[Advances on cyclopeptides of plants].

Cyclopeptides isolated from a variety of plants are a class of cyclic nitrogen-containing compounds, and they are primarily formed by peptide bonds between amino acids, generally containing 2 to 37 L-configuration encoded or non-encoded amino acid residues. Cyclopeptides have significant values in scientific research as natural small-molecule metabolites produced by plants. The available studies have revealed that such natural products are ubiquitous in plants, which mainly include cyclic dipeptides, cyclic tetrapeptides, cyclic pentapeptides, cyclic hexapeptides, cyclic heptapeptides, cyclic octapeptides, cyclic nonapeptides, and cyclic decapeptides. Among them, cyclic dipeptides, cyclic hexapeptides, and cyclic octapeptides are the major active compounds. It has been reported that plant cyclopeptides have novel and unique chemical structures. They possess diverse pharmacological activities, such as antineoplastic, antimicrobial, antimalarial, anti-inflammatory, and antiviral activities. This paper summarizes the research achievements of plant cyclopeptides since 2006, aiming to provide theoretical reference for the research and application of plant cyclopeptides in medicine, health, and agriculture fields.

A new methodology to reveal potential nucleic acid modifications associated with the risk of endometrial cancer through dispersive solid-phase extraction coupled with UHPLC-QE-Orbitrap-MS/MS and HPLC-UV.

Nucleic acid modifications have attracted increasing attention in recent years since they have been found to be related to a number of diseases including cancer. Previous studies have shown that the early development of endometrial cancer (EC) is often accompanied by changes in methylation levels of related genes, and the expression of related proteins that regulate reactive oxygen species (ROS) shows significant differences in EC cells and tissues. However, it has not been reported whether nucleic acid modifications related to methylation or ROS can serve as biomarkers for EC. Accurate quantification of these nucleic acid modifications still has challenges because their amounts in urine are very low and the interferences in urine are complicated. In this study, a novel dispersive solid-phase extraction (DSPE) method based on chitosan-carbon nanotube-Al2O3 (CS-CNT-Al2O3) has been established for the analysis of 5-hydroxymethyluracil (5 mU), 5-methyl-2'-deoxycytidine (5-mdC), 5-hydroxymethyl-2'-deoxycytidine (5-hmdC), 5-formyl-2'-deoxycytidine (5-fdC), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in EC patient urine samples coupled with UHPLC-QE-Orbitrap-MS/MS and HPLC-UV. Firstly, the synthesis of the CS-CNT-Al2O3 nanocomposite was conducted by a sono-coprecipitation method and was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and Fourier transform infrared (FTIR). Under the optimal extraction conditions of DSPE, we successfully quantified 5 mU, 5-mdC, 5-hmdC, 5-fdC, and 8-OHdG in urine samples from 37 EC patients and 39 healthy controls. The results showed that there were significant differences in the levels of 5-mdC, 5-hmdC, 5-fdC, and 8-OHdG in EC patients compared to the healthy control group. The receiver operator characteristic (ROC) curve analysis was carried out to evaluate the potential of 5-mdC, 5-hmdC, 5-fdC, and 8-OHdG to distinguish EC patients from healthy volunteers. The area under the curve (AUC) for 5-mdC, 5-hmdC, 5-fdC, and 8-OHdG was 0.7412, 0.667, 0.8438, and 0.7981, respectively. It indicated that 5-mdC, 5-hmdC, 5-fdC, and 8-OHdG had certain potential in distinguishing between EC patients and healthy volunteers and they could act as potential non-invasive biomarkers for early diagnosis of EC. Moreover, the present study would stimulate investigations of the effects of nucleic acid modifications on the initiation and progression of EC.

INTEDE 2.0: the metabolic roadmap of drugs.

