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Quinoxaline-based tetranitrogen ligand, N,N’-bis(2-quinoxalylmethyl)-N,N’-dimethylethylenediamine (L9), stabilizes the bis(µ-hydroxo) dinuclear manganese(II,II) core. Oxidation of the complex with hydrogen peroxide in methanol suspension affords the bis(µ-oxo) dinuclear manganese(III,III) complex. The quinoxaline-based tripod ligand, tris(2-quinoxalylmethyl)amine (L11), did not afford corresponding bis(hydroxo) dimanganese(II,II) complex due to the subsequent atmospheric oxygen-promoted oxidation in the reaction solution similar to its quinoline counterpart, tris(2-quinolylmethyl)amine (L10). The solid state structures of [Mn(II)Cl2(L9)], [(µ-OH)2Mn2(II,II)(L9)2]2+, [(µ-O)2Mn2(III,III)(L9)2]2+, [(µ-O)2Mn2(III,III)(L11)2]2+, and [(µ-O)2Mn2(III,III)(L10)2]2+ complexes were determined by X-ray crystallography. The magnetic susceptibility measurement of (µ-OH)2Mn2(II,II) complex and electrochemical oxidation of (µ-O)2Mn2(III,III) complexes were performed to evaluate the tetramine ligand effect stabilizing the low oxidation states of dinuclear metal center supported by two oxygen atom bridges.

A chlorophyll-a derivative possessing a trifluoroacetylacetonate moiety at the C3 position was prepared by Claisen condensation of the 3-acetyl group with ethyl trifluoroacetate in the presence of sodium methoxide. The Claisen condensation was successfully applied for the reaction of 3-acetyl-chlorin with ethyl pentafluoropropionate as well as that of 3-acetyl-bacteriochlorin with ethyl trifluoroacetate. The resulting Claisen condensation products took exclusively diketonate conformers in a CDCl3 solution and the single crystal, and gave red-shifted and broadened Qx/Qy absorption bands in the visible to near-infrared region, compared with the corresponding 3-acetyl-(bacterio)chlorins.

The ether oxygen coordination to the zinc center in the complexes with dipicolylamine (DPA)-derived ligands, N-(2-methoxyethyl)-N,N-bis(2-pyridylmethyl)amine (L), N-(3-methoxypropyl)-N,N-bis(2-pyridylmethyl)amine (L′), and N-{3-(2-pyridylmethyloxy)propyl}-N,N-bis(2-pyridylmethyl)amine (LPy) has been discussed. Upon chelation of the oxygen atom, L forms a five-membered chelate ring with respect to the 2-aminoethyl ether moiety whereas L′ forms a six-membered chelate in 3-aminopropyl ether unit. This difference was highlighted by the crystal structures of ZnCl2 complexes, in which [Zn(L)Cl2] (1) exhibited ether oxygen coordination but [Zn(L′)Cl2] (2) had the ether oxygen non-coordinated. The terminal pyridyl group of LPy facilitates the ether oxygen atom coordination via a metal binding from the basal plane trans to the aliphatic nitrogen.

Three carbohydrate conjugated dipicolylamine chelators, 2-bis(2-pyridinylmethyl)amino)ethyl 1-deoxy-1-thio-β-D-glucopyranoside ( L 1 ), 2-bis(2-pyridinylmethyl)amino)ethyl-β-D-glucopyranoside ( L 2 ), and 2-bis(2-pyridinylmethyl)amino)carboxamide-N-(2-amino-2-deoxy-D-glucopyranose) ( L 3 ) were complexed to the [M(CO) 3 ] + core (M=Tc, Re) and the properties of the resulting complexes were investigated. Synthesis and characterization of the chelator 2-bis(2-pyridinylmethyl)amino)ethyl 1-deoxy-1-thio-β-D-glucopyranoside ( L 1 ) and the corresponding Re complex are reported. All chelators were radiolabeled in high yield with [ 99m Tc(CO) 3 (H 2 O) 3 ] + (>98%) and [ 186 Re(CO) 3 (H 2 O) 3 ] + (>80%). The chelators and Re-complexes were determined to not be substrates for the glucose metabolism enzyme hexokinase. However, the biodistribution of each of the 99m Tc complexes demonstrated fast clearance from most background tissue, including >75% clearance of the activity in the kidneys and the liver within 2 h post-injection.

