NCA0424 (1), an indoloquinoxaline derivative, has a potent antitumor activity against in vitro and in vivo tumor models. To elucidate its structure-activity relationship, the interactions with various B-form DNAs were investigated by thermal denaturation, viscosity and circular dichroism (CD) measurements. The thermal stability of the DNA duplex was increased by the interaction with 1, and preferable binding for alternative purine-pyrimidine base sequence was suggested. Comparative viscometric measurements with ethidium bromide (an intercalator) and distamycin (a minor groove binder) suggested that 1 is an intercalator. The interaction of DNA with 1 revealed a new CD band at 340-390 nm. Taking advantage of this induced CD band, the equilibrium binding constants were determined for various DNAs, and the binding preference of 1 for the alternative purine-pyrimidine base sequence, especially for the case of guanine as purine base, was indicated. The appearance of the induced CD band implies the importance of 1 side chain for the effective and/or stable intercalation of the aromatic ring into the DNA base pair.

View full abstract

When 1-nitrocyclohexene (1) was treated with methyl 4-hydroxy-2-butynoate (2) in the presence of potassium tert-butoxide in tetrahydrofuran-tert-butanol at 0°C for 10 min, a tandem conjugate addition product, methyl cis-3a-nitrooctahydrobenzo[b]furan-Δ^{3, α}-acetate (3a), was obtained in quantitative yield as a 55 : 45 mixture of the (Z)- and (E)-isomers. The scope and limitations of this reaction were examined. Some transformation reactions of 3a are also described.

View full abstract

The reactions of N-acyl-N-benzyl-α-amino acids (1) or N-acylprolines (5) with trifluoroacetic anhydride in the presence of pyridine afford 5-trifluoromethyloxazoles (2 or 7) in good yields. The reaction could proceed through the transient formation of mesoionic 1, 3-oxazolium-5-olates, followed by oxazolium salts.

View full abstract

Monosilylation of 1, 2-thiazetidine 1, 1-dioxides (β-sultams) 3 gave (3R^*, 4S^*)-4-monosilyl-β-sultams 4 stereoselectively. Disilylated β-sultams 5 were obtained by the use of trimethylsilyl chloride. Treatment of 4-monosilyl-β-sultams 4 with EtAlCl₂ caused stereospecific C-N bond cleavage owing to β-cation stabilization of the silicon group to provide (E)-vinylsulfonamides (E)-7. (E)-α-Silylstyrylsulfonamides (E)-7j-l were generated in the reaction of 4, 4-disilyl-β-sultams 5 with EtAlCl₂. Reaction of 4-silyl-β-sultams with AlCl₃ afforded N-dealkylated (E)-vinylsulfonamides in good yields. Reaction of (E)-α-silylstyrylsulfonamide (E)-10 with benzaldehyde in the presence of tetrabutylammonium fluoride and BF₃·Et₂O provided the allylic alcohol (E)-12.

View full abstract

In addition to ten alkaloids previously described, we have isolated two alkaloid N-oxides from Tylophora tanakae MAXIM. (Asclepiadaceae). Further, the polar fraction of the leaves and caules of this plant cultivated in a farm afforded two new polar alkaloids. The structures of the four products were determined. The relation between the structure and cytotoxic activity of this group of alkaloids is discussed.

View full abstract

To develop non-prodrugs of taxoids with satisfactory stability in vivo, high water-solubility, and potent antitumor activity, we prepared several 10-O-sec-aminoethyl decetaxel analogs (3) and evaluated their cytotoxicity against mouse leukemia and human tumor cell lines, microtubule disassembly-inhibitory activity, and water-solubility. These analogs were synthesized from the 10-O-allyl baccatin derivatives (5a-c) using the β-lactam synthon method. Among these analogs, the 10-O-(2-morpholinoethyl) (18, 21) and 10-O-(2-thiomorpholinoethyl) (19, 24) analogs exhibited cytotoxicity comparable or superior to that of docetaxel (2). In addition, the methanesulfonic acid salt (18a) had a high water-solubility.

