A New Amino Acid Antibiotic KT–151, Produced by Streptomyces luteogriseus,Strain No. KT–151

From the results of taxonomic studies, Streptomyces sp. strain No. KT–151 isolated from a soil sample collected in Kumamoto City, was identified as a strain belonging to Streptomyces luteogriseus Schmitz, Deak, Crook and Hooper 1964. A new antibiotic, produced by this strain, was isolated as a leaflet crystal by ion-exchange chromatography and found to be an amino acid with the molecular formula, C₅H₁₂N₂O₂, and named antibiotic KT–151 (refered to as KT–151 hereinafter). The antibiotic showed antimicrobial activity against various Gram-positive and Gram-negative bacteria in a chemically defined medium but it was antagonized by several amino acids such as valine, leucine, isoleucine and threonine.     

Plant-growth inhibitory activity of heliannuol derivatives

In addition to (+)-, (-)- and (+/-)-heliannuol E, growth-inhibitory activities of five synthetic chromans and four tetrahydrobenzo[b]oxepins were examined against oat and cress. All heliannuol E isomers exhibited similar biological activities against cress, whereas when tested against oat roots, the unnatural optical isomer (+) showed no inhibitory activity. Four brominated chromans and two tetrahydrobenzo[b]oxepin derivatives also showed apparent inhibition against both cress and oat.     

Isolation and identification of lateral bud growth inhibitor,indole-3-aldehyde,involved in apical dominance of pea seedlings

A lateral bud growth inhibitor was isolated from etiolated pea seedlings and identified as indole-3-aldehyde. The indole-3-aldehyde content was significantly higher in the diffusates from explants with apical bud and indole-3-acetic acid treated decapitated explants, in which apical dominance is maintained, than in those from decapitated ones releasing apical dominance. When the indole-3-aldehyde was applied to the cut surface of etiolated decapitated plants or directly to the lateral buds, it inhibited outgrowth of the latter. These results suggest that indole-3-aldehyde plays an important role as a lateral bud growth inhibitor in apical dominance of pea seedlings.     

Growth inhibitory indole acetic acid polyacetylenic ester from Japanese ivy (Hedera rhombea Bean)

Polyacetylenes 1 and 2 were isolated from extracts of Japanese ivy (Hedera rhombea Bean) flower buds, with their chemical structures established on the basis of extensive 1D and 2D NMR and MS analyses. The absolute configurations of compounds 1 and 2 were determined by both chemical means, and by using the modified Mosher's method. Compound 1 is the first polyacetylene having an ester linkage between falcarindiol (3) and indole-3-acetic acid (IAA) moieties and 2 also had an unique substructure containing a conjugated diene adjacent to a hydroxy group. Polyacetylenes 1, 2, and 3 were also subjected to assessment of growth inhibition against the shoot and root growth of the monocotyledon plants, rice and perennial ryegrass, as well as the dicotyledons, cockscomb, lettuce, cress, and fenugreek. The most bioactive compound appeared to be compound 1, while 2 showed no activity. Compound 1 selectively showed growth inhibitory activity against dicotyledons.     

Specific terminal labeling of DNA molecules

We report a simple method to directly label or modify a specific terminus of linear DNA molecules. The method is based upon our finding that a presumably triple-stranded structure by RecA-mediated formation at the terminus formed with deoxyoligonucleotides, whose sequence is complementary to the 5' terminus of one of the strands of a double-stranded DNA molecule, is quite stable and can serve as a template for DNA polymerase reaction, with the nucleotides being incorporated by an exchange reaction. This novel type of nucleotide incorporation has made it possible to label a specific terminus of target double-stranded DNA molecules by a direct means (without amplification) regardless of its molecular size, a procedure previously unavailable. As an application, we show that large DNA molecules can be fixed to a solid support in a specific orientation, thus being utilized for various analytical purposes of DNA molecules.     

Antimitotic activity of moroidin, a bicyclic peptide from the seeds of Celosia argentea

A unique bicyclic peptide, moroidin (1), from the seeds of Celosia argentea (Amaranthaceae) strongly inhibited the polymerization of tubulin. The stereostructure of moroidin (1) was reinvestigated by spectroscopic data, chemical degradation, and molecular dynamics simulation.     

