Biological properties of new acyl derivatives of tylosin

The antibacterial activity of acyl derivatives of tylosin were examined in vitro and in vivo. The 4"-acyl group in the acylated tylosins enhanced the antibacterial activity and antimycoplasmal activity against some macrolide-resistant strains. The orally administered 3-acetyl-4" -isovaleryltylosin produced a higher blood level in mice and rabbits than tylosin and a good therapeutic effect on the infection of Staphylococcus aureus Smith in mice.

Synthesis of demethyl derivatives of istamycin A

4-N,6'-N,3-O-Tridemethylistamycin A0 (9) and 6'N,3-O-didemethylistamycin A0 (15) were synthesized from 3,2',6'-tri-N-benzyloxycarbonyl-3',4'-dideoxyneamine 1,6-carbamate (1) through an aziridine derivative 6 by an analogous procedure employed in the total synthesis of istamycin A0 (19). Acylation of 15 with glycine at the 4-methylamino group gave 6'-N,3-O-didemethylistamycin A (18) having interesting activities especially against pseudomonas, but 4-N,6'-N,3-O-tridemethylistamycin A (12) derived from 9 showed only weak activity. Therefore, the 4-N-methyl group of istamycin A (20) is essential for the antimicrobial activity.

Biosynthesis of leupeptin. IV. Is protein turnover in leupeptin producer cells affected by leupeptin?

There was no significant difference between the rates of protein degradation in cells of a leupeptin-producing strain and that of a leupeptin-nonproducing strain, the latter being derived from the former by mutation. Protein autodigestion in a cell homogenate of the leupeptin producer was sensitive to EDTA and chymotrypsin and less sensitive to leupeptin. On the contrary, protein degradation caused by exogenous trypsin in a similar homogenate was highly sensitive to leupeptin. A labeling experiment with [14C]-arginine of a culture of the leupeptin producer strain revealed that leupeptin was accumulated mostly in the medium and only slightly in the cells; the ratio between the amount in the medium and that in the cells was about 250:1. In contrast, leupeptin acid, the proximal intermediate having no antiplasmin activity, showed a ratio of 5:1.

Microbial conversion of anthracyclinones to daunomycin by blocked mutants of Streptomyces coeruleorubidus

Baumycin-negative mutants of Streptomyces coeruleorubidus ME130-A4 do not convert daunomycinone to daunomycin and baumycins. They biosynthesize daunomycin from aklavinone and epsilon-rhodomycinone, indicating the glycosidation of the aglycone before the synthesis of daunomycinone. The biosynthetic pathway from epsilon-rhodomycinone to daunomycin was further confirmed by studying the bioconversion of anthracyclinones and anthracyclines, which are presumed to be intermediates.

Microbial conversion of epsilon-pyrromycinone and epsilon-isorhodomycinone to 1-hydroxy-13-dihydrodaunomcyin and N-formyl-1-hydroxy-13-dihydrodaunomycin and their bioactivities

New anthracycline antibiotics, 1-hydroxy-13-dihydrodaunomycin and N-formyl-1-hydroxy-13-dihydrodaunomycin were biosynthesized by a blocked mutant of Streptomyces coeruleorubidus ME130-A4 from epsilon-pyrromycinone or epsilon-isorhodomycinone.

Antitumor effect of bactobolin and its influence on mouse immune system and hematopoietic cells

Bactobolin prolonged survival period of mice bearing leukemia L-1210 in various dose schedules. The administration of bactobolin before or at time of immunization with sheep red blood cells (SRBC) did not affect antibody formation and delayed-type hypersensitivity (DTH) to SRBC. The administration after immunization suppressed antibody formation markedly but not DTH response. Bactobolin showed stronger suppressive action on antibody formation in vitro than mitomycin C. Bactobolin did not reduce establishment of tumor immunity which was mediated by T cells and macrophages. Comparing to other antitumor antibiotics which were effective against L-1210, bactobolin did not affect phagocytosis of mouse peritoneal macrophages. It has an extremely low toxicity to mouse spleen cells treated by concanavalin A (Con A) and lipopolysaccharide (LPS). It did not affect colony formation of mouse bone marrow cells in the presence of LPS-induced colony stimulating factor. The administration of bactobolin did not reduce the number of leucocytes in peripheral blood. From these results, the usefulness of bactobolin in the treatment of cancer was discussed.

