The interaction between azathioprine (AZ) and bovine serum albumin (BSA) is mainly due to hydrophobic binding according to the dependence of the binding constant on the ionic strength obtained by equilibrium dialysis. The binding constant and partition coefficient of AZ were smaller than those of warfarin, phenylbutazone and ibuprofen. Little variation in the proton chemical shift of AZ was observed whether there was an absence or presence of BSA (7.25×10^-5 M). The spin-lattice relaxation time (T₁) of AZ decreased in the presence of BSA to 6-22%. The spin-spin relaxation rate (1/T₂) of AZ increased 16-24 times for the methyl group and the imidazole ring and 8-13 times for the purine ring in the presence of BSA. The ratio of the spin-spin relaxation rate of the free AZ to the bound AZ ((1/T₂)_b/(1/T₂)_f) of the methyl group and the imidazole ring was 2-3 times larger than that of the purine ring. The binding of AZ to BSA was concluded to be mainly at the methyl group on the imidazole ring of AZ.

View full abstract

The revised substituent entropy constants σ_S° representing both dispersion and repulsion interactions are expressed by the next equations; σ_S°(12)=0.859Σσ_S°(mono)-0.011;σ_S°(13)=0.894Σσ_S°(mono)-0.013;σ_S°(14)=0.905Σσ_S°(mono)-0.022; σ_S°(123)=0.779Σσ_S°(mono)-0.021; σ_S°(124)=0.765Σσ_S°(mono)-0.007; σ_S°(135)=0.817Σσ_S°(mono)-0.033; where the correction due to the symmetry number, n×Rln2, should be introduced optionally. The descriptors σ_S° of the substrates having two substituted phenyl rings-namely, biphenyls, diphenyl ethers, -amines, -methanes, sulfides and benzophenones-could be determined by the joint use of the next equations; σ_S°(1234)=0.704Σσ_S°(mono)-0.024;σ_S°(1235)=0.702Σσ_S°(mono)-0.018; σ_S°(1245)=0.706Σσ_S°(mono)-0.023; σ_S°(penta)=0.618Σσ_S°(mono)-0.012;σ_S°(hexa)=0.570Σσ_S°(mono)-0.012.Observed results suggest that the concept of isosterism could probably be related to a similar level of dispersion and repulsion interactions between receptor and substrate.

View full abstract

Two metal complexes of bleomycin (BLM), BLM-Ni-<2+> and BLM-VO³⁺ are used for studying interactions between BLM and deoxyribonucleic acid (DNA) by nuclear magnetic resonance. Although these BLMs do not mediate DNA strand acission under the usual conditions, they bind to DNA in the same manner as the active metal complexes of bleomycin (BLM-Fe²⁺ and BLM-Co³⁺). A self-complementary dodecanucleotide, d(CCCCAGCTGGGG), having a single site for cleavage was synthesized. d(CCCCAATTGGGG), which contains no -GpC- sequence, was also synthesized. The BLM-metal complexes were shown to bind specifically to the GpC site by circular dichroism and fluorescence titration studies. We assigned all the resonances for imino protons and phosphorus, and most of the nonexchangeable proton resonances of d(CCCCAGCTGGGG). No substantial change in the chemical shifts of these signals was observed upon titration with either BLM-Ni²⁺ or BLM-VO³⁺. This result is not consistent with a model of the strong intercalation of the BLMs between the base-pairs. The BLMs bind to DNA in a different manner, and DNA does not change its conformation upon binding with BLMs.

View full abstract

4-Methyl-4H-pyrrolo[1, 2-a]benzimidazol-2(1H)-one derivatives (11a-d) were synthesized by intramolecular acylation of 1-carboxymethyl-2, 3-dimethylbenzimidazolium halides (9a and 8b-d) in good yields. Treatment of the iodide (8a) with an excess of refluxing thionyl chloride gave 1, 1, 3-trichloro-4-methyl-4H-pyrrolo[1, 2-a]benzimidazol-2(1H)-one (14). Introduction of electrophiles into the 1-position of 11d and 6-position of 5-methyl-9, 10-dihydro-5H-azepino[1, 2-a]benzimidazol-7(8H)-one (2a) was achieved by successive treatment with lithium diisopropylamide and electrophiles such as methyl iodide and ketones. The azepinone 2a was reacted with various electrophiles to give 6-substituted products in good yields.

View full abstract

The amino group at the 7-position on the 3H-1, 2, 3-triazolo[4, 5-d]pyrimidine ring was converted into halogen atoms by treatment with isopentyl nitrite in halomethanes, in satisfactory yields. The halogen-metal exchange reaction between 7-iodo-3-phenyl-3H-1, 2, 3-triazolo[4, 5-d]pyrimidine (2) and butyllithium in the presence of N, N, N', N'-tetramethylethylenediamine proceeded, giving the 7-lithio compound (9). The lithio compound (9) reacted smoothly with electrophiles to give the corresponding 7-substituted compounds (15-18). On the other hand, the reaction of 7-chloro-3-phenyl-3H-1, 2, 3-triazolo[4, 5-d]pyrimidine (1) with butyllithium gave the ring fission product, 5-amino-1-phenyl-1H-1, 2, 3-triazole-4-carbonitrile (14).

