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H Tone

Publications and source records attributed to H Tone.

At least 37 records · Page 2Linked to original sources
PubMed1993

Microbial glycosidation of some anthracycline antibiotics by an antibiotic-negative mutant of aclarubicin producer.

Microbial conversion of anthracyclinone monosaccharides using aclarubicin-negative mutant of Streptomyces galilaeus was found to produce anthracyclinone disaccharides which had either rhodinose or 2-deoxyfucose as an additional sugar. By this conversion we obtained twelve new anthracyclines from seven anthracyclines which had rhodosamine, N-monomethyldaunosamine or daunosamine at C-7 as a glycosidic sugar. All products had a reduced cytotoxic activity in comparison with those of parent compounds. However, some of them showed a therapeutically improved antitumor effects against L1210 leukemia in vivo.

Aclarubicin↗
PubMed1992

A possible mechanism of endothelium-dependent relaxation induced by pirarubicin and carbachol in rat isolated aorta.

The mechanism of endothelium-dependent relaxation induced by pirarubicin, (2''R)-4'-O-tetrahydropyranyladriamycin, THP, or carbachol was investigated in the rat isolated aorta. The relaxant effect of THP (1.5 x 10(-6)-4.5 x 10(-5) M) or carbachol (10(-8)-10(-4) M) on the aorta with endothelium was decreased by lowering Ca2+ in the medium. The relaxation induced by THP was not inhibited by pretreatment with verapamil (10(-6)-10(-5) M), and that induced by carbachol was only partially inhibited. However, on replacement of all but 20 mM Na+ with either Li+ or choline, the THP- or carbachol-induced relaxation was inhibited. Furthermore, the relaxing effect of THP or carbachol was inhibited by pretreatment with amiloride (10(-4)-3 x 10(-4) M), with ouabain (10(-4)-10(-3) M), or with K(+)-depletion. These results suggest that the THP- or carbachol-induced relaxation depending on endothelium was affected by modifying the calcium ion concentration, and that a Na(+)-Ca2+ exchange process is involved.

Amiloride↗
PubMed1992

Production of new anthracycline antibiotics 1-hydroxy-oxaunomycin and 6-deoxyoxaunomycin by limited biosynthetic conversion using a daunorubicin-negative mutant.

A limited biosynthetic conversion of some known anthracyclinones using a specific daunorubicin-nonproducing mutant provided four new anthracycline antibiotics: 1-Hydroxy-10-methoxycarbonyl-13-deoxocarminomycin; 1-hydroxy-13-deoxocarminomycin; 1-hydroxyoxaunomycin and 6-deoxyoxaunomycin. Their isolation and purification from bioconversion broth, structural determination and antitumor activities against leukemic L1210 cells are described.

Animals↗
PubMed1992

Photochemically obtained N-demethyl derivatives of anthracyclines.

New N-monodemethyl and N-didemethyl derivatives were obtained from seven N-dimethylamino sugar (rhodosamine)-containing anthracyclines by photochemical reaction and their in vitro bioactivities against L1210 cell culture were compared with those of their N-dimethyl parent compounds. N-Demethyl derivatives obtained from betaclamycin T (7-O-rhodosaminyl-beta-rhodomycinone) were much more cytotoxic while those from the other six antibiotics were rather less active as compared with their parent compounds. The N-demethylation also gave a considerably greater decrease in the inhibitory activity on RNA synthesis as compared to DNA synthesis, so that the N-demethyl derivatives showed smaller IC50 ratios on DNA/RNA than their parent compounds.

Animals↗
PubMed1992

Production of new anthracycline antibiotics by microbial 4-O-methylation using a specific daunorubicin-negative mutant.