Inhibition of tyrosine hydroxylase, a Fe(II)-stimulated monooxygenase, by bleomycin

Tyrosine hydroxylase was shown to be inhibited in vitro by bleomycin. At a concentration of 1 X 10(-4) M, copper-free BLM-A2 inhibited tyrosine hydroxylase activity by 50%, and all other bleomycins investigated including copper-bound BLM-A2 showed similar degrees of inhibition of tyrosine hydroxylase. The kinetic data have shown that the inhibition by BLM-A2 is competitive with a tetrahydropterin cofactor (6-methyl-tetrahydropterin) and uncompetitive with tyrosine. The inhibition of tyrosine hydroxylase by bleomycin was not reversed by Fe(II) or superoxide dismutase. These results suggest that the inhibition may be neither due to the chelating action of bleomycin with ferrous ion nor due to the production of superoxide and hydroxyl radicals by the formation of an oxygen-labile Fe(II)-bleomycin complex.

Biosynthesis of leupeptin. III. Isolation and properties of an enzyme synthesizing acetyl-L-leucine

An enzyme which catalyzes acetylation of L-leucine with acetyl-CoA was partially purified from a cell extract of Streptomyces roseus MA839-A1, a leupeptin producer. The molecular weight of this enzyme is about 27,000 daltons. The enzyme has fairly broad specificity for acyl donors (I) and acceptors (II): as for I, propionyl-CoA was 1/10 as active as acetyl-CoA with L-leucine as the acceptor; as for II, L-leucyl-D-leucine, L-leucyl-L-leucine, L-arginine, L-leucyl-L-leucyl-L-leucine, L-phenylalanine, L-methionine, L-leucine, glycyl-L-phenylalanine and L-valine were acetylated in the decreasing order, as opposed to no or slight reactivity of D-phenylalanine, D-leucine, L-histidine, glycine, L-proline and L-glutamic acid. The Michaelis constants of acetyl-CoA and L-leucine were about 5 X 10(-6) M and 6 X 10(-5) M, respectively. The enzyme is stimulated by Fe++. p-Chloromercuribenzoic acid (PCMB), N-ethylmaleimide, Mg++ and Mn++ were inhibitory. A leupeptin-nonproducing mutant, Streptomyces roseus MA839-A1 LN-S, derived from the producer strain by acriflavine treatment, also produced this enzyme.

Chemistry of bleomycin. XXVI. Biosynthetic study using 13C-enriched precursors

3-Morpholinopropylamino-bleomycin (MOP-BLM) was produced by the culture of Streptomyces verticillus ATCC 15003 grown in the presence of a 13C-enriched compound and 3-morpholinopropylamine in the medium, and the resulting MOP-BLM was analyzed by 13C-NMR spectrometry. In the spectrum of MOP-BLM produced by addition of 13C-methyl-L-methionine, the intensities of two signals assigned to the methyl carbon of the pyrimidine chromophore and of the 2-position of the 4-amino-3-hydroxy-2-methylpentanoic acid moiety were remarkably enhanced. When DL-alanine-3-13C was added, the signals emanated from the 5-methyl and 2-methine carbons of the 4-amino-3-hydroxy-2-methylpentanoic acid moiety were markedly enhanced. These results definitely indicate that the methyl group of the pyrimidine moiety originates from methionine-methyl group and the carbon skeleton of the pentanoic acid moiety is formed from alanine, acetate and methionine-methyl group. This study also revealed that the former assignment of the two signals from the two methyl carbons of the 4-amino-3-hydroxy-2-methylpentanoic acid moiety must be reversed.

