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Marine natural products derived from special or extreme environment provide an important source for the development of anti-tumor drugs due to their special skeletons and functional groups. In this study, based on our previous work on the total synthesis and structure revision of the novel marine natural product Chrysamide B, a group of its derivatives were designed, synthesized, and subsequently of which the anti-cancer activity, structure-activity relationships and cellular mechanism were explored for the first time. Compared with Chrysamide B, better anti-cancer performance of some derivatives against five human cancer cell lines (SGC-7901, MGC-803, HepG2, HCT-116, MCF-7) was observed, especially for compound b-9 on MGC-803 and SGC-7901 cells with the IC 50 values of 7.88 ± 0.81 and 10.08 ± 1.08 μM, respectively. Subsequently, cellular mechanism study suggested that compound b-9 treatment could inhibit the cellular proliferation, reduce the migration and invasion ability of cells, and induce mitochondrial-dependent apoptosis in gastric cancer MGC-803 and SGC-7901 cells. Furthermore, the mitochondrial-dependent apoptosis induced by compound b-9 is related with the JAK2/STAT3/Bcl-2 signaling pathway. To conclude, our results offer a new structure for the discovery of anti-tumor lead compounds from marine natural products., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Thirteen new diterpenoid compounds, named agallolides A-M (1-13), including ten ent-atisanes, were isolated from the stems and twigs of the Chinese semi-mangrove plant, Excoecaria agallocha. Most notably, agallolides A (1) and B (2) are two rearranged ent-atisanes featuring a unique 6/6/5/7 tetracyclic carbon skeleton. Agallolides C-J (3-10) are ent-atisanes, among which agallolide C (3) represents the first example of 3,4-seco-17-nor-ent-atisane. Agallolides K (11) and L (12) are two ent-isopimaranes, whereas agallolide M (13) is a rare 3,4-seco-ent-trachylobane. The structures of these diterpenoid compounds were established by HR-ESIMS and extensive 1D and 2D NMR investigations. The absolute configurations of agallolide A (1) and agallolides I-K (9-11) were further confirmed by single-crystal X-ray diffraction analyses with Cu Kα radiation. The plausible biogenetic pathways for agallolides A (1), B (2), and I (9) were proposed. Agallolides I (9) and J (10) exhibited NF-κB inhibitory activity with inhibition rates of 23.4% and 19.4%, respectively, at the concentration of 100.0 µM., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Benzobicyclon is a systemic herbicide that was officially registered in China in 2018. The environmental behaviors of benzobicyclon hydrolysate (BH), the main metabolite and active product of benzobicyclon, remain poorly understood in paddy fields. Here, agricultural soil samples were collected from paddy fields in Jiangxi (Ferralsols), Shandong (Alisols), Hebei (Luvisols), Heilongjiang (Phaeozems), Zhejiang (Anthrosols), Sichuan (Gleysols), Hainan (Plinthosols), and Hubei (Lixisols) across China. The equilibrium oscillation method was used to study the adsorption-desorption behaviors of BH in the eight soils. The relationships between BH adsorption and soil physicochemical properties, environmental factors (temperature and initial solution pH), and other external conditions (addition of humic acid, biochar, and metal ions) were quantified. The adsorption-desorption parameters of BH in all soils were well fitted by the Freundlich model. The adsorption constant of BH varied between 0.066 and 4.728. The BH adsorption capacity decreased in the following order: Phaeozems > Alisols > Ferralsols > Lixisols > Plinthosols > Anthrosols > Luvisols > Gleysols. The Freundlich adsorption and desorption constants of BH were linearly positively correlated with soil clay content (R 2  = 0.711 and 0.709; P = 0.009 and 0.009, respectively), organic carbon content (R 2  = 0.684 and 0.672; P = 0.011 and 0.013, respectively), and organic matter content (R 2  = 0.698 and 0.683; P = 0.010 and 0.011, respectively); however, their linear relationships with soil cation exchange capacity were not significant (R 2  = 0.192 and 0.192; P = 0.278 and 0.278, respectively). The adsorption and desorption constants of BH had negative, albeit not significant, correlations with soil pH (R 2  = 0.104 and 0.100; P = 0.437 and 0.445, respectively). The adsorption of BH by soil occurred spontaneously and was mainly based on physical adsorption. Either low or high temperature reduced the ability of the soil to adsorb BH. The addition of humic acid to the soil increased BH adsorption, while the addition of biochar increased the solution pH, resulting in decreased BH adsorption. Cation type and ionic strength also had strong effects on BH adsorption. With the exception of Phaeozems, BH exhibited intermediate or high mobility in the agricultural soils and thus poses risks to surface water and groundwater., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The long identified toxic gas, hydrogen sulfide (H 2 S), which has also been confirmed as the third gaseous signaling molecule following NO and CO, plays important roles in various physiological and pathological process. The current most established quantification method for H 2 S is HPLC method coupled with fluorescence detection after derivatization with a costly fluorescent reagent, Monobromobimane (MBB). However, The MBB method is characterized by strict reaction condition, long reaction time, tedious operation, and inconsistent reported results. In this study, based on the thiolysis reaction of 7-nitro-2, 1, 3-benzoxadiazole (NBD) ether, the commonly used chromatographic modifier 4-chloro-7-nitro-2,1,3- benzoxadiazole (NBDCl) and four probes (NBDOMe, NBDOEt, NBDOTFE and NBDOCMR) synthesized from NBDCl were tested as alternatives for fast quantification of H 2 S by LC-MS/MS. The reaction product between NBD ethers/NBDCl and H 2 S showed special pink color visible to the naked eye and was easy to synthesize and separate in lab; it also showed good retention on common chromatographic columns and high instrument response; therefore it is a good determinand. After establishment of LC-MS/MS methods for all the related compounds, the reaction conditions were optimized for all the probes with H 2 S. Then the stability, selectivity, reaction rate, sensitivity and quantitative linear relationship between the reaction product and H 2 S concentration were studied for each probe. Finally, NBDOEt was selected for LC-MS/MS detection of H 2 S. In comparision with the MBB method, the established NBDOEt method showed matched sensitivity and linearity, better selectivity, and higher repeatability; and had the advantages of easy operation, simple reaction condition, and cheap raw materials. The method was successfully validated and applied to determination of Na 2 S content in Na 2 S∙9H 2 O bulk drug and injection. In conclusion, NBDOEt is a promising option for quantification of H 2 S in abiotic matrix., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

