Estrogenic and anti-neutrophilic inflammatory phenanthrenes from Juncus effusus L.

Juncus effusus L. (J. effusus) is a Traditional Chinese Medicine (TCM) that has long been used for dealing with gynaecological disorders, such as relieving insomnia, preventing tinnitus, reducing edema with diuretic effect. In our course of evidence-based medical research focused on this herb, one new phenanthrene, Junfusol B (2), together with seventeen known compounds were isolated and identified. All the structures of these compounds were elucidated by spectroscopic methods. The absolute stereochemistry of compounds 1 and 2 was further determined by comparing their calculated and experimental Electronic Circular Dichroism (ECD) spectra and optical rotation (OR) values. The isolates were evaluated for their estrogenic and anti-inflammatory activities which were considered as relevant etiological factors of insomnia, tinnitus and edema in the ancient TCM theory. The results revealed that most of the obtained phenanthrenes in this work were found exerting agonistic effects on estrogen receptor. This is the first report to declare the exact estrogen-regulating potential among this type of compounds from J. effusus. Moreover, phenanthrenes 3 - 7 exhibited significant inhibitions on superoxide anion generation and elastase release in fMLP/CB-induced human neutrophilic inflammation model. J. effusus may be developed as a complementary agent utilized in menopausal multiple syndromes.

Pharmacokinetics-Driven Evaluation of the Antioxidant Activity of Curcuminoids and Their Major Reduced Metabolites-A Medicinal Chemistry Approach.

Curcuminoids are the main bioactive components of the well-known Asian spice and traditional medicine turmeric. Curcuminoids have poor chemical stability and bioavailability; in vivo they are rapidly metabolized to a set of bioreduced derivatives and/or glucuronide and sulfate conjugates. The reduced curcuminoid metabolites were also reported to exert various bioactivities in vitro and in vivo. In this work, we aimed to perform a comparative evaluation of curcuminoids and their hydrogenated metabolites from a medicinal chemistry point of view, by determining a set of key pharmacokinetic parameters and evaluating antioxidant potential in relation to such properties.Reduced metabolites were prepared from curcumin and demethoxycurcumin through continuous-flow hydrogenation. As selected pharmacokinetic parameters, kinetic solubility, chemical stability, metabolic stability in human liver microsomes, and parallel artificial membrane permeability assay (PAMPA)-based gastrointestinal and blood-brain barrier permeability were determined. Experimentally determined logP for hydrocurcumins in octanol-water and toluene-water systems provided valuable data on the tendency for intramolecular hydrogen bonding by these compounds. Drug likeness of the compounds were further evaluated by a in silico calculations. Antioxidant properties in diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and oxygen radical absorbance capacity (ORAC) assays were comparatively evaluated through the determination of ligand lipophilic efficiency (LLE). Our results showed dramatically increased water solubility and chemical stability for the reduced metabolites as compared to their corresponding parent compound. Hexahydrocurcumin was found the best candidate for drug development based on a complex pharmacokinetical comparison and high LLE values for its antioxidant properties. Development of tetrahydrocurcumin and tetrahydro-demethoxycurcumin would be limited by their very poor metabolic stability, therefore such an effort would rely on formulations bypassing first-pass metabolism.

Liquid chromatographic enantioseparation of limonene-based carbocyclic ß-amino acids on zwitterionic Cinchona alkaloid-based chiral stationary phases.

The eight stereoisomers of limonene-based carbocyclic ß-amino acids containing three chiral centers have been directly separated on chiral stationary phases containing Cinchona alkaloid-based zwitterionic selectors. The effects of bulk solvent composition of the mobile phase, the nature of base additives, counterion concentration, and the structure of selector on the enantiorecognition were studied. Experiments were performed at constant mobile phase composition in the temperature range 5-40°C to study the effect of temperature. Thermodynamic parameters were calculated on the basis of the plots of ln α versus 1/T curves. The enthalpically or entropically driven enantioseparations were found to depend strongly on the structures of analyte and selector. The eight stereoisomers of limonene-based carbocyclic ß-amino acids could be differentiated as well-separated peaks in a traditional 1D chromatographic system in two runs by applying the two complementary ZWIX(+)™ and ZWIX(-)™ columns.

Hypothalamic dopamine is required for salsolinol-induced prolactin secretion in goats.