View full abstract

5-Alkylidene-3, 5-dihydro-4H-imidazol-4-one derivatives were synthesized and evaluated for activity as angiotensin II receptor antagonists. Substitutions at C-2 and C-5, respectively, with a propyl group and a 1-methylethylidene group resulted in the optimal compound, 3, 5-dihydro-5-(1-methylethylidene)-2-propyl-3-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-4H-imidazol-4-one (2b), with a pA₂ value of 8.85 in rabbit aorta. When administered orally to rats 2b showed a greater inhibitory effect on angiotesin II-induced pressor response than DuP 753. Compound 2b also showed a good antihypertensive effect when administered orally to conscious sodium-depleted spontaneously hypertensive rats, with a duration of action of 24 h. These data suggest that 2b may be a useful agent for the treatment of angiotensin II-dependent diseases such as hypertension.

View full abstract

In order to find new classes of non-peptide cholecystokinin (CCK) ligands, the conformational restriction of a series of weak 3-oxoindolizidine-based CCK antagonists has been both decreased and increased. This tactic yielded a series of monocyclic 2-oxopyrrolidine derivatives 4 with selectively for CCK-A or CCK-B receptors and with slightly improved binding affinity at the CCK-A receptor subtype with respect to the model 3-oxoindolizidines. In contrast, the incorporation o the Trp residue at the secondary amino group of a pyrrolo[1, 2-a]pyrazine template 5, involving a drastic restriction in the conformational flexibility of the molecule, resulted in a series of bicyclic derivatives that did not bind to CCK receptors at concentrations up to 10^-5 M.

View full abstract

2-Aminomethyl-1-azetidinyl, -1-pyrrolidinyl, and -1-piperidinyl groups were designed as novel C-7 substituents for potential antibacterial quinolone agents. Of the three substituents, the 2-aminomethyl-1-azetidinyl group (compound 12a) was found to be the most favorable for enhancing the activity of the 6, 8-difluoroquinoline molecule 12. Therefore the 2-aminomethyl-1-azetidinyl group was introduced into a variety of quinolines (giving 24-26a, and 28a) and naphthyridines (giving 31a and 32a). Through optical resolution of 1-benzylazetidine-2-carboxamide (19) and chiral synthesis of its R-isomer, both enantiomers of 2-aminomethyl-1-azetidinyl quinolines 12a and 24-26a were also prepared. The most active of all the compounds was 5-amino-6, 8-difluoroquinoline (R)-26a. The activity of (R)-26a was more potent than those of the corresponding 1-piperazinyl derivative (3) and sparfloxacin (1), and was comparable to those of the corresponding 3-amino-1-pyrrolidinyl (4), 3-aminomethyl-1-pyrrolidinyl (5), and 3-amino-1-azetidinyl (6) derivatives.

View full abstract

To investigate the biological selectin-ligand interactions, fourteen sulfated and eight phosphorylated β-D-galaco- and lactopyranosides containing branched fatty-alkyl residues in place of the ceramide have been synthesized. Regioselective sulfation of the parent glycolipids through the dibutylstannylene acetal with a certain amount of sulfur trioxide-trimethylamine complex produced the target sulfated glycolipids, while stepwise phosphorylation by treatment of the properly protected diol with dibenzyloxy(diisopropylamino)phosphine gave the phosphorylated glycolipids. The synthetic glycolipids showed an interesting mode of inhibition of the binding of HL-60 cells to immobilize P-, L- and E-selectins during in vitro experiments. In addition, using computer modeling techniques, we examined the molecular basis for the ligand-selectin complex formation. These glycolipids may be useful as therapeutic agents against selectin-dependent inflammation.