The metabolic roadmap of drugs (MRD) is a comprehensive atlas for understanding the stepwise and sequential metabolism of certain drug in living organisms. It plays a vital role in lead optimization, personalized medication, and ADMET research. The MRD consists of three main components: (i) the sequential catalyses of drug and its metabolites by different drug-metabolizing enzymes (DMEs), (ii) a comprehensive collection of metabolic reactions along the entire MRD and (iii) a systematic description on efficacy & toxicity for all metabolites of a studied drug. However, there is no database available for describing the comprehensive metabolic roadmaps of drugs. Therefore, in this study, a major update of INTEDE was conducted, which provided the stepwise & sequential metabolic roadmaps for a total of 4701 drugs, and a total of 22 165 metabolic reactions containing 1088 DMEs and 18 882 drug metabolites. Additionally, the INTEDE 2.0 labeled the pharmacological properties (pharmacological activity or toxicity) of metabolites and provided their structural information. Furthermore, 3717 drug metabolism relationships were supplemented (from 7338 to 11 055). All in all, INTEDE 2.0 is highly expected to attract broad interests from related research community and serve as an essential supplement to existing pharmaceutical/biological/chemical databases. INTEDE 2.0 can now be accessible freely without any login requirement at: http://idrblab.org/intede/.

High Hepcidin Levels Promote Abnormal Iron Metabolism and Ferroptosis in Chronic Atrophic Gastritis.

BACKGROUND: Chronic atrophic gastritis (CAG) is a chronic inflammatory disease and premalignant lesion of gastric cancer. As an antimicrobial peptide, hepcidin can maintain iron metabolic balance and is susceptible to inflammation. OBJECTIVES: The objective of this study was to clarify whether hepcidin is involved in abnormal iron metabolism and ferroptosis during CAG pathogenesis. METHODS: Non-atrophic gastritis (NAG) and chronic atrophic gastritis (CAG) patient pathology slides were collected, and related protein expression was detected by immunohistochemical staining. The CAG rat model was established using MNNG combined with an irregular diet. RESULTS: CAG patients and rats exhibited iron deposition in gastric tissue. CAG-induced ferroptosis in the stomach was characterized by decreased GPX4 and FTH levels and increased 4-HNE levels. Hepcidin, which is mainly located in parietal cells, was elevated in CAG gastric tissue. The high gastric level of hepcidin inhibited iron absorption in the duodenum by decreasing the protein expression of DMT1 and FPN1. In addition, the IL-6/STAT3 signaling pathway induced hepcidin production in gastric tissue. CONCLUSION: Our results showed that the high level of gastric hepcidin induced ferroptosis in the stomach but also inhibited iron absorption in the intestines. Inhibiting hepcidin might be a new strategy for the prevention of CAG in the future.

Discovery of selective HDAC6 inhibitors based on a multi-layer virtual screening strategy.

The abnormal enhancement of histone deacetylase 6 (HDAC6) has been demonstrated to be closely related to the occurrence and development of various malignant tumors, attracting extensive attention as a promising target for cancer therapy. Currently, only limited selective HDAC6 inhibitors have entered clinical trials, making the rapid discovery of selective HDAC6 inhibitors with safety profiles particularly urgent. In this study, a multi-layer virtual screening workflow was established, and the representative compounds screened were biologically evaluated in combination with enzyme inhibitory and anti-tumor cell proliferation experiments. The experimental results showed that the screened compounds L-25, L-32, L-45 and L-81 exhibited nanomolar inhibitory activity against HDAC6, and exerted a certain degree of anti-proliferative activities against tumor cells, especially the cytotoxicity of L-45 to A375 (IC50 = 11.23 ± 1.27 µM) and the cytotoxicity of L-81 against HCT-116 (IC50 = 12.25 ± 1.13 µM). Additionally, the molecular mechanisms underlying the subtype selective inhibitory activities of the selected compounds were further elucidated using computational approaches, and the hotspot residues on HDAC6 contributing to the ligands' binding were identified. In summary, this study established a multi-layer screening scheme to quickly and effectively screen out hit compounds with enzyme inhibitory activity and anti-tumor cell proliferation, providing novel scaffolds for the subsequent anti-tumor drug design based on HDAC6 target.

Inhibition of Kv7/M Channel Currents by Fangchinoline.