A simple but previously undescribed macrolide with unprecedented bicyclo 5/9 ring system, namely, cladocladosin A (1), along with two new sulfur-containing macrolides, namely, thiocladospolides F and G (2 and 3), were characterized from the mangrove-derived endophytic fungus Cladosporium cladosporioides MA-299. The structures of these compounds were established on the basis of spectroscopic interpretation, and the absolute configurations of compounds 1-3 were determined by X-ray crystallographic analysis, Mosher's method, and by a biogenetic point of view. The possible biogenetic pathway for compounds 1-3 as well as their congeners thiocladospolides A-D and pandangolide 3 was proposed, providing a role in distinguishing the position of sulfur substitution in thiomacrolides. Compounds 1-3 were evaluated for antimicrobial activities against human-, aquatic-, and plant-pathogenic microbes., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Studies on the substrate selectivity of recombinant ferrous-iron- and 2-oxoglutarate-dependent proline hydroxylases (PHs) reveal that they can catalyse the production of dihydroxylated 5-, 6-, and 7-membered ring products, and can accept bicyclic substrates. Ring-substituted substrate analogues (such hydroxylated and fluorinated prolines) are accepted in some cases. The results highlight the considerable, as yet largely untapped, potential for amino acid hydroxylases and other 2OG oxygenases in biocatalysis., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Despite recent advancements in its control, malaria is still a deadly parasitic disease killing millions of people each year. Progresses in combating the infection have been made by using the so-called artemisinin combination therapies (ACTs). Natural and synthetic peroxides are an important class of antimalarials. Here we describe a new series of peroxides synthesized through a new elaboration of the scaffold of bicyclic-fused/bridged synthetic endoperoxides previously developed by us. These peroxides are produced by a straightforward synthetic protocol and are characterized by submicromolar potency when tested against both chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum strains. To investigate their mode of action, the biomimetic reaction of the representative compound 6w with Fe(II) was studied by EPR and the reaction products were characterized by NMR. Rationalization of the observed structure-activity relationship studies was performed by molecular docking. Taken together, our data robustly support the hypothesized mode of activation of peroxides 6a-cc and led to the definition of the key structural requirements responsible for the antiplasmodial potency. These data will pave the way in future to the rational design of novel optimized antimalarials suitable for in vivo investigation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

A new optical chemical sensor based on medicinal compound, jaeschkeanadiol p-hydroxyben-zoate (Ferutinin), has been designed and utilized for Ca(II) ions detections. This natural optical sensor exhibits immense selectivity including fluorescence and absorption ratiometric for Ca(II) ions within precious physiological pH range. Further, the chelation process of the Ca(II) ions with the medicinal optical sensor ferutinin yields a 1:1 (metal: ligand) complex which is accompanied by fluorescence enhancement of the main emission band centered at 355 nm of the medicinal probe. The fluorescence "turn-on" effect is a clear evidence for the chelation process between ferutinin medicinal probe and Ca(II) ions and this could be simply detected. The new sensor was proposed depending on significant fluorescence mechanism, (MLCT, metal-ligand charge transfer). However, the interaction of the medicinal optical sensor with Ca(II) in presence of other cations was examined without any significant interference. Also, the new developed optical sensor consecutively exhibits low limit of detection (LOD) 1.5 nM for Ca(II) which is detected in very significant physiological pH range (pH = 7.4). Also, the probe provides high binding affinity towards Ca(II) with large binding constant K b 5.97 × 10 4  M -1 . As a result, this optical sensor may apply for detection Ca(II) in cell or biological samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

DNA is a major target for a number of anticancer substances. Interaction studies between small molecules and DNA are essential for rational drug designing to influence main biological processes and also introducing new probes for the assay of DNA. Tschimgine (TMG) is a monoterpene derivative with anticancer properties. In the present study we tried to elucidate the interaction of TMG with calf thymus DNA (CT-DNA) using different spectroscopic methods. UV-visible absorption spectrophotometry, fluorescence and circular dichroism (CD) spectroscopies as well as molecular docking study revealed formation of complex between TMG and CT-DNA. Binding constant (K b ) between TMG and DNA was 2.27×10 4 M -1 , that is comparable to groove binding agents. The fluorescence spectroscopic data revealed that the quenching mechanism of fluorescence of TMG by CT-DNA is static quenching. Thermodynamic parameters (ΔH<0 and ΔS<0) at different temperatures indicated that van der Waals forces and hydrogen bonds were involved in the binding process of TMG with CT-DNA. Competitive binding assay with methylene blue (MB) and Hoechst 33258 using fluorescence spectroscopy displayed that TMG possibly binds to the minor groove of CT-DNA. These observations were further confirmed by CD spectral analysis, viscosity measurements and molecular docking., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A facile method based on gas chromatography-mass spectrometry (GC-MS) and molecular docking was established to analyze, identify, and predict lipase inhibitors in volatile oil from Pinus massoniana L. needles (PMLN). The volatile oil, with an IC 50 value of 15.25 ± 0.06 μg/mL, exhibited potential inhibitory activity against lipase in vitro. In total, 33 compounds were identified from the volatile oil through GC-MS analysis. The major compounds in the volatile oil were β-pinene (39.24%), α-pinene (14.68%), germacrene D (9.08%), caryophyllene (6.94%), α-terpineol (5.39%), β-phellandrene (4.82%), and D-limonene (3.93%). The identified compounds were individually docked with lipase as the target through molecular docking. Among the compounds, longifolene characterized by preferable binding energy and the good inhibition constant exhibited potential lipase inhibitory activity. The IC 50 value of longifolene was 25.10 ± 0.49 μM, indicating that this compound is the active ingredient responsible for the lipase inhibitory activity of PMLN volatile oil., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