View full abstract

Optically active flavanones, dihydrowogonin and dihydrooroxylin A, were found in the urine of healthy volunteers who orally received the traditional Chinese remedies Shosaiko-to and Daisaiko-to on separate occasions. These remedies, which consisted of dried extracts of Scutellariae Radix and other herbs, contained the metabolic precursors of the flavanones, but not the flavanones themselves, in stoichiometrically sufficient amounts. Structures and stereochemistry of the flavanones were elucidated by UV, circular dichroism (CD), electron impact (EI)-MS and ¹H-NMR analyses, showing that the biotransformations from the corresponding flavones, wogonin and oroxylin A, were stereoselective with a preference for the S-enantiomers. The putative origins of the flavanones were confirmed in terms of pharmacokinetics. Renal excretion-time data of the flavanones and the flavones suggested that the stereoselective transformations might have occurred in the intestinal tract as a result of microfloral metabolism before absorption.

View full abstract

From the glycoside mixture with adjuvant activity obtained from the hyacinth bean, the seeds of Dolichos lablab L., six new oleanane-type triterpene bisdesmosides, lablabosides A, B, C, D, E, and F, were isolated together wiht chikusetsusaponin IVa. The structures of lablabosides A, B, and C were determined on the basis of chemical and physicochemical evidence as follows : 3-O-[α-L-rhamnopyranosyl (1→2)-β-D-galactopyranosyl (1→2)-β-D-glurcopyranosiduronic acid]-28-O-(β-D-glucopyranosyl) oleanolic acid (lablaboside A), 3-O-[α-L-rhamnopyranosyl (1→2)-β-D-galactopyranosyl (1→2)-β-D-glucopyranosiduronic acid]-28-O-(β-D-glucopyranosyl) 24-epi-hederagenin (lablaboside B), 3-O-[α-L-rhamnopyranosyl (1→2)-β-D-galactopyranosyl (1→2)-β-D-glucopyranosiduronic acid]-28-O-[α-L-rhamnopyranosyl (1→2)-β-D-glucopyranosyl] 24-epi-hederagenin (lablaboside C).

View full abstract

The interaction between drugs (tolbutamide (1), 1-butyl-3-(methylsulfonyl)urea (2)) and human serum albumin (3) was investigated by equilibrium dialysis and NMR spectroscopy. The binding of 1 and 2 to 3 was concluded to be hydrophobic and hydrophilic, respectively, on the basis of the dependence of the binding constants on temperature, ionic strength, and chain length of fatty acid added. In ¹H-NMR spectra of 1, there were no significant shifts with change in concentration or addition of 3. The spin-lattice relaxation time (T₁) and spin-spin relaxation rate (1/T₂) of the respective protons of 1 were independent of concentration, but depended on the concentration of 3 added. The binding position was determined from the ratio of 1/T₂ of 1 bound to 3 and free 1. 1 and 2 were found to bind to 3 through the tolyl group and sulfonylurea group, respectively. The binding property of 1 was considered to be governed by the competition between the hydrophobic effect of the tolyl group and the hydrophilic effect of the sulfonylurea group in the molecule.

View full abstract

Glassy tri-O-methyl-β-cyclodextrin (TMCD) was prepared by cooling the melt and the glassy state was confirmed by measuring the glass transition temperature (T_g) and the anomalous endothermic peak (heat capacity maximum) on a differential scanning calorimetry (DSC) curve. Glassy TMCD showed a glass transition at 356 K and an anomalous endothermic peak. The value of the ratio of T_g and the melting temperature (T_m) of TMCD was 0.83. The influence of the heating rate of the glass prepared at the cooling rate of -1.25 K/min on the glass transition was examined, and the apparent activation energy of glass transition was calculated to be 223.4 kJ/mol. The rate and quantity of relaxation of glass was determined by the area under the anomalous endothermic peak of the DSC curves of glasses prepared at various cooling rates, that of glassy TMCD was found to be extremely large. Enthalpy relaxation during the isothermal aging of glassy TMCD occurred most remarkably at 341 K. Devitrification of glassy TMCD did not occur for more than 1.5 years at 25°C. Pulverized glassy TMCD remained as glass for 1 year. Glassy TMCD was very stable and TMCD was found to be a good glass-former.

