Toxin from Fusarium moniliforme: Effects on Plants and Animals

A mycotoxin-producing strain of Fusarium moniliforme was isolated from southern leaf blight-damaged corn seed. A water-soluble toxin, subsequently purified from the fungus, had an oral median lethal dose of 4.0 milligrams per kilogram in 1-day-old cockerels. The toxin also produced plant growth-regulating and phytotoxic effects on plant systems. Physical and chemical data presented for the toxin suggest a structurally new toxin. The trivial name "moniliformin" has been assigned to the toxin.

Shipboard testing of the efficacy of SeaKleen as a ballast water treatment to eliminate non-indigenous species aboard a working tanker in Pacific waters

Trials were conducted aboard the tanker Seabulk Mariner to test a natural product, SeaKleen, as a biocide controlling non-indigenous populations of plankton and bacteria in ballast water. SeaKleen was dosed into matched ballast tanks at two different concentrations, 0.8 mg L(-1) active ingredient (a.i.) and 1.6 mg L(-1) a.i. during ballasting off the Oregon coast during a three-day passage to Prince William Sound, Alaska. Live organism counts from treated ballast water were compared with those from untreated (control tank) water collected from the same source location. Shipboard chemical analyses were made to verify dose and quantify chemical degradation and residuals following dilution. Results indicated that both SeaKleen doses resulted in complete zooplankton and phytoplankton mortality and that the higher dose (1.6 mg L(-1) a.i.) caused a two-log removal of culturable bacteria over a 92 h grow-out period. Spectrophotometry confirmed initial dosing to within 5% of nominal values. Shipboard bioassays were conducted using larval fish (Cyprinodon variegatus), brine shrimp (Artemia salina) and the bioluminescent dinoflagellate Pyrocystis lunula. Exposure of the test organisms to water drawn from treated ballast tanks 48 h after SeaKleen was added to the tanks resulted in 100% mortalities in Cyprinodon and Pyrocystis at both doses. Corresponding mortalities for Artemia larvae were 100% and 60% for high and low SeaKleen doses, respectively. Toxicity testing of treated water, subjected to varying dilutions, indicated that residual toxicity to even the most sensitive organisms would be eliminated once the discharge had dispersed beyond 100 feet from the vessel.

The influence of water quality on the toxicity and degradation of juglone (5-hydroxy 1,4-naphthoquinone)

This study was part of a broader investigation of low molecular weight quinones under consideration as biocides for the control of aquatic nuisance species (ANS). Preliminary investigations identified the 2-ring naphthoquinones as broad spectrum biocides controlling a wide range of aquatic organisms. All biocides were relatively short-lived in saline waters, with half-lives between 5 and 30h. Juglone (5-hydroxy 1,4-naphthoquinone) and plumbagin (5-hydroxy-2-methyl-1,4- naphthoquinone) showed the greatest toxicity against most aquatic organisms. These qualities formed the basis for a patent focusing on these two compounds as biocides for ANS control, with juglone identified as the more cost-effective of the two. Although juglone has been extensively studied as a plant toxin and reducing agent, remarkably little information exists on its use as an aquatic biocide. We describe the toxicity of juglone over the range of water quality parameters likely to be encountered in ballast water, a major vector for ANS. Tests indicated that its molecular stability was enhanced in freshwater and particularly under neutral to acid conditions. This was supported by results of bioassays on the freshwater cladoceran Daphnia magna that indicated enhanced juglone toxicity at pHs of < or =6.7. A low octanol:water partition coefficient for juglone indicated little capacity for these compounds to be adsorbed by suspended particulates and for bioaccumulation. These properties together with their relatively rapid degradation (t1/2 < or =30h), particularly in the marine environment, indicated a low the risk of residual toxicity associated with the release of juglone-treated water.