View full abstract

As a model of the C/D ring system of erythroidines, bicyclic unsaturated δ-lactones were synthesized in a regio-selective manner, and their isomerization reaction in the presence of acid, base (DBU, 1, 8-diazabicyclo[5.4.0]undec-7-ene), and NaOH were studied. In the lactone form, the 6-ene (3) was the most unstable and isomerized to the 5-ene (1) then to the 1⁽⁶⁾-ene (2). The latter two lactones equilibrate to give ca. 3 : 2 mixture of 1 and 2 in the presence of DBU. On the contrary, in the opened form (NaOH), the lactone 1 was the most unstable and isomerized to 2 and 3. The 1⁽¹⁰⁾-ene (4) was inert under all of the conditions examined.

View full abstract

Mesaconitine (1) in tetrahydrofuran reacted with sodium hydride, a catalytic amount of imidazole, carbon disulfide and methyl iodide at room temperature to give the di-O-(S-methyl)thiocarbonate (5). The reductive cleavage of 5 with tri-n-butyltin hydride gave isodelphinine (3) in a high yield of 83%. The exact same reactions of aconitine (2) and jesaconitine (6) gave penduline (4) and 3, 13-dideoxyjesaconitine (7) in 85 and 86% yields, respectively. The same reactions in diethylether, in place of tetrahydrofuran, gave the 3-deoxy compounds, hypaconitine (9), deoxyaconitine (10) and deoxyjessaconitine (11), in yields of 87, 88 and 85%, respectively. When the same reaction as used for the syntheses of the 3, 13-dideoxy compounds was done at refluxing temperature, 3, 13, 15-trideoxy compounds, that is, 3, 13, 15-trideoxymesaconitine, 3, 13, 15-trideoxyaconitine and 3, 13, 15-trideoxyjesaconitine, were obtained in yields of 83, 83 and 88%, respectively.

View full abstract

The structure of a novel immunomodulator, nectrisine (1), has been elucidated on the basis of chemical and spectroscopic evidence. Its absolute stereochemistry was predicted on the basis of the dibenzoate chirality rule and finally confirmed by a synthesis from D-glucose.

View full abstract

(2R, 5S)-2-Hydroxymethyl-1-carbapenam (3), the carba-analog of an antifungal β-lactam (2R, 5S)-2-(hydroxymethyl)clavam (1), was synthesized in an enantiocontrolled manner, starting from the coupling reaction of an optically active phthalimido-acetate (3S, 4S)-4 and an allylsilane 7, followed by removal of the phthalimido group that was crucial for asymmetric induction. Hydroboration, protecting-group interconversion, and cyclization gave 3 stereoselectively.

View full abstract

Sixteen-membered macrolide aglycons with different oxidation levels, leuconolide A₁ (3a), leuconolide A₃ (3b), midecanolide A₁ (3c), maridonolide II (4a), and maridonolide I (4b), were synthesized from two carbonolide type compounds (1, 2) by stereoselective reduction and epoxidation on the 16-membered ring system. The conformational analysis of macrolide rings based on nuclear magnetic resonance measurements and MMP2 calculations is also discussed in relation to the stereoselective synthesis of the five macrolide aglycons (3a-4b).

View full abstract

The cyclization of methyl (E)-6-oxo-6-[1-(phenylsulfonyl)-1H-pyrrol-3-yl]-2-hexenoate (8a) using an equimolar amount of palladium chloride gave methyl 4-hydroxy-1-(phenylsulfonyl)-1H-indole-7-acetate (11a) in 33% yield. The similar cyclization of methyl (E)-6-acetoxy-6-[1-(phenylsulfonyl)-1H-pyrrol-3-yl]-2-hexenoate (8c) proceeded smoothly to give methyl 1-(phenylsulfonyl)-1H-indole-7-acetate (11c) and 4-acetoxy-7-methyoxycarbonylmethylidene-1-phenylsulfonyl-4, 5, 6, 7-tetrahydro-1H-indole (10c) in 41% and 22% yields, respectively. Conversion of the tetrahydroindole (10c) to the indole (11c) was accomplished in 44% yield by treatment with p-toluenesulfonic acid in benzene. Methyl (E)-6-[1-(phenylsulfonyl)-1H-pyrrol-3-yl]-2-hexenoate (8d) gave 11c and 7-methoxycarbonylmethylidene-1-phenylsulfonyl-4, 5, 6, 7-tetrahydro-1H-indole (10d) in 27% and 40% yields, respectively. The cyclization of ethyl (E)-4-(5-methoxycarbonyl-4-pentenyl)-1H-pyrrole-2-carboxylate (18) also gave the corresponding indole-7-acetate (20) and 7-methoxycarbonylmethylidene-4, 5, 6, 7-tetrahydro-1H-indole (21) in 16% and 49% yields, respectively.