LY-354,740 (eglumegad) is a selective and potent agonist of the metabotropic glutamate group II receptors (mGluR2,3) that has already entered clinical trials as a potential anti-psychotic agent and therefore has well-documented pharmacokinetic (PK), safety and tolerability profiles in human. Whereas its development as an anti-psychotic agent has not been pursued, LY-354,740 may have potential in other neuroscience-related fields, notably anxiety and neuro-protection. The common marmoset is a small primate that has long been used in neuroscience. However, given its small size and small circulating blood volume, conducting PK studies to determine the therapeutic effectiveness of LY-354,740 at clinically-relevant doses is challenging. Here, we have developed and validated a simple, sensitive and selective analytical method that enables quantification of LY-354,740 using a small volume of plasma. The analytical method consisted of protein precipitation followed by high-performance liquid chromatography with heat assisted electrospray ionisation mass spectrometry (UHPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of acetonitrile and 10mM ammonium formate (pH 3) on a Thermo Scientific Acclaim Trinity P1 analytical column (100x3.0mm I.D., 3μm) operating at 45°C and at a flow rate of 900μl/min. The method displays a linear relationship ranging from 20.0 to 5000ng/ml. Intra- and inter-day relative standard deviations are less than 5.7% and 7.0%, respectively and the accuracy ranged from 91.0 to 106.0%. The UHPLC-HESI-MS/MS analytical method we describe here is simple, sensitive, specific and capable of quantifying LY-354,740 in both rat and marmoset plasma, and is suitable to conduct PK studies after a single sub-cutaneous dose of 1.0mg/kg or lower in both species., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Basil (Ocimum basilicum L.), a medicinal plant of the Lamiaceae family, is used in traditional medicine; its essential oil is a rich source of phenylpropanoids. Methylchavicol and methyleugenol are the most important constituents of basil essential oil. Drought stress is proposed to enhance the essential oil composition and expression levels of the genes involved in its biosynthesis. In the current investigation, an experiment based on a completely randomized design (CRD) with three replications was conducted in the greenhouse to study the effect of drought stress on the expression level of four genes involved in the phenylpropanoid biosynthesis pathway in O. basilicum c.v. Keshkeni luvelou. The genes studied were chavicol O-methyl transferase (CVOMT), eugenol O-methyl transferase (EOMT), cinnamate 4-hydroxylase (C4H), 4-coumarate coA ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD). The effect of drought stress on the essential oil compounds and their relationship with the expression levels of the studied genes were also investigated. Plants were subjected to levels of 100%, 75%, and 50% of field capacity (FC) at the 6-8 leaf stage. Essential oil compounds were identified by gas chromatography/mass spectrometry (GC-MS) at flowering stage and the levels of gene expression were determind by real time PCR in plant leaves at the same stage. Results showed that drought stress increased the amount of methylchavicol, methyleugenol, β-Myrcene and α-bergamotene. The maximum amount of these compounds was observed at 50% FC. Real-time PCR analysis revealed that severe drought stress (50% FC) increased the expression level of CVOMT and EOMT by about 6.46 and 46.33 times, respectively, whereas those of CAD relatively remained unchanged. The expression level of 4CL and C4H reduced under drought stress conditions. Our results also demonstrated that changes in the expression levels of CVOMT and EOMT are significantly correlated with methylchavicol (r = 0.94, P ≤ 0.05) and methyleugenol (r = 0.98, P ≤ 0.05) content. Thus, drought stress probably increases the methylchavicol and methyleugenol content, in part, through increasing the expression levels of CVOMT and EOMT., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Hydrogen sulfide (H 2 S) plays major functional and structural roles in diverse physiological functions and the pathogenesis of a variety of disorders in biological matrices. The significance of H 2 S has prompted the development of sensitive and selective methods to determine its concentration in biological samples. The fluorescent reagent monobromobimane (MBB) has been widely used to measure various thiol-containing species through alkylation. MBB may prevent the oxidation of sulfide and the reaction of sulfide with several different species (such as superoxide radicals, hydrogen peroxide and peroxynitrite). An isomers of MBB, 3-(bromomethyl)-2, 6, 7-trimethyl-1H, 5H-pyrazolo [1,2-a] pyrazole-1, 5-dione (MMB), is cheaper than MBB and its use in the analysis of H 2 S has not previously been reported. In the present study, we compared the derivatization reactions of hydrogen sulfide with MMB and MBB and developed a sensitive method to quantify H 2 S in blood. In our method, H 2 S was incubated in the dark with excess MMB in 0.1M Tris-HCl buffer (pH 10.1) at 50°C for 120min. 50μL aliquots of the derivatized product were analyzed using HPLC system with gradient elution of 0.1% (v/v) formic acid-acetonitrile. The limit of detection for the derivatized product was 0.03nmol/mL. The derivatization reaction was suitable for detecting low concentrations of H 2 S. The derivate product is stable over time, permitting batch storage and analysis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In screening for antioxidant and α-glucosidase inhibitors from the extracts of Hertia cheirifolia L. flowers, the petroleum ether extract showed interesting antioxidant activity and inhibitory effect on the activity of α-glucosidase. The fractionation of this extract resulted in the isolation of a compound which is characterized by NMR and ESI-MS as a nopol. The nopol exhibited potent α-glucosidase inhibitory potential with IC 50 value of 220μM. The kinetic evaluation indicated that it acts as a non-competitive inhibitor. A molecular docking study proved that the nopol presented a strong affinity with amino acid residues of α-glucosidase., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Current evidence suggests that the closed-state membrane model for the channel-forming domain of colicin E1 involves eight amphipathic α-helices (helices I-VII and X) that adopt a two-dimensional arrangement on the membrane surface. Two central hydrophobic α-helices in colicin E1 (VIII and IX) adopt a transmembrane location-the umbrella model. Helices I and II have been shown to participate in the channel by forming a transmembrane segment (TM1) in the voltage-induced open channel state. Consequently, it is paramount to determine the relative location and orientation of helix I in the two-dimensional arrangement of the membrane. A new, low-resolution, three-dimensional model of the closed state of the colicin E1 channel was constructed based on FRET measurements between three naturally occurring Trp residues and three sites in helix I, in addition to previously reported FRET distances for the channel domain. Furthermore, a new mechanism for the channel integration process involving the transition of the soluble to membrane-bound form is presented based on a plethora of kinetic data for this process., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

Current antidepressants often remain the inadequate efficacy for many depressive patients, which warrant the necessary endeavor to develop the new molecules and targets for treating depression. Recently, the two-pore domain potassium channel TREK1 has been implicated in mood regulation and TREK-1 antagonists could be the promising antidepressant. This study has screened a TREK1 blocker (SID1900) with a satisfactory blood-brain barrier permeation and bioavailability. Electrophysiological research has shown that SID1900 and the previously reported TREK1 blocker (spadin) efficiently blocked TREK-1 current in HEK293 cells and specifically blocked two-pore domain potassium channels in primary-cultured rat hippocampal neurons. SID1900 and spadin induced a significant antidepressant-like response in the rat model of chronic unpredictable mild stress (CUMS). Both two TREK1 blockers substantially increased the firing rate of 5-HT-ergic neurons in the dorsal raphe nuclei (DRN) and PFC of CUMS rats. SID1900 and spadin significantly up-regulated the expression of PKA-pCREB-BDNF signaling in DRN, hippocampus and PFC of CUMS rats, which were enhanced and reversed by a 5-HTR1A agonist (8-OH-DPAT) and antagonist (WAY100635) respectively. The present findings suggested that TREK1 channel blockers posses the substantial antidepressant-like effect and have the potential synergistic effect with 5-HT1A receptor activation through the common CREB-BDNF signal transduction., (Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.)