INTRODUCTION: Voltage-gated Kv7/M potassium channels play an essential role in the control of membrane potential and neuronal excitability. Fangchinoline, a bisbenzylisoquinoline alkaloid, displays extensive biological activities including antitumor, anti-inflammatory, and antihypertension effects. In this study, we investigated the effects of fangchinoline on Kv7/M channels. METHODS: A perforated whole-cell patch technique was used to record Kv7 currents from HEK293 cells and M-type currents from mouse dorsal root ganglion (DRG) neurons. RESULTS: Fangchinoline inhibited Kv7.2/Kv7.3 currents in a concentration-dependent manner, with an IC50 of 9.5 ± 1.2 µM. Fangchinoline significantly inhibited Kv7.1, Kv7.2, Kv7.3, Kv7.4, and Kv7.3/Kv7.5 channels without selective effects. Furthermore, fangchinoline significantly slowed the activation of Kv7.1-Kv7.5 channels and inhibited native M-channel currents of DRG neurons. CONCLUSION: Taken together, our findings indicate that fangchinoline concentration-dependently inhibited Kv7/M channel currents.

Jujuboside B inhibits febrile seizure by modulating AMPA receptor activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Febrile seizure is a common neurologic disorder with limited treatment occurring in infants and children under the age of five. Jujuboside B (JuB) is a main bioactive saponin component isolated from the Chinese anti-insomnia herbal medicine Ziziphi Spinosae Semen (ZSS), seed of Ziziphus jujuba Mill, which has been proved to exhibit neuroprotective effects recently. AIM OF THE STUDY: In this study, we aimed at elucidating the effect of JuB on suppressing febrile seizure and the potential mechanisms. METHODS: Electroencephalogram (EEG) recording was used to monitor the severity of febrile seizures. The JuB in the brain was identified by mass spectrometry. Neuronal excitability was investigated using patch clamp. RESULTS: JuB (30 mg/kg) significantly prolonged seizure latency and reduced the severity in hyperthermia-induced seizures model mice. Hippocampal neuronal excitability was significantly decreased by JuB. And JuB significantly reduced the excitatory synaptic transmission mediated by α-amino-3-hydroxy-5-methyl-4-iso-xazolepropionic acid receptor (AMPAR), including evoked excitatory postsynaptic currents (eEPSCs), and miniature EPSCs (mEPSCs) in hippocampal neurons. Furthermore, JuB also significantly inhibited recombinant GluA1 and GluA2 mediated AMPA current in HEK293 cell and decreased the upregulation of [Ca2+]i induced by AMPA in primary cultured cortex neurons. CONCLUSIONS: JuB suppressed the excitability of hippocampal neurons by inhibiting the activity of AMPAR and reducing the intracellular free calcium, thereby relieving febrile seizures.

Liquiritin Protects Against Cardiac Fibrosis After Myocardial Infarction by Inhibiting CCL5 Expression and the NF-κB Signaling Pathway.

Purpose: Despite significant advances in interventional treatment, myocardial infarction (MI) and subsequent cardiac fibrosis remain major causes of high mortality worldwide. Liquiritin (LQ) is a flavonoid extract from licorice that possesses a variety of pharmacological properties. However, to our knowledge, the effects of LQ on myocardial fibrosis after MI have not been reported in detail. The aim of our research was to explore the potential role and mechanism of LQ in MI-induced myocardial damage. Methods: The MI models were established by ligating the left anterior descending branch of the coronary artery. Next, rats were orally administered LQ once a day for 14 days. Biochemical assays, histopathological observations, ELISA, and Western blotting analyses were then conducted. Results: LQ improved the heart appearance and ECG, decreased cardiac weight index and reduced levels of cardiac-specific markers such as CK, CK-MB, LDH, cTnI and BNP. Meanwhile, LQ reduced myocardial infarct size and improved hemodynamic parameters such as LVEDP, LVSP and ±dp/dtmax. Moreover, H&E staining showed that LQ attenuated the pathological damage caused by MI. Masson staining showed that LQ alleviated myocardial cell disorder and fibrosis while reducing collagen deposition. LQ also decreased the levels of oxidative stress and inflammation. Western blotting demonstrated that LQ significantly down-regulated the expressions of Collagen I, Collagen III, TGF-ß1, MMP-9, α-SMA, CCL5, and p-NF-κB. Conclusion: LQ protected against myocardial fibrosis following MI by improving cardiac function, and attenuating oxidative damage and inflammatory response, which may be associated with inhibition of CCL5 expression and the NF-κB pathway.

Do biological activities of selective histone deacetylase 6 (HDAC6) inhibitors rely on the modification of cap group?