View full abstract

1, 3, 4-Thiadiazol-5-ylacetic, propionic, and glutaric acids (3-5) were synthesized via ethyl 2-substituted 1, 3, 4-thiadiazol-5-ylacetates (11 and 17) as key intermediates.

View full abstract

The synthesis of 16 metabolites of S-1452, an orally active thromboxane A₂ (TXA₂) receptor antagonist, is described. Regioselective hydroxylation at C-5 or C-6 of the bicyclo[2.2.1]heptane skeleton of the optically active intermediate 16 was attempted by using 9-borabicyclo[3.3.1]nonane followed by H₂O₂ or m-chloroperbenzoic acid (m-CPBA) and then LiAlH₄, to obtain the hydroxylated product 17a or 17b, respectively. Modification of the C-2 substituent of 17a and 17b afforded eight metabolites of S-1452. Eight non-hydroxylated metabolites were synthesized by using a similar reaction sequence.

View full abstract

Two new monomeric hydrolyzable tannins [remurins A (12) and B (13)] and a new dimer [hirtellin A (7)], have been isolated from Reaumuria hirtella JAUB. et Sp. (Tamaricaceae). Hirtellin A and an additional new dimeric hydrolyzable tannin, tamarixinin A (6), along with three known tannins including hirtellin B (5), have also been isolated from Tamarix pakistanica QAISER.The structures of the new tannins have been elucidated based on chemical method and two-dimensional nuclear magnetic resonance analyses indluding ¹H-¹³C long-range shift correlation spectroscopy. Tamarixinin A (6) exhibited a host-mediated antitumor activity comparable to that of hertellin B.

View full abstract

A general synthetic route to 3, 7-dialkylxanthines (type 9) from 3, 7-dialkyladenines (6) [hence from 3- or 7-alkyladenines (11 or 10)] has been established. The route started with ethoxycarbonylation of 1-alkyl-4-(alkylamino)-1H-imidazole-5-carboxamides (7), readily obtainable from 6 by alkaline hydrolysis, and proceeded through cyclization of the resulting carbamates (8) under alkaline conditions. Alkylation of 9 with alkyl halide in N, N-dimethylformamide in the presence of anhydrous K₂CO₃ extended the above synthetic route to the 1, 3, 7-trialkylxanthine level (type 14). Hydrogenolytic debenzylation of 3-benzyl-1, 7-dimethylxanthine (16), prepared by following this general synthetic route, furnished paraxanthine (26) in fair yield. Conversion of 26 into 3-(4-hydroxy-3-nitrobenzyl)-1, 7-dimethylxanthine (24), isomeric with the bryozoan purine phidolopin (2), was effected through aralkylation with 4-(methoxymethocy)-3-nitrobenzyl bromide (28) followed by O-deprotection.On the basis of proton nuclear magnetic resonance data for the 3, 7-dialkylxanthines (3 and 9b-i) and 1, 3, 7-trialkylxanthines (5 and 14-22) thus prepared, reliable criteria for distinguishing signals of N-alkyl substituents at various positions are put forward.

View full abstract

The aldol reaction of tricarbonyl(o-trimethylsilyl(TMS)-benzaldehyde)chromium(0) complex (1a) with cyclic ketene silyl acetals (2-4) afforded the corresponding erythro products selectively. Changing the ortho TMS group to a triisopropylsilyl (TIPS) group in the complex brought about an improvement of the erythro selectivity in the case of the five-membered acetal (4).

View full abstract

The chemical structures of sarasinosides A₁, A₂, A₃, B₁, B₂, B₃, C₁, C₂, and C₃, nine 30-norlanostane-triterpenoidal oligoglycosides isolated from the Palauan marine sponge Asteropus sarasinosum have been elucidated on the basis of chemical and physicochemical evidence. Sarasinosides A₂ (2) and A₃ (3) were shown to be the 7, 9(11)-diene and 8, 14-diene analogs of sarasinoside A₁ (1), whereas sarasinosides B₂ (7) and B₃ (9) were the 7, 9(11)-diene and 8, 14-diene analogs of sarasinoside B₁ (5), respectively. Similar structural correlations of sarasinosides C₂ (6) and C₃ (8) with sarasinoside C₁ (4) were demonstrated. These sarasinosides characteristically contain one mole each of N-acetyl-glucosamine and N-acetylgalactosamine in their oligosaccharide moieties.

View full abstract

The rearrangement of a series of dimethylsulfonium α-substituted benzylides, e.g., 8, in ethanol has been examined. The ylides 8a, b generated in situ by treatment of the sulfonium salts 7a, b with 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU) in ethanol at room temperature, afforded the o-(methylthiomethyl)phenylacetic esters 10a, b as a result of the Sommelet-Hauser rearrangement of the tautomeric ylides 9a, b. By contrast, the ylide 14 possessing a furan ring was stable at room temperature, but, on heating in ethanol, gave the rearranged product 15. The ylide 22 stabilized by an acetyl group provided three rearranged products, 23, 24, and 25, in boiling ethanol. Treatment of the sulfonium salts 30a, b with DBU at room temperature afforded the corresponding rearranged products 31a, b. The sulfonium salt 34a prepared from 33a, on treatment with sodium ethoxide, gave the rearranged product 36a, which was then S-methylated and treated with DBU to give the 1, 2, 3-trisubstituted benzene 37a. This method was applied to the synthesis of the fenoprofen analog 39 from 39 from 33b, c.

