Relative acidity scale of glycine- and taurine-conjugated bile acids through ESI-MS measurements

The most important bile acids, in the form of glycine and taurine conjugates, have been ordered in terms of relative acidity scale. The measurements have been carried out using mass spectrometric techniques. The group of taurine conjugates confirm the superior acidity over the glycine derivatives. Rationale of the differences found in gas-phase and comparison with the data reported in solution-phase are discussed with the support of theoretical calculations. The study has been completed with the acidity sequence of mixed oxo-hydroxy bile acids.     

The circular dichroism and differential scanning calorimetry study of the properties of DNA aptamer dimers

We have applied circular dichroism (CD), temperature-gradient gel electrophoresis (TGGE) and differential scanning calorimetry (DSC) to study the properties of novel bioengineered DNA aptamer dimers sensitive to fibrinogen (F) and heparin (H) binding sites of thrombin and compared them with canonical single stranded aptamer sensitive to fibrinogen binding site of thrombin (Fibri). The homodimer (FF) and heterodimer (FH) aptamers were constructed based on hybridization of their supported parts. CD results showed that both FF and FH dimers form stable guanine quadruplexes in the presence of potassium ions like those in Fibri. The thermal stability of aptamer dimers was slightly lower compared to those of canonical aptamers, but sufficient for practical applications. Both FF and FH aptamer dimers exhibited a potassium-dependent inhibitory effect on thrombin-mediated fibrin gel formation, which was on average two-fold higher than those of canonical single stranded Fibri aptamers.     

Sesquiterpenoids from Chloranthus henryi and Their Anti‐neuroinflammatory Activities

Five new and seven known mono‐sesquiterpenoids ( 1 – 5 and 6 – 12 , resp.) together with five known lindenane‐type disesquiterpenoids, 13 – 17 , were isolated from the whole plant of Chloranthus henryi. Based on spectroscopic methods, the new structures were established to be (5S,6R,8S,10R)‐6‐hydroxyeudesma‐4(15),7(11)‐diene‐12,8‐olide ( 1 ), 6α‐hydroxyeudesma‐4(15),7(11),8(9)‐triene‐12,8‐olide ( 2 ), 8,12‐epoxy‐1β‐hydroxyeudesma‐4(15),7,11‐trien‐6‐one ( 3 ), 12‐oxochloraniolide A ( 4 ), and (4α)‐8‐hydroxy‐12‐norcardina‐6,8,10‐trien‐11‐one ( 5 ), respectively. Among the isolates, compound 2 , zederone epoxide ( 8 ), spicachlorantin G ( 13 ), chloramultilide A ( 14 ), shizukaol B ( 15 ), and spicachlorantin B ( 17 ) showed significant anti‐neuroinflammatory effects by inhibiting nitric‐oxide (NO) production in lipopolysaccharide (LPS)‐stimulated murine BV‐2 microglial cells with relatively low cytotoxicity.     

UV-B辐射和NaCl胁迫对绿豆幼苗叶片DNA损伤的复合效应

研究了0·4W/m2UV-B辐射和0·4%NaCl胁迫对两绿豆品种中绿_1和秦豆-20(PhaseolusraditusL.cv.Zhongl櫣-1andQindou-20)幼苗叶片DNA损伤的复合效应。结果表明:(1)中绿-1抗UV-B辐射和NaCl胁迫的能力均强于秦豆-20;NaCl胁迫能降低中绿-1UV-B敏感性,但对秦豆-20UV-B敏感性无明显影响。(2)两逆境因子单独胁迫或复合胁迫下DNA增色效应均明显降低,但中绿-1降低程度小于秦豆-20,复合胁迫下降低程度小于单独NaCl胁迫下。(3)UV-B辐射诱导的中绿-1DNA链内环丁烷嘧啶二聚体(CPD)累积量明显低于秦豆-20;NaCl胁迫能降低UV-B诱导的中绿-1CPD累积,而对UV-B诱导的秦豆-20CPD累积无影响。(4)各种胁迫处理均导致两品种幼苗DNA含量降低,但两品种间相比中绿-1降低程度较大。结果说明UV-B辐射不仅能诱导DNA链内交联形成CPD,而且能诱导DNA链间交联和DNA含量降低,且不同绿豆品种或同一品种在有无NaCl胁迫时UV-B敏感性的差异主要与CPD累积量和DNA链间交联程度有关。     

Synthesis and evaluation of new diaryl ether and quinoline hybrids as potential antiplasmodial and antimicrobial agents

Synthesis and bioevaluation of new diaryl ether hybridized quinoline derivatives as antiplasmodial, antibacterial and antifungal agents is reported. It was encouraging to discover that several compounds displayed 2–3 folds better efficacy than chloroquine in chloroquine-resistant K1 strain of Plasmodium falciparum. Further, a few members of the library displayed good antibacterial efficacy against gram positive strains of bacteria but none of the compounds displayed any significant antifungal activity.     

MONITORING ULTRAVIOLET-B-INDUCED DNA DAMAGE IN INDIVIDUAL DIATOM CELLS BY IMMUNOFLUORESCENT THYMINE DIMER DETECTION1

We developed a method to investigate the effect of ultraviolet-B radiation (UVBR) on the formation of thy-mine dimers in microalgal DNA that can be used for both laboratory and in situ research. Antibody labeling of dimers was followed by a secondary antibody (fluorescein isothiocyanate) staining to allow visualization of DNA damage with flow cytometry or fluorescence microscopy. Thymine dimer-specific fluorescence in nuclear DNA of the marine diatom Cyclotella sp. was linearly related to the UVBR dose. Simultaneous measurements of cellular DNA content showed that the vulnerability of G2 cells to DNA damage did not differ significantly from the vulnerability of G1 cells. The formation and removal of thymine dimers in Cyclotella sp. cells was monitored for 3 consecutive days at two realistic UVBR irradiance levels. Thy-mine dimers were removed within 24 h when exposed to a saturating photosynthetically active radiation intensity following the UVBR treatment. This new method allows the study of UVBR-induced DNA damage on a cell-to-cell basis. It is also feasible for field studies because cells remain intact and can be recognized readily after antibody treatment.     

