Quantitative determination of periplocymarin in rat plasma and tissue by LC-MS/MS: application to pharmacokinetic and tissue distribution study

Inhibition of the HIF-1 Survival Pathway as a Strategy to Augment Photodynamic Therapy Efficacy

Photodynamic therapy (PDT) is a non-to-minimally invasive treatment modality that utilizes photoactivatable drugs called photosensitizers to disrupt tumors with locally photoproduced reactive oxygen species (ROS). Photosensitizer activation by light results in hyperoxidative stress and subsequent tumor cell death, vascular shutdown and hypoxia, and an antitumor immune response. However, sublethally afflicted tumor cells initiate several survival mechanisms that account for decreased PDT efficacy. The hypoxia inducible factor 1 (HIF-1) pathway is one of the most effective cell survival pathways that contributes to cell recovery from PDT-induced damage. Several hundred target genes of the HIF-1 heterodimeric complex collectively mediate processes that are involved in tumor cell survival directly and indirectly (e.g., vascularization, glucose metabolism, proliferation, and metastasis). The broad spectrum of biological ramifications culminating from the activation of HIF-1 target genes reflects the importance of HIF-1 in the context of therapeutic recalcitrance. This chapter elaborates on the involvement of HIF-1 in cancer biology, the hypoxic response mechanisms, and the role of HIF-1 in PDT. An overview of inhibitors that either directly or indirectly impede HIF-1-mediated survival signaling is provided. The inhibitors may be used as pharmacological adjuvants in combination with PDT to augment therapeutic efficacy.

Simultaneous determination of periplocin, periplocymarin, periplogenin, periplocoside M and periplocoside N of Cortex Periplocae in rat plasma and its application to a pharmacokinetic study

A sensitive and specific ultra-performance liquid chromatographic-tandem mass spectrometric method was developed and validated to simultaneously determine periplocin, periplocymarin (PM), periplogenin (PG), periplocoside M (PSM) and periplocoside N (PSN) in rat plasma. Acetonitrile was employed to precipitate plasma with appropriate sensitivity and acceptable matrix effects. Chromatographic separation was performed using a Waters HSS T3 column with a gradient elution using water and acetonitrile both containing 0.1% formic acid and 0.1 mm ammonium formate within 8 min. Detection was performed in positive ionization mode using multiple reaction monitoring. The method was fully validated in terms of selectivity, linearity, accuracy, precision, recovery, matrix effects and stability. Using this method, the concentrations of periplocin, PM, PG, PSM and PSN were established after oral administration of Cortex Periplocae extract to rats, and the pharmacokinetic characteristics of periplocin, PM, PG, PSM and PSN were assessed. Generally, PM, PG, PSM and PSN were eliminated slowly and their half-lives were all >8 h. In addition, the systemic exposure of PSM showed significant differences between genders with more than 10 times higher area under the concentration-time curve in female rats than in male rats. The findings of this study provide useful information for further research on Cortex Periplocae.

Periplocymarin protects against myocardial fibrosis induced by β-adrenergic activation in mice

Periplocymarin is an effective component of Periplocae Cortex, which was wildly used as an ingredient in Traditional Chinese Medicine. Our group previously reported that periplocymarin exerted cardiotonic role via promoting calcium influx. However, its exact role in the pathogenesis of myocardial fibrosis has not been elucidated yet. The present study was aimed at determining the potential effect and underlying mechanism of periplocymarin in isoproterenol (ISO)-induced myocardial fibrosis. C57BL/6 mice were subcutaneously injected with ISO (5 mg/kg/day) or saline for 1 week. The early-to-atrial wave ratio (E/A ratio) measured by echocardiography revealed that ISO-induced heart stiffness was remarkably reversed by administration of periplocymarin (5 mg/kg/day). Masson trichrome staining exhibited that treatment of periplocymarin reduced the excessive deposition of extracellular matrix (ECM). Further investigations employing real-time PCR and western blot demonstrated that periplocymarin suppressed the expression of fibrosis related genes (Col1a1, Col3a1, Acta2 and Tgfb1) and proteins (Collagen I, Collagen III, α-SMA and TGF-β1) induced by ISO. Metabolomics analysis demonstrated that periplocymarin ameliorated the disorders triggered by ISO and many of the differential metabolic substances were involved in amino acid, glucose and lipid metabolism. Further analysis using network pharmacology revealed that three key genes, namely NOS2, NOS3 and Ptgs2, may be the potential targets of periplocymarin and responsible for the disorders. Validation using heart tissues showed that the mRNA expression of NOS3 was decreased while Ptgs2 was increased upon ISO treatment, which were reversed by periplocymarin. Moreover, the expression of COX-2 (Ptgs2 encoded protein) was consistent with the aspect of Ptgs2 mRNA, while eNOS (NOS3 encoded protein) expression was unchanged. In vitro studies exhibited that periplocymarin exerts anti-fibrotic function via regulating at least eNOS and COX-2 in cardiomyocyte. Taken together, periplocymarin protects against myocardial fibrosis induced by β-adrenergic activation, the potential mechanism was that periplocymarin targeted on, at least eNOS and COX-2, to improve the metabolic processes of cardiomyocyte and thus attenuated the myocardial fibrosis. Our study highlighted that periplocymarin is a potential therapeutic agent for the prevention of myocardial fibrosis.