View full abstract

Tosylation of non-protected glycopyranosides with p-toluenesulfonyl chloride in the presence of 4-dimethyl-aminopyridine, after activiation of the glycosides by dibutyltin oxide, gave mono-O-tosylates in good yield. The regioselectivity in this tosylation was different from that in the corresponding benzoylation for some glycosides. The reason for this difference is discussed based on an equilibrium of the tin intermediates and kinetic attack of the tosyl chloride on the intermediates. Thus, by application of this tosylation method to non-protected and partially protected glycosides, various glycoside mono-O-tosylates were synthesized regioselectively.

View full abstract

New 2H-1, 4-benzothiazin-3(4H)-one derivatives possessing (4-phenyl-1-piperazinyl)alkyl moieties at the 2-position were synthesized and tested for calcium antagonistic and calmodulin antagonistic activities. Antihypertensive effects in spontaneously hypertensive rats were also evaluated. In general, these compounds were rather weak calcium channel blockers, although, in contrast, many of tham had moderate to potent calmodulin antagonistic activity, and 2-[3-(4-(4-fluorophenyl)-1-piperazinyl]propyl]-2H-1, 4-benzothiazin-3(4H)-one derivatives 45, 74 and 75 showed potent antihypertensive effects.

View full abstract

A series of new 1, 4-benzoxazine derivatives (XI, XII) possessing (4-phenyl-1-piperazinyl)alkyl moieties at the 2-position and related compounds (XIII) were synthesized and tested for calcium antagonistic, calmodulin antagonistic and antihypertensive activities. Various compounds had in vitro calmodulin antagonistic activity superior or comparable to that of trifluoperazine. Among these compounds, tetrahydronaphtho[2, 3-b][1, 4]oxazine derivatives such as 51, 53, 54, 58, 59, 60, 73 and 75 showed potent antihypertensive effects in spontaneously hypertensive rats. Optical isomers of 51 were also synthesized and evaluated biologically. No differences in biological activities were seen between the enantiomers.

View full abstract

The enantiomers of 2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl]propionic acid [(±)-1, rebamipide, OPC-12759], a new antiulcer agent that enhances mucosal resistance, were synthesized from optically active α-amino acid derivatives of 2(1H)-quinolinone. The key intermediates, α-amino acid derivatives, were prepared by asymmetric synthesis and optical resolution. The (+)-1 was about 1.7 times as potent as the (-)-isomer in antiulcer activity against ethanol-induced gastric ulcers.

View full abstract

7, 8-Dihydroxy-4-(3, 4-dihydroxyphenyl)-1, 2, 3, 4-tetrahydroisoquinoline (1) and 4-(3, 4-dihydroxyphenyl)-7-hydroxy-8-methyl-1, 2, 3, 4-tetrahydroisoquinoline (2) are potent renal vasodilators which selectively stimulate DA₁ (peripheral dopamine receptor-1) receptors. Especially, (S)-(-)-1 is the most potent. Its DA₁ agonist activity is about 10 times stronger than dopamine for increasing renal blood flow in anesthetized dogs. The renal and cardiovascular effects of (S)-(-)-1 may be suitable for the treatment of patients with renal insufficiency, heart failure and hypertension.

View full abstract

A series of 1, 1'-biphenyl-2, 6-dicarboxylic acid diesters were synthesized and examined for their inhibitory activity on guinea-pig detrusor muscle contraction at electrical field stimulation in vitro. Among them, 6-isopropyl 2-methyl 3-hydroxy-5-methyl-2'-nitro-(1, 1'-biphenyl)-2, 6-dicarboxylate, FR75513 (8a) was one of the potent compounds (IC₅₀=3.3×10^-6 g/ml). This compound (8a) exhibited a strong inhibitory activity on detrusor contraction after intravenous administration in anesthetized rats (ID₅₀=0.04 mg/kg).

View full abstract

Our previous study on the relationship between the logarithm of 1-octanol/water prtition coefficient (log P) by the shake-flask method and the logarithm of the capacity factor (log k') by reversed-phase liquid chromatography for monosubstituted pyrazines (2PR) has been extended to the 2-chloro-6-substituted pyrazine series (6PR) and also to other reversed-phase high-performance liquid chromatographic conditions. Analyses have shown that 6PR behave similarly to 2PR. The influences of stationary and mobile phases were studied using several commercially available reversed-phase columns, and various organic modifiers. The results, from any combination of the stationary phases and the modifiers examined, have presented analogous trends to those previously observed : (1) The log P-log k' relationship becomes more complicated as the concentration of organic modifier in the mobile phase decreases due to the intervention of the electronic interactions and the retardation effect ascribed to ester and amide substituents. (2) Amphiprotic substituents usually exhibit an acceleration effect and should be treated separately. Practical conditions to be used for predicting the log P values are proposed.