The Lewis acid-promoted reaction of an ethenetricarboxylate derivative (1) with CF3-substituted propargyl alcohols has been examined. Reaction of γ-CF3 propargyl alcohols in the presence of zinc bromide gave five-membered CF3-containing tetrahydrofurans in 66–85% yield. The CF3 group activates alkyne as an electron-withdrawing group. On the other hand, reaction of γ-trifluoromethyl-α-aryl propargyl alcohols 2 with 1 in the presence of 1 equiv of SnCl4 gave cyclobutane derivatives 6 in 29–49% yield. Formation of cyclobutane 6a arises from the [2+2] cycloaddition between ethenetricarboxylate 1 and chloroallene 8, which is produced by the reaction of propargyl alcohol 2a and SnCl4.

Ten C -glycosyl β 2 - and β/β 2 - peptides with three to eight amino acid residues have been prepared. Solution and solid-phase peptide syntheses were employed to assemble β 2 -amino acids in which C -glycosylic substituents are attached to the C-2 position of β-amino acids. Conformational analysis of the C -glycosyl β 2 -peptides using NMR and CD spectra indicates that the tripeptide can form a helical secondary structure. Besides, helix directions of the C -glycosyl β/β 2 -peptides are governed by the configuration at the α-carbon of the peptide backbone that originates from the stereocenter of the C -glycosyl β 2 -amino acids.

A general method has been developed for accumulation of a dinuclear ruthenium complex [Ru 2 (dhpta)( μ -O 2 CCH 3 ) 2 ] − (H 5 dhpta = 1,3-diamino-2-hydroxypropane- N , N , N ′, N ′-tetraacetic acid) on a gold surface. The accumulation using a ligand substitution reaction of bridging acetate in the complex by terminal benzoic acid in a self-assembled monolayer (SAM) with ω-mercaptoalkoxy benzoic acid (HOOC-C 6 H 4 -O-(CH 2 ) n -SH) ( n = 4, 6, 12) is undergone. The methyl benzoate-containing alkyl disulfides capable to form SAMs on gold electrode have been synthesized utilizing reductive dimerization of the corresponding alkyl thiocyanates with tetraphenylphosphonium tetrathiomolybdate. The methyl benzoate group in the SAM was converted into benzoic acid group by base hydrolysis, which was confirmed by surface-enhanced Raman scattering measurements for silver electrode. After the ligand substitution reactions to accumulate the complex on the gold electrode surface, in the case of n = 6 and n = 12, voltammetric waves for surface confined redox process, which corresponds to Ru III Ru III /Ru III Ru II redox couple are observed, respectively, and these surfaces of gold electrodes are covered with the complex completely. The present ligand substitution reaction should be widely applicable for the accumulation of other complexes and useful for designing of functional electrodes.

The crystal structures of the diastereomeric esters prepared from ( S )-2-methoxy-2-(1-naphthyl)propanoic acid [( S )-MαNP acid] and ( R )-1-octen-3-ol or ( S )-β-ionol were analyzed using X-ray crystallography. The conformation of the MαNP moiety determined from NMR analyses was observed in the crystals. In these esters, the larger, more hydrophobic alcohol substituents were coupled and matched in length with the 1-naphthyl groups. The intra- and intermolecular CH/π interactions bridged the larger alcohol substituents and the 1-naphthyl groups. These crystal structures suggest that the CH/π interaction is a key function of chiral resolving agents for enantioresolution. The twisted s- cis conformation was observed at the conjugated double bonds of the β-ionol ester. Thus, MαNP acid is useful in clarifying the stereochemistry and conformations of biofunctional molecules. Normal-phase HPLC separation of the diastereomeric MαNP esters is also discussed.

A convenient preparation of both stereoisomers of a (2R)/(2S)-2-C-glycosylated β-amino acid is described. β-C-Glycoside was formed by the reaction of α-acetobromoglucose with carbanion of cyanoacetate. The steric bulk of the C-glycoside moiety does not hinder amino acid coupling, showing the utility of this carbohydrate-containing building block for glycopeptide synthesis.

Inhibitory activity of organobismuth compounds, triarylbismuthanes 1 and their dihalides 2 and 3, was examined against jack bean urease. Besides triarylbismuth dichlorides 2, triarylbismuth difluorides 3 and bismuthanes 1 exhibited the activity. Of all these compounds, triphenylbismuth difluoride 3a and tris(4-fluorophenyl)bismuth dichloride 2b showed the highest activity. These results indicate that generation of the inhibitory effect is not always governed by the Lewis acidity at the bismuth center. Such a tendency of inhibition by the organobismuth compounds is in good accord with that observed in the antibacterial activity against Helicobacter pylori, suggesting that H. pylori-produced urease may be a therapeutic target by bismuth-based drugs.

