Polymeric micelles incorporating (1,2-diaminocyclohexane)platinum (II) suppress the growth of orthotopic scirrhous gastric tumors and their lymph node metastasis

Nano-scaled drug carriers have great potential for the treatment of solid tumors. Nevertheless, hypovascularity and fibrosis in some types of solid tumors have been demonstrated to reduce the penetration and accumulation of nano-scaled drug carriers. Diffuse-type scirrhous gastric cancers present such characteristics as well as frequent metastasis to the lymph nodes; therefore, it remains a great challenge to eradicate scirrhous gastric cancers based on the drug targeting using nanocarriers. Herein, we demonstrated that polymeric micelles with 30-nm diameter incorporating (1,2-diaminocyclohexane)platinum(II) (DACHPt), the parent complex of the anticancer drug oxaliplatin, efficiently penetrated and accumulated in an orthotopic scirrhous gastric cancer model, leading to the inhibition of the tumor growth. Moreover, the elevated localization of systemically injected DACHPt-loaded micelles in metastastic lymph nodes reduced the metastatic tumor growth. These results suggest DACHPt-loaded micelles as a promising nanocarrier for the treatment of scirrhous gastric cancers and their lymphatic metastases.

Daily use of dentifrice with and without xylitol and fluoride: effect on glucose retention in humans in vivo

The effect of daily use of three different dentifrices on glucose retention after glucose mouth rinsing was tested in this study regarding xylitol and fluoride. Six experimental groups used three different dentifrices produced by two different companies: xylitol- and fluoride-containing dentifrice (XF), non-xylitol- and fluoride-containing dentifrice (F), and non-xylitol- and non-fluoride-containing dentifrice (NonX-NonF). Subjects were divided at random and rinsed their mouths for 15s with 20ml of 0.5M glucose solution. Glucose and lactate retention were determined by collecting samples of saliva from the approximal areas of the maxillary and mandibular anterior teeth and using the enzyme membrane test. Samples were collected 0, 1 and 2 months after the start of regular dentifrice use. There were significant differences in glucose retention in relation to the dentifrice used, month of sampling, site of sampling, and time since start of rinsing. Their contribution ratios were 2.0, 4.4, 11.7 and 7.4%, respectively (P<0.01). There were significant differences observed between the XF and NonX-NonF groups, with the XF group presenting lower glucose retention than the NonX-NonF group. The XF group presented lower glucose retention than the F group. The F group showed lower glucose retention than the NonX-NonF group. There were significant differences in lactate retention in relation to the month and site of sampling, and their contribution ratios were 3.3 and 2.8%, respectively (P<0.01). There were, however, no significant differences in glucose and lactate retention in relation to the dentifrice manufacturer. It was concluded that the XF dentifrice was the most effective, and the F dentifrice was more effective in reducing glucose retention than the NonX-NonF dentifrice.

Total synthesis of (+/-)-stemodinone via an efficient ring-exchange strategy

A total synthesis of (+/-)-stemodinone, a tetracyclic stemodane diterpene, from the known tricyclic methyl olefin 11 is described. The key steps involve an efficient ring-exchange reaction and palladium(0)-catalyzed lactone migration. The ring-exchange strategy for controlling the stereochemistry was based on an initial Diels-Alder reaction to form a new ring followed by cleavage of the original ring. Cleavage of the original ring of the Diels-Alder adduct 9 was achieved by an initial regio- and chemoselective Baeyer-Villiger oxidation followed by the Pd(0)-catalyzed lactone-migration reaction reported by us.

Total synthesis of (+/-)-scopadulin

The first total synthesis of (+/-)-scopadulin, an aphidicolane diterpene, is described. The core structure (A/B/C/D ring system) was constructed by an initial synthesis of the B/C/D ring system by our reported methods and a subsequent A ring cyclization by intramolecular aldol condensation. A highly stereoselective cyanation of the tetracyclic enone by Et2AlCN gave a trans-fused A/B ring system with a beta-cyanide at C-4. Stereoselective construction of a quaternary carbon at C-4 was achieved by alpha-alkylation of the cyano group and conversion of the sterically hindered cyano group to a methyl group via our novel reaction for conversion of primary aliphatic amines into alcohols. Finally, the total synthesis of (+/-)-scopadulin was accomplished by a highly chemo- and stereoselective methylation at C-16 and modification of the C-4 alpha-functionality. The stereoselectivity observed in the MeTi(O-i-Pr)3-mediated methylation for the generation of a tertiary axial alcohol at C-16 is extremely high.