Out of 107 fungal strains belonging to three phyla (Ascomycota, Basidiomycota and Zygomycota) and 46 genera, 86 exhibited Baeyer-Villiger monooxygenase (BVMO) activity against racemic bicyclo[3.2.0]heptenone. The strains were classified into three "profiles" based on regio- and enantioselectivity. Statistical analyses of our results, extended by literature data, showed that these profiles could be related to the taxonomic classification of the strains, and suggest that the BVMOs from the Zygomycota phylum may be different in their primary structures from established ones., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A new mixed thia-aza macrocyclic complexes with Schiff base viz. 15-thia-3,4,9,10-tetraazabicyclo[10.2.1]pentadeca-1(14),2,10,12-tetraene-5,8-dione containing transition metals, M = Co(II), Ni(II), Cu(II) and Zn(II) and X = Cl(-), NO3(-), OAc(-), has been synthesized, resulting in the final constitution of 1:1:1 M ratio, by the condensation of succinyldihydrazide and thiophenedicarboxaldehyde. The metal complexes have been investigated with the help of various physico-chemical techniques viz. elemental analyses, magnetic susceptibility, thermal, conductivity measurements, spectral (IR, UV, ESR, NMR and mass) and X-ray diffraction techniques. The low value of molar conductivity indicates the non-electrolytic nature of the complexes and a distorted octahedral geometry has been proposed on the basis of various physico-chemical studies. X-ray diffraction indicates the presence of monoclinic crystal system. The complexes have been investigated for in vitro antibacterial, antifungal and antioxidant activity. All the complexes show moderate to significant activity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Ubiquinol-cytochrome c reductase binding protein (UQCRB) is one of the subunits of mitochondrial complex III and is a target protein of the natural anti-angiogenic small molecule terpestacin. Previously, the biological role of UQCRB was thought to be limited to the maintenance of complex III. However, the identification and validation of UQCRB as a target protein of terpestacin enabled the role of UQCRB in oxygen sensing and angiogenesis to be elucidated. To explore the biological role of this protein further, UQCRB mutant stable cell lines were generated on the basis of a human case report. We demonstrated that these cell lines exhibited glycolytic and pro-angiogenic activities via mitochondrial reactive oxygen species (mROS)-mediated HIF1 signal transduction. Furthermore, a morphological abnormality in mitochondria was detected in UQCRB mutant stable cell lines. In addition, the proliferative effect of the UQCRB mutants was significantly regulated by the UQCRB inhibitors terpestacin and A1938. Collectively, these results provide a molecular basis for UQCRB-related biological processes and reveal potential key roles of UQCRB in angiogenesis and mitochondria-mediated metabolic disorders., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to numerous issues involving sample processing, detection methods used, and actual biochemical products measured. Our group and others have reported that reverse phase HPLC detection of sulfide dibimane (SDB) product from the reaction of H2S/HS(-) with monobromobimane allows for analytical detection of hydrogen sulfide bioavailability in free and other biochemical forms. However, it remains unclear whether possible interfering contaminants may contribute to HPLC SDB peak readings that may result in inaccurate measurements of bioavailable sulfide. In this study, we critically compared hydrogen sulfide dependent SDB detection using reverse phase HPLC (RP-HPLC) versus quantitative SRM electrospray ionization mass spectrometry (ESI/MS) to obtain greater clarity into the validity of the reverse phase HPLC method for analytical measurement of hydrogen sulfide. Using an LCQ-Deca ion-trap mass spectrometer, SDB was identified by ESI/MS positive ion mode, and quantified by selected reaction monitoring (SRM) using hydrocortisone as an internal standard. Collision induced dissociation (CID) parameters were optimized at MS2 level for SDB and hydrocortisone. ESI/MS detection of SDB standard was found to be a log order more sensitive than RP-HPLC with a lower limit of 0.25 nM. Direct comparison of tissue and plasma SDB levels using RP-HPLC and ESI/MS methods revealed comparable sulfide levels in plasma, aorta, heart, lung and brain. Together, these data confirm the use of SDB as valid indicator of H2S bioavailability and highlights differences between analytical detection methods., (Copyright © 2014. Published by Elsevier Inc.)

Clusianone is a member of the polycyclic polyprenylated acylphloroglucinol family of natural products; its cytotoxic mechanism is unknown. Clusianone is a structural isomer of nemorosone, which is a mitochondrial uncoupler and a well-known cytotoxic anti-cancer agent; thus, we addressed clusianone action at the mitochondria and its potential cytotoxic effects on cancer cells. In the HepG2 hepatocarcinoma cell line, clusianone induced mitochondrial membrane potential dissipation, ATP depletion and phosphatidyl serine externalization; this later event is indicative of apoptosis induction. In isolated mitochondria from rat liver, clusianone promoted protonophoric mitochondrial uncoupling. This was evidenced by the dissipation of mitochondrial membrane potential, an increase in resting respiration, an inhibition of Ca(2+) influx, stimulation of Ca(2+) efflux in Ca(2+)-loaded mitochondria, a decrease in ATP and NAD(P)H levels, generation of ROS, and swelling of valinomycin-treated organelles in hyposmotic potassium acetate media. The cytotoxic and uncoupling actions of clusianone were appreciably less than those of nemorosone, likely due to the presence of an intra-molecular hydrogen bond with the juxtaposed carbonyl group at the C15 position. Therefore, clusianone is capable of pharmacologically increasing the leakage of protons from the mitochondria and with favorable cytotoxicity in relation to nemorosone., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

A method based on the differential reactivity of thiol and thiolate with monobromobimane (mBBr) has been developed to measure nucleophilicity and acidity of protein and low-molecular-weight thiols. Nucleophilicity of the thiolate is measured as the pH-independent second-order rate constant of its reaction with mBBr. The ionization constants of the thiols are obtained through the pH dependence of either second-order rate constant or initial rate of reaction. For readily available thiols, the apparent second-order rate constant is measured at different pHs and then plotted and fitted to an appropriate pH function describing the observed number of ionization equilibria. For less available thiols, such as protein thiols, the initial rate of reaction is determined in a wide range of pHs and fitted to the appropriate pH function. The method presented here shows excellent sensitivity, allowing the use of nanomolar concentrations of reagents. The method is suitable for scaling and high-throughput screening. Example determinations of nucleophilicity and pK(a) are presented for captopril and cysteine as low-molecular-weight thiols and for human peroxiredoxin 5 and Trypanosoma brucei monothiol glutaredoxin 1 as protein thiols., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: α7-nicotinic acetylcholine receptor (α7-nAChR) is one of the major neuronal nAChR subtypes. α7-nAChR is involved in variety of neuronal processes and disorders including schizophrenia and Alzheimer's disease. A number of α7-nAChR PET radioligands have been developed, but a quality radiotracer remains to be discovered., Methods: High binding affinity α7-nAChR ligands A-833834 and A-752274 were radiolabeled with (11)C. Baseline and blockade biodistribution studies in the mouse brain of [(11)C]A-833834 (5-(6-(5-[(11)C]methylhexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl)pyridazin-3-yl)-1H-indole) and [(11)C]A-752274 (2-(6-[(11)C]methyl-3,6-diazabicyclo[3.2.0]heptan-3-yl)-7-(6-methyl-3,6-diazabicyclo[3.2.0]heptan-3-yl)-9H-fluoren-9-one) were performed. [(11)C]A-752274 was evaluated in a baseline baboon PET study., Results: [(11)C]A-833834 and [(11)C]A-752274 were synthesized by radiomethylation of corresponding des-methyl precursors. The radioligands were prepared with radiochemical yield of 12%-32%, high specific radioactivity (330-403GBq/μmol) and radiochemical purity>95%. Dissection studies with [(11)C]A-833834 demonstrated low specific α7-nAChR binding in the mouse brain. [(11)C]A-752274 specifically (~50%) labeled α7-nAChR in the mouse thalamus. However, [(11)CA-752274 exhibited low brain uptake in baboon (%SUV<100)., Conclusion: Two novel α7-nAChR ligands radioligands were synthesized and studied in animals. Specific binding of [(11)C]A-833834 in the mouse brain is low due to the insufficient binding affinity of the radioligand. The very high binding affinity [(11)C]A-752274 exhibited good specific binding in the α7-nAChR-rich mouse brain regions. The low uptake of [(11)C]A-752274 in the baboon brain is due to its high hydrophilicity, rapid metabolism or other properties. Future development of α7-nAChR PET radioligands will be based on compounds with high binding affinities and good blood-brain barrier permeability., (Copyright © 2013 Elsevier Inc. All rights reserved.)

