manner in 3T3-L1 cells that were induced to differentiate into adipocytes. We also found that MC and PN were responsible for the anti-adipogenetic effect of KSS and significantly suppressed the expression of CCAAT/enhancer-binding proteins-δ (C/EBP-δ) mRNA 3 days after the induction of differentiation. Thus, PN may contribute to the anti-adipogenetic property of MC in 3T3-L1 cells. In addition, PN inhibited dexamethasone (Dex)-induced glucocorticoid receptor (GR) promoter activity. Taken together, these results suggest that PN suppresses C/EBP-δ expression by inhibiting Dex-induced GR promoter activity at the early stage of differentiation and, consequently, delays differentiation into mature adipocytes. Our results suggest that the habitual intake of Kampo-containing PN contributes to the prevention of the onset of metabolic diseases by decreasing the excessive accumulation of triglycerides in lipid-metabolizing tissues.

Design, synthesis, and antitumor activity of novel paeonol derivatives containing the 1,4-benzoxazinone and 1,2,3-triazole moieties

A new series of paeonol derivatives containing the 1,4-benzoxazinone and 1,2,3-triazole moieties were synthesized and evaluated for their cytotoxicity in vitro against human non-small cell lung cancer NCI-H1299 cells and human cervical carcinoma HeLa cells. Among them, compared with that of paeonol, compounds 8-acetyl-4-{[(1-(5-chloro-2-nitrophenyl)-1 H-1,2,3-triazol-4-yl]methyl}-5-methoxy-2 H-1,4-benzoxazin-3(4 H)-one, 8-acetyl-4-[(1-mesityl-1 H-1,2,3-triazol-4-yl)methyl]-5-methoxy-2 H-1,4-benzoxazin-3(4 H)-one, and 8-acetyl-5-methoxy-4-{[(1-(naphthalen-1-yl)-1 H-1,2,3-triazol-4-yl]methyl}-2 H-1,4-benzoxazin-3(4 H)-one exhibited significant inhibitory activity toward the human non-small cell lung cancer NCI-H1299 cells (IC50 = 13.36 ± 0.003, 19.75 ± 0.3, 15.79 ± 0.05 μg mL−1). The last compound also exhibited significant inhibitory activity toward the human cervical carcinoma HeLa cells (IC50 = 19.73 ± 1.0 μg mL−1).

Beneficial Effects Exerted by Paeonol in the Management of Atherosclerosis

Atherosclerosis, a chronic luminal stenosis disorder occurred in large and medium arteries, is the principle pathological basis of cardiovascular diseases with the highest morbidity and mortality worldwide. In oriental countries, traditional Chinese medicine Cortex Moutan has been widely used for the treatment of atherosclerosis-related illnesses for thousands of years. Paeonol, a bioactive monomer extracted from Cortex Moutan, is an important pharmacological component responsible for the antiatherosclerotic effects. Numerous lines of findings have established that paeonol offers beneficial roles against the initiation and progression of atherosclerotic lesions through inhibiting proatherogenic processes, such as endothelium damage, chronic inflammation, disturbance of lipid metabolism, uncontrolled oxidative stress, excessive growth, and mobilization of vascular smooth muscle cells as well as abnormality of platelet activation. Investigations identifying the atheroprotective effects of paeonol present substantial evidence for potential clinical application of paeonol as a therapeutic agent in atherosclerosis management. In this review, we summarize the antiatherosclerotic actions by which paeonol suppresses atherogenesis and provide newly insights into its atheroprotective mechanisms and the future clinical practice.

Focusing on claudin-5: A promising candidate in the regulation of BBB to treat ischemic stroke

Claudin-5 is a tight junction (TJ) protein in the blood-brain barrier (BBB) that has recently attracted increased attention. Numerous studies have demonstrated that claudin-5 regulates the integrity and permeability of the BBB. Increased claudin-5 expression plays a neuroprotective role in neurological diseases, particularly in cerebral ischemic stroke. Moreover, claudin-5 might be a potential marker for early hemorrhagic transformation detection in ischemic stroke. In light of the distinctive effects of claudin-5 on the nervous system, we present the elaborate network of roles that claudin-5 plays in ischemic stroke. In this review, we first introduce basic knowledge regarding the BBB and the claudin family, the characterization and regulation of claudin-5, and association between claudin-5 and other TJ proteins. Subsequently, we describe BBB dysfunction and neuron-specific drivers of pathogenesis of ischemic stroke, including inflammatory disequilibrium and oxidative stress. Furthermore, we summarize promising ischemic stroke treatments that target the BBB via claudin-5, including modified rt-PA therapy, pharmacotherapy, hormone treatment, receptor-targeted therapy, gene therapy, and physical therapy. This review highlights recent advances and provides a comprehensive summary of claudin-5 in the regulation of the BBB and may be helpful for drug design and clinical therapy for treatment of ischemic stroke.