View full abstract

Specific plasma kallikrein inhibitors were disigned and synthesized and their structure-activity relationship was studied. trans-4-Aminomethylcyclohexanecarbonyl(Tra)-lysyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC₅₀ values of 23 and 210 μM, respectively, indicating that this compound is fairly specific to plasma kallikrein. Tra-arginyl-4-ethoxycarbonylanilide inhibited plasma kallikrein and plasmin with IC₅₀ values of 16 and 480 μM, respectively. Tra-homoarginyl-4-carboxyanilide inhibited plasma kallikrein and plasmin with IC₅₀ values of 14 μM and 1 mM, respectively. Finally, Tra-Arg(Mts)-4-acetylanilide (ACA) exhibited potent and seletive inhibitory activity against plasma kallikrein (IC₅₀ value for plasma kallikrein : 2 μM and for plasmin : 42 μM).

View full abstract

A series of imidazo[1, 2-α]pyridinyl-2-oxobenzoxazolidines (4a-i), -3-oxo-2H-1, 4-benzoxazines (5a-q), their thio-analogues (4j-p and 5r-t) and 5, 6, 7, 8-tetrahydroimidazo[1, 2-α]pyridinyl derivatives (8 and 9) were synthesized and tested for anti-stress ulcer activity in rats. Several compounds were found to be more active than the reference compounds, zolimidine, cimetidine and sucralfate. Among them, compound 4e, 5i and 5l also exhibited potent protective activity against ethanol-induced gastric lesion. The synthesis and structure-activity relationships of these compounds are discussed.

View full abstract

Sixteen new acylated iridoid glycosides, called buddlejosides A₁-A₁₆, were isolated from Buddleja japonica HEMSL., together with four known iridoid glycosides; 6-vanilloyl-ajugol, 6-feruloyl-ajugol, verbascoside A, and 6-O-[α-L-(4-O-feruloyl)-rhamnopyranosyl]-catalpol. Structures of the new compounds were determined on the basis of chemical and spectroscopic evidence. Buddlejosides A₁ was an ajugol derivative acylated with monoterpenic acid, A₂ was an sinuatol and A₃-A₁₆ were 6-rhamnopyranosyl-catalpol derivatives acylated with cinnamic acid derivative and acetic acid.

View full abstract

Five new lignoid glycosides including a novel lignan were isolated from Albizziae Cortex, the dried stem bark of Albizzia julibrissin DURAZZ. Three of them appear to be key metabolites of a biodegradation pathway for syringaresinol.

View full abstract

Three phenolic compounds were isolated from the roots of Arnebia euchroma as inhibitors of in vitro prostaglandin biosynthesis. Two known compounds were identified as shikonofurans and des-O-methyllasiodiplodin. The other new compound was named arnebinol and its structure was elucidated as a novel ansa-type monoterpenylbenzenoid derivative.

View full abstract

Two quinonic compounds, arnebinone and arnebifuranone, were isolated from the roots of Arnebia euchroma and their structures were elucidated on the basis of spectral evidence. Arnebinone is a monoterpenyl-benzoquinoe in which the monoterpene moiety forms a fused ring to the benzoquinone. Arnebifuranone is another monoterpenylbenzoquinone with a furan ring containing side chain which is bonded to the benzoquinone at the head carbon of C₁₀ moiety originating from the geranyl moiety of geranylhydroquinone.

View full abstract

Deoxyribonucleic acid (DNA) strand break caused by a synthetic cyclic peroxide, 4-ethoxy-1, 4-dihydro-2, 3-benzodioxin-1-ol (Bd) was studied by both ethidium bromide fluorescence quenching and agarose gel electrophoresis. The Bd-mediated DNA strand break occurred dependently on temperature and also on Bd concentration. The reaction proceeded at a temperature higher than 30°C (decomposition temperature of Bd), indicating that the reactive species generated by Bd-decomposition are responsible for the reaction. The reaction was protected by 1, 4-diazabicyclo[2.2.2]octane and NaN₃. and also moderately by OH radical scavengers such as Na-benzoate and NaBr. Possible involvement of active oxygen radicals including OH radical in the DNA strand break is discussed in relation to the mechanism of Bd decomposition.

View full abstract

An acidic polysaccharide, designated as AMon-S, was isolated from the roots of Astragalus mongholicus BUNGE. It was homogeneous on electrophoresis and gel chromatography, and its molecular mass was estimated to be 7.6×10⁴. It showed significant reticuloendothelial system-potentiating activity in a carbon clearance test. It is composed of L-arabinose : D-galactose : D-galacturonic acid : D-glucuronic acid in the molar ratio of 18 : 18 : 1 : 1, in addition to small amounts of O-adetyl groups and peptide moiety. A part of the hexuronic acid residues exist as the methyl esters. Methylation analysis, carbon-13 nuclear magnetic resonance and periodate oxidation studies enabled elucidation of its structural features and revealed mainly α-arabino-β-3, 6-galactan type structural units.