An alkane hydroxylase from the marine organism Alcanivorax borkumensis (AbAlkB) was purified. The purified protein retained high activity in an assay with purified rubredoxin (AlkG), purified maize ferredoxin reductase, NADPH, and selected substrates. The reaction mechanism of the purified protein was probed using the radical clock substrates bicyclo[4.1.0]heptane (norcarane), bicyclo[3.1.0]hexane (bicyclohexane), methylphenylcyclopropane and deuterated and non-deuterated cyclohexane. The distribution of products from the radical clock substrates supports the hypothesis that purified AbAlkB hydroxylates substrates by forming a substrate radical. Experiments with deuterated cyclohexane indicate that the rate-determining step has a significant CH bond breaking character. The products formed from a number of differently shaped and sized substrates were characterized to determine the active site constraints of this AlkB. AbAlkB can catalyze the hydroxylation of a large number of aromatic compounds and linear and cyclic alkanes. It does not catalyze the hydroxylation of alkanes with a chain length longer than 15 carbons, nor does it hydroxylate sterically hindered C-H bonds., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The synthesis of three conformationally locked d-glucopyranoside analogs displaying the hydroxyl pattern of the parent sugar is described. A two carbon bridge connecting the C-2 and C-5 atoms of the pyranose ring allows a torsion of the sugar ring toward a (2,5)B conformation as confirmed by conformational analysis. This conformation is strongly believed to be adopted by the oxacarbenium ion-like transition state of several inverting glucosidases., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Syntheses of six N-homobicyclic dideoxynucleoside analogues are described. The reaction of mannose diacetonide with trimethylsulfoxonium iodide gave a mixture of diastereomeric hydroxymethyl mannose diacetonides in a ratio of 2:5, which was separated by fractional crystallization. The two stereoisomers were converted to bicyclic furanolactols each of which was coupled with three nucleoside bases. Further debenzylations gave the six target N-homobicyclic dideoxynucleosides., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This work reports isolation of an unusual lignan with a bicyclic [2.2.2] octene skeleton, named rufescenolide (1), from stems of Cordia rufescens, along with β-sitosterol, stigmasterol, syringaldehyde, 3-β-O-D-glucopyranosyl-sitosterol, methyl caffeate, 4-methoxy-protocatechuic acid and methyl rosmarinate. Structural characterizations employed IR spectroscopic, ESIHRMS and mono and dimensional NMR spectroscopy., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Membrane gas separation technologies (air separation, hydrogen recovery from dehydrogenation processes, etc.) use traditionally the glassy polymer membranes with dominating permeability of "small" gas molecules. For this purposes the membranes based on the low free volume glassy polymers (e.g., polysulfone, tetrabromopolycarbonate and polyimides) are used. On the other hand, an application of membrane methods for VOCs and some toxic gas recovery from air, separation of the lower hydrocarbons containing mixtures (in petrochemistry and oil refining) needs the membranes with preferable penetration of components with relatively larger molecular sizes. In general, this kind of permeability is characterized for rubbers and for the high free volume glassy polymers. Data files accumulated (more than 1500 polymeric materials) represent the region of parameters "inside" of these "boundaries." Two main approaches to the prediction of gas permeability of polymers are considered in this paper: (1) the statistical treatment of published transport parameters of polymers and (2) the prediction using model of ≪diffusion jump≫ with consideration of the key properties of the diffusing molecule and polymeric matrix. In the frames of (1) the paper presents N-dimensional methods of the gas permeability estimation of polymers using the correlations "selectivity/permeability." It is found that the optimal accuracy of prediction is provided at n=4. In the frames of the solution-diffusion mechanism (2) the key properties include the effective molecular cross-section of penetrating species to be responsible for molecular transportation in polymeric matrix and the well known force constant (ε/k)(eff i) of {6-12} potential for gas-gas interaction. Set of corrected effective molecular cross-section of penetrant including noble gases (He, Ne, Ar, Kr, Xe), permanent gases (H(2), O(2), N(2), CO), ballast and toxic gases (CO(2), NO(,) NO(2), SO(2), H(2)S) and linear lower hydrocarbons (CH(4), C(2)H(6), C(3)H(8), C(4)H(10), C(2)H(4), C(3)H(6), C(4)H(8) - 1, C(2)H(2), C(3)H(4)-m (methylacetylene) and C(3)H(4)-a (allen) is determined by using two above mentioned approaches. All of this allows calculating preliminary the permeability parameters of above mentioned gases for most part of known polymers based on limited experimental data. The new correlations suggested demonstrate that the available free volume of polymeric matrix plays an important role in providing of rate and selectivity of gas diffusion for glassy-like polymers; the rate and selectivity of gas diffusion in rubbers is affected mainly by cohesion energy density (CED) the both polymer parameters being calculated by traditional additive group contributions technique. Results of present study are demonstrated by calculation of expected permeability parameters in relation to lower hydrocarbons and some toxic gases for polynorbornene based polymers, PIM and PTMSP outlining potential of practical application for new membrane polymers., (Copyright © 2010 Elsevier B.V. All rights reserved.)