Eight 5,10,15,20-tetrakis[3- or 4-(β- d -glycopyranosyloxy)phenyl]chlorins were synthesized by means of the Whitlock method with diimide reduction and purified by reversed-phase thin layer chromatography (RP-TLC). All compounds were characterized by 1H NMR spectroscopy, electron-spray ionization time-of-flight mass spectrometry (ESI-TOF MS), and UV–Vis spectroscopy. ESI-TOF MS could detect the 2H difference in molecular weight between a glycoconjugated chlorin and its corresponding porphyrin (i.e., 5,10,15,20-tetrakis[3- or 4-(β- d -glycopyranosyloxy)phenyl]porphyrin). The cellular uptake of the eight chlorins was evaluated in HeLa cells. All glycoconjugated chlorins showed higher cellular uptake than tetraphenylporphyrin tetrasulfonic acid (TPPS), and 5,10,15,20-tetrakis[3-(β- d -xylopyranosyloxy)phenyl]chlorin showed 50-fold higher uptake than TPPS. The photocytotoxicity of 5,10,15,20-tetrakis[3-(β- d -glucopyranosyloxy)phenyl]chlorin, 5,10,15,20-tetrakis[3-(β- d -xylopyranosyloxy)phenyl]chlorin and TPPS towards HeLa cells was examined at the concentration of 2 × 10−7 M (mol/dm3). These photosensitizers had no cytotoxicity in the dark, but their photocytotoxicity decreased in the order of 5,10,15,20-tetrakis[3-(β- d -glucopyranosyloxy)phenyl]chlorin > 5,10,15,20-tetrakis[3-(β- d -xylopyranosyloxy)phenyl]chlorin > TPPS. The results indicate that the photocytotoxicity is not related simply to cellular uptake.

A straightforward route to C-glycoside linked sugar-pendant 1,3-propanediamines is described. The three-step preparation procedure involves (1) C-glycosylation of an OH-protected α-glycosyl halide with malononitrile, (2) catalytic hydrogenation of the nitriles to amines, and (3) deprotection of acetyl groups via acid-catalyzed hydrolysis. In the case of the galactose derivative, excess sodiomalononitrile promotes the second addition of a carbanion in the first step. The β-anomeric configuration was confirmed by X-ray crystallography of the glycosylated intermediates. This method demonstrates a general method to access a new class of carbohydrate-pendant C-glycoside chelators.

Six palladium(II) complexes as cisplatin derivatives with a sugar unit ( d -glucose, d -galactose, d -mannose, d -xylose, and maltose) have been prepared. The structural features of the complexes have been characterized by NMR spectroscopy, elemental analysis, mass spectroscopy, and X-ray crystallography. The complexes have been tested for in vivo cytotoxicity against P388 cells implanted in mice. All of Pd compounds are apparently nontoxic. A T/C value of 120% was obtained for maltose derivative at the dose of 400 mg/kg, which indicates that the compound may be endowed with antitumor activity.

Sugar-pendant [60] fullerene derivatives have been prepared from carbohydrate-linked azides 1a-e. Both monosugar (4a-e) and bissugar derivatives (5a-e) produce singlet oxygen ((1)O(2)) under laser irradiation (355 nm) proved by the direct observation of (1)O(2) emission at 1270 nm. Monosugar derivatives exhibit photocytotoxicity varying by the attached sugar molecule.

6-Nitro- and 8-nitro-5-deazaflavin derivatives have been found to enhance prominently the radiation-induced formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) at the expense of formation of 2,6-diamino-4-hydroxy-5-formamidopyrimidine nucleosides (FapydGuo) both in deaerated and in N(2)O saturated aqueous 2'-deoxyguanosine solutions. The radiosensitizing capacity of a 9-nitro-5-deazflavin derivative was observed only in the N(2)O saturated aqueous solutions.

Optically pure diastereomeric iodobismuthanes 3a and 3b underwent the substitution at the chiral bismuth center by 4-methylphenyl- and 4-chlorophenylmagnesium bromide to give bismuthane 4a and 4b as a single diastereomer, respectively. Each reaction was highly stereoselective. Comparison of 4a with 4b by 1H-NMR spectrum revealed that the chemical shifts of the aromatic ring protons are quite different from each other due to the anisotropic effect of the ferrocenyl group, which reflects the difference of the configuration around the chiral bismuth center. The differential 1H-NMR NOE experiments of 4a and 4b provided a critical evidence for the configuration in each compound. The X-ray crystallographic study of 4 demonstrated that the substitution proceeds with inversion of the configuration at the chiral bismuth center.