The fate of cytochrome b559during anaerobic photoinhibition and its recovery processes

The function of the cytochrome b₅₅₉, a Photosystem II (PS II) reaction center ubiquitous component is not yet known. Cytochrome b₅₅₉appears in a high (HP) or low (LP) potential form. The HP form is converted into the LP form during aerobic photoinhibition. It has been proposed before that this conversion, assumed to be reversible, ascribes protection against light stress of PS II by redirecting electron flow within PS II thus avoiding charge recombination of the primary radical pair and related oxidative damage. Here, we have used an experimental system allowing to assay the relation between the cytochrome b₅₅₉redox potential shift, its reversibility and protection against light induced PS II inactivation. Under anaerobic conditions fast reversible photoinactivation of PS II in isolated spinach thylakoids is observed accompanied by monomerisation of PS II. Monomers did not dissociate further into PS II sub-particles and did not migrate out of the grana partitions as observed in aerobic photoinactivation. The anaerobic photoinactivation is accompanied by an increase in the cytochrome b₅₅₉LP/HP ratio. However, despite recovery of PS II activity and partially of its dimeric form in darkness under aerobic conditions, no reversal of the cytochrome b₅₅₉redox potential shift accompanied these processes. Re-exposure of reactivated thylakoids having an increased PS II population in the LP form of the cytochrome b₅₅₉to strong illumination under aerobic conditions, did not result in a measurable protection of PS II as compared to control thylakoids. While it is possible that cytochrome b₅₅₉may play a protective role against light stress in PS II, the results presented here do not indicate that the increase in the ratio LP/HP form is involved in this process.     

Combination of 4-anilinoquinazoline,arylurea and tertiary amine moiety to discover novel anticancer agents

In present study, 4-anilinoquinazolines scaffold, arylurea and tertiary amine moiety were combined to design, synthesize gefitinib analogs and discover novel anticancer agents. A series of 4-anilinoquinazoline derivatives (1, 2, 3 and 4) bearing arylurea and tertiary amine moiety at its 6-position were synthesized. Their antiproliferative activities in vitro were evaluated via MTT assay against A431 cell and A549 cell. The SAR of the title compounds was discussed. The compounds 2d, 2i and 2j with potent antiproliferative activities were evaluated their inhibitory activity against EGFR-TK. Compound 2j displayed potent inhibitory activity against EGFR-TK. In addition, compound 2j, at 50 mg/kg, can completely inhibit cancer growth in established nude mouse A549 xenograft model in vivo. These results suggest that the 4-anilinoquinazoline derivatives bearing diarylurea and tertiary amino moiety at its 6-position can serve as anticancer agents and EGFR inhibitors.     

Three new sesquiterpene lactone dimers from Carpesium faberi

Three new 2,4-linked sesquiterpene lactone dimers (SLDs), faberidilactones F-H (1–3), have been isolated from Carpesium faberi. Unlike 1 and 2, 3 was a modified Diels-Alder adduct, characteristic by a 1′-OH and a Δ^5′(6′) double bond. Furthermore, the relative configuration of 1′-OH in 3 was assigned as β-configuration by comparison the experimental NOESY data with those of its two possible epimers. The exo/endo stereochemistry of 1–3 was determined by the spectrographic features of 2,4-linked SLDs that we discovered in our previous works. Compounds 1 and 2 showed potent cytotoxicity against human leukemia (CCRF-CEM) cells with IC₅₀ value of 5.62 and 3.74 μM, respectively.     

Alkyl-phenyl cleavage of the lignin model compounds guaiacylglycol and glycerol-β-guaiacyl ether by Phanerochaete chrysosporium

The white rot basidiomycete Phanerochaete chrysosporium metabolized guaiacylglycol--guaiacyl ether (I) in high nitrogen, shaking and stationary cultures. 2-(o-Methoxyphenoxy) ethanol (X), 2-(o-methoxyphenoxy) acetic acid (IX) and methoxy-phydroquinone (MHQ) were identified as products of the metabolism of (I). P. chrysosporium also metabolized guaiacylglycerol--guaiacyl ether (IV) in high nitrogen stationary cultures. 2-(o-Methoxyphenoxy)-1,3 propanediol (XII) and 3-hydroxy, 2-(o-methoxy-phenyxy) propionic acid (XIV) were identified as products of the metabolism of (IV). Finally, P. chrysosporium metabolized -deoxyguaiacylglycol--guaiacyl ether (VI) and -deoxyguaiacylglycerol--guaiacyl ether (VII) in limiting nitrogen cultures. 2-(o-Methoxyphenoxy) ethanol (X) and 2-(o-methoxyphenoxy)-1,3 propanediol (XII) were identified as products of the metabolism of VI and VII respectively indicating hydroxylation of those substrates with subsequent alkyl-phenyl bond cleavage. Metabolites were identified after comparison with chemically synthesized standards by GLC-mass spectrometry.Abbreviations GLC Gas liquid chromatography - TMSi trimethylsilyl - TLC thin layer chromatography - MHQ methoxyhydroquinone