Periplocymarin Plays an Efficacious Cardiotonic Role via Promoting Calcium Influx

Periplocymarin, which belongs to cardiac glycosides, is an effective component extracted from Periplocae Cortex. However, its cardiovascular effects remain unidentified. In the present study, injection of periplocymarin (5 mg/kg) through external jugular vein immediately increased the mean arterial pressure (MAP) in anesthetized C57BL/6 mice. Ex vivo experiments using mouse mesenteric artery rings were conducted to validate the role of periplocymarin on blood vessels. However, periplocymarin failed to induce vasoconstriction directly, and had no effects on vasoconstriction induced by phenylephrine (Phe) and angiotensin II (Ang II). In addition, vasodilatation induced by acetylcholine (Ach) was insusceptible to periplocymarin. Echocardiography was used to evaluate the effects of periplocymarin on cardiac function. The results showed that the injection of periplocymarin significantly increase the ejection fraction (EF) in mice without changing the heart rate. In vitro studies using isolated neonatal rat ventricular myocytes (NRVMs) revealed that periplocymarin transiently increased the intracellular Ca²⁺ concentration observed by confocal microscope. But in Ca²⁺-free buffer, this phenomenon vanished. Besides, inhibition of sodium potassium-activated adenosine triphosphatase (Na⁺-K⁺-ATPase) by digoxin significantly suppressed the increase of MAP and EF in mice, and the influx of Ca²⁺ in cardiomyocytes, mediated by periplocymarin. Collectively, these findings demonstrated that periplocymarin increased the contractility of myocardium by promoting the Ca²⁺ influx of cardiomyocytes via targeting on Na⁺-K⁺-ATPase, which indirectly led to the instantaneous rise of blood pressure.

An LC-MS/MS Method for Simultaneous Determination of the Toxic and Active Components of Cortex Periplocae in Rat Plasma and Application to a Pharmacokinetic Study

A sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously determine the toxic and other active components including isovanillin, scopoletin, periplocin, periplogenin, and periplocymarin after oral administration of cortex periplocae extract to rats. Plasma samples were prepared by protein precipitation with methanol. All compounds were separated on a C₁₈ column with gradient elution using acetonitrile and formic acid aqueous solution (0.1%, v/v) as the mobile phase at a flow rate of 0.3 mL/min. The detection of all compounds was accomplished by multiple-reaction monitoring (MRM) in the positive electrospray ionization mode. The LC-MS/MS method exhibited good linearity for five analytes. The lower limit of quantification (LLOQ) was 0.48 ng/mL for scopoletin, periplogenin, and periplocymarin; 2.4 ng/mL for isovanillin and periplocin. The extraction recoveries of all compounds were more than 90% and the RSDs were below 10%. It was found that the absorption of scopoletin and periplocin was rapid in vivo after oral administration of cortex periplocae extract. Furthermore, periplocymarin possessed abundant plasma exposure. The results demonstrated that the validated method was efficiently applied for the pharmacokinetic studies of isovanillin, scopoletin, periplocin, periplogenin, and periplocymarin after oral administration of cortex periplocae extract.