PM(2.5) samples collected at Cork Harbour, Ireland during summer, autumn, late autumn and winter, 2008-2009 were analyzed for polar organic compounds that are useful markers for aerosol source characterization. The determined compounds include tracers for biomass burning primary particles, fungal spores, markers for secondary organic aerosol (SOA) from isoprene, α-/β-pinene, and d-limonene. Seasonal and temporal variations and other characteristic features of the detected tracers are discussed in terms of aerosol sources and processes. The biogenic species were detected only during the summer period where the contributions of isoprene SOA and fungal spores to the PM(2.5) organic carbon (OC) were estimated to be 1.6% and 1% respectively. The biomass burning markers, and in particular levoglucosan, were present in all samples and attributed to the combustion of cellulose-containing fuels including wood, peat, bituminous and smokeless coal. The contribution of domestic solid fuel (DSF) burning to the measured OC mass concentration was estimated at 10.8, 50, 66.4 and 74.9% for summer, autumn, late autumn and winter periods, respectively, based on factors derived from a series of burning experiments on locally available fuels. Application of an alternative approach, namely principal component analysis-multiple linear regression (PCA-MLR), to the measured concentrations of the polar organic marker compounds used in conjunction with real-time air quality data provided similar trends and estimates for DSF combustion during all seasons except summer. This study clearly demonstrates that, despite the ban on the sale of bituminous coal in Cork and other large urban areas in Ireland, DSF combustion is still the major source of OC during autumn and winter periods and also makes a significant contribution to PM(2.5) levels. The developed marker approach for estimating the contribution of DSF combustion to ambient OC concentrations can, in principle, also be applied to other locations., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Conformationally constrained analogues of the hormone melatonin with a side chain incorporated into the bicyclic bridgehead core were synthesized based on the homology modeling and molecular docking studies performed for the MT(2) melatonin receptor. The methoxy-indole derivative fused with exo-N-acetamino-substituted bicyclo[2.2.2]octane was found to possess nanomolar MT(2) receptor affinity., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Counter-current chromatography (CCC) combined with pre-separation by ultrasonic solvent extraction was successively used for the separation of series bioactive compounds from the crude extract of Hypericum perforatum L. The petroleum ether extract was separated by the solvent system of n-heptane-methanol-acetonitrile (1.5:0.5:0.5, v/v) and n-heptane-methanol (1.5:1, v/v) in gradient elution, yielding a phloroglucinol compound, hyperforin with HPLC purity over 98%. The ethyl acetate extract was separated by using the solvent system composed of hexane-ethyl acetate-methanol-water (1:1:1:1 and 1:3:1:3, v/v) in gradient through both reverse phase and normal phase elution mode, yielding a naphthodianthrone compound, hypericin with HPLC purity about 95%. The n-butanol extract was separated with the solvent system composed of n-butanol-ethyl acetate-water (1:4:5 and 1.5:3.5:5, v/v) in elution and back-extrusion mode, yielding two of flavones, rutin and hyperoside, with HPLC purity over 95%. HPLC-MS, reference sample and UV spectrum were selectively used in separation to search for target compounds from HPLC-DAD profiles of different sub-extracts. The structures of isolated compounds were further identified by ESI-MS, ¹HNMR and ¹³CNMR., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Santolina insularis (Genn ex Fiori) Arrig. is a medicinal plant whose essential oil shows antiviral and antibacterial activities and potent and selective cytotoxic activity against the human colon carcinoma cell line. The occurrence of several chemotypes makes the taxonomic identification of S. insularis hard to achieve. GC-MS essential oil analyses of four chemotypes (SI1, SI2, SI3 and SI4) revealed the presence of different percentages of santolina triene, beta-pinene, myrcene, beta-phellandrene, artemisia ketone and cis-chrysanthemol, allowing a chemical discrimination. Single fragments of the 5S-rRNA-NTS region of approximately 150, 170, 260 and 280bp were produced by SI1, SI2, SI3 and SI4, respectively, and the sequence alignment of the 5S-rRNA spacer region flanked by the 3'-and 5'-ends of the coding region confirmed a consistent difference between chemotypes. Furthermore, a PCR-RFLP method was applied. From the identified sequences, an EcoRV site could be found in chemotypes SI1, SI2 and SI3 in the 5S-rRNA spacer regions at 81 bp position; however, this site was absent in the chemotype SI4. This study, by showing remarkable chemical variation in the terpenoid profile and consistent genomic difference in the 5S-rRNA spacer regions, identified four chemotypes of S. insularis which could be grouped into two ecotypes, based on chemical and genomic analyses. The identification of specific gene sequences of the 5S-rRNA-NTS region and of a EcoRV site identified in this work can be used for a rapid and precise identification of the plant chemo-/ecotypes, complementing the essential oil chemical analysis., (Copyright 2010 Elsevier Ltd. All rights reserved.)

A modified QuEChERS-GC-MS method for analysis of procymidone residue in leeks and soil was developed and validated. Procymidone residue dynamics and residues in supervised field trials at GAP conditions in leeks and soil in greenhouses were studied. Leek samples were treated under microwave radiation for 1min before homogenization, followed by extracting with acetonitrile and clean-up with reverse solid phase dispersion by primary and secondary amine (PSA). Procymidone residue was determined by GC-MS in selected ion monitoring (SIM) mode. At fortification levels of 0.02, 0.2 and 2mg/kg in leeks and soil, it was shown that recoveries ranged from 74.9% to 100.8% with relative standard deviations of 1.3-8.5%. At four geographical experimental plots, procymidone residue in leeks and soil showed a relatively fast dissipation rate, with half-lives of 4.52-8.76 days for leeks and 3.76-5.65 days for soil. At pre-harvest intervals of 21-30 days, procymidone residue ranged from 0.033 to 0.17mg/kg in leeks, and 0.020-1.75mg/kg in soil. Residues persistence varied in leeks and soil in four field trials, suggesting that it might be affected by some physical and chemical factors, growth dilution factor, soil characteristics and microorganisms.

Mutation of RAS genes is a critical event in the pathogenesis of different human tumors and in some developmental disorders. Here we present an arabinose-derived bicyclic compound displaying selective cytotoxicity in human colorectal cancer cells expressing K-Ras(G13D), that shows high intrinsic nucleotide exchange rate. We characterize binding of bicyclic compounds by docking and NMR experiments and their inhibitory activity on GEF-mediated nucleotide exchange on wild-type and mutant Ras proteins. We demonstrate that the in vitro inhibition of Ras nucleotide exchange depends on the molar ratio between Ras and its GEF activator, suggesting that the observed in vivo selective effect may depend on biochemical parameters and actual intracellular concentration of the Ras protein and its regulators.

A simple, specific and sensitive derivatization with monobromobimane (mBrB) and the corresponding HPLC-fluorescence quantitation method for the analysis of bucillamine in human plasma was developed and validated. The analytical procedure involves a simple protein precipitation, pre-column fluorescence derivatization, and separation by reversed-phase high performance liquid chromatography (RP-HPLC). The calibration curve showed good linearity over a wide concentration range (50 ng/mL to 10 microg/mL) in human plasma (r(2)=0.9998). The lower limit of quantitation (LLOQ) was 50 ng/mL. The average precision and accuracy at LLOQ were within 6.3% and 107.6%, respectively. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (300 mg) of bucillamine to 20 healthy Korean volunteers.