Nowadays, significant progress has been made in the development of selective histone deacetylase 6 (HDAC6) inhibitors, exerting great potential in the treatment of various malignant tumors and neurodegenerative diseases. Previously, selective inhibitory activities of HDAC inhibitors were generally considered sensitive to the interactions between the Cap group and the binding site of HDAC6, and a large number of selective HDAC6 inhibitors have been designed and synthesized based on the strategy. However, some inhibitors without Cap group could also exhibit excellent potency and selective inhibition towards HDAC6, and in this study, BRD9757 and compound 8, as capless selective HDAC6 inhibitors, were selected as molecular probes to explore the difference of their binding interactions in HDAC1&6. Through the analysis of binding-free energies and conformational rearrangements after 1 µs molecular dynamics simulation, it could be learned that although the residues in the binding site remained highly consistent, the binding mechanisms of BRD9757 and compound 8 in HDAC1&6 were different, which will provide valuable hints for the discovery of novel selective HDAC6 inhibitors.

Protective effects and possible mechanism of 6-gingerol against arsenic trioxide-induced nephrotoxicity based on network pharmacological analysis and experimental validation.

BACKGROUND AND OBJECTIVE: Nephrotoxicity induced by the chemotherapeutic drug arsenic trioxide (ATO) is often overlooked, and the underlying mechanisms remain poorly understood. Based on network pharmacology and experimental validation, this study investigates the protection of 6-gingerol (6G) against ATO-induced nephrotoxicity and the potential mechanisms. METHODS: We screened and collected 6G and disease-related targets and then imported the interaction targets into a String database to construct protein-protein interaction (PPI) networks. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID). Mice were injected intraperitoneally with ATO (5 mg/kg) for seven days to induce nephrotoxicity, and then the histological morphology of the kidneys, biochemical indices of serum and tissues, and associated protein expressions were observed. RESULTS: The network pharmacology results revealed that the effects of 6G against nephrotoxicity are closely related to apoptosis, and the MAPKs pathway was screened for validation. In animal experiments, 6G improved the histopathological morphology of the kidneys, reduced the levels of renal function markers, enhanced antioxidant activity, and decreased the levels of inflammation. Furthermore, 6G reduced apoptotic cells in kidney tissues, decreased the levels of Bax and c-Caspase-3, and increased the level of Bcl-2. The results of immunohistochemistry and western blotting revealed that 6G significantly inhibited the expressions of p-p38, p-ERK, and p-JNK. CONCLUSION: The results comprehensively demonstrate the protective effects of 6G against ATO-induced nephrotoxicity. The effects are related to anti-oxidant, anti-inflammatory, and anti-apoptotic properties, possibly through inhibition of the MAPKs pathway.

Protective Effects of 6-Gingerol on Cardiotoxicity Induced by Arsenic Trioxide Through AMPK/SIRT1/PGC-1α Signaling Pathway.

Background and Objective: Arsenic trioxide (As2O3) induced cardiotoxicity to limit the clinical applications of the effective anticancer agent. 6-Gingerol (6G) is the main active ingredient of ginger, a food with many health benefits. The present study aims to investigate the potential pharmacological mechanisms of 6G on As2O3-induced myocardial injury. Methods and Results: Fifty KunMing mice were divided into five groups (n = 10) receiving: 1) physiological saline; 2) 6G (20 mg/kg) alone; 3) As2O3 (5 mg/kg); 4) 6G (10 mg/kg) and As2O3 (5 mg/kg); 5) 6G (20 mg/kg) and As2O3 (5 mg/kg). 6G was given orally and As2O3 was given intraperitoneally once per day for seven consecutive days. Biochemical, histopathological, transmission electron microscopy, ELISA, and western blotting analyses were then performed. Based on the resultant data, As2O3 was found to induce cardiotoxicity in mice. 6G significantly ameliorated As2O3-induced heart injury, histopathological changes, oxidative stress, myocardial mitochondrial damage, inflammation, and cardiomyocyte apoptosis, while reversed As2O3-induced inhibition of the AMPK/SIRT1/PGC-1α pathway. Conclusion: Our experimental results reveal that 6G effectively counteracts As2O3-induced cardiotoxicity including oxidative stress, inflammation and apoptosis, which might be attributed to its activation action on AMPK/SIRT1/PGC-1α signaling pathway.

