First report of the cyanotoxins cylindrospermopsin and deoxycylindrospermopsin from Raphidiopsis curvata (Cyantobacteria)

A strain of Raphidiopsis (Cyanobacteria) isolated from a fish pond in Wuhan, P. R. China was examined for its taxonomy and production of the alkaloidal hepatotoxins cylindrospermopsin (CYN) and deoxy-cylindrospermopsin (deoxy-CYN). Strain HB1 was identified as R. curvata Fritsch et Rich based on morphological examination of the laboratory culture. HB1 produced mainly deoxy-CYN at a concentration of 1.3 mg(.)g(-1) (dry ut cells) by HPLC and HPLC-MS/MS. CYN was also detected in trace amounts (0.56 mug(.)g(-1)). A mouse bioassay did not show lethal toxicity when tested at doses up to 1500 mg dry weight cells(.)kg(-1) body weight within 96 h, demonstrating that production of primarily deoxy CYN does not lead to significant mouse toxicity by strain BB I. The presence of deoxy-CYN and CYN in R curvata suggests that Raphidiopsis belongs to the Nostocaceae, but this requires confirmation by molecular systematic studies. Production of these cyanotoxins by Raphidiopsis adds another genus, in addition to Cylindrospemopsis, Aphanizomenon, and Umezakia, now known to produce this group of hepatotoxic cyanotoxins. This is also the first report from China of a CYN and deoxy-CYN producing cyanobacterium.

Structure Of 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-O-Isopropylideneuridine, C12h16n2o5s

Mr=300.33 , triclinic, P1, a=5.635 (2), b=11.077(2), c=11.582(2)A, a= 70.48 (1), fl= 88.16 (3), y=80.56(3) ° , V= 670.325 A3, Z=2, D x = 1.49 Mg m -3, Cu Ka, n= 1.54184 ,A, g = 2.308mm -1, F(000)=316, T=301K, R=0.054, R w = 0.093 for 1944 observed counter reflections. The sulphur position with respect to the dihydrouracil ring, which is of possible relevance to the action of thymidylate synthetase, is axial in molecule A and equatorial in B. Both molecules show the anti conformation about the glycosidic bond [torsion angle C(6)-N(1)-C(1')-O(4'), 2'CN = 21.6 (9) and 29.4 (10) °] and have the C(4')-endo, O(4')-exo (40T) sugar conformation. The dioxolane-ring conformation is O(2')-endo in A and C(7)-endo in B. The dihydrouracil rings show self base pairing with hydrogen bondsN(3A)...O(ZB) and N(3B)...O(ZA).

Structure of a thionucleoside: 5'-deoxy-5',6-epithio-5,6-dihydro-2',3'-O-isopropylidene-3-methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3'-O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Structure Of A Thionucleoside - 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-Ortho-Isopropylidene-3-Methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3' O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Crystal structures and thermal analyses of alkyl 2-deoxy-alpha-D-arabino-hexopyranosides

The crystal structures of alkyl 2-deoxy-alpha-D-arabino-hexopyranosides, with the alkyl chain lengths from C-8 to C-18, are established by the single crystal X-ray structural determination. The even-alkyl chain length derivatives crystallized orthorhombic, with space group P2(1)2(1)2(1), whereas the odd-alkyl chain length derivatives crystallized monoclinic, with space group P2(1). The sugar moieties retained a C-4(1) chair conformation and the conformation of the alkyl chains was all-trans. The molecules formed a bilayer structure, in which alkyl chains were interdigitated.The hydrogen bonds, originating from the sugar moieties, were observed in adjacent layers and also within the same layer, resulting in the formation of infinite chains. The alkyl chains arranged parallel to each other and formed planar structures. The thermal properties of the alkyl 2-deoxy glucosides were analyzed further. It was observed that none of the derivatives exhibited mesomorphism. This study establishes that the absence of the hydroxyl group at C-2 of the sugar moiety results in a non-mesogenic nature of the alkyl 2-deoxy-alpha-D-glycosides, as opposed to the profound mesogenic nature of the normal alkyl glycosides.