6-Nitro-5-deazaflavin derivatives bearing O -(methyl 5-acetamido-4,7,8,9-tetra- O -acetyl-3,5-dideoxy- d - glycero -α- and β- d - galacto -non-2-ulopyranosylonate)alkyl group (sialosylalkyl group) at N(3) or N(10) and 8-amino-5-deazaflavin substituted with the sialosylalkyl group at the amino group were synthesized and their physicochemical properties as well as antitumor effects on KB and L1210 cells have been investigated. The configurations of the glycosides were determined by 1 H NMR and rate of hydrolysis of the glycosidic bond. It has been found that these conjugate molecules show significant antitumor activities. Combination of an 8-amino-5-deazaflavin with the sialosylalkyl group have been found to give rise to significant increase in antitumor activities of the compound. Antitumor effects of 6-nitro-5-deazaflavin-sialic acid conjugate molecules were similar or rather weak in comparison with those of the 6-nitro-5-deazaflavin derivatives without sialosylalkyl group.

NADH model compounds with a dihydroquinoline ring can reduce methyl benzoylformate with very high reactivity and stereospecificity. Chiral column HPLC is effective in the separation and analysis of enantiomers of NADH and NAD model compounds, respectively.

The action of C60 fullerene and its derivatives as a radical-scavenging antioxidant has received much attention, but their reactivity toward free radicals and antioxidant capacity have not been well elucidated yet. In the present study, the reactivity of the two types of water-soluble, sugar-pendant C60 fullerenes, C60-1S and C60-2S, toward peroxyl radical and their effect against human plasma lipid peroxidation were measured. The rate constants for the reaction of C60-1S and C60-2S with peroxyl radicals were obtained from their effect on the bleaching of beta-carotene in lipid-SDS micelle system as 4.6 x 10(3) and 8.0 x 10(3) M(-1) s(-1) at 37 degrees C, respectively. They inhibited the free radical-induced lipid peroxidation in human plasma in a concentration-dependent manner. These results suggest that the sugar-pendant fullerenes C60-1S and C60-2S act as a radical-scavenging antioxidant with the activity similar to the phenolic antioxidants.

Electrolytically reduced 6- and 8-nitro-5-deazaflavin derivatives have been found to interact to react specifically with guanine base by means of cyclic voltammetry. Electrolytic reductions of 6- and 8-nitro-5-deazaflavin derivatives in the presence of the 2'-deoxyguanosine under anaerobic conditions resulted in prominent formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine.

New tetraphenylchlorin derivatives having four or eight glucose molecules were synthesized. Phototoxicity against the HeLa cell, singlet oxygen producing ability, and cell permeability were examined to evaluate the activity on photodynamic therapy of the compounds.

A useful preparation of an ethylenediamine derivative linked to d- glucose, 2,3-diaminopropyl β- d- glucopyranoside, has been described. The optically pure compound was obtained conveniently via recrystallization of the diastereomeric mixture of the diazido precursor. The stereochemistry of the ethylenediamino compound was elucidated by X-ray crystallography.

Three novel intercalator-linked cisplatin-type platinum complexes, cis-[ PtCl 2 (9−(2- aminoethyl)aminomethylacridine )/ ( 1 ) , cis-[PtCl2(4−(2-aminoethyl)aminomethyl-2-phynylquinoline)] (2), and cis-[PtCl2(8−(2-aminoethyl)aminomethl-2-phenylquinoline)] (3) were synthesized. The structure of 1 was determined by X-ray crystallography (triclinic, space group P l with a = 15.007(b), b = 15.597(4), c = 10.398(3), A , a = 98.51°, β = 96.79(3)°, γ = 114.61(2)°, Z = 4, R = 0.053, R w = 0.063 ). The antitumor activity of the platinum complexes was investigated against the HeLa cell. Compound 3 was the most cytotoxic among the complexes synthesized here and was more effective than cisplatin. It was suggested from microscopic analysis that the acridine complex 1, which had no cytotoxicity against the HeLa cell, was not incorporated in the nucleus of the cell. Against the P388 cell, however, complex 1 gave a more therapeutic result than 3. The covalent binding ability of the cisplatin moiety was suppressed significantly in these compounds. The results of molecular mechanics showed that interculation and covalent binding could be compatible. The cytotoxicity and DNA binding ability of phenylquinoline-type ligands were also studied to evaluate the intrinsic cytotoxicity of the intercalator. From the duplex DNA denaturation experiment and fluorescent ethidium displacement assay, the DNA binding affinities of the ligands are in agreement with the cytotoxicity of these compounds and the corresponding platinum complexes.