Role of Paeonol in an Astrocyte Model of Parkinson's Disease

Background

Parkinson’s disease (PD) is characterized by a progressive degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). Inflammation and neural degeneration are implicated in the pathogenesis of PD. Paeonol has been verified to attenuate inflammation.

Material/Methods

1-methyl-4-phenylpyridnium ion (MPP+, 100 μM) was used to induce the cell model of PD in primary cultured astrocytes. Astrocyte cell viability and apoptosis were determined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry (FCM), respectively. Protein levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthases (iNOS) in culture medium were tested by enzyme-linked immunosorbent (ELISA) assay. Protein levels of casapse-1, COX2, iNOS, B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2, and phosphorylated Jun N-terminal kinase (p-JNK)/phosphorylated extracellular signal-regulated kinase (p-ERK)/p-P38 were examined by Western blot.

Results

Pretreatment with paeonol remarkably rescued MPP+-induced cell viability reduction, up-regulation of cell apoptosis, caspase-1 activity, COX-2, iNOS, and Bax/Bcl-2 ratio in primary astrocytes. Furthermore, paeonol repressed MPP+ -induced elevation of p-JNK/p-ERK in primary cultured astrocytes.

Conclusions

The present study found that paeonol protected cells from apoptosis by repressing the activation of the JNK/ERK related signalling pathway induced by MPP+ in astrocytes. We propose that paeonol is a neuroprotective agent for the treatment of PD patients, with great promise in the future.

Recent Advances in Traditional Chinese Medicine for Kidney Disease

Because current treatment options for chronic kidney disease (CKD) are limited, many patients seek out alternative therapies such as traditional Chinese medicine. However, there is a lack of evidence from large clinical trials to support the use of traditional medicines in patients with CKD. Many active components of traditional medicine formulas are undetermined and their toxicities are unknown. Therefore, there is a need for research to identify active compounds from traditional medicines and understand the mechanisms of action of these compounds, as well as their potential toxicity, and subsequently perform well-designed, randomized, controlled, clinical trials to study the efficacy and safety of their use in patients with CKD. Significant progress has been made in this field within the last several years. Many active compounds have been identified by applying sophisticated techniques such as mass spectrometry, and more mechanistic studies of these compounds have been performed using both in vitro and in vivo models. In addition, several well-designed, large, randomized, clinical trials have recently been published. We summarize these recent advances in the field of traditional medicines as they apply to CKD. In addition, current barriers for further research are also discussed. Due to the ongoing research in this field, we believe that stronger evidence to support the use of traditional medicines for CKD will emerge in the near future.

Design, Synthesis and Antifungal Activity of Novel Paeonol Derivatives Linked with 1,2,3-Triazole Moiety by the Click Reaction

For obtaining novel bioactive compounds with significant antifungal activities, a series of novel paeonol derivatives linked with a 1,2,3-triazole moiety have been designed and synthesised by a click reaction under mild conditions using Cu(OAc)2·H2O/sodium ascorbate as a catalyst. The antifungal activities of all the target compounds were evaluated in vitro against two plant pathogenic fungi, Colletotrichum capsici and Rhizoctonia cerealis. Preliminary results indicated that 1-(4-methoxy-2-{[1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl]-methoxy}phenyl)ethanone showed the best antifungal activities against C. capsici, while 1-(2-{[1-(2-fuorophenyl)-1H-1,2,3-triazol-4-yl]methoxy}-4-methoxyphenyl)ethanone and 1-(4-methoxy-2-{[1-(o-tolyl)-1H-1,2,3-triazol-4-yl]methoxy}phenyl)ethanone were found to have better antifungal activities against the tested two fungi. All the synthesised compounds have been determined by IR, HR MS and NMR spectra.

