Drechslerol-A,a new phytotoxic metabolite produced by Drechslera maydis,a strain from costus speciosus

Drechslera maydis causes severe leaf blight disease of Costus speciosus. One compound, drechslerol-A, isolated from the culture filtrate of this fungus was elucidated as (cis) hentetracont-10-ene-12-hydroxymethyl-4-ol on the basis of spectral analysis. The production of necrotic lesion was observed on the leaves of Costus speciosus with 1.6 × 10⁻⁴ M concentration. In the most sensitive reaction drechslerol-A shows complete killing effect on the root growth of wheat seedlings at the concentration of 3.2 × 10⁻⁵ M.     

Drazepinone, a trisubstituted tetrahydronaphthofuroazepinone with herbicidal activity produced by Drechslera siccans

When grown in a minimal-defined medium, a strain of Drechslera siccans, a pathogenic fungus isolated from seeds of Lolium perenne, produced phytotoxic metabolites. This strain is one of the best toxin producers among several grass pathogenic fungal strains collected and tested to find phytotoxins to be used as natural herbicides of monocot weeds. From the culture filtrates of D. siccans, we isolated a new phytotoxic trisubstituted naphthofuroazepinone, named drazepinone, and characterised it as a 3,5,12a-trimethyl-2,5,5a,12a-tetrahydro-1H-naphtho[2',3':4,5]furo[2,3-b]azepin-2-one. Assayed at 2 microg microl(-1) solution the novel metabolite proved to have broad-spectrum herbicidal properties, without antibacterial and antifungal activities, and low zootoxic activity. Its original chemical structure and the interesting biological properties make drazepinone a potential natural herbicide.     

Trans-4-aminoproline, a phytotoxic metabolite with herbicidal activity produced by Ascochyta caulina

A phytotoxic metabolite, characterized through NMR techniques and synthetic methods as trans-4-aminoproline, was isolated from the culture filtrates of Ascochyta caulina, a promising mycoherbicide for biological control of Chenopodium album. The metabolite, which shows interesting phytotoxic properties, together with ascaulitoxin (recently characterized as N.2-beta-D-glucoside of the unusual bis-amino acid 2,4,7-triamino-5-hydroxyoctandioc acid) and another unidentified compound, compose an active fraction of A. caulina culture filtrates with promising herbicidal properties. When assayed on leaves of host and non host dicots, including wild and cultivated plants, the trans-4-aminoproline showed a wide range of toxicity, with leaves of C. album being the most sensitive. Other interesting aspects were its inefficacy on several monocots, both cultivated and wild, and its lack of antifungal, antibiotic and zootoxic activities. This is the first report on trans-4-aminoproline as naturally occurring compound and phytotoxic metabolite produced by A. caulina.     

Detection and quantification of phytotoxic metabolites of Sarocladium oryzae in sheath rot-infected grains of rice

AIMS: The present study describes the detection and quantification of the Sarocladium oryzae metabolites, helvolic acid and cerulenin in extracts of rice grains collected from plants infected with sheath rot. It also describes the phytotoxicity of these metabolites on rice seedlings. METHODS AND RESULTS: Helvolic acid and cerulenin in sheath rot-infected rice grains were detected using thin layer chromatography (TLC) and nuclear magnetic resonance (NMR) analyses. On the TLC plates helvolic acid and cerulenin moved as brownish yellow spots and showed R(F) values of 0.61 and 0.49, respectively. A standard assay curve was developed on the basis of selective toxicity of helvolic acid towards Calvibacter michiganensis ATCC 2140 and cerulenin towards Candida albicans 1150. The amounts of helvolic acid and cerulenin on the basis of standard assay curve were 2.2 and 1.75 microg g(-1) of infected seeds. Treatment of IR 36 rice seedlings with metabolites induced chlorosis and reduced shoot length by 20%, root length by 30% and root number by 7% relative to control. CONCLUSIONS: Helvolic acid and cerulenin were detected in infected rice grains and these metabolites induced chlorosis and reduced the seed viability and seedling health of rice. SIGNIFICANCE AND IMPACT OF THE STUDY: Antimicrobial and phytotoxic metabolites, helvolic acid and cerulenin are present in infected grains and reduce the seed viability and seedling health. These metabolites may increase the pathogenic potential and survival of S. oryzae in rice seed by competing with other seed-borne fungi.     