Microbial 4-O-methylation using a specific daunorubicin-blocked, nonproducing mutant provided the new anthracycline antibiotics 4-O-methylbetaclamycin T, 4-O-methylyellamycin A and 4-O-methyl-13-hydroxyoxaunomycin, from which 4-O-methyloxaunomycin and 4-O-methyl-6-deoxyoxaunomycin were then prepared by further photochemical N-demethylation. Antitumor activities in vitro and in vivo against L1210 cells were compared with those of their 4-O-demethyl derivatives. It was found that all the 4-O-methyl derivatives had a markedly reduced cytotoxicity in vitro as compared with the 4-O-demethyl compounds. However, some of them were endowed with a significantly improved antitumor activity in vivo.

Animals↗
PubMed1991

Effects of pirarubicin, an antitumor antibiotic, on the cardiovascular system.

In the present study we examined the effects of pirarubicin [(2"R)-4'-O-tetrahydropyranyladriamycin, THP] on a cardiovascular system. An injection of THP (0.39-3.13 mg/kg, i.v.) reduced the mean blood pressure and caused an increase in the respiratory air rate in anesthetized rats. At 1.5 x 10(-6)-1.5 x 10(-5) M, THP markedly relaxed a contraction induced by 10(-7) M norepinephrine in rat aorta with endothelium but not in that without endothelium. At a dose of 0.02-0.5 mg, THP produced an increase in the contractile force and the perfusion flow of isolated perfused guinea pig hearts. At a higher concentration (4.5 x 10(-5)-1.5 x 10(-4) M), it produced a slight increase in the contractile force of the left atria in guinea pigs. This positive inotropic action of THP was inhibited by diphenhydramine (10(-6)-5 x 10(-5) M), chlorpheniramine (3 x 10(-7)-3 x 10(-5) M), and tripelennamine (3 x 10(-7)-3 x 10(-5) M) but not by propranolol (10(-6) M), cimetidine (10(-5) M), diltiazem (10(-6) M), or ryanodine (10(-8) M). THP given i.v. at 2.5 mg/kg elevated the plasma histamine level in anesthetized dogs. From these data, we conclude that THP mainly relaxed the rat aorta in the presence of endothelium and that at higher concentrations, it increased the contractile force in the cardiac muscle, probably mediated through the release of histamine.

Animals↗
PubMed1991

Pirarubicin-induced endothelium-dependent relaxation in rat isolated aorta.

The mechanism of relaxation produced by pirarubicin [(2"R)-4'-O-tetrahydropyranyladriamycin, THP] has been studied in rat isolated aorta. THP (1.5 x 10(-6)-4.5 x 10(-5) M) markedly relaxed contractions induced by noradrenaline (10(-7) M) in the aorta with endothelium, but not in that without endothelium. The relaxation induced by 1.5 x 10(-5) M THP was inhibited by methylene blue (5 x 10(-6) M), hydroquinone (10(-4) M), phenidone (5 x 10(-5) M), haemoglobin (10(-6) M) and p-bromophenacyl bromide (5 x 10(-5) M), but not by indomethacin (2.5 x 10(-5) M). The relaxation induced by THP (1.5 x 10(-7) -4.5 x 10(-5) M) was inhibited by NG-nitro-L-arginine (10(-5) M), but enhanced by superoxide dismutase (10 units mL-1) or by L-arginine (10(-2) M). However, the THP-induced relaxation was not inhibited by various receptor antagonists such as atropine (10(-6) M), cimetidine (10(-5) M), diphenhydramine (3 x 10(-6) M) and [D-Pro4, D-Trp7,9,10]-substance P(4-11) (1.5 x 10(-6) M). In fifteen anthracycline analogues, THP and 13-dihydropirarubicin (both with a tetrahydropyranyl group) produced endothelium-dependent relaxations. These results suggest that the THP-induced relaxation which is probably mediated by endothelium-derived relaxing factor (EDRF) was not produced by an activation of muscarine, histamine H1 or H2, or substance P receptor, and further that the tetrahydropyranyl group must play an important role in the THP-induced relaxation.

Animals↗
PubMed1991

Kinetic analysis of dehydropeptidase-I and comparative in vitro and in vivo stabilities of PS-5 derivatives modified at the C-3 side chain.

