| 6620728 |
On the inhibitory mechanism of bassianolide, a cyclodepsipeptide, in acetylcholine-induced contraction in guinea-pig taenia coli |
10.1254/jjp.33.573. |
Jpn J Pharmacol |
On the inhibitory mechanism of bassianolide, a cyclodepsipeptide, in acetylcholine-induced contraction in guinea-pig taenia coli
Abstract
- The effect of bassianolide (BASS), a cyclodepsipeptide, was investigated on mechanical response, membrane potential, intracellular Na and K contents and 45Ca uptake in response to acetylcholine (ACh) in guinea-pig taenia coli. BASS (10(-5) M) as well as verapamil (5 X 10(-7) M) and papaverine (3 X 10(-5) M) selectively inhibited the tonic component of the contraction induced by ACh (10(-5) M), but scarcely affected the phasic one. In contrast, atropine (3 X 10(-8) M) inhibited both components of contraction. BASS did not modify the change in membrane potential by ACh. BASS, ACh and the combination of both did not influence the intracellular Na and K contents and the 45Ca uptake. These data show that BASS seems unlikely to have the property of an ionophore. BASS slightly inhibited both the tonic and phasic components of contraction induced by 60 mM K in a non-selective manner, though verapamil and papaverine inhibited the tonic component more potently than the phasic one. Verapamil decreased the increased 45Ca uptake in the muscle soaked in 60 mM K medium, but BASS did not. Since BASS selectively inhibits the tonic component of the ACh-induced contraction, the inhibitory mechanism of BASS seems to be different from that of verapamil, papaverine or atropine; and the mechanism may be beyond the interactions with a binding activity of ACh to the muscarinic receptor, membrane potential and the contractile machinery of the intestinal smooth muscle.
|
| 6625543 |
Sporulation in Bacillus licheniformis during altered bacitracin synthesis |
None |
Antibiotiki |
Sporulation in Bacillus licheniformis during altered bacitracin synthesis
Abstract
- Sporulation in different strains of Bacillus licheniformis, 10716 and 1001 in connection with changes in synthesis of bacitracin was studied. It was shown that the sporulation efficiency did not depend on the synthesis of the antibiotic: in some strains with low potency for the antibiotic production, the sporulation level was lowered, while in the others, it was not lowered. Moreover, normal sporulation was also observed, when the synthesis of bacitracin was inhibited. Therefore, it is suggested that there is no correlation between the sporulation and antibiotic production.
|
| 6630058 |
The revised structure of bottromycin A2 |
10.7164/antibiotics.36.1076. |
J Antibiot (Tokyo) |
The revised structure of bottromycin A2
Abstract
|
| 6644590 |
Microbial transformations of natural antitumor agents XXII: Conversion of bouvardin to O-desmethylbouvardin and bouvardin catechol |
10.1002/jps.2600721114. |
J Pharm Sci |
Microbial transformations of natural antitumor agents XXII: Conversion of bouvardin to O-desmethylbouvardin and bouvardin catechol
Abstract
- Bouvardin is a cyclic hexapeptide antitumor agent which undergoes two major microbial transformation reactions. Screening with 220 cultures revealed 17 different strains capable of producing O-desmethylbouvardin in good yield. O-Desmethylbouvardin was isolated and characterized from preparative scale incubations with Streptomyces rutgersensis NRRL B-1256. Four aspergilli and one streptomycete formed bouvardin catechol when O-desmethylbouvardin was used as substrate. Bouvardin catechol was isolated and characterized from a preparative scale incubation with Aspergillus ochraceous UI 398.
|
| 6654601 |
Role of the carboxamide groups of the asparagine and glycinamide residues of oxytocin. Syntheses and biological properties of 5-beta-cyanoalanine oxytocin and 9-alpha-aminoacetonitrile oxytocin |
10.1111/j.1399-3011.1983.tb02125.x. |
Int J Pept Protein Res |
Role of the carboxamide groups of the asparagine and glycinamide residues of oxytocin. Syntheses and biological properties of 5-beta-cyanoalanine oxytocin and 9-alpha-aminoacetonitrile oxytocin
Abstract
- In an attempt to see whether the C=O and the NH2 of CONH2 of asparagine5 and glycinamide9 are both essential for biological activity, 5-beta-cyanoalanine oxytocin and 9-alpha-aminoacetonitrile oxytocin have been synthesized. Each of these analogs contains a nitrile group in place of the carboxamide group of Asn5 and GlyNH92 respectively; the nitrile group can simulate the carbonyl portion of the carboxamide, but lacks the hydrogen-bond donating capacity of its NH2 portion. Substitution of a nitrile group produced opposite biological effects in the 5 and the 9 positions; the 5-substituted analog showed very low activities (less than 3% of those of oxytocin) while the 9-substituted analog showed extremely high activities (with an in vivo uterine activity of 906 U/mg almost twice that of oxytocin). The results clearly suggest that the mechanisms of interaction of the carboxamide groups with the receptor sites are different for residues 5 and 9.