The first total synthesis of (+/-)-scopadulin, an antiviral aphidicolane diterpene

[reaction: see text] The first total synthesis of (+/-)-scopadulin was accomplished by a stereoselective construction of a quaternary carbon at C-4, conversion of the hindered cyano group to a methyl group via our novel reaction for conversion of primary aliphatic amines into alcohols, and a highly chemo- and stereoselective methylation at C-16.

First total synthesis of mosin B

[figure: see text] The first total synthesis of mosin B and a diastereomer was accomplished using asymmetric desymmetrization of the sigma-symmetric diol and the Nozaki-Hiyama-Kishi reaction as the key steps. The THF core segment was stereoselectively constructed employing a stereodivergent synthesis starting from a common intermediate, 4-cyclohexene-1,2-diol, based on a desymmetrization strategy. By virtue of these synthetic results, it is suggested that the absolute configuration is 1a.

Asymmetric total synthesis of halicholactone

The asymmetric total synthesis of the marine metabolite, halicholactone 1, is described. The bisallylic triol 6 with three chiral centers at C8, C12, and C15 was constructed by [2,3]-sigmatropic rearrangement of the sulfoxide 18, which was prepared stereoselectively using the chirality of (diene)Fe(CO)3 complexes. Introduction of the trans-substituted cyclopropane subunit into 21 was successfully achieved using the modified regio- and stereoselective Simmons-Smith reaction. The use of RCM (ring-closing metathesis) methodology (4-->35) was pivotal for the formation of a nine-membered unsaturated lactone fragment of halicholactone 1. As this approach is flexible and stereoselective, other oxylipins could be synthesized by the protocol described herein.

Efficient one-step conversion of primary aliphatic amines into primary alcohols: application to a model study for the total synthesis of (+/-)-scopadulin

[reaction: see text] Treatment of primary aliphatic amines with KOH in diethylene glycol at 210 degrees C gives primary alcohols directly in good yields. A synthetic application to a model study of (+/-)-scopadulin is also described.

[Development and applications of new reactions for construction of basic structures of natural products]

This review deals with the development of efficient methods to construct the basic structure of natural products and the versatile methods to control the stereochemistry, and these methods were applied to the synthesis of natural compounds. The photochemical spirodienone formation reaction was applied to the synthesis of proaporphine alkaloids. The alternative spirodienone formation reactions by the metal-catalyzed degradation reaction of phenolic alpha-diazoketones were applied to many natural spirocyclic compounds, such as chamigrane type sesquiterpenes, spirovetivane type phytoalexins, marine natural products, and so on. Lewis acid mediated spirocyclization reaction of cyclohexene bis-acetal derivative was developed, and this reaction was applied to the synthesis of aphidicolane and stemodane diterpenes. The regioselective cleavage reaction of the cyclopropane ring of tricyclooctanone derivatives was used for the syntheses of diquinane and triquinane compounds. A chiral pool synthesis of several aromadendrane sesquiterpenes was achieved via common tricyclic enone intermediates. The synthesis of macrocarpals, coupling products of aromadendrane skeleton and isopentylphloroglucinol dialdehyde, was also accomplished for the first time using an arene Cr(CO)3 complex as a chiral benzyl cation equivalent. The Fe(diene)(CO)3 complexes were used for the highly stereoselective asymmetric synthesis of several natural products, such as insect pheromones and alkaloid, as a versatile mobile chiral auxiliary.

[Development of new reactions utilizing feature of sulfur atom and the applications]

Several novel reactions utilizing the latent feature of sulfur atoms have been developed. We found that chiral p-toluenesulfinyl groups on olefines control the stereochemistry in highly diastereoselective manners as show in the following three types of reactions: 1) intramolecular Michael addition reactions, 2) Pummerer-type reactions, and 3) cyclopropanation reactions. These chiral auxiliary groups are also very efficient for the asymmetric desymmetrization of sigma-symmetric diols via diastereoselective acetal fission. In addition, it was revealed that an aryl sulfide group on the cyclopropyl ring triggers single electron transfer reactions via cation radical species, resulting in the following reactions: 1) tandem oxidative ring cleavage-cyclization reactions and 2) intramolecular [3 + 2] cycloaddition reactions. These reactions have been applied to the syntheses of natural products.

Structure-activity relationship study of TXA2 receptor antagonists. 4-[2-(4-substituted phenylsulfonylamino)ethylthio]phenoxyacetic acids and related compounds

We have recently reported that 4-[2-(4-substituted phenylsulfonylamino) ethylthio]phenoxyacetic acids and related compounds showed potent thromboxane A2 (TXA2) receptor antagonist activity. To understand how substituents affect the biological activity, the quantitative structure-activity relationship (QSAR) was analyzed by using the Hansch-Fujita method for 36 compounds, including newly synthesized compounds. The positive coefficient for pi R and FR in the results of the QSAR study suggested that a hydrophobic an sigma electron-withdrawing substituent R at the para-position of the phenylsulfonyl moiety is required to improve the activity. Further, a substituent R which is long and moderately wide, was suggested to be preferable for the activity. The positive coefficients for pi X,Y,W-COOH and sigma Q(1)-(6) may indicate that the introduction of a hydrophobic and electron-withdrawing group on the benzene ring of the phenoxy acetic acid moiety enhances the activity. The length of the W-COOH moiety may also be important. On the other hand, the effect of the presence of methylene (n = 1) was not clear.