Binding of paeonol to human serum albumin: a hybrid spectroscopic approach and conformational study

The purpose of this study was to elucidate the binding of paeonol to human serum albumin (HSA) through spectroscopic methods. The fluorescence quenching of HSA by paeonol was a result of the formation of the HSA-paeonol complex with low binding affinity (K = 4.45 × 10(3) M(-1) at 298 K). Thermodynamic parameters (ΔG(°) = -2.08 × 10(4) J · mol(-1), ΔS(°) = 77.9 J · mol(-1) · K(-1), ΔH(°) = 2.41 × 10(3) J · mol(-1), kq = 9.67 × 10(12) M(-1) · s(-1)) revealed that paeonol mainly binds HSA through hydrophobic force following a static quenching mode. The binding distance was estimated to be 1.91 nm by fluorescence resonant energy transfer. The conformation of HSA was changed and aggregates were formed in the presence of paeonol, revealed by synchronous fluorescence, circular dichroism, Fourier transform infrared spectroscopy, three-dimensional fluorescence spectroscopy, and resonance light scattering results.

Synthesis, vibrational, NMR, quantum chemical and structure-activity relation studies of 2-hydroxy-4-methoxyacetophenone

The stable geometry of 2-hydroxy-4-methoxyacetophenone is optimised by DFT/B3LYP method with 6-311++G(∗∗) and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the optimised geometry have been determined. The effects of substituents (hydroxyl, methoxy and acetyl groups) on the benzene ring vibrational frequencies are analysed. The vibrational frequencies of the fundamental modes of 2-hydroxy-4-methoxyacetophenone have been precisely assigned and analysed and the theoretical results are compared with the experimental vibrations. 1H and 13C NMR isotropic chemical shifts are calculated and assignments made are compared with the experimental values. The energies of important MO's, the total electron density and electrostatic potential of the compound are determined. Various reactivity and selectivity descriptors such as chemical hardness, chemical potential, softness, electrophilicity, nucleophilicity and the appropriate local quantities are calculated.

Competitive molecular interaction among paeonol-loaded liposomes: differential scanning calorimetry and synchrotron X-ray diffraction studies

Thermotropic phase behavior of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes containing 5 mol% cholesterol, or 5 mol% stigmasterol, or 5 mol% paeonol have been investigated by differential scanning calorimetry (DSC) and synchrotron X-ray diffraction (XRD) techniques, to investigate the competitive molecular interaction among paeonol-loaded liposomes. The results show that both sterol and paeonol can incorporate into hydrophobic region and interact with acyl chains of DPPC. Both 5 mol% sterols and 5 mol% paeonol can promote the formation of rippled gel phase of DPPC liposomes at room temperature. 5 mol% paeonol can induce the occurrence of phase separation in DPPC liposomes, but 5 mol% cholesterol or 5 mol% stigmasterol cannot induce this phenomenon. Both the repeat distance and the correlation length of paeonol-poor domain are larger than those of coexisted paeonol-rich domain. Both calorimetric data and SAXS patterns show that sterols have more favorable, stabilizing interactions with DPPC than paeonol, implying that high concentrations of sterols will have a negative effect on the loading of paeonol. In addition, calorimetric data show that cholesterol have a little more favorable, stabilizing interactions with DPPC than stigmasterol. The results of this study will play an important role in optimizing the formulation of paeonol-loaded liposomes.

Electrochemical oxidation and detection of paeonol on modified electrode with acetylene black nanoparticles

With an aim to construct a sensing platform for the electrochemical detection of paeonol, we modified the glassy carbon electrode with acetylene black nanoparticle (AB). A sensitive oxidation peak of paeonol was observed with remarkably increased peak current on the modified electrode because the electrode has a big surface area due to three dimensional structure of AB nanoparticles. The optimization of detection conditions was performed, including pH value of the buffer, the amount of AB nanoparticles on the electrode surface, the accumulation potential and time of paeonol. Under the optimized conditions, the oxidation peak current of paeonol increased linearly with its concentration over the range from 5×10(-7) to 1×10(-4) M. The detection limit was calculated to be 1×10(-7) M. The modified electrode was successfully applied to detect the content of paeonol in cortex moutan, a common traditional Chinese medicine. The method is new, sensitive, rapid and convenient for the detection of paeonol.