A Review on Liquid Chromatography-Tandem Mass Spectrometry Methods for Rapid Quantification of Oncology Drugs

In the last decade, the tremendous improvement in the sensitivity and also affordability of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has revolutionized its application in pharmaceutical analysis, resulting in widespread employment of LC-MS/MS in determining pharmaceutical compounds, including anticancer drugs in pharmaceutical research and also industries. Currently, LC-MS/MS has been widely used to quantify small molecule oncology drugs in various biological matrices to support preclinical and clinical pharmacokinetic studies in R&D of oncology drugs. This mini-review article will describe the state-of-the-art LC-MS/MS and its application in rapid quantification of small molecule anticancer drugs. In addition, efforts have also been made in this review to address several key aspects in the development of rapid LC-MS/MS methods, including sample preparation, chromatographic separation, and matrix effect evaluation.

Tissue distribution study of periplocin and its two metabolites in rats by a validated LC-MS/MS method

Periplocin is a cardiac glycoside and has been used widely in the clinic for its cardiotonic, anti-inflammatory and anti-tumor effects. Although it is taken frequently by oral administration in the clinic, there have been no reports demonstrating that periplocin could be detected in vivo after an oral administration, so there is an urgen need to determine the characteristics of periplocin in vivo after oral administration. In this study, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed and validated to identify and quantify periplocin and its two metabolites in rat tissue after a single dosage of perplocin at 50 mg/kg. The results demonstrated that periplocin and its two metabolites were detected in all of the selected tissues; periplocin could reach peak concentration quickly after administration, while periplocymarin and periplogenin reached maximum concentration > 4.83 h after administration. The tissue distribution of analytes tended to be mostly in the liver, and higher analyte concentrations were found in the heart, liver, spleen, lung and kidney, but a small amount of chemical constituents was distributed into the brain. The consequences obtained using this method might provide a meaningful insight for clinical investigations and applications.

Octreotide-periplocymarin conjugate prodrug for improving targetability and anti-tumor efficiency: synthesis, in vitro and in vivo evaluation

Cardiac glycosides could increase intracellular Ca²⁺ ion by inhibiting the Na⁺/K⁺ATPase to induce apoptosis in many tumor cells. However, narrow therapeutic index, poor tumor selectivity and severe cardiovascular toxicity hinder their applications in cancer treatment. To improve the safety profile and tumor targetablility of cardiac glycosides, we designed octreotide conjugated periplocymarin, a cardiac glycoside isolated from Cortex periplocae. The conjugate showed higher cytotoxicity on MCF-7 cells and HepG2 tumor cells (SSTRs overexpression) but much less toxicity in L-02 normal cells. Tissue distribution studies of the conjugate using H₂₂ tumor model in mice showed higher accumulation in tumor and lower distribution in heart and liver than periplocymarin. Furthermore, in vivo anticancer effects of the conjugate on mice bearing H₂₂ cancer xenografts confirmed enhanced anti-tumor efficacy and decreased systemic toxicity. Altogether, octreotide-conjugated periplocymarin demonstrated tumor selectivity and may be useful as a targeting agent to improve the safety profile of cardiac glycosides for cancer therapy.

Redox-responsive PEGylated self-assembled prodrug-nanoparticles formed by single disulfide bond bridge periplocymarin-vitamin E conjugate for liver cancer chemotherapy

Periplocymarin (PPM), a cardiac glycoside, has a narrow therapeutic index, poor tumor selectivity and severe cardiovascular toxicity which hinder its wide clinical applications in cancer treatment. Herein, we report novel redox-responsive prodrug-nanoparticles (MPSSV-NPs) self-assembled by co-nanoprecipitation of PPM-vitamin E conjugate and a PEG derivative of linoleate (mPEG2000-LA) in water. It was found that the characteristics of PPM-vitamin E nanoparticles (PSSV-NPs) were improved through co-nanoprecipitation with increased percentages of mPEG2000-LA. Moreover, the MPSSV-NPs were optimized according to the in vitro release and cytotoxicity study. Furthermore, the optimized MPSSV-NPs dramatically enhanced the circulation time and tumor distribution of PSSV-NPs after single intravenous injection. The in vivo studies in malignant H22-bearing mice revealed that MPSSV-NPs could effectively suppress tumor growth without causing obvious systemic toxicity. Altogether, these results suggested that MPSSV-NPs could offer a safe, multifunctional and viable nanoplatform for cardiac glycosides in cancer treatment.