With partially purified kidney dehydropeptidase-I (DHP-I) preparations, the hydrolysis kinetics of glycyldehydrophenylalanine (Gly-dPh) by DHP-I were found to be completely non-Michaelian, whereas those of PS-5 and imipenem were composed of at least two-phase reactions which were also observed using Bacillus cereus type II beta-lactamase. Thus the DHP-I stabilities of 34 PS-5 carbapenem derivatives which were synthesized by chemical modification at the C-3 side chain of PS-5 were examined in vitro using fresh mouse, dog and human DHP-I preparations, and are tentatively expressed in reference to the DHP-I stabilities of PS-5. The in vitro DHP-I stability of PS-5 was significantly improved by introduction of basic side chains and cysteines at C-3. More particularly, the D-cysteinyl side chain was more stable relative to DHP-I than the L-cysteinyl. In vivo, however, the degree of improvement of the DHP-I-stability by chemical modification at C-3 was not sufficient enough to establish therapeutically effective levels of serum concentrations and urinary recoveries of the carbapenem derivatives after parenteral administration.

Animals↗
PubMed1989

Sequencing and high expression of aminopeptidase P gene from Escherichia coli HB101.

A plasmid pAPP1 with a 4 kbp insert at the PstI site of pBR322, encoding aminopeptidase P gene of Escherichia coli HB101 (Yoshimoto et al. (1988) J. Biochem. 104, 730-734), was subcloned into pUC18 and pUC19. The transformant of E. coli JM83 harboring pAPP4 with a 1.9 kbp fragment showed more than 50-fold higher enzyme activity than that of the host, after cultivation at 37 degrees C for 40 h in LB-medium containing ampicillin. When the gene DNA was inserted reversely in pAPP4, the enzyme productivity decreased markedly. The whole nucleotide sequence of the inserted fragment of plasmid pAPP4 was clarified by the dideoxy chain-terminating method. Within this sequence, the mature enzyme protein-encoding sequence was found to start just after an ATG codon, as judged by comparison with amino-terminal protein sequencing. Eleven bases upstream from the proposed initiation codon was an AGGAGA sequence which seemed to be a ribosome binding site. Thirty-four bases upstream from the proposed start codon was the 6-base sequence TACAAA, the so-called -10 region or Pribnow box. Further, the 6-base sequence TTTACT around 77 bases upstream from the start codon was deduced to be a putative -35 region consensus sequence. The inverted repeat at 1334 was tentatively assumed to be a terminator. The molecular weight of the enzyme was estimated to be 49,650 from the nucleotide sequence. The purified enzyme contained 0.2 gram atom of zinc per subunit. The enzyme activity was inhibited by EDTA and activated 5-fold by Mn2+.

Amino Acid Sequence↗
PubMed1988

Cloning and expression of subtilisin amylosacchariticus gene.

The gene encoding subtilisin Amylosacchariticus from Bacillus subtilis var. amylosacchariticus was isolated and the entire nucleotide sequence of the coding sequence was determined. The deduced amino acid sequence revealed an N-terminal signal peptide and pro-peptide of 106 residues followed by the mature protein comprising 275 residues. There were discrepancies in 10 amino acids between the sequence elucidated from the nucleotide sequence and the published protein sequence (Kurihara et al. (1972) J. Biol. Chem. 247, 5619-5631). The nucleotide sequence was highly homologous to that of subtilisin E gene from B. subtilis 168, with discrepancies at 12 nucleotides out of 1,426 nucleotides we sequenced. Ten of them were found in mature subtilisin coding sequence, which resulted in two amino acid changes and another one was in the putative promoter region between two genes. The productivity of subtilisin in culture broth of B. subtilis var. amylosacchariticus was much higher than that of B. subtilis 168. The enzyme gene was inserted in a shuttle vector pHY300PLK, with which B. subtilis ISW1214 was transformed. The proteolytic activity found in the culture broth of the transformed bacterium was 20- and 4-fold higher than those of the host strain and B. subtilis var. amylosacchariticus, respectively. Subtilisin Amylosacchariticus was easily purified to a crystalline form from culture filtrate of cloned B. subtilis, after a single step of chromatography on CM-cellulose.