N-linked glycan structures of human lactoferrin produced by transgenic rice

Human lactoferrin was produced in genetically engineered rice. N-linked glycan structures of recombinant human lactoferrin were determined. The oligosaccharides liberated by hydrazinolysis were labeled with 2-aminopyridine (PA). The PA-labeled glycans were purified by reverse-phase and size-fractionation HPLCs. The structures of these glycans were identified by HPLC, exoglycosidase digestion, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The glycan structures determined were ManFucXylGlcNAc(2) (3.4%), Man(2)FucGlcNAc(2) (2.1%), Man(3)FucGlcNAc(2) (2.5%), Man(3)FucXylGlcNAc(2) (42.5%), two isomers of Man(2)FucXylGlcNAc(2) (39.1%), Man(3)XylGlcNAc(2) (6.5%), and Man(2)XylGlcNAc(2) (3.9%).     

Isolation and characterization of phytotoxic compounds produced by Phomopsis helianthi

The isolation, chemical characterization and biological activity of two phytotoxic metabolites of Phomopsis helianthi Munt-Cvet et al. is reported. These compounds were identified by spectroscopic methods (UV, IR, 1H and 13C NMR, and MS) as trans-4,6-dihydroxymellein (trans-3-methyl-4,6,8-trihydroxy-3,4-dihyroisocoumarin) and cis-4,6-dihydroxymellein (cis-3-methyl-4,6,8-trihydroxy-3,4-dihydroisocoumarin). This is the first report of the isolation of trans-4,6-dihydroxymellein from fungal cultures and of the production of cis- and trans-4,6-dihydroxymelleins by P. helianthi. Rice was found to be a good substrate for the production of the dihydroxymelleins. Culture extracts of some Italian and French strains of P. helianthi showed different degrees of phytotoxicity towards sunflower leaves and seedlings. The minimum effective doses of trans- and cis-4,6-dihydroxymelleins with different bioassays were 76 and 135 microg per spot (leaf puncture bioassay), 3 and 5 micromol g(-1) fresh tissue (absorption by leaf cutting) and 5 and 2 micromol g(-1) fresh tissue (absorption by cut seedlings), respectively. These compounds may contribute to the severity of the sunflower disease caused by P. helianthi.     

The isolation, purification and biological activity of a novel antibacterial compound produced by Pseudomonas stutzeri

A novel compound designated zafrin [4beta-methyl-5, 6, 7, 8 tetrahydro-1 (4beta-H)-phenanthrenone] was isolated from a crude extract of a marine bacterium identified as Pseudomonas stutzeri. Zafrin showed strong antibacterial activity against both Gram-positive and Gram-negative bacteria. The compound was purified and its structure was elucidated by spectroscopic methods including 1H-nuclear magnetic resonance (NMR), 13C-NMR, 1D-NMR and 2D-NMR spectroscopy. It could be demonstrated that a purified solution of zafrin was active against several human pathogens, including Staphylococcus aureus, and Salmonella typhi. By contrast, zafrin did not inhibit the growth of eukaryotic organisms Candida albicans and Schizosaccharomyces pombe. The minimal inhibitory concentration for Gram-positive bacteria ranged from 50 to 75 microg mL(-1) and varied between 75 and 125 microg mL(-1) for Gram-negative bacteria. Zafrin lysed Bacillus subtilis cells grown in an osmotically protected medium, suggesting that it does not act upon the cell wall. Further investigation using B. subtilis indicated that the compound is bactericidal and is likely to target the cell membrane.     