Design, Synthesis, and biological evaluation of HDAC6 inhibitors based on Cap modification strategy.

The abnormal biological functions of HDAC6 were closely related to the occurrence and development of various tumors, making HDAC6 gradually become promising therapeutic target for cancer treatment and inspiring researchers to explore and develop selective HDAC inhibitors. In this study, based on the classical pharmacophore model of HDAC inhibitors, 20 compounds were designed and synthesized by modifying the Cap group, and the biological activities of the target compounds were assessed through anti-proliferation and enzyme inhibition experiments. The title compounds exhibited varying degrees of inhibitory activities against the selected tumor cell lines, especially the compounds 9m, 9q, and 12c, which were further evaluated at the enzymatic level. The enzyme inhibition assay showed that compound 12c exerted broad-spectrum enzyme inhibitory activities and compounds 9m and 9q were more inclined to inhibit HDAC6, exhibiting certain selective inhibitory activities among the representative subtypes. Moreover, the binding modes of compounds 9q and 12c in HDAC1&6 were further explored via computational approaches to elucidate the molecular mechanisms underlying selective inhibitory activities, providing valuable hints for the discovery of novel HDAC6 inhibitors.

Protective mechanisms of 10-gingerol against myocardial ischemia may involve activation of JAK2/STAT3 pathway and regulation of Ca2+ homeostasis.

10-Gingerol (10-Gin), an active ingredient extracted from ginger, has been reported to have beneficial effects on the cardiovascular system. However, its protective effects on myocardial ischemia (MI) and the underlying cellular mechanisms are still unclear. To investigate the protection conferred by 10-Gin against MI injury and its potential mechanisms in cardiomyocytes via patch-clamp and molecular biology techniques. A rat MI model was established using the subcutaneous injection of isoproterenol (85 mg/kg) administered on two consecutive days. 10-Gin was pre-administered to rats for seven days to assess its cardio-protection. The patch-clamp and IonOptix Myocam detection techniques were used to investigated 10-Gin's effects on L-type Ca2+ channels (LTCCs), Ca2+ transients and cell contractility in isolated rat cardiomyocytes. 10-Gin administration alleviated MI injury, improved cardiac function and myocardial histopathology, reduced myocardial infarct area, downregulated oxidative stress and Ca2+ levels, and decreased the expression of apoptotic factors. Importantly, 10-Gin led to an increase in phosphorylated Janus kinase 2 and signal transducer and activator of transcription 3 (JAK2 and STAT3, respectively) expressions. Furthermore, 10-Gin inhibited LTCCs in a concentration-dependent manner with a half-maximal inhibitory concentration of 75.96 µM. Moreover, 10-Gin administration inhibited Ca2+ transients and cell contractility. Our results suggest that 10-Gin exerts cardioprotective effects on MI in vivo and in vitro in connection with the inhibition of oxidative stress and apoptosis via activation of the JAK2/STAT3 signalling pathway, and regulation of Ca2+ homeostasis by LTCCs.

Multistage pH-responsive codelivery liposomal platform for synergistic cancer therapy.

BACKGROUND: Small interfering RNA (siRNA) is utilized as a potent agent for cancer therapy through regulating the expression of genes associated with tumors. While the widely application of siRNAs in cancer treatment is severely limited by their insufficient biological stability and its poor ability to penetrate cell membranes. Targeted delivery systems hold great promise to selectively deliver loaded drug to tumor site and reduce toxic side effect. However, the elevated tumor interstitial fluid pressure and efficient cytoplasmic release are still two significant obstacles to siRNA delivery. Co-delivery of chemotherapeutic drugs and siRNA represents a potential strategy which may achieve synergistic anticancer effect. Herein, we designed and synthesized a dual pH-responsive peptide (DPRP), which includes three units, a cell-penetrating domain (polyarginine), a polyanionic shielding domain (ehG)n, and an imine linkage between them. Based on the DPRP surface modification, we developed a pH-responsive liposomal system for co-delivering polo-like kinase-1 (PLK-1) specific siRNA and anticancer agent docetaxel (DTX), D-Lsi/DTX, to synergistically exhibit anti-tumor effect. RESULTS: In contrast to the results at the physiological pH (7.4), D-Lsi/DTX lead to the enhanced penetration into tumor spheroid, the facilitated cellular uptake, the promoted escape from endosomes/lysosomes, the improved distribution into cytoplasm, and the increased cellular apoptosis under mildly acidic condition (pH 6.5). Moreover, both in vitro and in vivo study indicated that D-Lsi/DTX had a therapeutic advantage over other control liposomes. We provided clear evidence that liposomal system co-delivering siPLK-1 and DTX could significantly downregulate expression of PLK-1 and inhibit tumor growth without detectable toxic side effect, compared with siPLK-1-loaded liposomes, DTX-loaded liposomes, and the combinatorial administration. CONCLUSION: These results demonstrate great potential of the combined chemo/gene therapy based on the multistage pH-responsive codelivery liposomal platform for synergistic tumor treatment.