Screening of natural product biocides for control of non-indigenous species

Several benzo-, naphtho- and anthraquinones were tested for their efficacy as biocides in controlling aquatic nuisance species in ships' ballast water. A requirement of this application was broad spectrum aquatic toxicity, coupled with a relatively rapid rate of degradation, in order to comply with coastal discharge requirements. Compounds were screened using a suite of toxicity bioassays designed to establish their relative toxicity to an array of planktonic organisms including larval bivalves Dreissena and Crassostrea, various developmental stages of the estuarine copepod Eurytemora affinis, brine shrimp larvae (Artemia salina), the freshwater invasive water flea Bythotrephes, larval sheepshead minnows CCyprinodon variegates) and two unicellular algal genera Isochrysis and Neochloris.. The majority of the data were recorded as the lowest concentration of the test compound resulting in complete mortality or inactivation of test organisms (LC ,m). The naphthoquinones juglone, plumbagin, menadione and naphthazarin showed the highest toxicity to the broadest range of organisms, often at levels much less than 1 mg l(-1), and most of the attention was focused on this group. While plumbagin and juglone appeared overall to be the most toxic compounds, it was concluded that menadione was probably the most cost-effective candidate compound for shipboard use for controlling invasive species in ballast water, particularly in view of the large volumes of water that would require treatment.

Naphthoquinones as broad spectrum biocides for treatment of ship's ballast water: toxicity to phytoplankton and bacteria

Current UN International Maritime Organization legislation mandates the phased introduction of ballast water treatment technologies capable of complying with rigorous standards related to removal of waterborne organisms. Doubts concerning mechanical treatments at very high ballasting rates have renewed interest in chemical treatment for very large vessels. High removal rates for biota require broad spectrum biocides that are safe to transport and handle and pose no corrosion problems for ships' structure. The current study focuses on the naphthoquinone group of compounds and extends a previously reported set of screening bioassays with an investigation of the toxicity of four naphthoquinones to select protists and prokaryotes, representative of typical ballast water organisms. Vegetative dinoflagellate cysts exposed to 2.0 mg/L of the naphthoquinones juglone, plumbagin, menadione and naphthazarin showed varying degrees of chloroplast destruction, with menadione demonstrating the most potency. Laboratory and mesocosm exposures of various phytoplankton genera to menadione showed toxicity at 1.0 mg/L. Juglone demonstrated the most bactericidal activity as judged by a Deltatox assay (Vibrio fischeri) and by acridine orange counts of natural bacterial populations.

Botcinins E and F and Botcinolide from Botrytis cinerea and structural revision of botcinolides

Botcinins E and F were isolated together with the known botcinolide. The structures of botcinins E and F were determined to be 3-O-deacetylbotcinin A (5) and 3-O-deacetyl-2-epi-botcinin A (6), respectively, by spectroscopic methods and chemical conversion. The structure of botcinolide was revised on the basis of spectroscopic data and chemical conversion. Botcinolide was originally reported as a nine-membered lactone (7), but the revised structure is the seco acid of botcinin E (13). Thus botcinolide is renamed botcinic acid, and homobotcinolide is renamed botcineric acid. Reinvestigation of the spectroscopic data reported for all botcinolide analogues indicates that 4-O-methylbotcinolide and 3-O-acetyl-2-epibotcinolide are the same as a methyl ester of botcinic acid (13a) and botcinin A (1), respectively, and that 2-epibotcinolide may be the same as botcinin E (5). Compounds 5, 6, and 13 showed weak antifungal activity against Magnaporthe grisea, a pathogen of rice blast disease.

Prevention of organochlorine-induced inhibition of gap junctional communication by chaetoglobosin K in astrocytes

Innumerable toxic substances present in the environment inhibit gap junctions, intercellular membrane channels that play fundamental roles in coordinated function of cells and tissues. Included are persistent organochlorine compounds, which pose health risks to humans and animals owing to their widespread use, bioaccumulation, and ability to inhibit gap junction channel-mediated intercellular communication in liver, lung, skin, heart, and brain cells. In this study, the organochlorine xenobiotics dieldrin and endosulfan, at micromolar concentrations, were found to inhibit gap junction-mediated intercellular communication and induce hypophosphorylation of connexin 43 in cultured rat astrocytes, the predominant cell type in the brain coupled through gap junctions. This inhibition of gap junctional communication was substantially reduced by preincubation with chaetoglobosin K (ChK), a bioactive natural produce previously shown to have ras tumor suppressor activity. Chaetoglobosin K also prevented dieldrin and endosulfan-induced hypophosphorylation of connexin 43 and prevented dieldrin-induced connexin 43 plaque dissolution in both astrocytes and cultured liver epithelial cells. The results suggest that stabilization of the native, phosphorylated form of connexin 43 by ChK may contribute to its ability to prevent organochlorine-induced inhibition of gap junction-mediated communication and dissolution of gap junction plaques within the plasma membrane.