View full abstract

To compress coated particles into tablets without mechanical damage to the coating membrane during compression, the effect of the particle size of various pharmaceutical additives was investigated by comparing the dissolution rate and the membrane integrity of ethylcellulose coated theophylline powder. Results showed that smaller additive particle size was superior in protecting the membrane from damage, and thus additive particle size might be one of the most omportant factors affecting the dissolution characteristics of compressed tablets containing coated particles. Twenty μm seemed to be the critical particle size for each kind of additive to obtain good protective effect. Up to this size, all additives played the role of cushioning and the coating membrane was almost perfectly protected from potential damage by the compression force.

View full abstract

The enhancing effects of N-dodecyl-2-pyrrolidone (NDP) on the percutaneous absorption of doxifluoridine (DOX), 5-fluorouracil (5-FU), tegafur (TEG) and carmofur (CAR) were examined using an in vitro penetration technique and rat skin. Phosphate buffered isotonic saline (PBS), propylene glycol (PG) and PG containing 0.4 M NDP (PGNDP) were applied as the donor solution. The correlation between the n-octanol/water partition coefficients and the permeability coefficient of DOX, 5-FU and TEG was investigated using both logarithmic plots. It was determined that the permeability coefficients are significantly correlated with their n-octanol/water partition coefficients on PBS. This result suggested that the non-polar stratum corneum lipid lamella in the skin might act as a rate limiting step on the skin penetration of DOX, 5-FU and TEG. The permeability coefficient of DOX, 5-FU and TEG was increased on PGNDP. The enhancing effect of NDP on the permeability coefficient was more effective at higher hydrophilic drugs, the values of the permeability coefficient had almost the same values on PGNDP and the dependency of the permeability coefficient on the n-octanol/water partition coefficient disappeared in the presence of NDP. These results indicated that the enhancing effect of NDP on the percutaneous absorption of DOX, 5-FU and TEG might be closely related to the perturbation of stratum corneum lipid lamella. Since in has been well recognized that CAR is decomposed into 5-FU in neutral and alkaline solution, the decomposition rate of CAR was measured using PBS solution and was found to be very rapid (K_d=3.17 h^-1, t_1/213.1 min). The total concentrations of CAR plus 5-FU in the acceptor compartment were used to determine the permeability coefficient of CAR. The obtained value of the permeability coefficient of CAR on PG was almost the same as that of TEG on PG (CAR : 1.11×10^-3 cm/h, TEG : 1.24×10^-3 cm/h), while that of CAR on PGNDP was smaller than that of TEG on PGNDP (CAR : 6.06×10^-3 cm/h, TEG : 1.24×10^-2 cm/h). To determine the lipophilic property of CAR, the lipophilic index (log k') was measured by HPLC. The value of the lipophilic index of CAR was 92 times higher than that of TEG. These results indicated that CAR is a higher lipophilic compound, and the smaller value of the permeability coefficient of CAR compared with that of TEG on PGNDP might be caused by the strong binding of CAR to the rat skin (dermis). The dermis might act as a rate limiting step on the skin penetration of CAR, and the percutaneous absorption of CAR might be controlled by both the stratum corneum and the dermis.

View full abstract

A new synthetic route to a chiral 2, 5-disubstituted tetrahydropyran has been achieved by asymmetric reductive acetal cleavage of a bicyclic acetal having a chiral sulfinyl group as a chiral auxiliary. It was found that the (5S)-tetrahydropyran was obtained preferentially (up to 96 : 4) with an R-sulfinyl chiral auxiliary by an efficient 1, 6-asymmetric induction from sulfinyl chirality to the prochiral center on the bicyclic ring.

View full abstract

Enantio- and diastereoselective synthesis of N-[(1R, 2R, 3R, 4R)-2, 3-diacetoxy-4-(acetoxymethyl)cyclopentyl]-acetamide 1, a synthetic key intermediate of (+)-cyclaradine, has been achieved by using enzyme-catalyzed asymmetric hydrolysis and subsequent modification of a functional group.