APRESS: apical regulatory super system, serotonin, and dopamine interaction

BACKGROUND

THE MONOAMINES SEROTONIN AND DOPAMINE ARE KNOWN TO EXIST IN TWO SEPARATE STATES: the endogenous state and the competitive inhibition state. The presence of the competitive inhibition state has been known to science for many years, but from a functional standpoint it has been noted in the literature as being "meaningless."

METHODS

A large database of monoamine transporter response to amino acid precursor administration variations with clinical outcomes was accumulated. In the process, a new organic cation transporter (OCT) model has been published, and OCT functional status determination along with amino acid precursor manipulation methods have been invented and refined.

RESULTS

Methodology was developed whereby manipulation of the OCT, in the competitive inhibition state, is carried out in a predictable manner. This, in turn, has disproved the long-held assertion that the monoamine competitive inhibition state is functionally meaningless.

CONCLUSION

The most significant aspect of this paper is the documentation of newly recognized relationships between serotonin and dopamine. When transport of serotonin and dopamine are both in the competitive inhibition state, manipulation of the concentrations of one will lead to predictable changes in concentrations of the other. From a functional standpoint, processes regulated and controlled by changes to only serotonin can now be controlled by changes to dopamine, and vice versa, in a predictable manner.

Action potential bursts in central snail neurons elicited by paeonol: roles of ionic currents

AIM

to investigate the effects of 2'-hydroxy-4'-methoxyacetophenone (paeonol) on the electrophysiological behavior of a central neuron (right parietal 4; RP4) of the giant African snail (Achatina fulica Ferussac).

METHODS

intracellular recordings and the two-electrode voltage clamp method were used to study the effects of paeonol on the RP4 neuron.

RESULTS

the RP4 neuron generated spontaneous action potentials. Bath application of paeonol at a concentration of ≥ 500 micromol/L reversibly elicited action potential bursts in a concentration-dependent manner. Immersing the neurons in Co(2+)-substituted Ca(2+)-free solution did not block paeonol-elicited bursting. Pretreatment with the protein kinase A (PKA) inhibitor KT-5720 or the protein kinase C (PKC) inhibitor Ro 31-8220 did not affect the action potential bursts. Voltage-clamp studies revealed that paeonol at a concentration of 500 micromol/L had no remarkable effects on the total inward currents, whereas paeonol decreased the delayed rectifying K(+) current (I(KD)) and the fast-inactivating K(+) current (I(A)). Application of 4-aminopyridine (4-AP 5 mmol/L), an inhibitor of I(A), or charybdotoxin 250 nmol/L, an inhibitor of the Ca(2+)-activated K(+) current (I(K(Ca))), failed to elicit action potential bursts, whereas tetraethylammonium chloride (TEA 50 mmol/L), an I(KD) blocker, successfully elicited action potential bursts. At a lower concentration of 5 mmol/L, TEA facilitated the induction of action potential bursts elicited by paeonol.

CONCLUSION

paeonol elicited a bursting firing pattern of action potentials in the RP4 neuron and this activity relates closely to the inhibitory effects of paeonol on the I(KD).

Paeonol pharmacokinetics in the rat following i.m. administration

The pharmacokinetic behavior and bioavailability of paeonol were determined after a single intramuscular (i.m.) injection of 10 mg/kg to rats. Plasma paeonol concentrations were measured by high performance liquid chromatography (HPLC). The main pharmacokinetic parameters were as follows: mean elimination half-life (t(1/2z)) 59.85 +/- 10.23 min, time to reach peak concentration (Tmax) 7.50 +/- 2.74 min, maximum concentration (Cmax) 0.71 +/- 0.13 mg/l, total body clearance (CLz) 0.24 +/- 0.03 l/min/kg, the area under concentration-time curve from 0 to 4 h (AUC(0-4h)) 39.01 +/- 5.69 mg/l x min, the area under concentration-time curve from 0 to infinity (AUC(0-infinity)) 43.06 < or = 6.10 mg/l x min. The absolute bioavailability of paeonol after i.m. administration amounted to 68.68%.