New tetraphenylporphyrin derivatives having eight glucose molecules were synthesized. Phototoxicity of these compounds against the HeLa cell line were compared to tetraglycosylated tetraphenylporphyrins. The highest activity was observed for a derivative having four OH-protected glucose moieties. Singlet oxygen producing ability was also examined to explain the difference in photocytotoxicities.

A series of 6-nitro-5-deazaflavins bearing at N(3) or N(10) position the pyrrolecarboxamide(s) group as DNA minor groove binder has been synthesized. These hybrid molecules show similar redox properties to those of 6-nitro-5-deazaflavins with no pyrrolecarboxamide(s) group, suggesting that they generate stable one- and two-electron reduction product(s). Electrolytic reductions of the hybrid molecules were carried out at a controlled potential under anaerobic conditions in the presence of plasmid pBR322 DNA. Significant conversions of the supercoiled circular pBR322 DNA (form I) to the open circular DNA (form II) have been found by treatment with the reductively activated 6-nitro-5-deazaflavin derivatives. Their DNA damaging effects have been found to be enhanced as the number of pyrrolecarboxamide group as the DNA binder increases. Antitumor activities of the hybrid molecules towards KB and L1210 cells were evaluated in vitro. It has been found that the antitumor effects of the compounds on KB cells slightly change and those on L1210 cells decrease as the number of the pyrrolecarboxamide group increases. These results reveal that the combination of 6-nitro-5-deazaflavin molecule with the pyrrolecarboxamide(s) group increase the DNA binding properties of the compounds, giving rise to promoted DNA damaging effects, and also suggest that the combination would affect the capacity of the compounds to act as the substrate for intracellular reductases and/or the cellular uptake of the compounds.

A cisplatin-type complex tethered to acridine intercalator via one methylene chain has been synthesized. Its structure was elucidated by X-ray crystallography. A permeability into cell, interaction with calf thymus DNA (ct-DNA), and antitumor activity against HeLa and P388 cells were studied.

Diethyl(2-pyridyl)boranes ( 2a, 2b ) comprise cyclic dimers via intermolecular boronnitrogen coordination bonds. The boron atoms of diethyl[2-(5-methylpyridyl)]borane ( 2b ) show clear pyramidalization. The high tetrahedral character of these boron atoms in 2b indicates that the dimer is far rigid compared with the tetramer composed of diethyl(3-pyridyl)borane ( 1a ).

A series of nitro 5-deazaflavins, 5-deazaflavins possessing a nitro group at C(6)–C(9) position, has been designed and synthesized as a novel class of bioreductive nitrohetero-aromatic compounds and their cytotoxicities towards L1210 and KB cells were evaluated. It has been found that the nitro 5-deazaflavins undergo one electron reduction on the nitro group and undergo two electrons or “(net) hydride” reduction on the C(5)-C(4a)-C(10a)-N(1) redox system. They showed much more potent antitumor activities than the other 5-deazaflavins bearing no nitro group. These results suggest that an activation of nitro group by biological one electron reduction is crucial for an expression of cytotoxicity.

Cytotoxicities of nitro 5-deazaflavins were evaluated in vitro towards hypoxic and oxic Chinese hamster cells (V79). 6-Nitro and 8-nitro derivatives were generally more toxic towards hypoxic cells than oxic cells, showing marked hypoxic selectivity. In contrast, 7-nitro and 9-nitro derivatives showed no significant hypoxic selectivity. Electrochemical study using cyclic voltammetry (CV) revealed that 6-nitro and 8-nitro derivatives generate a stable two electrons reduction product as well as a stable one electron reduction product and that 7-nitro and 9-nitro derivatives afford an unstable one electron reduction product. These results strongly support that not solely electron affinity but also stability of the one electron reduction products is crucial for the differential hypoxic cytotoxicities of nitro 5-deazaflavins.

Enantioselectivities in the reduction of methyl benzoylformate with NAD(P)H model compounds, N - α -methylbenzyl-1-propyl-1,4-dihydronicotinamide (PNPH) and N -benzyl-1-propyl-1,4-dihydronicotinamide (PNBH), in the presence of N -protected amino acids have been studied. The stereoselectivity was perturbed by the amino acids which have a side chain capable of coordinating onto Mg 2+ .

A mechanism for amine-catalysis of stereospecificity in electrochemical oxidation of (4 R )-Me 3 MQPH and (4 R )-Me 3 PNPH is discussed.