稻镰状瓶霉促进水稻生长的机制

稻镰状瓶霉Falciphora oryzae是本实验室从野生稻根系分离获得的一株DSE,具有促生、防病等作用。本研究旨在对其促生机制进行初探。在室内平板共培养条件下,对水稻种子接种稻镰状瓶霉菌饼（4个/皿）,测定植株生长指标、营养元素含量及营养吸收相关基因表达量;温室盆栽条件下,将稻镰状瓶霉以菌肥形式（60g/桶）与水稻进行盆栽共培养,测定植株农艺性状指标。结果表明,接种稻镰状瓶霉后,平板上的水稻幼苗的株高、叶宽和茎秆直径显著增加,根长并未受影响。稻镰状瓶霉能够促进水稻根系对营养元素的吸收,提高地上部分和根系组织中N、P、K、S、Fe和Mg元素的含量,诱导根部与营养元素吸收相关的调控基因OsPTR9、OsAMT3;2、OsPT4、OsSULTR3;1、OsMRS2-8、OsHAK16、OsYSL15和OsIRO2的显著上调表达。盆栽试验表明,稻镰状瓶霉显著提高了水稻各农艺性状指标,包括叶宽、茎秆直径、植株鲜重、植株干重、叶绿素含量和光合强度。结果表明,稻镰状瓶霉的根部定殖能够诱导营养元素吸收相关基因的上调表达,从而促进根系对营养元素的吸收,进而促进水稻植株的生长。     

Novel hydrophobic surface binding protein, HsbA, produced by Aspergillus oryzae

Hydrophobic surface binding protein A (HsbA) is a secreted protein (14.5 kDa) isolated from the culture broth of Aspergillus oryzae RIB40 grown in a medium containing polybutylene succinate-co-adipate (PBSA) as a sole carbon source. We purified HsbA from the culture broth and determined its N-terminal amino acid sequence. We found a DNA sequence encoding a protein whose N terminus matched that of purified HsbA in the A. ozyzae genomic sequence. We cloned the hsbA genomic DNA and cDNA from A. oryzae and constructed a recombinant A. oryzae strain highly expressing hsbA. Orthologues of HsbA were present in animal pathogenic and entomopathogenic fungi. Heterologously synthesized HsbA was purified and biochemically characterized. Although the HsbA amino acid sequence suggests that HsbA may be hydrophilic, HsbA adsorbed to hydrophobic PBSA surfaces in the presence of NaCl or CaCl(2). When HsbA was adsorbed on the hydrophobic PBSA surfaces, it promoted PBSA degradation via the CutL1 polyesterase. CutL1 interacts directly with HsbA attached to the hydrophobic QCM electrode surface. These results suggest that when HsbA is adsorbed onto the PBSA surface, it recruits CutL1, and that when CutL1 is accumulated on the PBSA surface, it stimulates PBSA degradation. We previously reported that when the A. oryzae hydrophobin RolA is bound to PBSA surfaces, it too specifically recruits CutL1. Since HsbA is not a hydrophobin, A. oryzae may use several types of proteins to recruit lytic enzymes to the surface of hydrophobic solid materials and promote their degradation.     

Ophiobolin E and 8-epi-ophiobolin J produced by Drechslera gigantea, a potential mycoherbicide of weedy grasses

Drechslera gigantea, a fungal pathogen isolated from large crabgrass (Digitaria sanguinalis) and proposed as a potential mycoherbicide of grass weeds, produces phytotoxic metabolites in liquid and solid cultures. Ophiobolin A and three minor ophiobolins i.e., 6-epi-ophiobolin A, 3-anhydro-6-epi-ophiobolin A and ophiobolin I were obtained from the liquid culture broths. Interestingly and unexpectedly, ophiobolins also appeared in cultures of this fungus and they were isolated together with the known ophiobolins B and J, and designed as ophiobolin E and 8-epi-ophiobolin J. They were characterized using essentially spectroscopic methods. It is noteworthy that D. gigantea produces such a plethora of bioactive organic substances. Some structure-activity relationship results are also discussed in this report.     