Novel bioactive breviane spiroditerpenoids from Penicillium brevicompactum Dierckx

The structures of four new, naturally occurring bioactive spiroditerpenoids, (+)-breviones B, C, D, and E, potential allelopathic agents, have been determined from extracts of semisolid fermented Penicillium brevicompactum Dierckx. The structures display the novel breviane spiroditerpenoid skeleton. Structure elucidation was performed by chemical transformations and by homo- and heteronuclear 2D-NMR spectral data. On the basis of combined studies of the theoretical conformations and NOEDIFF data, their relative stereochemistry is proposed. A mixed biogenesis for this novel family of spiroditerpenoids is tendered. The levels of activity shown by breviones B, C, and E in the etiolated wheat coleoptiles bioassay, especially breviones E (100% inhibition) and C (80% inhibition) both at 10(-4) M, suggest them as lead compounds for new agrochemicals.

Bioactive carotanes from Trichoderma virens

Four new metabolites with carotane skeletons, trichocaranes A (1), B (2), C (3), and D (4), were isolated from Trichoderma virens and their structures established by the interpretation of NMR and mass spectroscopic data. The trichocaranes significantly inhibited the growth of etiolated wheat coleoptiles: 40% at 10(-4) M with 1 and 2 and 86% at 10(-3) M with 3.

Fractional extraction of compounds from grape seeds by supercritical fluid extraction and analysis for antimicrobial and agrochemical activities

White grape seeds were subjected to sequential supercritical fluid extraction. By increasing the polarity of the supercritical fluid using methanol as a modifier of CO(2), it was possible to fractionate the extracted compounds. Two fractions were obtained; the first, which was obtained with pure CO(2), contained mainly fatty acids, aliphatic aldehydes, and sterols. The second fraction, obtained with methanol-modified CO(2), had phenolic compounds, mainly catechin, epicatechin, and gallic acid. The fractions were bioassayed. Antimicrobial activities were checked on human pathogens, and a high degree of activity was obtained with the lipophilic fraction. Agrochemical activities on phytopathogenic fungi and activities on the etiolated wheat coleoptile bioassay were also checked. The more polar fraction was active in the latter bioassay.

Koninginin G, a new metabolite from trichoderma aureoviride

A new metabolite, koninginin G (1), was isolated from a strain of Trichoderma aureoviride and its structure established by the interpretation of spectroscopic data. The metabolite significantly inhibited the growth of etiolated wheat coleoptiles by 56% at 10(-3) M.

Isolation of Actinomyces viscosus strain GA: characteristics of its cellular biological retardant(s)

Actinomyces viscosus strain GA produces an exocellular biological retardant(s) that prevents certain vegetable plants from becoming overgrown. The biological retardant(s) was assayed using the etiolated wheat coleoptile assay, and fractionation of culture supernatant fluid resulted in a partial purification of the retardant(s). The biological retardant(s) was most active around pH 7 in the bioassay and when applied to sterile soil mixture. The biological retardant(s) was tentatively identified as a derivative of a rare hexose carbohydrate (but not an amino sugar) but an exact structure was not determined. In a sterilized synthetic soil system, the biological retardant(s) has an effect on tomato cultivars similar to that observed by the synthetic plant growth regulators Alar (succinic acid 2,2,-dimethylhydrazide) and Bonzi (paclobutrazol).

Ruakuric acid: a natural product from Aspergillus fumigatus

A new chroman derivative, named ruakuric acid, was isolated from a strain of Aspergillus fumigatus growing in conjunction with a coral lichen. The structure was determined as 6-acetyl-5-hydroxy-4-methoxy-chroman-2-carboxylic acid (mixture of 2,4-cis,trans isomers).

Homobotcinolide: a biologically active natural homolog of botcinolide from Botrytis cinerea

A novel natural product exhibiting biological activity was isolated from a strain of Botrytis cinerea that had infected raspberry fruit (Rubus ideaus). Liquid fermentation and bioassay-directed fractionation of the organism yielded a compound with molecular formula C22H38O8 that is trivially named homobotcinolide. It significantly inhibited etiolated wheat coleoptile growth. Greenhouse-grown bean, corn, and tobacco plants were also affected by exogenous application of homobotcinolide, severe chlorosis and necrosis being exhibited in corn. The compound is a polyhydroxylated nonalactone esterified with 4-hydroxy-2-decenoic acid.