The aim of the present study was to clarify the relationship between hypothalamic dopamine (DA) and salsolinol (SAL) for the secretion of prolactin (PRL) in goats. SAL or thyrotropin-releasing hormone (TRH) was intravenously injected into female goats treated with or without the D2 DA receptor antagonist haloperidol (Hal), which crosses the blood-brain barrier, and the PRL-releasing response to SAL was compared with that to TRH. PRL-releasing responses to SAL, Hal, and Hal plus SAL were also examined after a pretreatment to augment central DA using carbidopa (Carbi) and L-dopa. The PRL-releasing response to Hal alone was greater than that to SAL or TRH alone. The PRL-releasing response to Hal plus SAL was similar to that of Hal alone. In contrast, the PRL-releasing response to Hal plus TRH was greater than that to TRH or Hal alone. The treatment with Carbi plus L-dopa inhibited SAL- and Hal-induced PRL secretion. The inhibition of the PRL-releasing response to SAL disappeared when SAL was injected with Hal. These results indicate that the mechanisms underlying the SAL-induced PRL response differ from those of TRH, and suggest that hypothalamic DA and its synthesis is associated in part with SAL-induced PRL secretion in goats.

Developing a QSAR model for hepatotoxicity screening of the active compounds in traditional Chinese medicines.

The perception that natural substances are deemed safe has made traditional Chinese medicine (TCM) popular in the treatment and prevention of disease globally. However, such an assumption is often misleading owing to a lack of scientific validation. To assess the safety of TCM, in silico screening provides major advantages over the classical laboratory approaches in terms of resource- and time-saving and full reproducibility. To screen the hepatotoxicity of the active compounds of TCMs, a quantitative structure-activity relationship (QSAR) model was firstly established by utilizing drugs from the Liver Toxicity Knowledge Base. These drugs were annotated with drug-induced liver injury information obtained from clinical trials and post-marketing surveillance. The performance of the model after nested 10-fold cross-validation was 79.1%, 91.2%, 53.8% for accuracy, sensitivity, and specificity, respectively. The external validation of 91 well-known ingredients of common herbal medicines yielded a high accuracy (87%). After screening the TCM Database@Taiwan, the world's largest TCM database, a total of 6853 (74.8%) ingredients were predicted to have hepatotoxic potential. The one-hundred chemical ingredients predicted to have the highest hepatotoxic potential by our model were further verified by published literatures. Our study indicated that this model can serve as a complementary tool to evaluate the safety of TCM.

Effects of hypothalamic dopamine (DA) on salsolinol (SAL)-induced prolactin (PRL) secretion in male goats.

The aim of the present study was to clarify the effects of hypothalamic dopamine (DA) on salsolinol (SAL)-induced prolactin (PRL) release in goats. The PRL-releasing response to an intravenous (i.v.) injection of SAL was examined after treatment with augmentation of central DA using carbidopa (carbi) and L-dopa in male goats under 8-h (8 h light, 16 h dark) or 16-h (16 h light, 8 h dark) photoperiod conditions. The carbi and L-dopa treatments reduced basal PRL concentrations in the 16-h photoperiod group (P < 0.05), while a reduction was not observed in the 8-h photoperiod group. The mean basal plasma PRL concentration in the control group for the 8-h photoperiod was lower than that for the 16-h photoperiod (P < 0.05). SAL significantly stimulated the release of PRL promptly after the injection in both the 8- and 16-h photoperiod groups (P < 0.05). PRL-releasing responses for the 16-h photoperiod were greater than those for the 8-h photoperiod (P < 0.05). The carbi and L-dopa treatments blunted SAL-induced PRL release in both the 8- and 16-h photoperiods (P < 0.05). These results indicate that hypothalamic DA blunts the SAL-induced release of PRL in male goats, regardless of the photoperiod, which suggests that both SAL and DA are involved in regulating the secretion of PRL in goats.

Kynurenines in the CNS: recent advances and new questions.

Various pathologies of the central nervous system (CNS) are accompanied by alterations in tryptophan metabolism. The main metabolic route of tryptophan degradation is the kynurenine pathway; its metabolites are responsible for a broad spectrum of effects, including the endogenous regulation of neuronal excitability and the initiation of immune tolerance. This Review highlights the involvement of the kynurenine system in the pathology of neurodegenerative disorders, pain syndromes and autoimmune diseases through a detailed discussion of its potential implications in Huntington's disease, migraine and multiple sclerosis. The most effective preclinical drug candidates are discussed and attention is paid to currently under-investigated roles of the kynurenine pathway in the CNS, where modulation of kynurenine metabolism might be of therapeutic value.

The influence of salsolinol on dopaminergic system activity within the mediobasal hypothalamus of anestrous sheep: a model for studies on the salsolinol-dopamine relationship.