Effects of temperature, pH and additives on the activity of tannase produced by a co-culture of Rhizopus oryzae and Aspergillus foetidus

Summary Tannase was produced by modified solid-state fermentation (MSSF) of tannin rich substrates by a co-culture of the two filamentous fungi, Rhizopus oryzae and Aspergillus foetidus. The enzyme thus produced was then partially purified by solvent precipitation and DEAE-Sephadex column chromatography. A study on the effects of temperature and pH was made on the activity of tannase so purified. The optimum values of incubation time, reaction temperature and pH for tannase activity were 5 min, 40 °C and 5.0 respectively. The half-life period thermal stability and kinetic constants (K _m 0.21 mM, V _max 4.9×10⁻² M min^-1 at 40 °C) of this tannase were determined and the effects of different metal ions, surfactants, chelators, denaturants and inhibitors on the enzyme activity were also studied.     

Mycoflora of stored rice in relation to the biological control of Sitophilus oryzae by Anisopteromalus calandrae

In this study, we determined the effect of controlling rice weevils on the mycoflora of stored brown rice by using Anisopteromalus calandrae (Howard), a parasite of the rice weevil. The mycoflora in brown rice with the parasitoid was similar to that without the parasitoid; however, the dominant mold species differed. Without the parasitoid, Aspergillus candidus Link and Penicillium islandicum Sopp were the dominant species, whereas Aspergillus penicilloides Speg. and P. islandicum were dominant when the parasitoid was present. The difference appeared to be due mainly to the difference in the grain moisture content with and without the parasitoid. A. candidus was the dominant species in the communities without the parasitoid and was not observed when the weevils were suppressed. P. islandicum dominated or co-dominated regardless of the presence of the parasitoid which suggested that P. islandicum is tolerant to low grain moisture content or is positively affected by the presence of the rice weevil.     

Chemical and biological characterisation of sapinopyridione, a phytotoxic 3,3,6-trisubstituted-2,4-pyridione produced by Sphaeropsis sapinea, a toxigenic pathogen of native and exotic conifers, and its derivatives

A phytotoxic trisubstituted 2,4-pyridione, named sapinopyridione, was isolated from the culture filtrates of Sphaeropsis sapinea, a fungal pathogen of conifers occurring world-wide. Three strains were isolated from two cypress species. Strain D-55 isolated from Cupressus sempervirens resulted high producer of sapinopyridione (12.3 mg l(-1)), whereas strain D-54 isolated from the same cypress species was low producer (1.1 mg l(-1)); strain D-50 isolated from C. macrocarpa was intermediate producer (5.4 mg l(-1)). Sapinopyridione was characterised by spectroscopic and chemical methods, as the 6-methyl-2-(2-methyl-1-oxobutyl)-1-oxa-5-azaspiro[2.5]oct-6-ene-4,8-dione. The structure was supported by the preparation of three key derivatives, whose phytotoxic and antimycotic activities were also tested on host plants and on three Seiridium species, virulent fungal agents of cypress canker disease. Some structure-activity relationships were identified for both phytoxicity and antifungal activities. These activities appear related to the presence of both pyridione and oxiran rings. Also the carbonyl group of the side chain seems to play a role into impart activity.     

Relationship between growth rate of Helminthosporium oryzae isolates on calluses of rice cultivars and their disease reaction on rice plants

Rice cultivars showed differential reaction to various isolates of Helminthosporium oryzae, the brown spot pathogen. The calluses obtained from those cultivars behaved in a similar manner to the mycelial growth of pathogenic isolates on them. However, amount of inoculum, size of the callus and period of incubation influenced the reaction of the callus to the fungal isolates.     

New methyl pyruvate thiosemicarbazones and their copper and zinc complexes: synthesis, characterization, X-ray structures and biological activity.