A kinetic analysis of the tumor-associated galactopyranosyl-(1→3)-2-acetamido-2-deoxy-α-d-galactopyranoside antigen—lectin interaction

A kinetic study of the tumor-associated galactopyranosyl-(1→3)-2-acetamido-2-deoxy-α-d-galactopyranoside (T-antigen) with lectin peanut agglutinin is described. The disaccharide antigen was synthesized by chemical methods and was functionalized suitably for immobilization onto a carboxy-methylated sensor chip. The ligand immobilized surface was allowed interaction with the lectin peanut agglutinin, which acted as the analyte and the interaction was studied by the surface plasmon resonance method. The ligand—lectin interaction was characterized by the kinetic on-off rates and a bivalent analyte binding model was found to describe the observed kinetic constants. It was identified that the antigen-lectin interaction had a faster association rate constant (k a1) and a slower dissociation rate constant (k d1) in the initial binding step. The subsequent binding step showed much reduced kinetic rates. The antigen-lectin interaction was compared with the kinetic rates of the interaction of a galactopyranosyl-(1→4)-β-d-galactopyranoside derivative and a mannopyranoside derivative with the lectin.

Role of hydroxyl group on the mesomorphism of alkyl glycosides:synthesis and thermal behavior of alkyl 6-deoxy-beta-D-glucopyranosides

A homologous series of alkyl 6-deoxy-beta-D-glucopyranoside amphiphiles was prepared,in an effort to identify the role of hydroxyl group in the mesomorphic behavior of alkyl glycosides. Synthesis was performed by a chlorination of the sugar moiety in alkyl-beta-D-glucopyranosides with methylsulfonyl chloride in DMF, followed by a metal mediated dehalogenation to secure alkyl 6-deoxy-beta-D-glucopyranosides, wherein the alkyl chain length varied from C-9 to C-16. The mesomorphic behavior of these 6-deoxy alkyl glycosides was assessed using polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction method. Whereas the lower homologues exhibited a monotropic SmA phase till sub-ambient temperatures, the higher homologues formed a plastic phase. A partial interdigitized bilaye structure of SmA phase is inferred from experimental d-spacing and computationally derived lengths of the molecules. The results were compared with those of normal alkyl glucopyranosides, retained with hydroxyl groups at C-2-C-6 carbons, and alkyl 2-deoxy-glucopyranosides, devoid of a hydroxyl group at C-2 and the comparison showed important differences in the mesomorphic behavior.(C)2010 Elsevier Ireland Ltd. All rights reserved.

Chemical approaches of penicillin allergy—III Isolation of the penicillin-free carrier receptor protein (CRP) on a polymeric 7-deoxy penicillin analogue template and its role in penicillin immunogeneses in rabbit and man

Specific penicillin-carrier receptor proteins (CRP) have been isolated from the sera of penicillin allergic rabbits and human subjects in the unconjugated native state in electrophoretically homogeneous form by employing a synthetic polymeric affinity template containing the 7-deoxy analogue of penicillin G. The synthesis of the 7-deoxy analogue has been described. In this affinity system the antipenicillin-antibody is desorbed by 0·9M thiourea and the CRP in 8M urea. The CRP after incubation with penicillin is converted into the full-fledged antigen. Studies on the origin of CRP and the nature of antibody as well as comparative studies on the properties of the rabbit antibody and those of antibodies elicited by a BSA-BPO conjugate are reported.

Synthesis of 2-Deoxy-2-C-alkyl Glycal and Glycopyranosides from 2-Hydroxy Glycal Ester

A method to convert 2-hydroxy glycol ester to the corresponding corresponding 2-deoxy-2-C-alkyl glycol in a facile manner, through key reactions including (i) C-allylation at C-1, (ii) Wittig reaction, and (iii) Cope rearrangement of a 1,5-diene derivative, is reported. The alpha-anomer of the 1,5-diene derivative underwent Cope rearrangement to afford 2-deoxy-2-C-glycal derivative, whereas the beta-anomer was found to be unreactive. Employing this sequence, was transformed to 3,4,6-tri-O-benzyl-2-deoxy-2-C-alkyl-1,5-anhydro-D-arabino-hex-1-enitol. 2-Deoxy-2-C-alkyl glycol derivative is a suitable glycosyl donor to prepare 2-deoxy-2-C-alkyl glycosides, mediated through haloglycosylation and a subsequent dehalogenation. A number of 2-deoxy-2-C-alkyl glycosides, with both glycosyl and nonglycosyl moieties at the reducing end, are thus prepared from the glycol.