Maize plants attacked by lepidopteran larvae emit a volatile mixture that consists mostly of the sesquiterpene olefins, (E)-alpha-bergamotene and (E)-beta-farnesene. These volatiles are produced by the herbivore-induced terpene synthase TPS10 and attract natural enemies to the damaged plants. A survey of volatiles in maize lines and species of teosinte showed that the TPS10 products (E)-alpha-bergamotene and (E)-beta-farnesene are consistently induced by herbivory, indicating that release of TPS10 volatiles is a defense trait conserved among maize and its wild relatives. Sequence comparison of TPS10 from maize and its apparent orthologs from four teosinte species demonstrated stabilizing selection on this defense trait. The teosinte volatiles and the enzymatic activity of the apparent TPS10 orthologs were not completely uniform but varied in the ratio of (E)-alpha-bergamotene to (E)-beta-farnesene products formed. We identified a single amino acid in the active center which determines the ratio of (E)-alpha-bergamotene to (E)-beta-farnesene and has changed during the evolution of maize and teosinte species. Feeding experiments with the substrate (Z,E)-farnesyl diphosphate revealed that this amino acid controls the rate of isomerization of the (E,E)-farnesyl carbocation intermediate to the (Z,E)-configuration.

Functionalized monolithic columns were prepared via ring-opening metathesis polymerization (ROMP) within silanized fused silica capillaries with an internal diameter of 200 microm by in situ grafting. This procedure is conducted in two steps, the first of which is the formation of the basic monolithic structure by polymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) in a porogenic system (toluene and 2-propanol) using RuCl(2)(PCy(3))(2)(CHPh) as ROMP initiator. In the second step the still active initiator sites located on the surface of the structure-forming microglobules were used as receptor groups for the attachment ("grafting") of functional groups onto the monolithic backbone by flushing the monolith with 7-oxanorborn-2-ene-5,6-carboxylic anhydride (ONDCA). Functionalization conditions were first defined that did not damage the backbone of low polymer content (20%) monoliths allowing high-throughput chromatographic separations. Variation of the functionalization conditions was then shown to provide a means of controlling the degree of functionalization and resulting ion-exchange capacity. The maximum level of in situ ONDCA grafting was obtained by a 3h polymerization in toluene at 40 degrees C. The weak cation-exchange monoliths obtained provided good separation of a standard peptide mixture comprising four synthetic peptides designed specifically for the evaluation of cation-exchange columns. An equivalent separation was also achieved using the lowest capacity column studied, indicative of a high degree of robustness of the functionalization procedure. As well as demonstrably bearing ionic functional groups enabling analyte separation in the cation-exchange mode, the columns exhibited additional hydrophobic characteristics which influenced the separation process. The functionalized monoliths thus represent useful tools for mixed-mode separations.

The title compounds trans- and cis-2,2,2',2'-tetrachloro-3,3,3',3'-tetramethyl-bicyclopopylidene were synthesized, and their infrared and Raman spectra were recorded. Non-coincidence between the IR and Raman bands of the trans compound suggested C(2h) symmetry and a planar ring system. In the cis compound most of the IR and Raman bands coincided and a C(2v) symmetry seems likely. The exocyclic CC double bond gave rise to a medium/weak Raman band at 1,847 cm(-1) in the trans compound. In the cis derivative IR and Raman bands both at 1,825 cm(-1) were observed. From similarities with related molecules, the ring breathing, the antisymmetric ring stretch, the CCl(2) out-of-phase and in-phase stretch and the out-of-plane ring bending modes have been tentatively assigned for the trans and cis compounds.

The biotin switch assay has recently been proposed as the eligible method to identify different S-nitrosated proteins in biological matrices. However, notwithstanding its wide application, a thorough validation of this method is still lacking. In particular, it has been suggested that ascorbate concentrations higher than 1mM (as proposed in the original method) are needed since ascorbate reaction with S-nitrosothiols is slow. But the selectivity of ascorbate as a cleaving agent of the S-N bond under these conditions has not been well characterized. Our data indicate that ascorbate is able to reduce disulfide bridges of DTNB, cystine, cystinylglycine, glutathione disulfide, protein mixed disulfides and biotin-HPDP with pH and concentration dependent rates. Additionally, we tested the effect of indirect sunlight on ascorbate-mediated cleavage of both disulfides and S-nitrosothiols.

A method for enantioselective determination of bromocyclen enantiomers in fish tissue has been developed. The enantiomers were resolved by capillary gas chromatography (GC) using a commercial chiral column (CP-Chirasil-Dex CB) and a temperature program from 50 degrees C (held for 1 min), raised to 140 degrees C at 40 degrees C min(-1) and then raised at 0.2 degrees C min(-1) to 155 degrees C. This enantioselective gas chromatographic separation was combined with a clean-up/enrichment procedure based on solid-phase microextraction (SPME). Under SPME optimized conditions, precision, linearity range and detection limits of the developed SPME-enantioselective GC procedure were evaluated and compared using two different detection systems: a classical electron-capture detection (ECD) and an element specific detection using inductively coupled plasma mass spectrometry (ICP-MS). The SPME-GC-ECD method exhibited an excellent sensitivity, with detection limits of 0.2 ng L(-1) for each enantiomer of bromocyclen. Although ICP-MS offered poorer detection limits (7 ng L(-1) as Br, equivalent to 36 ng L(-1) of each enantiomer) than conventional ECD detector, it proved to be clearly superior in terms of selectivity. The relative potential and performance of the two compared methods for real-life analysis has been illustrated by the determination of enantiomers of bromocyclen in spiked tissue extracts of trout.

We have determined the structural changes that accompany the formation of a stable complex between a destabilized mutant of T4 lysozyme (T4L) and the small heat shock protein alpha-crystallin. Using pairs of fluorescence or spin label probes to fingerprint the T4L tertiary fold, we demonstrate that binding disrupts tertiary packing in the two domains as well as across the active-site cleft. Furthermore, increased distances between i and i+4 residues of helices support a model in which the bound structure is not native-like but significantly unfolded. In the confines of the oligomer, T4L has a preferential orientation with residues in the more hydrophobic C-terminal domain sequestered in a buried environment, while residues in the N-terminal domain are exposed to the aqueous solvent. Furthermore, electron paramagnetic resonance spectral line shapes of sites in the N-terminal domain are narrower than in the folded, unbound T4L reflecting an unstructured backbone and an asymmetric pattern of contacts between T4L and alpha-crystallin. The net orientation is not affected by the location of the destabilizing mutation consistent with the notion that binding is not triggered by recognition of localized unfolding. Together, the structural and thermodynamic data indicate that the stably bound conformation of T4L is unfolded and support a model in which the two modes of substrate binding originate from two discrete binding sites on the chaperone.