|
| 6661504 |
Cytotoxicity of cyclodepsipeptides on murine lymphocytes and on L 1210 leukemia cells |
None |
Biomed Pharmacother |
Cytotoxicity of cyclodepsipeptides on murine lymphocytes and on L 1210 leukemia cells
Abstract
- By in vitro experiments we have demonstrated an important cytotoxic effect of destruxins A, A2, B, B1 and E on L 1210 leukemia cells. This cytotoxic effect was measured by DNA synthesis. The cytotoxic effect on normal mouse spleen lymphocytes was also evaluated. For the most cytotoxic compound, destruxin E, 16 mg/kg was found to be the minimal dose necessary to kill all mice.
|
| 6686819 |
Amanita virosa peptides: viroidin and viroisin are more effective than phalloidin for the in vitro protection of actin against the effects of osmic acid |
None |
Eur J Cell Biol |
Amanita virosa peptides: viroidin and viroisin are more effective than phalloidin for the in vitro protection of actin against the effects of osmic acid
Abstract
- Virotoxins are a group of monocyclic peptides recently identified in the deadly mushroom Amanita virosa by Faulstich and coll. We found that two of these peptides, which have a methyl sulfonyl group, namely viroidin and viroisin are very effective to protect F-actin against oxidative degradation by osmium tetroxide in vitro. Their desoxo analogs, which have a methyl sulfoxyde group instead of methyl sulfonyl are less active, therefore there exists a relationship between the chemistry of the sulfur group and the activity of the peptides.
|
| 6688782 |
Antinociceptive effect of centrally administered cyclo(N-methyl-L-Tyr-L-Arg) in the rat |
10.1016/0014-2999(83)90024-9. |
Eur J Pharmacol |
Antinociceptive effect of centrally administered cyclo(N-methyl-L-Tyr-L-Arg) in the rat
Abstract
- The tail-flick test was used to test cyclo(N-methyl-L-Tyr-L-Arg) (C.NMTA), kyotorphin (L-Tyr-L-Arg) and morphine for antinociceptive effects following injection into the cerebroventricles (lateral ventricle (VL), third ventricle (V3) and fourth ventricle (V4)) and into the spinal subarachnoid space in the rat. When injected into the VL, V3 and V4, but not into the spinal subarachnoid space, C.NMTA produced a dose-dependent inhibition of the tail-flick response to thermal stimulation. The ED50 values for each site were 61.0 (48.0-77.5), 40.0 (27.4-58.4) and 163.0 (86.7-306.4) nmol/rat, respectively. Behavioral sedation was seen when C.NMTA was injected into the VL, V3 and V4, but not into the spinal subarachnoid space. Kyotorphin was without antinociceptive effect when given by all routes. However, weak sedation was seen after injection into the cerebroventricles. Naloxone (2, 4 and 20 mg/kg), an opiate antagonist, injected intraperitoneally (i.p.) 20 min before C.NMTA injection, did not significantly alter the C.NMTA-induced antinociceptive effect. Additionally, naloxone (2, 4 and 20 mg/kg i.p.) did not abolish the sedative effect of this peptide. It is suggested that C.NMTA produced a naloxone-resistant antinociceptive effect mainly on the upper brain stem.
|
| 6689517 |
Monte Carlo simulations of peptide solvation |
10.1002/bip.360220106. |
Biopolymers |
Monte Carlo simulations of peptide solvation
Abstract
|
| 6716712 |
Comparison of the antinociceptive effect between the cyclic dipeptide cycloTyr(Et)-homoarginine and the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe in rats |
10.1254/jjp.34.1. |
Jpn J Pharmacol |
Comparison of the antinociceptive effect between the cyclic dipeptide cycloTyr(Et)-homoarginine and the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe in rats
Abstract
- The antinociceptive effect of the cyclic dipeptide cycloTyr(Et)- homoarginine (C.TEHA) was examined utilizing the tail flick test and the digitus pinching test in rats in comparison with the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe (B.TEHM). Though both dipeptides administered into the lateral, 3rd and 4th cerebroventricles produced antinociceptive effects equipotent to morphine, except for the 4th cerebroventricular administration of B.TEHM, the administration into the spinal subarachnoid space was without effect. The effect of B.TEHM was completely antagonized by the pretreatment of naloxone (i.p.) when administered into the 3rd cerebroventricle where its effect was demonstrated to be the most potent. However, naloxone had no significant effect on C.TEHA administered into the 3rd cerebroventricle in both tests. It was concluded that both dipeptides act on the upper brain stem, especially around the 3rd cerebroventricle. Moreover, it was also thought that the effect of B.TEHM may be involved in the brain opioid system, and that of C.TEHA can be produced via a naloxone-resistant opioid system or a non-opioid system.