Synthesis and evaluation of novel thiazolidine derivatives as thromboxane A2 receptor antagonists

A series of 3-benzoyl or 3-phenylsulfonyl-2-substituted thiazolidine derivatives were synthesized, and evaluated for their thromboxane A2 (TXA2) receptor-antagonizing effect on (15S)-15-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5(Z),13(E)-dienoic acid (U-46619)-induced aggregation of rabbit platelet-rich plasma (PRP). A simple 2-aryl-thiazolidine derivative, 3-benzoyl-2-(4-hydroxy-3-methoxyphenyl)thiazolidine (5a), showed mild TXA2 receptor antagonist activity. Modification of 5a led to 2-chloro-4-[3-(4-chlorophenylsulfonyl)thiazolidin-2-ylmet hyl]phenoxyacetic acid (29d), which showed 10 times more potent TXA2 receptor antagonist activity than 5a.

A novel dihydrodiol dehydrogenase in bovine liver cytosol: purification and characterization of multiple forms of dihydrodiol dehydrogenase

Three enzymes (DD1, DD2, and DD3) having dihydrodiol dehydrogenase activity were purified to homogeneity from bovine cytosol. DD1 and DD2 were identified as 3 alpha-hydroxysteroid dehydrogenase and high-Km aldehyde reductase, respectively, as judged from their molecular weights, substrate specificities and inhibitor sensitivities. DD3 was a unique enzyme which could specifically catalyze the dehydrogenation of trans-benzenedihydrodiol and trans-naphthalenedihydrodiol without any activity toward the other tested alcohols, aldehydes, ketones, and quinones. The Km value of DD3 (0.18 mM) for benzenedihydrodiol was lower than those of other dihydrodiol dehydrogenases so far reported. DD3 immunologically crossreacted with DD1, but showed no crossreactivity with DD2. Additionally, DD3 was inhibited in a competitive manner, with a low Ki value of 1 microM, by androsterone, which was a good substrate for DD1. It was assumed that DD3 is a novel enzyme which is specific to dihydrodiols, exhibiting similarity to DD1 in immunological and structural properties.

Comparative platelet anti-aggregant activity of D-cysteinolic acid analogues

D-Cysteinolic acid (1) analogues with an S-C-C-N skeleton showed increased platelet anti-aggregant activity in the following order: 2-aminoethanesulfonic acids, thiazolidines, 2-aminoethanethiols and 2-aminoethyl disulfides. Methyl substitutions at the 2-position potentiated the activity. Of these analogues, bis [(R)-2-aminopropyl] disulfide was the most potent inhibitor of platelet aggregation, with about 600-fold the activity of (1).

Difference between two isozymes of (Na+ + K+)-ATPase in the interaction with omeprazole

The difference in functional SH groups between two isozymes (alpha(+) and alpha forms) of (Na+ + K+)-ATPase was examined using omeprazole, a hydrophobic drug which was reported to modify SH groups of gastric (H+ + K+)-ATPase. Omeprazole inhibited rat brain and kidney (Na+ + K+)-ATPase activities in a time- and dose-dependent manner, and it inhibited incorporation of [3H]NEM into the catalytic subunit of the enzymes. The inhibition was greater in the brain enzyme than in the kidney enzyme. The inhibition of the brain enzyme showed a lag time, whereas the kidney enzyme was inhibited according to pseudo-first order kinetics. The inhibition by omeprazole of Na+-dependent phosphorylation and K+-stimulated phosphatase activity in the brain enzyme preparation was parallel with that of the overall (Na+ + K+)-ATPase reaction, while the partial reactions of the kidney enzyme showed different sensitivities to inhibition by omeprazole. Furthermore, the inhibition by omeprazole of [3H]NEM reactivity in the brain alpha(+) form was greater in the presence of SDS than in the absence, whereas the inhibition in the brain and kidney alpha forms was less in the presence of SDS than in the absence. These findings suggest that the isozymes of (Na+ + K+)-ATPase differ in hydrophobicity of SH groups of their catalytic subunits.