Hyperforin is a pharmacologically active constituent of Hypericum perforatum (St. John's wort). In vitro cultures of this medicinal plant were found to contain hyperforin and three related polyprenylated acylphloroglucinol derivatives. The accumulation of these compounds was coupled to shoot regeneration, with secohyperforin being the major constituent in morphogenic cultures. The structure of secohyperforin was elucidated online by LC-DAD, -MS, and -NMR. In multiple shoot cultures, the ratio of hyperforin to secohyperforin was strongly influenced by the phytohormones N6-benzylaminopurine (BAP) and naphthalene-1-acetic acid (NAA). While increasing concentrations of BAP stimulated the formation of hyperforin, increasing concentrations of NAA elevated the level of secohyperforin. No differential stimulation was observed after elicitor treatment. Hyperforin and secohyperforin are proposed to arise from a branch point in the biosynthetic pathway.

The synthesis of a bicyclic analogue of the naturally occurring alpha-L-iduronic acid locked in a biologically active (2)S0 skewboat conformation is disclosed. The desired (2)S0 conformation has been obtained by tethering the C-2 and C-5 carbon atoms of the sugar ring with a dimethyloxy bridge and confirmed by NMR and molecular modeling. The new mimic displays the exact hydroxyl pattern of alpha-L-iduronic acid, a major monosaccharide component of glycosaminoglycans and thus represents a closer mimic of the latter, compared to previously reported bicyclic analogs.

The synthesis of a fused bicyclic thioglycoside analogue of mycothiol, (3R)-3-acetylamino-4-one-6,7-dihydro-(1',2'-dideoxy-beta-D-glucopyranoso)[2',1'-f]-1,5-thiazepane (5), is reported. Treatment of phthalimido-protected peracetylated glucosamine with N-acetyl-cysteine and boron trifluoride-etherate gave the beta-linked thioglycoside, which was deprotected and cyclized, using HOBt and EDCl to form the lactam and giving the target structure. This mycothiol mimic and its tri-O-acetate will be investigated as potential inhibitors of enzymes involved in the biosynthesis of mycothiol. The protected derivative also has the potential to be an alpha-selective N-cysteinyl glucosamine donor; however, initial glycosylation attempts failed due to the apparent stability of the fused bicyclic system.

Novel nojirimycin-derived bicyclic structures, containing cyclic carbamate, urea and guanidine moieties have been synthesised starting from suitably protected alpha-C-vinylnojirimycin and alpha-C-allylnojirimycin, respectively, and their biological activity against different glycosidases and as antibacterial agents tested.

Hyperforin and adhyperforin contribute to the antidepressant effects of Hypericum perforatum. The involvement of branched-chain amino acids in the biosynthesis of hyperforin and adhyperforin was demonstrated in H. perforatum shoot cultures. L-[U-(13)C(5)]Valine and L-[U-(13)C(6)]isoleucine, upon administration to the shoot cultures, were incorporated into acyl side chain of hyperforin and adhyperforin, respectively. Feeding the shoot cultures with unlabelled L-isoleucine at a concentration of 2mM induced a 3.7-fold increase in the production of adhyperforin. The addition of 3mM L-threonine, a precursor of isoleucine, stimulated a 2.0-fold increase in the accumulation of adhyperforin. The administration of L-valine at concentrations of 0-5mM had no stimulating effect on the hyperforin production in H. perforatum shoot cultures.

Glutathione (GSH) was assayed in must and wine using capillary electrophoresis coupled with laser-induced fluorescence (LIF) detection. Sample preparation involved conjugating thiols with monobromobimane (MBB) in a 2-(N-cyclohexylamino)ethanesulfonic acid [CHES] buffer (179mM). The electrophoretic conditions were 30kV with a capillary length of 105cm from the inlet to the detector (120cm total length) and a 50microm inner diameter. Under these conditions, the complete separation from the other main non-volatile thiols took less than 20min. We also described the optimum conditions for derivatizing wine samples with MBB to increase eletrophoretic sensitivity. The detection limit for glutathione assay is 65nmol/L. This simple, sensitive method provides a specific assay of glutathione in reduced form, as the sample preparation technique does not modify the balance of oxidized and reduced forms. We used this method to monitor changes in the reduced glutathione content of a white wine during alcoholic fermentation and barrel aging.

Literature indicates that herb-drug interaction of St. John's wort is largely due to increased metabolism of the co-administered drugs that are the substrates of cytochrome P450 (CYP) 3A4 enzyme, alteration of the activity and/or expression of the enzyme. The major St. John's wort constituents, acylphloroglucinols, were evaluated for their effects on CYP3A4 enzyme activity to investigate their roles in herb-drug interaction. Hyperforin and four oxidized analogues were isolated from the plant and fully characterized by mass spectral and NMR analysis. These acylphloroglucinols inhibited activity of CYP3A4 enzyme potently in the fluorometric assay using the recombinant enzyme. Furoadhyperforin (IC(50) 0.072 microM) was found to be the most potent inhibitor of CYP3A4 enzyme activity, followed by furohyperforin isomer 1 (IC(50) 0.079 microM), furohyperforin isomer 2 (IC(50) 0.23 microM), hyperforin (IC(50) 0.63 microM) and furohyperforin (IC(50) 1.3 microM). As the acylphloroglucinols are potent inhibitors of the CYP3A4 enzyme, their modulation of the enzyme activity is unlikely to be involved in increased drug metabolism by St. John's wort.

Hyperforin is a polyprenylated acylphloroglucinol derivative from Hypericum perforatum (St. John's wort). It exhibits antidepressant activity by a novel mechanism of action, antibiotic activity against gram-positive bacteria, and antitumoral activity in vivo. However, it also produces drug-drug interactions by activation of the pregnan X receptor. No total synthesis has been described. Some natural and semisynthetic analogues are available to study structure-activity relationships. Enzymatically, the skeleton of hyperforin is formed by isobutyrophenone synthase from isobutyryl-CoA and three molecules of malonyl-CoA. The first prenylation step is catalyzed by a soluble and ion-dependent dimethylallyltransferase. Hyperforin mainly accumulates in pistils and fruits where it probably serves as defensive compound.

Diffusion ordered spectroscopy (DOSY) is a powerful two-dimensional NMR method to study molecular translation in various systems. The diffusion coefficients are usually retrieved, at each frequency, from a fit procedure on the experimental data, considering a unique coefficient for each molecule or mixture. However, the fit can be improved if one regards the decaying curve as a multiexponential function and the diffusion coefficient as a distribution. This work presents a computer code based on the Hopfield neural network to invert the data. One small-molecule binary mixture with close diffusion coefficients is treated with this approach, demonstrating the effectiveness of the method.