Structure-activity relationship of clovamide and its related compounds for the inhibition of amyloid β aggregation

Alzheimer’s disease (AD), a neurodegenerative disorder, is characterized by aggregation of amyloid β-protein (Aβ). Aβ aggregates through β-sheet formation and induces cytotoxicity against neuronal cells. Inhibition of Aβ aggregation by naturally occurring compounds is thus a promising strategy for the treatment of AD. We have already reported that caffeoylquinic acids and phenylethanoid glycosides, which possess two or more catechol moieties, strongly inhibited Aβ aggregation. Clovamide (1) containing two catechol moieties, isolated from cacao beans (Theobroma cacao L.), is believed to exhibit preventive effects on Aβ aggregation. To investigate the structure-activity relationship of clovamide (1) for the inhibition of Aβ aggregation, we synthesized 1 and related compounds 2–11 through reaction between l-DOPA, d-DOPA, l-tyrosine, or l-phenylalanine and caffeic acid, p-coumaric acid, or cinnamic acid, and compounds 12 and 13 were derived from 1. Among tested compounds 1–13, those containing one or two catechol moieties exhibited potent anti-aggregation activity, whereas the non-catechol-type related compounds showed little or no activity. This suggests that at least one catechol moiety is essential for inhibition of Aβ42 aggregation, and this activity increases depending on the number of catechol moieties. Consequently, clovamide (1) and its related compounds may be a promising therapeutic option for inhibiting Aβ-mediated pathology in AD.     

A gravitropic stimulation-induced growth inhibitor, β-(isoxazolin-5-on-2yl)-alanine,is a possible mediator of negative gravitropic bending of epicotyls in etiolated <Emphasis Type="Italic">Pisum sativum</Emphasis> seedlings

Negative gravitropic bending and its possible mediator in etiolated Alaska pea seedlings were intensively studied in comparison with seedlings of an agravitropic mutant, ageotropum. When 3.5-day-old etiolated Alaska seedlings were horizontally placed, the growth suppression at the upper side of the epicotyls began 10 min after the onset of the gravitropic stimulation, whereas the growth acceleration at the lower side began at 30 min, resulting in negative gravitropic bending. In contrast, no gravitropic bending was observed in the etiolated ageotropum seedlings, for which the epicotyls show an automorphogenesis-like growth. Strenuous efforts to identify a possible mediator that induces the gravitropic bending resulted in successfully identifying β-(isoxazolin-5-on-2yl)-alanine (βIA). The unilateral application of βIA to the etiolated Alaska epicotyls substantially induced epicotyl bending toward the application site, indicating that βIA could act as a growth inhibitor. Analyses of the distribution of βIA in the upper and lower flanks of the etiolated Alaska epicotyls revealed that its content rapidly increased twice in the upper flanks compared with that in the lower ones in response to gravitropic stimulation, whereas its content in the lower flanks was almost equal to that in the vertical control. In etiolated ageotropum epicotyls, an almost equal amount of βIA was distributed in the upper and lower flanks of epicotyls. These results suggest that a gravitropic stimulation increases βIA in the upper flank, resulting in the negative gravitropic bending of epicotyls via the suppression of the growth rate at the upper side of epicotyls in the etiolated Alaska pea seedlings.     

Alkali-tolerant high-activity catalase from a thermophilic bacterium and its overexpression in Escherichia coli

We have purified an alkali-tolerant catalase from the thermophilic bacterium Metallosphaera hakonensis. The catalase gene, which encodes 303 amino acids and has a calculated molecular mass of 33 kDa, including its putative signal peptide encoding sequence, was cloned. The deduced amino acid sequence exhibited a region-specific homology with the sequences of manganese catalases from thermophilic bacteria such as Thermus thermophilus and Thermus brockianus. When this gene was overexpressed in Escherichia coli, proteins of the expected size (33 kDa) were overproduced in the inactive form. We made several attempts to obtain active forms of or to activate these overproduced proteins. Upon their induction into E. coli, a 100-fold increase in the catalase activity was detected when high-concentration manganese was used as the medium. The catalase activity of the purified enzyme was optimal at a pH of 10.0. The alkali-tolerant property of this catalase makes it a promising enzyme in biotechnological applications such as H(2)O(2)-detoxifying systems.     

Inhibitory effect of tannins from galls of Carpinus tschonoskii on the degranulation of RBL-2H3 Cells

In this study, the anti-allergy potency of thirteen tannins isolated from the galls on buds of Carpinus tschonoskii (including two tannin derivatives) was investigated. RBL-2H3 (rat basophilic leukemia) cells were incubated with these compounds, and the release of β-hexosaminidase and cytotoxicity were measured. Of the thirteen tannins, tetragalloylglucose (2), pentagalloylglucose (3), casuarictin (4), and casuarinin (9) were the most potent inhibitors, and all the tannins showed no cytotoxic effect after 24 h of incubation. The results obtained suggest that tannins from C. tschonoskii are capable of inhibiting allergic reactions and may be useful for the treatment or prevention of type I allergic diseases.