View full abstract

Microbiological enantioselective transformation of 4, 9-dimethyl-3, 5-dioxo-Δ⁴⁽¹⁰⁾-octalin, (±)-1 was accomplished with various yeasts, e.g. Rhodotorula rubra. With properly selected microorganisms, (+)-4, 9S-dimethyl-5S-hydroxy-(2a) and (-)-4, 9R-dimethyl-5S-hydroxy-3-oxo-Δ⁴⁽¹⁰⁾-octalin (3b), (-)-4, 9R-dimethyl-3S-hydroxy- (6b) and (+)-4, 9S-dimethyl-3S-hydroxy-5-oxo-Δ⁴⁽¹⁰⁾-octalin (7a) were obtained with high optical purity.These compounds have now become available for the total syntheses of sesquiterpenoids such as tuberiferine and temisin.

View full abstract

The hydrolytic activity of phosphatidylinositol (PI)-specific phospholipase C (PI-PLC) from Bacillus thuringiensis was studied in detail toward mixed liposomes consisting of PI and one of other phospholipids and cholesterol. Among PI-liposomes, small unilamellar vesicles (SUV) were the most sensitive to PI-PLC; the enzymatic hydrolysis of PI in SUV was not less than 10-fold that in large unilamellar vesicles (LUV) or in multilamellar vesicles (MLV). Thus, in a survey of the effects of coexisting lipids on PI-PLC activity, PI-SUV was used. Phosphatidylcholine (PC) was stimulative for the enzyme activity toward PI-SUV at any molar ratio of PC to PI. Also, the effects of the addition of sphingomyelin (SM), phosphatidylethanolamine (PE) and cholesterol on the enzymatic hydrolysis of PI were studied in detail on the basis of concentration of total lipids or PI.

View full abstract

Human chorionic gonadotropin (hCG) is a glycoprotein consisting of noncovalently bound α- and β-subunits which shows hormonal activity (stimulatory effect on testosterone production) toward rat Leydig cells. To modify the hormonal activity of hCG, hybrid molecules composed of hCG and other glycoproteins, either the A or B chain of lectin ricin (hCG-A and hCG-B) through disulfide bridges and horseradish peroxidase (hCG-HRP) through Schiff's base, were synthesized. Hormonal activity and the effect of these hybrids on [¹²⁵I]hCG binding to rat Leydig cells were compared to those of native hCG. Modification of hCG resulted in a significant decrease in hormonal activity for hCG-HRP but not for hCG-A to aproximately 1/100 and 1/10 that of native hCG, respectively. On the other hand, hCG-B unexpectedly showed hormonal activity similar to that of native hCG. These hybrids inhibited the binding of ¹²⁵I-labeled hCG to rat Leydig cells with potencies of 1/10, 1/100 and 1/500 that of hCG for hCG-B, hCG-A and hCG-HRP, respectively. These results indicate that the B chain of ricin, the active component hCG-B, participated in stimulating testosterone production according to its own nature. Data which indicate that hybrids consisting of hCG subunits and the B chain of ricin (α-B and β-B) stimulated testosterone significantly more than hybrids consisting of hCG subunits and A chain (α-A and β-A) support the above finding. When asialofetuin was added to the assay system as an inhibitor of binding of the B chain to galactose residues attached to the cell surface membrane, the inhibition of hCG-B with the binding of [¹²⁵I]hCG to rat Leydig cells was depressed and testosterone production provoked by hCG-B was repressed to the level induced by hCG-A. Furthermore, a hybrid consisting of hCG and enzymatically deglycosylated B chain stimulated testosterone production, but its activity was significantly weaker than that of hCG-B with the level approaching that of hCG-HRP. These results suggested that three kinds of binding of hCG-B to rat Leydig cells participate in expression of hormonal activity of hCG-B as follows : (1) binding of the hCG moiety to its receptor, (2) binding of the B chain moiety, as lectin, to terminal galactose residues attached to cell-surface membrane, and (3) binding of a lectin-like protein(s) in the cell-surface membrane to oligosaccharides of the B chain moiety.

View full abstract

Hydrogen sulfide (H₂S) was efficiently removed from air by Hyphomicrobium neptunium ATCC 15444. When the loading of H₂S was less than 68.3 mmol of H₂S per liter-culture per day, the H₂S was completely removed. At this point, the inlet maximum concentration of H₂S was 850 ppm. This H₂S removal effect was strongly dependent on the pH of the medium and the existence of Mg²⁺, Ca²⁺ in the medium which were growth factors of H. neptunium ATCC 15444.