Study on the pharmacokinetics and metabolism of paeonol in rats treated with pure paeonol and an herbal preparation containing paeonol by using HPLC-DAD-MS method

Paeonol, a principal bioactive component of the Chinese herb Moutan Cortex with anti-inflammatory and analgesic effects, was comparatively studied to determine its pharmacokinetic behavior and metabolic profile in rat following oral administration of the pure paeonol alone and an herbal preparation "Qingfu Guanjieshu" (QFGJS) containing paeonol. An HPLC-DAD method was developed and validated for determining the concentration of paeonol in rat plasma. The in vivo time curves and AUC of paeonol at three doses were increased in a dose-dependent manner, while the pharmacokinetic parameters of paeonol in QFGJS at a comparable dosage were significantly elevated in comparison with those of pure paeonol. By using LC-Q/TOF-MS technique, four metabolites of paeonol were identified in plasma at 5min after dosing, with T(max) around 20min after treatment with the pure paeonol or QFGJS. Interestingly, relative concentrations of metabolites P2, P3 and P5 were markedly increased in plasma of rats treated with QFGJS compared with those of pure paeonol. These results indicate that other components in QFGJS could effectively influence the pharmacokinetic behavior and metabolic profile of paeonol in rats. The current studies emphasize the significance of the research toward an understanding of pharmacokinetic interactions of the co-existing components in the herbal preparations.

Fast determination of paeonol in plasma by headspace solid-phase microextraction followed by gas chromatography–mass spectrometry

Paeonol is the active component in the traditional Chinese medicines (TCMs), such as Cynanchum paniculatum, which has been used to treat many diseases, such as eczema. In this work, a simple, rapid and sensitive method was developed for the determination of paeonol in rabbit plasma, which was based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The extraction parameters of fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized; the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg mL(-1), R(2)>0.990), low detection limit (2.0 ng mL(-1)) and good precision (R.S.D. value less than 8%). Finally, GC/MS following HS-SPME was applied to fast determination of paeonol in rabbit plasma at different time point after oral demonstration of Cynanchum paniculatum essential oil. The experimental results suggest that the proposed method provided an alternative and novel approach to the pharmacokinetics study of paeonol in the TCMs.

Identification and analysis of absorbed and metabolic components in rat plasma after oral administration of 'Shuangdan' granule by HPLC-DAD-ESI-MS/MS

A valid method using liquid chromatography-diode array detection-electrospray ionization (ESI) ion trap mass spectrometry was established for the study of the absorbed and metabolic components of a Chinese medicine 'Shuangdan' granule in rat plasma after oral administration. The plasma samples were acidified with 1M hydrochloric acid and extracted with ethyl acetate (EtOAc) of two-fold volume for three times. The chromatographic separation was carried out on a Zorbax SB-C18 column with a linear gradient whereas 0.1% acetic acid/water/acetonitrile was used as mobile phase. Mass spectra were acquired in both negative and positive modes. More than 20 components including 16 components from 'Shuangdan' granule and 5 metabolites were simultaneously identified by comparing their mass spectra and retention behavior with reference compounds or literature data. The results proved that the established method could be used to identify the structure of active components responsible for the pharmacological effects of 'Shuangdan' granule.

Isothermal titration calorimetry and 1H NMR studies on host–guest interaction of paeonol and two of its isomers with β-cyclodextrin

Thermodynamic parameters of inclusion complex of beta-cyclodextrin (beta-CD) with paeonol and two of its isomers in aqueous solution have been determined with nano-watt-order isothermal titration calorimetry (ITC) and the host-guest inclusion structure has been investigated by using 1H NMR spectra at 298.2 K. The analysis of thermodynamic data reveals that stoichiometry of beta-CD complex with paeonol (Pae) or acetovanillone (Ace) is 1:1 whereas the inclusion complex of beta-CD with 2-hydroxyl-5-methoxyacetophone (Hma) is in 1:1 coexistence with 2:1 stoichiometry. Further analysis indicates that formation of all the complexes is simultaneously driven by enthalpy and entropy, the inclusion complexation of Pae.beta-CD, Ace.beta-CD and Ham.beta-CD2 is predominantly driven by entropy while Ham.beta-CD by enthalpy. The 1H NMR spectra data provide clear evidence of the inclusion phenomena, which shows that the aromatic ring of the guest molecule insert itself into the torus from the narrow side of the cavity.