Purification by affinity chromatography using amastatin and properties of aminopeptidase A from pig kidney

1. Amastatin, a specific inhibitor of aminopeptidase A (L-alpha-aspartyl(L-alpha-glutamyl)-peptide hydrolase, EC 3.4.11.7), was linked to an agarose matrix and by this affinity chromatography aminopeptidase A of pig kidneys was purified as a single protein shown by acrylamide gel electrophoresis. 2. Aminopeptidase A which was purified 710-fold, hydrolyzed only acidic amino acid beta-naphthylamide. The optimum pH and the optimum temperature was 7.5 and 45-50 degrees C, respectively. 3. The molecular weight was approx. 300 000 as determined by Sephadex G-200 gel filtration. 4. The activity of aminopeptidase A was not affected by sulfhydryl agents, S-S dissociating agents and serine proteinase inhibitor, but was inhibited strongly by metal chelating agents, and enhanced by alkaline earth metals. 5. Amastatin inhibited aminopeptidase A in a competitive manner with L-glutamic acid beta-naphthylamide, and the Ki value was calculated to be 2.5 x 10(-7) M. The inhibitory effect of amastatin on aminopeptidase A was not reversed by addition of Ca2+.

Antitumor effect of a new antibiotic, neothramycin

A new anthramycin-group antitumor antibiotic, neothramycin, isolated from a Streptomyces culture, showed activity against experimental tumors such as lymphocytic leukemia P388 ascites sarcoma-180, hepatoma AH130, Walker carcinosarcoma-256 and mouse mammary adenocarcinoma (CCMT). In particular, the tumor growth inhibition ratio was as high as 96% when neothramycin was injected intraperitoneally at a daily dose of 2 mg/kg into Wistar strain rats previously inoculated with Walker carcinosarcoma-256 by the subcutaneous route. Successive intraperitoneal injections of the compound were more effective than a single injection with the P388 system.

Mitogenic effect of bestatin on lymphocytes

The incorporation of 3H-thymidine into the acid insoluble fraction of spleen cells was increased intraperitoneal injection of 10 microgram bestatin/mouse. Bestatin (0.01, 0.1, 1.0 microgram/ml) which was added to mouse spleen cell culture increased 3H-thymidine incorporation into lymphocytes, but 10 microgram/ml did not. This mitogenic action of bestatin was not observed when adherent cells were removed or T cells were destroyed, suggesting that bestatin causes the proliferate T cells probably through the activation of macrophages. Bestatin given to mice did not modulate mitogenicity of lectins. Bestatin treatment of human peripheral buffy coat cells increased 3H-thymidine incorporation into lymphocytes. The addition of bestatin at a high concentration such as 100 microgram/ml to mouse spleen cell cultures exhibited a high mitogenic effect on B cells in preference to T cells but this effect was not seen with bestatin at 50 microgram/ml. In this case, the mitogenicity of Con A or LPS was expanded and antibody formation to SRBC in spleen cell cultures were also stimulated.

Effect of bestatin on mouse immune system and experimental murine tumors

Effect of bestatin on the establishment of delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) and oxazolone was examined in normal and immunity-impaired mice. Administration of a low dose of bestatin (0.1 approximately 100 microgram/mouse) augmented DTH to SRBC and restored their impaired DTH to oxazolone. The effect of bestatin in the mouse was age-dependent. Bestatin retarded the growth of slow growing solid tumors of Gardner lymphosarcoma and IMC carcinoma and the effect was influenced by the time of the administration and the number of cells inoculated. Bestatin enhanced the antitumor action of the antitumor antibiotics, bleomycin and adriamycin. Bestatin also retarded the induction of skin cancer by 20-methylcholanthrene.

Inhibition of dopamine-beta-hydroxylase, A copper enzyme, by bleomycin

Bleomycin was found to be one of the most potent inhibitors of dopamine-beta-hydroxylase. Bleomycin-A2 at 8 X 10(-8) M inhibited the enzyme activity by 50%. Kinetic studies showed that the inhibition by bleomycin-A2 was of the competitive type with both the substrate and the cofactor, ascorbate, and was not affected by fumarate, a stimulator for the enzyme. The inhibition mechanism is possibly due to chelating action of bleomycin toward the copper atom at the active site of the enzyme together with some other kinds of binding, for the addition of the cupric ions or extensive dialysis completely reversed the inhibition and bleomycin Cu(II)-complex did not inhibit the enzyme.