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

This paper deals with the synthesis of 2-deoxy-2-C-alkyl/aryl septanosides. A range of such septanoside derivatives was synthesized by using a common bromo-oxepine intermediate, involving C-C bond forming organometallic reactions. Unsaturated, seven-membered septanoside vinyl bromides or bromo-oxepines, obtained through a ring expansion methodology of the cyclopropane derivatives of oxyglycals, displayed a good reactivity towards several acceptor moieties in C-C bond forming Heck, Suzuki and Sonogashira coupling reactions, thus affording 2-deoxy-2-C-alkyl/aryl septanosides. Whereas Heck and Sonogashira coupling reactions afforded 2-deoxy-2-C-alkenyl and -alkynyl derivatives, respectively, the Suzuki reaction afforded 2-deoxy-2-C-aryl septanosides. Deprotection and reduction of the 2-deoxy-2-alkenyl derivative afforded the corresponding 2-deoxy-2-C-alkyl septanoside free of protecting groups. The present study illustrates the reactivity of bromo-oxepine in the synthesis of hitherto unknown septanosides, branching out at C-2, through C-C bond formation with alkyl and aryl substituents.

2,3-Unsaturated enoses. A Pummerer rearrangement route to sugar vinyl sulfides and synthesis of 3-deoxy-3-alkyl/arylsulfinyl pyranosides

A Pummerer rearrangement of 2,3-dideoxy-3-alkyl/arylsulfinyl-arabino-hexopyranosides is reported. Treatment of sulfinyl-arabino-hexopyranoside derivatives, obtained through oxidation of the corresponding thio-derivatives, with trifluoroacetic anhydride (TFAA)/pyridine led to a facile formation of 2,3-dideoxy-3-alkyl/arylthio-hex-2-enopyranosides. Upon conversion of sugar vinyl sulfides to vinyl sulfoxides, conjugate addition reactions were conducted with alkoxides, to afford 3-deoxy-3-alkyl/arylsulfinyl pyranosides, in the manno-configuration exclusively. Whereas the conjugate addition reaction did not proceed with ether protecting groups, ester protecting groups and free hydroxyl groups in the sugar vinyl sulfoxide permitted the reaction. (C) 2012 Elsevier Ltd. All rights reserved.

Dense network of O-H ... O and C-H ... O interactions in the solid state structure of n-pentyl-2-chloro-2-deoxy-alpha-D-manno-sept 3-uloside

Single crystal X-ray structural analysis of a septanoside, namely, n-pentyl-2-chloro-2-deoxy sept-3-uloside (1) provides many finer details of the molecular structure, in addition to its preferred twist-chair conformation, namely, (TC3,4)-T-5,6 conformation. Structural analysis reveals a dense network of O-H...O, C-H...O and van der Waals interactions that stabilize interdigitized, planar bi-layer structure of the crystal lattice. (C) 2014 Elsevier Ltd. All rights reserved.

Glycosidic bond hydrolysis in septanosides: a comparison of mono-, di-, and 2-chloro-2-deoxy-septanosides

A kinetic study of the hydrolytic stabilities of mono-, di-, and 2-chloro-2-deoxy septanosides, under acid-catalysis, is reported herein. A comparison of mono-and diseptanosides, shows that the glycosidic bond in the disaccharide is more stable than the monosaccharide. Further the glycosidic bond at the reducing end hydrolyzes almost twice as faster than that of the non-reducing end of the disaccharide. 2-Chloro-2-deoxy septanoside is found to be the most stable and its glycosidic bond hydrolysis occurs at elevated temperatures only. The orientation of the exo-cyclic hydroxymethyl group and the inductive effect are suggested to play a role in the rates of hydrolysis. (C) 2014 Elsevier Ltd. All rights reserved.