By reacting thiosemicarbazides substituted on the aminic nitrogen with both alkyl or aryl groups, and methyl pyruvate a new group of methylpyruvate thiosemicarbazones (Hmpt) derivatives was obtained. These ligands were then treated with copper and zinc inorganic salts. All isolated compounds were characterized using spectroscopic methods. The single crystal structural analysis of the ligands Me-Hmpt x 0.5H2O 1, Et-Hmpt x H2O 2, Ph-Hmpt 5, Meph-Hmpt 6 showed that only compound 6 presents significant deviation from planarity. The X-ray structure of [Zn(Me-Hmpt)Cl2] x H2O 8 showed that in this complex Me-Hmpt behaves as a neutral ligand SNO terdentate and that the penta coordination is achieved by chloride ions according to spectroscopic and elemental analyses. On the basis of the analytical data the same behavior is proposed for the other zinc complexes. All the ligands in copper complexes seem to be monodeprotonated; nevertheless the same SNO behavior is expected. Tests on cell proliferation of human leukemic cell line U937 showed that the copper complex Cu(Et-mpt)Cl x H2O is the most active compound among those reported even though it is not able to induce apoptosis.     

Natural phenanthrenes and their biological activity

The aim of this review is to survey the various naturally occurring phenanthrene compounds that have been isolated from different plants. Only one review has previously been published on this topic. Gorham (1989) reviewed the structures, biosynthesis, separations and spectroscopy of stilbenes and phenanthrenes. The present study furnishes an overview of the hydroxy or/and methoxy-substituted 9,10-dihydro/phenanthrenes, methylated, prenylated and other monomeric derivatives, dimeric and trimeric phenanthrenes and their biological activities. A fairly large number of phenanthrenes have been reported from higher plants, mainly in the Orchidaceae family, in the species Dendrobium, Bulbophyllum, Eria, Maxillaria, Bletilla, Coelogyna, Cymbidium, Ephemerantha and Epidendrum. A few phenanthrenes have been found in the Hepaticae class and Dioscoreaceae, Combretaceae and Betulaceae families. Their distribution correlates strongly with the taxonomic divisions. These plants have often been used in traditional medicine, and phenanthrenes have therefore been studied for their cytotoxicity, antimicrobial, spasmolytic, anti-inflammatory, antiplatelet aggregation, antiallergic activities and phytotoxicity. On the basis of 120 references, this review covers the phytochemistry and pharmacology of phenanthrenes, describing 252 compounds. This contribution stems from our work on the medicinal plant Tamus communis.     

New azidometalkojates and their biological activity

Azidometalkojates of the general formula MX₂ (M=Cu, Mn, Mg, Zn or Ni and X=5-hydroxy-2-azidomethyl-4H-pyran-4-one) were prepared and tested for antibacterial, antifungal and cytotoxic effects. The mangan and zinc derivatives are not active against any the tested microorganisms. A weak antibacterial activity was found with the copper derivative. The strongest antifungal effects were shown by the nickel derivative while the highest cytotoxic effect on HeLa cells was manifested by the zinc derivative.     

Tuftsin analogs and their biological activity

Summary In this paper the literature data on the structure-activity relationship for the series of tuftsin analogs are summarized. Among others, the questions of the substitution of particular amino acid residues in different positions of the peptide chain, as well as the questions of shortening and lengthening of the peptide chain of tuftsin, are reviewed. The existing models of the biologically active conformation of tuftsin are also summarized.     

Isolation and characterization of phytase isozymes produced by Aspergillus oryzae

A mutant strain (KL-38) of Aspergillus oryzae was obtained by UV irradiation. Phytase activity of KL-38 in molded rice (koji rice) was about 2.7-fold of that obtained from the parent strain (BP-1). Phytase activity of KL-38 in the submerged culture was similar to that of BP-1. Two types of phytase were produced from koji culture: phytase I (Phy I) was produced during incubation of both koji and submerged cultures, and phytase II (Phy II) was obtained only from koji culture. Phy II production was increased in KL-38 compared with BP-1, whereas the production of Phy I was similar for both KL-38 and BP-1. This finding indicates that A. oryzae has at least two types of phytase isozyme.