Amino Acid Sequence↗
PubMed1988

Cloning and expression of aminopeptidase P gene from Escherichia coli HB101 and characterization of expressed enzyme.

The aminopeptidase P gene in Escherichia coli HB101 was cloned into the plasmid pBR322. Introduction of the hybrid plasmid, pAPP01, into the E. coli DH1 resulted in an 8-fold increase of aminopeptidase P activity as compared with that of the host. The enzyme was purified by series of chromatographies on DEAE-Sephadex, QAE-Sephadex, and hydroxyapatite. The purified enzyme was homogeneous as judged by disc-gel and SDS-gel electrophoreses. the enzyme was inhibited strongly by EDTA and slightly by p-chloromercuribenzoate, but was not affected by diisopropyl phosphorofluoridate, E-64, or iodoacetic acid. The optimum pH of the enzyme was 8.5. The enzyme was stable at pH 8 to 9. After incubation for 30 min at pH 8.0, 50% remaining activity was observed at 50 degrees C. The enzyme was activated 3-fold by the addition of 5 microM Mn2+. The molecular weight of the enzyme was estimated to be 50,000 and 200,000 by SDS-PAGE and gel filtration, respectively. The amino terminal amino acid was identified to be serine by Edman degradation, indicating that the enzyme is composed of a homo-tetramer. The enzyme hydrolyzed X-Pro bonds (X = amino acid) of peptides. These characteristics suggest that cloned aminopeptidase P is identical to APP-II reported by Yoshimoto et al. (Agric. Biol. Chem. 52(8), in press (1988].

Amino Acid Sequence↗
PubMed1986

Pharmacokinetics of doxorubicin, (2"R)-4'-O-tetrahydropyranyl-adriamycin and aclarubicin.

The following paragraphs summarize the properties of ADR, THP and ACR in terms of their pharmacokinetics. The blood level of anthracyclines shows a three-phase function of decline: alpha, beta and gamma phases. Compared with other classes of anticancer agents, the anthracyclines are characterized by an extremely short T1/2(alpha) and an extremely long T1/2(gamma). These characteristics reflect the facts that anthracyclines are rapidly transferred to the tissues and that they are retained for a long time in the body. In comparison with ADR, the T1/2(alpha) of THP is relatively short and T1/2(alpha, beta and gamma) of ACR are also short. Anthracyclines show large values for K12 and K13, transfer rate constants of the drug from the blood to the tissues, and small values for K21 and K31 transfer rate constants of the drug from the tissues to the blood. This means that these drugs are rapidly transferred to the tissues, from which they are then slowly released. The order of magnitude of K12 and K13 was THP greater than ACR greater than ADR. The order for K21 and K31 was ACR greater than THP greater than ADR. Anthracyclines are also characterized by small distribution volumes (V1) in the blood circulation, and very large distribution volumes (V2 and V3) in the tissue compartments. The order of magnitude for V2 and V3 was THP greater than ADR greater than ACR. Anthracyclines achieved high concentrations in such thoracic and abdominal organs such as lung, heart, thymus, liver, kidney, spleen and digestive tract. ADR showed the highest levels in liver and kidney, while THP and ACR showed their highest concentrations in lung and spleen. A decrease in the drug concentration in various organs is slow in the case of ADR, while rapid in the cases of THP and ACR. Most of the distributed drug is the unchanged form with ADR, whereas metabolites are common with ACR. THP is partially converted to ADR in liver. Anthracyclines were usually excreted over a long period of time at a high rate in the bile and at a low rate in the urine. Orally-administered ACR showed considerably good absorption from the digestive tract. The metabolism of anthracyclines was carried out in vivo and resulted in the formation of bioactive glycoside metabolites and inactive aglycone metabolites.(ABSTRACT TRUNCATED AT 400 WORDS)

Aclarubicin↗
PubMed1986

[Toxicological studies on (2''R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic. Acute toxicity study in mice].