Salsolinol with its derivatives has been considered as a potential neurotoxin for the dopaminergic system in the human and rat brain. Investigating a sheep model for studies on the action of salsolinol within the central nervous system we examined whether this compound is able to affect the hypothalamic neuroendocrine dopaminergic (NEDA) system during its high seasonal activity, when sheep entered to anestrus under the long day conditions. Therefore, salsolinol was infused into the third ventricle of the brain in combination with the in vivo push-pull perfusion of the mediobasal hypothalamus/median eminence (MBH/ME). The effects of this drug on either perfusate noradrenaline (NA) or plasma prolactin concentration were also studied. The infusion of salsolinol resulted in rapid and permanent diminution in dopamine (DA) release into the extracellular spaces of the MBH/ME up to an undetectable level and in the 57% decrease in DA metabolite 3,4-dihydroxyphenylacetic acid concentration, compared to the control. This effect of salsolinol was accompanied by the significant enhancement of the pituitary prolactin release into circulation. The concentration of other DA metabolite, homovanillic acid, as well as NA in the MBH/ME was not affected. Thus, our results in the anestrous sheep underline the role played by salsolinol as a neuromodulator for the hypothalamic NEDA system and as a signal transmitter for the pituitary prolactin release. We suggest that the hypothalamic NEDA system of anestrous sheep during its high secretory activity may be set as a model for studies on the salsolinol-dopamine relationship.

Time-course of kynurenic acid concentration in mouse serum following the administration of a novel kynurenic acid analog.

The changes in concentration of kynurenic acid (KYNA) in different biological samples are of great interest in the pathomechanism and medication of several disorders, and especially those affecting the nervous system. Besides the recent pharmaceutical advances targeting the kynurenine pathway, there is a constant need for further drug development through the synthesis of novel analogs. Reliable analytical methods should be set up to monitor the metabolism and effects of these analogs in both preclinical experiments and human studies. Following a sample preparation procedure based on protein precipitation, new high-performance liquid chromatographic methods with fluorescence and mass spectrometric detection were developed for the determination of KYNA and a novel KYNA analog (N-(2-N,N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride; KYNA amide) in mouse serum samples. The analytical parameters obtained in the validation procedure suggest that the developed method with mass spectrometric detection is simple, fast, accurate and suitable for the measurement of KYNA and its analogs. The results reveal the good in vivo stability of the novel KYNA amide.

Vascular amine oxidases are needed for leukocyte extravasation into inflamed joints in vivo.

OBJECTIVE: Leukocyte traffic from the blood to the joints is crucial in the pathogenesis of arthritis. A bifunctional endothelial cell-surface glycoprotein, AOC3 (amine oxidase, copper-containing 3; also known as vascular adhesion protein 1), has both adhesive and enzymatic properties. We undertook this study to determine the contribution of AOC3 and its oxidase activity to leukocyte trafficking into inflamed joints in vivo. METHODS: We used gene-modified animals, molecular modeling, an AOC3 enzyme inhibitor, oxidase assays, and arthritis models (adjuvant-induced arthritis [AIA] in rats and anti-type II collagen antibody-induced arthritis in mice) to dissect the importance of AOC3 in vivo. RESULTS: The AOC3 inhibitor fitted well with a covalent binding mode into the active site of the AOC3 crystal structure. It selectively blocked the oxidase activity of AOC3 in enzyme assays. Intraperitoneal and oral administration of the AOC3 inhibitor significantly ameliorated rat AIA. In anti-type II collagen antibody-induced arthritis in mice, the AOC3 inhibitor also improved the outcome of the joint inflammation. The acute semicarbazide-sensitive amine oxidase blockade by the inhibitor had even more pronounced effects than genetic deletion of AOC3. Enzymatic analyses showed that the inhibitor also blocked 2 other structurally very closely related AOCs, but not any of more than 100 other enzymes tested. CONCLUSION: These are the first data to demonstrate that the enzymatic activity of the atypical endothelial adhesion molecule AOC3, and possibly that of other closely related ecto-oxidases, is crucial for leukocyte exit from the vessels in inflamed joints in vivo.

Physiological role of salsolinol: its hypophysiotrophic function in the regulation of pituitary prolactin secretion.

We have recently observed that 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol) produced by hypothalamic neurons can selectively release prolactin from the anterior lobe (AL) of the pituitary gland. Moreover, high affinity binding sites for SAL have been detected in areas, like median eminence (ME) and the neuro-intermediate lobe (NIL) that are known terminal fields of the tuberoinfundibular DAergic (TIDA) and tuberohypophysial (THDA)/periventricular (PHDA) DAergic systems of the hypothalamus, respectively. However, the in situ biosynthesis and the mechanism of action of SAL are still enigmatic, these observations clearly suggest that sites other than the AL might be targets of SAL action. Based on our recent observations it may be relevant to postulate that an "autosynaptocrine" regulatory mechanism functioning at the level of the DAergic terminals localized in both the ME and NIL, may play a role in the hypophyseotrophic regulation of PRL secretion. Furthermore, SAL may be a key player in these processes. The complete and precise mapping of these intra-terminal mechanisms should help us to understand the tonic DAerg regulation of PRL secretion. Moreover, it may also give insight into the role of pre-synaptic processes that most likely have distinct and significant functional as well as pathological roles in other brain areas using DAergic neurotransmission, like striatonigral and mesolimbic systems.