View full abstract

Two series of "inverse substrates", N-Boc-amino acid p-guanidinophenyl and p-(guanidinomethyl)phenyl esters, were prepared as acyl donor components for enzymatic peptide synthesis. The kinetic behavior of these esters toward bovine and Streptomyces griseus (SG) trypsin was analyzed. The spatial requirement of the active site of these enzymes for catalytic efficiency is discussed based on the steric characteristics of the substrates. These substrates were found to couple readily with amino acid p-nitroanilides to produce peptides. SG trypsin was the most efficient catalyst among the enzymes tested (bovine, porcine, and SG trypsin).

View full abstract

Two new 18, 22-cyclosterols, emesterones A (2) and B (3), were isolated along with Mer-NF8054X (1) from the culture filtrate of Emericella heterothallica. The structures of 2 and 3 were established as 3, 11-dioxo-18, 22-cycloergosta-6, 8(14)-diene-5β, 9β, 23S-triol and 3, 11-dioxo-18, 22-cycloergosta-4, 6, 8(14)-triene-9β, 23S-diol, respectively, on the basis of spectroscopic and chemical investigations. The antifungal activity of emesterone B (3) towards Aspergillus fumigatus was slightly weaker than that of Mer-NF8054X (1).

View full abstract

Oxidation of 2-vinylazetidine 6a with m-chloroperbenzoic acid (mCPBA) in methylene dichloride (CH₂Cl₂) gave a mixture of dihydro-7H-[1, 2]oxazepine 9a and the nitrone 10a. It was clarified that the former was obtained via the [2, 3]-Meisenheimer rearrangement of the corresponding cis-N-oxide A, and the latter was formed by successive oxidation of the isoxazolidine 11 formed via the [1, 2]-Meisenheimer rearrangement of the corresponding trans-N-oxide B.

View full abstract

Treatment of taxinine, which is a taxane diterpenoid readily available from needles of the Japanese yew Taxus cuspidata, with a large excess amount of sodium borohydride in slightly hydrous N, N-dimethylformamide at ambient temperature resulted in regio- and stereo-selective hydration at the C₁₁, C<12>-double bond to give an siomeric texuspine D derivative.

View full abstract

An efficient and general preparation of several chiral N-protected 5-(aminomethyl)oxazoles has been accomplished by treatment of N-protected α-amino esters with α-lithiated isocyanides, obtained by metalation of methyl and benzyl isocyanides with BuLi or of ethyl isocyanide with lithium diisopropylamide.

View full abstract

Two series of new pyridines bearing thiazoline (3a-n) and thiazolidinone (5a-e) moieties were prepared via the cyclization of the corresponding substituted pyridyl thiourea (2a-g) with an appropriately substituted phenacyl bromide or chloroacetic acid, respectively. The antimicrobial activity was determined for representative compounds and most of them showed moderate activity against Gram-positive bactera.

View full abstract

Some dipeptide-type human immunodeficiency virus (HIV) protease inhibitors derived from KNI-102, with a N-carbomethoxycarbonylprolyl-phenylalanine benzyl ester (CPF) moiety as a binding site to gp120, were synthesized. Compounds 11a showed 7-100 times higher HIV protease-inhibitory activity (11a; IC₅₀=0.90 μg/ml, 1.1 μM) than the standard compound 3 or 4 (3; IC₅₀=3.7 μg/ml, 7.7 μM, 4; IC₅₀=75 μg/ml, 155 μM). Generally, the compounds substituted at the o-position of the phenoxyacetyl group 7a, 11a, 16a and 12a showed several times higher inhibitory activity than 3.

View full abstract

The MeOH extract of the root and the ground part of Anthriscus sylvestris HOFFM. showed a high inhibitory activity against MK-1, HeLa, and B16F10 cell growth in vitro. The activity was found only in the CHCl₃-soluble fractions. From the CHCl₃-soluble fraction of the root, falcarindiol, 1-(3'-methoxy-4', 5'-methylenedioxyphenyl)-1ξ-methoxy-2propene, elemicin, and nemerosin were newly isolated in addition to deoxypodophyllotoxin (anthricin), anthriscusin, (-)-deoxypodorhizone, and anthriscinol methyl ether which were reported earlier as constituents of the root of this plant.From the CHCl₃-soluble fraction of the ground part, deoxypodophyllotoxin, (-)-deoxypodorhizone, nemerosin, and falcarindiol were isolated.In vitro antiproliferative activities of the isolates against MK-1, HeLa, and B16F10 cells are reported.