2-Substituted 1, 3, 4-thiadiazole-5-sulfonamides as carbonic anhydrase inhibitors: their effects on the transepithelial potential difference of the isolated rabbit ciliary body and on the intraocular pressure of the living rabbit eye

In order to understand the pharmacology of carbonic anhydrase inhibitors in reduction of aqueous secretion, three sorts of studies were conducted using five 2-substituted 1, 3, 4-thiadiazole-5-sulfonamides: an inhibition study of carbonic anhydrase II, electrical measurements of the isolated ciliary body, and pharmacological study on intraocular pressure of living animals. The inhibitors of carbonic anhydrase employed here were 2-amino-1, 3, 4-thiadiazole-5-sulfonamide; 2-methylamino-1, 3, 4-thiadiazole-5-sulfonamide; 2-formylamino-1, 3, 4-thiadiazole-5-sulfonamide; 2-acetylamino-1, 3, 4-thiadiazole-5-sulfonamide (acetazolamide); and 2-propionylamino-1, 3, 4-thiadiazole-5-sulfonamide. All of these compounds showed significant inhibitory activity to carbonic anhydrase II which exists in the ciliary epithelium, but their potencies of inhibition varied relative to one another (I50S were 1.91 X 10(-7) to 3.3 X 10(-8) M). The effects of the five compounds on electrical phenomena were observed using isolated rabbit ciliary body mounted on an Ussing's chamber. Each compound decreased the negative electrical potential of the tissue (-0.70 mV as the average of the initial values) by 10- to 33%, and this effect was proportional to its inhibitory activity to carbonic anhydrase II. The effects of the five compounds on intraocular pressure were determined, and each compound decreased the intraocular pressure (18 mmHg as the average of the initial values) by 7- to 32%. This effect was also proportional to the inhibitory activity to the enzyme. Correlation between the two effects was studied, and good correlation was observed. This implies that both effects have a common basis which relates to the physiological role of carbonic anhydrase. The present study, therefore, shows the importance of the bicarbonate ion in the aqueous humor formation since it is both substrate and product of carbonic anhydrase II.

Phosphonate analogues of pyridoxal phosphate with shortened side chains

A phosphonate analogue of pyridoxal 5'-phosphate containing a 5'-phosphonomethyl group and its monoethyl and diethyl esters have been prepared. Except for the diethyl ester, the compounds appear to bind into the active site of aspartate aminotransferase. However, they lack detectable catalytic activity with this enzyme and with glutamate decarboxylase of Escherichia coli. The phosphonomethyl analogue bound to aspartate aminotransferase does react slowly with substrates, as determined by spectrophotometric observations; the monomethyl ester reacts about 20 times less rapidly. Because of the stability of the phosphonate linkage, these compounds may be useful as modifying reagents for various proteins.

Promoting effects of 3-amino-1,2,4-triazole on the development of thyroid tumors in rats treated with N-bis(2-hydroxypropyl)nitrosamine

3-Amino-1,2,4-triazole (AT) promoted the development of thyroid tumors in rats treated with a subeffective dose of N-bis(2-hydroxypropyl)nitrosamine (DHPN) for thyroid tumorigenesis. The incidences of thyroid tumors at the end of the 20-week experiment were 91% in rats injected s.c. once a week for four weeks with 70 mg DHPN per 100 g body weight and then given diet containing 2000 p.p.m. AT for 12 weeks, 100% in rats injected s.c. once a week for eight weeks with 70 mg DHPN per 100 g body weight and then given diet containing 2000 p.p.m. AT for 12 weeks, and 58% in rats injected s.c. once a week for 8 weeks with 70 mg DHPN per 100 g body weight. Rats only injected s.c. once a week for four weeks with DHPN or only given diet containing AT for 12 weeks had no thyroid tumors at the end of the experiment.

Histopathological studies on renal tubular cell tumors in rats treated with N-ethyl-N-hydroxyethylnitrosamine

Administration of a diet containing 0.2% N-ethyl-N-hydroxyethylnitrosamine (EHEN) for 2 weeks induced hepatocellular carcinoma in 3 and renal tubular cell tumors in 7 of 9 Wistar rats. Diet containing 0.1% EHEN induced renal tubular cell tumors in 6 of 10 rats, but no hepatocellular carcinomas. Both diets induced atypical cell population of tubules in the kidney, but no nephroblastoma.

Ultrastructure of an anaplastic giant-cell carcinoma found 8 years after operation on a papillary carcinoma of the thyroid

Light and electron microscopic studies have been made on an anaplastic giant-cell tumor that developed in a woman 8 years after an operation on the thyroid for papillary carcinoma. Many giant cells were observed in the anaplastic tumor tissue, but no follicles. Numerous tightly-packed mitochondria and abundant ribosomes were present, but there were no desmosomes. The basement membrane was not distinct.