Kinetics of the reaction of bleomycin-Fe(II)-O2 complex with DNA

The kinetics of the reaction of BLM-Fe(II)-O2 with DNA in the absence or presence of 2-mercaptoethanol (2-ME) were studied. The total number of bases released by BLM-Fe(II)-O2 in the presence of 2-ME increased about 6.5 times more than that in the absence of 2-ME in the reaction of 6 hours at 37 degrees C. The molar ratios of the released bases ware little affected by the reaction time, temperature or 2-ME. Among the four bases, thymine was preferentially released. On the basis of a reaction scheme of BLM-Fe(II)-O2 with DNA, the equations were derived by the steady-state method. In the absence of 2-ME, the release of bases from DNA was dependent on the concentration of BLM-Fe(II)-O2, but independent of the concentration of DNA. In the presence of 2-ME, a biphasic reaction was observed; the first one is due to BLM-Fe(II) which originally existed and the second one is due to BLM-Fe(II) produced by the reduction of BLM-Fe(III) with 2-ME. In the second reaction, the rate of the release of bases from DNA was proportional to the concentration of BLM-Fe(II) and 2-ME, but inversely proportional to the concentration of DNA. The rate-determining step in the reaction of BLM-Fe(II)-O2 with DNA in the presence of 2-ME was found to be the reduction of BLM-Fe(III) to BLM-Fe(II). By these kinetic studies, the reaction of BLM-Fe(II)-O2 with DNA in the presence of 2-ME was elucidated to proceed in a catalytic fashion. Furthermore, the maximum number of bases released by BLM from DNA was one base per twelve to thirteen bases.

Chemical modification of the ester group of diketocoriolin B

5,8-Di-O-tetrahydropyranylcoriolin B (2) was synthesized and its two expoxide groups were found to be resistant to alkaline hydrolysis to give di-O-tetrahydropyranldihydrocoriolin (3). Acylation or alkylation of the free hydroxyl group at C-1 of 3 followed by hydrolysis of the tetrahydropyranylether groups and oxidation of the hydroxyl groups at C-5 and C-8 afforded a numer of 1-O-acyl or alkyl analogs of diketocoriolin B. All of them showed antibacterial and antitumor activities.

Syntheses of corliolin, 1-deoxy-1-ketocoriolin and 1,8-dideoxy-1,8-diketocoriolin from coriolin B

Hydrolysis of 5,8-di-O-tetrahydropyranyl-5-deoxo-5-hydroxycoriolin which was prepared from coriolin B, followed by oxidation of the hydroxy groups at C-5, or C-1 and C-5, or C-1, C-5 and C-8 afforded coriolin (2), 1-deoxy-1-ketocoriolin (3) and 1,8-dideoxy-1,8-diketocoriolin (4). All three ketones were found to have antitumor activity, whereas antibacterial activity was observed in 2 and 3 but not in 4.

Effects of a new adenosine deaminase inhibitor, isocoformycin, on toxicity, antitumor activity and tissue distribution of formycin A and 9-beta-D-arabinofuranosyladenine

Single intraperitoneal and intravenous injections of isocoformycin at 1,200 mg/kg did not cause the death of mice. Isocoformycin which inhibited adenosine deaminase enhanced significantly the toxicity of formycin A and ara-A at various combination ratios. Isocoformycin potentiated antitumor activity of formycin A and ara-A against L1210 leukemia. Formycin A and ara-A disappeared rapidly from the blood and tissues and could not be found in any tissues even 0.5 hour after a single intraperitoneal injection. However, when used in combination with isocoformycin both were detected in the blood and tissues, especially at high concentration in liver and kidney. These indicate that the deamination of formycin A and ara-A is blocked by isocoformycin in vivo.

Current status of Japanese studies with the new anthracycline antibiotic aclacinomycin A

Fundamental and clinical studies on a new yellow anthracycline antibiotic aclacinomycin A are reviewed. Favorable responses were seen in patients with acute leukemia refractory to daunomycin and adriamycin, malignant lymphoma, and breast, ovarian, lung, gastric, intestinal, and urinary bladder cancers by intravenous and intraperitoneal infusions or bladder instillation of aclacinomycin A alone in the phase II study.