Comparison of the Inhibitory Binding Modes Between the Planar Fascaplysin and Its Nonplanar Tetrahydro-ß-carboline Analogs in CDK4.

Fascaplysin is a natural marine product originating from sponges, attracting widespread attention due to its potential inhibitory activities against CDK4. However, its clinical application has been largely limited because of serious adverse effects caused by planar skeleton. To reduce the serious adverse effects, 18 tetrahydro-ß-carboline analogs (compounds 6a-i and 7a-i) were designed and synthesized via breaking the planarity of fascaplysin, and the biological activities of the synthesized compounds were evaluated by MTT assay and CDK4/CycD3 enzyme inhibition assay. The title compounds showed varying degrees of inhibitory activities, especially the cytotoxicity of compound 6c against HeLa cells (IC50 = 1.03 ± 0.19 µM) with quite weak cytotoxicity toward the normal cells WI-38 (IC50 = 311.51 ± 56.06 µM), and the kinase inhibition test indicated that compound 6c was a potential CDK4 inhibitor. In order to further compare the action mechanisms of planar and nonplanar molecules on CDK4, the studied complexes of CDK4 bound with fascaplysin and three representative compounds (compound 6a-c) with bioactivities gradient were constructed by molecular docking and further verified through molecular dynamic simulation, which identified the key residues contributing to the ligands' binding. By comparing the binding modes of the constructed systems, it could be found that the residues contributing significantly to compound 6c's binding were highly consistent with those contributing significantly to fascaplysin's binding. Through the design, synthesis of the nonplanar fascaplysin derivatives, and binding mechanism analysis, some valuable hints for the discovery of antitumor drug candidates could be provided.

Mechanisms Underlying Gastrodin Alleviating Vincristine-Induced Peripheral Neuropathic Pain.

Gastrodin (GAS) is the main bioactive ingredient of Gastrodia, a famous Chinese herbal medicine widely used as an analgesic, but the underlying analgesic mechanism is still unclear. In this study, we first observed the effects of GAS on the vincristine-induced peripheral neuropathic pain by alleviating the mechanical and thermal hyperalgesia. Further studies showed that GAS could inhibit the current density of NaV1.7 and NaV1.8 channels and accelerate the inactivation process of NaV1.7 and NaV1.8 channel, thereby inhibiting the hyperexcitability of neurons. Additionally, GAS could significantly reduce the over-expression of NaV1.7 and NaV1.8 on DRG neurons from vincristine-treated rats according to the analysis of Western blot and immunofluorescence results. Moreover, based on the molecular docking and molecular dynamic simulation, the binding free energies of the constructed systems were calculated, and the binding sites of GAS on the sodium channels (NaV1.7 and NaV1.8) were preliminarily determined. This study has shown that modulation of NaV1.7 and NaV1.8 sodium channels by GAS contributing to the alleviation of vincristine-induced peripheral neuropathic pain, thus expanding the understanding of complex action of GAS as a neuromodulator.

Inhibition of the INa/K and the activation of peak INa contribute to the arrhythmogenic effects of aconitine and mesaconitine in guinea pigs.