View full abstract

The constituents in the fruit of Anthriscus sylvestris HOFFM. were investigated, and four ligans [deoxypodophyllotoxin, morelensin, (-)-deoxypodorhizone, and (-)-hinokinin], one phenylpropanoid [1, (3', 4'-dimethoxyphenyl)-1ξ-hydroxy-2-propene], two phenylpropanoid esters [3', 4'-dimethoxycinnamyl (Z)-2-angeloyloxymethyl-2-butenonate and 3', 4'-dimethoxycinnamyl (Z)-2-tigloyloxymethyl-2-butenoate], and one polyacetylenic compound (falcarindiol) were isolated. Their antiproliferative activity against MK-1, HeLa and B16F10 cell lines is reported.

View full abstract

Two new bisdesmosidic spirostanol saponins were isolated from the underground parts of Ruscus aculeatus. Their structures were determined to be (23S)-spirosta-5, 25(27)-diene 1β, 3β, 23-triol 1-O-{O-β-D-glucopyranosyl-(1→3)-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl} 23-O-β-D-glucopyranoside and (23S)-spirosta-5, 25(27)-diene-1β, 3β, 23-triol 1-O-{O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl} 23-O-β-D-glucopyranoside on the basis of spectroscopic analysis, including two-dimensional NMR techniques, and the result of hydrolysis.

View full abstract

Several hydrophilic polymers changed the cumulative amount of morphine (MOR) permeated through excised hairless rat skin from 1% MOR hydrochloride solution containing ethanol and l-menthol at concentration of 40% and 5%, respectively, as permeation enhancers, Anionic polymers (carboxyvinylpolymer and methylvinylether-maleic anhydride copolymer) in the test solutions decreased the skin permeation of MOR, whereas cationic polymers (polyethyleneimine and chitosan) increased it, compared with that without polymers. Little change, however, was observed by the addition of nonionic polymers (ydroxypropylcellulose and polyethyleneoxide). ON the other hand, the cationic and anionic polymers in the test solutions decreased and increase, respectively the skin permeation of salicyclic acid (SA) from the same enhancing system containing sodium salicylate. These opposite results were probably caused by the change in escaping tendency of the drugs from the vehicles, which was due to the drug-polymer interaction. (The escaping tendency has a great effect on the drug partition from the polymer solution to the skin barrier). The effect of hydrophilic polymers on the partition was then evaluated by Donnan membrane theory. The partition of MOR was increased and decreased by the presence of polymers having identical and opposite charge to MOR. The low partition of the drugs to skin may also be caused by low diffusion of the drugs in the polymer solutions. The drug release from the hydrophilic polymer solutions was then measured, and the release rate was found to have decreased in the presence of polymers having opposite charge to MOR and SA. It is suggested that these drug-polymer interactions changed the drug partition to skin thus changing the skin permeation of the drug.

View full abstract

The methanolic extracts from Calathe discolor LINDL. and C. liukiuensis SCHLTR. were found to exhibit hair restoring and skin blood flow promoting activities. Through bioassay-guided separation using the skin blood flow increasing effect, a novel indole S, O-bisdesmoside, calanthoside, was isolated together with three new components, glucoindican, calaliukiunenoside, and calaphenanthrenol, and known compounds such as tryptathrin, indirubin, isatin, and indican. The structures of the new compounds were determined on the basis of physicochemical and chemical evidence and they showed an activating effect on skin blood flow. In addition, it was found that enzymatic hydrolysis of calanthoside with β-glucosidase furnished tryptanthrin togethwer with a small amount of indirubin and isatin, whereas indirubin and isatin were obtained from calanthoside by acid hydrolysis. Based on their contents in the fresh and dried plant, calanthoside may be a common genuine glycoside of tryptanthrin, indirubin, and isatin in the plant.

View full abstract