|
| 6717754 |
Comparison of the antinociceptive effects of intracerebroventricular injection of kyotorphin, cyclo (N-methyl-Tyr-Arg) and Met-enkephalin in mice |
10.1016/0028-3908(84)90209-0. |
Neuropharmacology |
Comparison of the antinociceptive effects of intracerebroventricular injection of kyotorphin, cyclo (N-methyl-Tyr-Arg) and Met-enkephalin in mice
Abstract
- Intracerebroventricular (i.c.v.) administration of kyotorphin (L-Tyrosine-L-Arginine) or Metenkephalin (Met-ENK) to conscious mice resulted in a dose-dependent antinociceptive effect as measured by three pain tests. Cyclo(N-methyl-L-Tyrosine-L-Arginine) (cyclo NMTA), an analogue of kyotorphin, increased the reaction time in the tail-pressure and tail-flick tests. Both dipeptides also decreased writhing induced by acetic acid. However, the antinociceptive activity of cyclo NMTA was substantially greater than that of kyotorphin or Met-enkephalin. At the maximum effective dose of 62.7 nmol/mouse, this cyclic dipeptide produced a more long-lasting antinociceptive effect than did kyotorphin or Met-enkephalin. Antinociception induced by cyclo NMTA or kyotorphin was significantly reversed by pretreatment with naloxone (2 or 8 mg/kg, i.p.), though naloxone was not as effective an antagonist of the antinociceptive action of these peptides as it was against Met-enkephalin. The results indicate that the antinociceptive effect induced by cyclo NMTA may in part involve the endogenous opioid system in mice.
|
| 6826281 |
Conformational studies of cyclic tetrapeptides. Evidence for a bis gamma-turn conformation for chlamydocin and Ala4-chlamydocin in nonpolar solvents |
None |
Int J Pept Protein Res |
Conformational studies of cyclic tetrapeptides. Evidence for a bis gamma-turn conformation for chlamydocin and Ala4-chlamydocin in nonpolar solvents
Abstract
- The conformations of chlamydocin and cyclo (Ala-Aib-Phe-D-Pro) (Ala4-chlamydocin) in chloroform have been investigated by nuclear magnetic resonance, infrared and circular dichroism spectroscopy. The data obtained from these experiments establish an all transoid, bis gamma-turn conformation for both compounds in chloroform with the following torsional angles (+/- 20 degrees): Ala4-chlamydocin: Aib, phi + 60 degrees, psi - 50 degrees; omega + 160 degrees; Phe phi - 120 degrees, psi + 120 degrees, omega - 160 degrees; D-Pro phi + 60 degrees, psi - 55 degrees, omega + 160 degrees; Ala phi - 110 degrees, psi + 110 degrees, omega - 160 degrees. Chlamydocin adopts a closely related conformation in neat chloroform. Nuclear Overhauser Effect (NOE) data are utilized to assign amide bond geometries in the cyclic tetrapeptide ring system.
|
| 6874598 |
Synthetic studies on gratisin. II |
10.7164/antibiotics.36.751. |
J Antibiot (Tokyo) |
Synthetic studies on gratisin. II
Abstract
|
| 6953262 |
Inhibitory effect of bassianolide, a cyclodepsipeptide, on drug-induced contractions of isolated smooth muscle preparations |
10.1254/jjp.32.55. |
Jpn J Pharmacol |
Inhibitory effect of bassianolide, a cyclodepsipeptide, on drug-induced contractions of isolated smooth muscle preparations
Abstract
- Bassianolide (BASS) is a cyclodepsipeptide isolated from cultured mycelia of Beauveria bassiana and is pathogenic to insects. In a longitudinal muscle preparation from guinea pig ileum, 10(-6) M BASS almost irreversibly inhibited an isotonic contraction induced by acetylcholine (ACH) and made the dose-response curve shift in parallel to the right (pA2: 7.6). It also inhibited the contractions induced by carbachol, pilocarpine, histamine, 5-hydroxytriptamine (5-HT) and prostaglandin E2, but did not inhibit the contraction induced by barium or a high concentration (40-60 mM) of potassium (high K). When applied to the guinea pig vas deferens, 10(-8) - 10(-7) M BASS inhibited an isometric contraction induced by norepinephrine (NE) (3 x 10(-6) - 10(-5) M), phenylephrine (3 x 10(-6) - 10(-5) M) or ACH (10(-6) - 10(-5) M). When the contractions of the three agonists exceeded the concentrations mentioned above, BASS failed to exert an inhibitory effect upon any of these agonists. It also inhibited the contraction caused by carbachol and histamine, but did not inhibit that induced by barium or high K. BASS itself failed to cause the contraction or relaxation of both muscle preparations. From these results, it is suggested that BASS inhibits the contraction induced by an agonist which acts upon selective sites of smooth muscle cells, but which does not inhibit a contraction induced by an agonist that has an effect on non-selective sites of cells.
|
| 6986689 |
Skin transplantation in mice and dogs. Effect of cyclosporin A and dihydrocyclosporin C |
None |
Transplantation |
Skin transplantation in mice and dogs. Effect of cyclosporin A and dihydrocyclosporin C
Abstract
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