Simultaneous determination of cinnamaldehyde, eugenol and paeonol in traditional Chinese medicinal preparations by capillary GC-FID

A capillary GC method was established for simultaneous determination of cinnamaldehyde (CNMD), eugenol (EL) and paeonol (PL) in two traditional Chinese herbal medicinal preparations, Weitongding tablet (WTDT) and Guifu Dihuang pill (GDHP). The assays were based on a programmed temperature GC in a 30 m x 0.53 mm capillary column with nitrogen as carrier and FID detector. Good linearities were obtained over ranges of 0.45-452 mg/l CNMD, 0.31-625 mg/l EL and 0.30-610 mg/l PL, respectively. The spike recoveries were within 84-111%.

Development of microwave-assisted extraction followed by headspace single-drop microextraction for fast determination of paeonol in traditional Chinese medicines

Paeonol is an important active component present in traditional Chinese medicines (TCMs), which was used for the treatment of many diseases such as eczema. In this work, microwave-assisted extraction (MAE) was firstly combined with headspace single-drop microextraction (HS-SDME), and applied to rapid determination of paeonol in two TCMs of Cynanchum paniculatum and Paeonia suffruticosa. In the proposed method, paeonol in TCMs was isolated by using MAE, followed by extraction and concentration by HS-SDME, and detected by gas chromatography-mass spectrometry (GC-MS). The experiment parameters of MAE and HS-SDME were discussed, and the method precision, recovery and detection limit were also studied. To further demonstrate the reliability of the quantification, both the proposed method and a standard method of steam distillation (SD) were simultaneously applied to quantitative analysis of paeonol in TCM samples from different growing areas. The experimental results show that MAE-HS-SDME is a simple and rapid method for the quantitative analysis of paeonol in TCMs, and is also a potential and alternative tool for quality monitoring for the two TCMs of C. paniculatum and P. suffruticosa.

Extraction of paeonol fromJisheng Shenqi Wan using supercritical fluid extraction

Supercritical carbon dioxide with or without methanol and 95% ethanol modifiers was used to extract paeonol from the pills of Jisheng Shenqi Wan and high-performance liquid chromatography (HPLC) was used to analyze the extract. The effect of temperature and pressure on the yield of paeonol was tested. The results show that the recovery of paeonol was improved by adding a polar modifier, such as methanol and 95% ethanol in supercritical fluid. The yield obtained after 120 min extraction with 95% ethanol modified-supercritical carbon dioxide was the highest (1.51, w/w at 60 degrees C and 400 bar), while that obtained with supercritical carbon dioxide only at 40 degrees C was the lowest from 0.67 to 0.83 over a range of 200-600 bar.

Determination of glycosides and sugars in Moutan Cortex by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of paeoniflorin, sucrose, paeonoside, glucose, and fructose in Moutan Cortex for the first time. Effects of several important factors such as the concentration of NaOH, separation voltage, injection time, and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 300 microm diameter copper disc electrode at a working potential of +0.60 V (versus saturated calomel electrode (SCE)). The five analytes can be well-separated within 12 min in a 40 cm length fused silica capillary at a separation voltage of 12 kV in a 75 mM NaOH aqueous solution. The relation between peak current and analyte concentration was linear over about 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.9 to 1.3 microM for all analytes. The proposed method has been successfully applied to monitor glycoside and sugar contents in the real plant samples with satisfactory assay results.

Determination of Three Bioactive Constituents in Moutan Cortex by Capillary Electrophoresis with Electrochemical Detection

Capillary electrophoresis with electrochemical detection has been employed for the separation and determination of the three active constituents (paeonol, benzoyloxypaeoniflorin, and oxypaeoniflorin) in traditional Chinese medicine, Moutan Cortex (root cortex of Paeonia suffruticosa Andrews). The effects of several important factors, such as the concentration of running buffer, the separation voltage, the injection time, and the detection potential, were investigated to determine the optimum conditions. The detection electrode was a 300 microm diameter carbon-disc electrode at a working potential of +0.90 V (versus SCE). The three analytes could be well separated within 7 min in a 40 cm length fused-silica capillary at a separation voltage of 12 kV in a 50 mM borate buffer (pH 9.2). The relation between the peak current and the analyte concentration was linear over 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.4 to 0.7 microM for all analytes. The proposed method has been successfully applied to the determination of paeonol, benzoyloxypaeoniflorin, and oxypaeoniflorin in real plant samples with satisfactory assay results.