A new antitumor anthracycline antibiotic; (2''R)-4'-O-tetrahydropyranyladriamycin hydrochloride (THP) was administered to ddY mice via different routes for acute toxicity studies. The LD50 values were calculated from mortality rates during a 14-day observation period, and were 14-21 mg/kg when i.v., i.p. or s.c. route was used and 420-570 mg/kg when the drug was given p.o. Upon administration of the drug, mice showed depression of spontaneous activity, anorexia, diarrhea and slight alopecia. Autopsy of the mice killed by the drug revealed atrophy of thymus, spleen, testes, uterus and ovaries, and congestion and hemorrhage in the intestines. The mice which survived through the observation period, however, showed only atrophy of thymus and sexual organs.

Administration, Oral↗
PubMed1986

Toxicological studies on (2"R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic. Subacute toxicity study in rats.

(2"R)-4'-O-Tetrahydropyranyladriamycin X HCl (THP), a new anthracycline antitumor antibiotic, was administered to Sprague-Dawley rats intraperitoneally for 13 weeks. In rats receiving 0.4 mg/kg/day, piloerection, emaciation, loose feces and thickening of the injection site were evident, and 7 males and 2 females died after week 12. Inferior body weight gain was observed in both sexes starting week 4 approximately 6. The food consumption also decreased. Hematological examination revealed lower counts of total leucocyte and lymphocyte. At termination there were lower spleen, thymus and testes weights, thickening of the walls of the intestine and stomach, gastric ulceration, presence of ascitic fluid, and congestion and thickening at the injection site. Decreases in the lymphocyte populations of the thymus, spleen and lymph nodes were observed microscopically. A decrease in the number of hematopoietic cells in the bone marrow and a degeneration of the germinal epithelium in the testes were also seen, as were gastrointestinal disturbances. These treatment-related effects were mainly confined to rats receiving 0.4 mg/kg/day and to a lesser extent, to rats receiving 0.1 mg/kg/day. The effects on rats receiving 0.025 mg/kg/day were only at the microscopic level. No rats receiving 0.006 mg/kg/day were toxicologically affected.

Animals↗
PubMed1986

Toxicological studies on (2"R)-4'-tetrahydropyranyladriamycin, a new antitumor antibiotic. Chronic toxicity study in rats.

(2"R)-4'-O-Tetrahydropyranyladriamycin X HCl (THP), a new anthracycline antitumor antibiotic, was administered to Sprague-Dawley rats (each group 20 rats) intraperitoneally at dosages of 0.001, 0.008, 0.06 and 0.3 mg/kg/day for 53 weeks. Piloerection, loose feces or perianal staining and thin or emaciated build were observed from week 12 in rats receiving 0.06 or 0.3 mg/kg/day. All rats receiving 0.3 mg/kg/day and 3 males and 1 female receiving 0.06 mg/kg/day died or were prematurely sacrificed in the period from weeks 13 to 44. The overall food consumption and body weight gain of both sexes receiving 0.06 or 0.3 mg/kg/day were lower than those of the controls. Hematological examination showed low leucocyte counts, disturbance in neutrophil and lymphocyte number and low erythrocytic characteristics in animals receiving 0.06 or 0.3 mg/kg/day. At necropsy, macroscopic changes were found at the injection site, throughout the gastrointestinal tract and in the male reproductive system in rats receiving 0.06 or 0.3 mg/kg/day. Microscopic examination revealed decrease in the small lymphocyte population in the hematopoietic and lymphoid system in rats receiving 0.008 to 0.3 mg/kg/day. Degeneration of the germinal epithelium of the subcapsular tubules of the testes, gastric ulceration, epithelial adnexal atrophy of the skin and chronic cellulitis and necrosis at the injection sites were also observed. No rats receiving 0.001 mg/kg/day were affected in these respects.

Animals↗