View full abstract

Substrate specificity of a novel sulfotransferase produced by Eubacterium A-44 isolated from human feces has been studied. Phenolic drugs, catecholamines, were good acceptors of this bacterial enzyme. With regard to dopamine, sulfation mostly occurred at the 4-aromatic hydroxy group.We also investigated the effects of enzymatic sulfaction on pharmacologically active phenolic compounds. Sulfation of phenolic compounds generally led to inactivation (e.g. tyramine and Leu-enkephalin), with the exception of cholecystokinin (CCK) and some gastrointestinal peptides. Proteolytic hydrolysis in vitro did not occur at the C-terminal of the sulfated tyrosine residues of peptices such as Leu-enkephalin and kyotorphin. These results suggest that the sulfation by bacterial enzyme plays an important role in detoxification, activation and stability of phenolic compounds in the human body.

View full abstract

The pharmacokinetics of caffeine (CAF) and its metabolites, dimethylxanthines, were examined in horses administered 2.5 mg/kg of CAF intravenously (i.v.), intramusculary (i.m.), or orally (p.o.). The plasma samples were extracted by Extrelut^[○!R] and the concentrations of CAF and metabolites were determined by high performance liquid chromatography (HPLC) with a short column. The pharmacokinetics of CAF after bolus i.v. injection were described by the assumption of a two-compartment model, and those of CAF after i.m. or p.o. administration were done by the assumption of a one-compartment model. The biologic half lives of CAF were 15.5, 18.6, and 16.4 h after administering i.v., i.m. and p.o., respectively. The extent of the bioavailability of the p.o. administration was determined as 1.04 times the dose. The differences in pharmacokinetic parameters were not statistically significant among administration routes. A straight correlation existed between the logarithms of body weights of different species of animals and those of their biologic half lives of CAF. Therefore, the biologic half life of CAF in an animal might be predictable as a function of its body weight.

View full abstract

Irreversible bindings of cis-diamminedichloroplatinum(II) (cis-DDP) to human serum albumin (HSA) were investigated in a pH 7.4 buffer containing 0.1 M NaCl at various molar ratios (cis-DDP/HSA) up to 60 over a 14 d period (37°C). The metal binding seemed to reach a plateau when incubated at less than 10 times excess of cis-DDP. As the molar ration increased, the reaction rate was relatively fast within the first day, followed by a moderate increase in the metal binding. When incubated at 60 times excess of cis-DDP, the metal bound as mush as 20 mol per mol of HSA in 14 d. Fluorescence quenching of the metal-bound protein suggested that the tryptophan residue was gradually exposed to a hydrophilic environment as the metal binding increased. Furthermore, cis-DDP cleaved disulfide bonds at the ratio of 1 mol of disulfide bond per 5.3 mol of the metal binding. It was therefore suggested that the metal binding also occurred at several sites other than the disulfide bond. Warfarin binding to the metal-bound protein, examined by fluorescence changes, also decreased with increasing metal binding or cleavage of the disulfide bonds. Thus, cis-DDP bound to multiple sites in addition to the lone sulfhydryl group (Cys-34), suggesting that massive conformational changes of the protein took place.

View full abstract

The absorption of two kinds of insulin (from porcine or bovine pancreas) from the rectum of rabbits after the administration of hollow-type suppositories containing insulin and glyceryl-1-monooctanoate (GMO) as an absorption-enhancing agent was investigated. Two types of suppositories were employed : type I containing insulin in an aqueous solution (approx. 25 IU/mg/100 μl citric buffer solution at pH 3.0) in the cavity of the suppository and GMO mixed with a base material (Witepsol H-15), and type II containing insulin in a crystalline form in the same amount as in type I. Without GMO, the insulin and glucose levels in plasma were unchanged, whereas a marked increase in the plasma levels of insulin and a decrease of glucose concentrations were found following coadministration of insulin and GMO by the type I suppository. Similar enhancement of rectal absorption of insulin was obtained from porcine and bovine sources. In the case of the crystalline insulin, despite the use of the same amount of GMO, porcine insulin was more efficiently absorbed than bovine insulin by the type II suppository. GMO enhances the absorption of insulin in an aqueous solution or a crystalline form, and the dissolution rate of insulin may be an important factor in the rectal absorption of insulin.

View full abstract

Solid dispersions of four benzodiazepins, nitrazepam (NZP), nimetazepam (NMP), diazepam (DZP) and medazepam (MZP), with phosphatidylcholine (PC) were prepared to investigate the effect of functional groups of benzodiazepins. These benzodiazepins were present in an amorphous state immediately after preparation of the solid dispersion. The limit mole fractions for the amorphous state were 0.50 (NZP), 0.25 (NMP), 0.25-0.40 (DZP) and 0.25 (MZP). Infrared spectra and thermal analysis suggested an interaction, probably a hydrogen bond, between PC and NZP. In contrast, no interaction was suggested between PC and NMP, DZP or MZP, because they have no functional donor groups for the hydrogen bond. NZP solid dispersion showed no change after 1 year, but NMP, DZP and MZP solid dispersion showed recrystallization of drugs after 1 year. Thus, it was considered that some interaction between PC and the drug was needed to prevent the recrystallization. Dissolution of NZP in pH 7.0 phosphate buffer solution was much faster from NZP solid dispersion than from NZP crystals, and there was no aging effect of the solid dispersion. Dissolution of DZP also improved with the formation of a solid dispersion, but the dissolution rate became slower with time.