Aconitine (ACO), a main active ingredient of Aconitum, is well-known for its cardiotoxicity. However, the mechanisms of toxic action of ACO remain unclear. In the current study, we investigated the cardiac effects of ACO and mesaconitine (MACO), a structurally related analog of ACO identified in Aconitum with undocumented cardiotoxicity in guinea pigs. We showed that intravenous administration of ACO or MACO (25 µg/kg) to guinea pigs caused various types of arrhythmias in electrocardiogram (ECG) recording, including ventricular premature beats (VPB), atrioventricular blockade (AVB), ventricular tachycardia (VT), and ventricular fibrillation (VF). MACO displayed more potent arrhythmogenic effect than ACO. We conducted whole-cell patch-clamp recording in isolated guinea pig ventricular myocytes, and observed that treatment with ACO (0.3, 3 µM) or MACO (0.1, 0.3 µM) depolarized the resting membrane potential (RMP) and reduced the action potential amplitude (APA) and durations (APDs) in a concentration-dependent manner. The ACO- and MACO-induced AP remodeling was largely abolished by an INa blocker tetrodotoxin (2 µM) and partly abolished by a specific Na+/K+ pump (NKP) blocker ouabain (0.1 µM). Furthermore, we observed that treatment with ACO or MACO attenuated NKP current (INa/K) and increased peak INa by accelerating the sodium channel activation with the EC50 of 8.36 ± 1.89 and 1.33 ± 0.16 µM, respectively. Incubation of ventricular myocytes with ACO or MACO concentration-dependently increased intracellular Na+ and Ca2+ concentrations. In conclusion, the current study demonstrates strong arrhythmogenic effects of ACO and MACO resulted from increasing the peak INa via accelerating sodium channel activation and inhibiting the INa/K. These results may help to improve our understanding of cardiotoxic mechanisms of ACO and MACO, and identify potential novel therapeutic targets for Aconitum poisoning.

Synthesis and Biological Evaluation of HDAC Inhibitors With a Novel Zinc Binding Group.

Vorinostat (SAHA) with great therapeutic potential has been approved by the FDA for the treatment of cutaneous T-cell lymphoma as the first HDACs inhibitor, but the drawbacks associated with hydroxamic acid group (poor stability, easy metabolism, weak binding ability to class IIa isozymes, and poor selectivity) have been exposed during the continuous clinical application. Based on the pharmacophore of HDAC inhibitors, two series of compounds with novel zinc binding group (ZBG) were designed and synthesized, and the antitumor bioactivities were evaluated in four human cancer cell lines (A549, Hela, HepG2, and MCF-7). Among the synthesized compounds, compounds a6, a9, a10, b8, and b9 exhibited promising inhibitory activities against the selected tumor cell lines, especially compounds a9 and b8 on Hela's cytostatic activity (a9: IC50 = 11.15 ± 3.24 µM; b8: IC50 = 13.68 ± 1.31 µM). The enzyme inhibition assay against Hela extracts and HDAC1&6 subtypes showed that compound a9 had a certain broad-spectrum inhibitory activity, while compound b8 had selective inhibitory activity against HDAC6, which was consistent with Western blot results. In addition, the inhibitory mechanism of compounds a9 and b8 in HDAC1&6 were both compared through computational approaches, and the binding interactions between the compounds and the enzymes target were analyzed from the perspective of energy profile and conformation. In summary, the compounds with novel ZBG exhibited certain antitumor activities, providing valuable hints for the discovery of novel HDAC inhibitors.

A Complete Study of Farrerol Metabolites Produced in Vivo and in Vitro.

Although farrerol, a characteristically bioactive constituent of Rhododendron dauricum L., exhibits extensive biological and pharmacological activities (e.g., anti-oxidant, anti-immunogenic, and anti-angiogenic) as well as a high drug development potential, its metabolism remains underexplored. Herein, we employed ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multiple data post-processing techniques to rapidly identify farrerol metabolites produced in vivo (in rat blood, bile, urine and feces) and in vitro (in rat liver microsomes). As a result, 42 in vivo metabolites and 15 in vitro metabolites were detected, and farrerol shown to mainly undergo oxidation, reduction, (de)methylation, glucose conjugation, glucuronide conjugation, sulfate conjugation, N-acetylation and N-acetylcysteine conjugation. Thus, this work elaborates the metabolic pathways of farrerol and reveals the potential pharmacodynamics forms of farrerol.