View full abstract

The alkaline hydrolysis of several powdered methacryloyl polymeric prodrugs (1P-3P) prepared by mechanochemical polymerization, each of which contains acetaminophen (1), 7-theophyllineacetic acid (2) and 5-fluorouracil (3) as a pendant drug group has been examined in a heterogeneous system on its comparison with that of the corresponding polymeric prodrugs prepared by conventional radial-initiated polymerizations. The rate of hydrolysis depended largely on the structural features of the polymer hydrolyzates; carboxyl groups are formed with the progress of hydrolysis of 1P and 3P so that the rate of hydrolysis is markedly lowered due to suppression of a subsequent nucleophilic attack of hydroxyl anions, and the reaction ceased before its completion. In contrast, the hydrolysis of 2P was completed within several hours and finally the suspended powders had been completely solubilized, since non-acidic hydroxylethyl groups are formed as a polymer hydrolyzate. Thus, the kinetics for hydrolysis of 2P was shown to be well correlated with the powder dissolution rate, which is known as the Hixson-Crowell cube root law. It has also been observed that the rate of hydrolysis of 1Pm was higher than that of 1Pr. This fact has been ascribed to the difference in the stereochemical configuration (tacticity) of the polymer main chain between 1Pm and 1Pr, where m and r denote mechanochemical and radical-initiated, respectively.

View full abstract

The crystal structure of trans-dichlorodimethylsulfoxide-Tenonitrozole (synthesized from cis-PtCl₂(DMS)₂ and tenonitrozole in methanol) was determinated by X-ray analysis.

View full abstract

A solvent effect in the oxygenation reactions of cis-stilbene in the mixed solvents, MeCN-C₆H₆, MeCN-CCl₄, and MeCN-CH₂Cl₂, catalyzed by a non-porphyrin iron(II) complex Fe(MeCN)₆·(ClO₄)₂ and tetraphenylporphinato iron(III) chloride, resulted in significant changes of the product ratio.

View full abstract

1, 1'-Carbonyldiimidazole (1) is a useful reagent for the preparation of arylacetonitriles (9) from 3-aryl-2-hydroxyiminopropionic acids (8), and 2, 2'-oxalyldi (o-sulfobenzimide) (2) can also be used for this purpose under essentially neutral conditions.

View full abstract

Two new pregnane glycosides, cynanformosides A and B, together with α-amyrin acetate, taraxerol, chrysoeriol, and isorhamnetin were isolated from the aerial part of Cynanchum formosanum. The structures of the new pregnane glycosides have been elucidated by spectroscopic and chemical methods.

View full abstract

The amino group at the 5-position on the 3H-1, 2, 3-triazolo[4, 5-d]pyrimidine (triazolopyrimidine) ring was converted into a halogen atom by treatment with isopentyl nitrite in halomethanes in satisfactory yields.The 5-halotriazolopyrimidines not having a substituent at the 7-position reacted with butyllithium to give 7-butyl-6, 7-dihydro-3-phenyl-3H-1, 2, 3-triazolo[4, 5-d]pyrimidines by addition of butyllithium across the C⁷, N⁶-double bond. In the case of the 7-substituted 5-halotriazolopyrimidines, the halogen-metal exchange reaction proceeded and the resultant 5-lithio compound reacted with electrophiles to give the 5-substituted triazolopyrimidines.

View full abstract

(R)-6-Hydroxy-7-isopropyl-3-(3-methoxypropyl)-3, 4-dimethylnaphtho[2, 3-b]furan-2(3H)-one (3), prepared from (+)-dehydroabietic acid (2), was converted into (R)-9-acetoxy-6-benzoyloxy-7-isopropyl-3-(3-methoxypropyl)-3, 4-dimethylnaphtho[2, 3-b]furan-2, 5, 8(3H)-trione (10) and its 9-acetyl compound (11) by a series of reactions : sodium borohydride reduction, acetylation, alkaline hydrolysis, benzoyl peroxide oxidation, Jones oxidation, and m-chloroperbenzoic acid oxidation. The trione 10 was further transformed into (R)-5, 6, 8, 9-tetraacetoxy-7-isopropyl-3-(3-methoxypropyl)-3, 4-dimethylnaphtho[2, 3-b]furan-2(3H)-one (15) by alkaline hydrolysis and reductive acetylation. Since the conversion of 15 into coleon A (1) has already been reported, the present work can be regarded as a new formal synthesis of coleon A.

View full abstract

Three new glycosidic antibiotics, glykenin (GK)-III A, B, and C (2a-c), were isolated as a mixture from a strain of Basidiomycetes sp. and identified as glycosides of C₂₆-fatty acids and a diacetylated trisaccharide composed of glucose and two xyloses. The locations of the two acetyl groups were elucidated by secondary ion mass spectrometry (SIMS), double quantum filter (DQF), and relayed chemical shift correlation spectroscopy (COSY) spectral analysis.

View full abstract