Koninginin C: a biologically active natural product from Trichoderma koningii

Koninginin C, a congener of koninginins A and B, was isolated from Trichoderma koningii fermented on a shredded wheat medium. The compound inhibited the growth of etiolated wheat coleoptiles by 100% at 10(-3) M. It was a fine, white crystalline substance with a molecular formula of C16H28O4 and a melting point of 70-72 degrees C.

Properties and cost effective method for production of the antitumor agent declauxin from sporulating Penicillium herquei

Duclauxin, an antitumor agent, was isolated from sporulating Penicillium herquei (ATCC34665) grown on a medium of peanut hulls supplemented with potato starch solution (termed "Gostar"). The medium was inoculated with a sporulating subculture of P. herquei established on a 2% potato starch slurry supplemented with mineral salts. The P. herquei grew as well on Gostar as on an enriched medium. Duclauxin was isolated in crystalline form from Gostar-grown P. herquei. Comparison of costs of duclauxin obtained from inexpensive Gostar versus costly enriched media indicated that Gostar reduces production expenses. Duclauxin was not effective as an antibiotic against certain species of gram-positive and gram-negative bacteria, fungi, and viruses, but a concentration-dependent inhibition of wheat coleoptile growth was observed. Duclauxin was characterized by melting point, optical rotation, IR and NMR spectroscopy, MS and X-ray diffraction.

Isocladosporin, a biologically active isomer of cladosporin from Cladosporium cladosporioides

Extraction of the fungus Cladosporium cladosporioides yielded the known isocoumarin, cladosporin [1], and a new compound. This metabolite, which inhibited the growth of etiolated wheat coleoptiles slightly more than did cladosporin, was characterized as a diastereoisomer of cladosporin at C-14 and was named isocladosporin [2].

Studies on aldose reductase inhibitors from fungi. I. Citrinin and related benzopyran derivatives

The fungal metabolites, citrinin (4,6-dihydro-8-hydroxy-3,4,5-trimethyl-6- oxo-3H-2-benzopyran-7-carboxylic acid) and DHMI (3,4-dihydro-6-methoxy-3,7-dimethyl-1H-2-benzopyran-8-ol), as well as certain synthetic derivatives, have been evaluated for aldose reductase inhibitory activity using a rat lens enzyme preparation. Citrinin and its reduction product, dihydrocitrinin, were found to have significant activity (IC50 approximately 10 microM), whereas the other compounds were 3-10 times less potent. Kinetic studies showed that citrinin was not an irreversible inhibitor of the enzyme, as might be expected of a quinone methide. Spectroscopic (NMR) evidence is presented for the existence of citrinin predominantly in the form of its hemi-acetal in aqueous solutions, suggesting that it is this benzo[c]pyran derivative which interacts with the enzyme, rather than the quinone methide form.

Toxicity of trichothecenes, moniliformin, zearalenone/ol, griseofulvin, patulin, PR toxin and rubratoxin B on protozoan tetrahymena pyriformis

The inhibitory effects of some fungal products from Fusarium, Trichothecium, Myrothecium and Penicillium were investigated on the protozoan Tetrahymena pyriformis. The dose of mycotoxin which decreased the protozoa growth by 50% in 24 h was defined as inhibitory dose 50 (ID50). The order of toxicity according to the ID50 values were: T-2 toxin greater than trichothecin greater than 4, 15-diacetylverrucarol greater than patulin greater than trichothecolone greater than verrucarol greater than zearalenone greater than PR toxin greater than 3 alpha-acetyldiacetoxyscirpenol greater than zearalenol greater than griseofulvin greater than acetyl T-2 greater than iso T-2 greater than T-2 triol greater than scirpentriol greater than rubratoxin B greater than T-2 tetraol greater than moniliformin. In analogous pairs of trichothecenes their toxicities depended upon the substituents at certain positions of the molecules. Thus, the order of toxicity by the substituents was: at C3 position, H greater than OH greater than OAc [e.g., verrucarol (H at C3) greater than scirpentriol (OH at C3); T-2 toxin (OH at C3) greater than acetyl T-2 (OAc at C3); 4,15-diacetylverrucarol (H at C3) greater than 3 alpha-acetyldiacetoxyscirpenol (OAc at C3)]; at C4 position, OAc greater than OH, and isocrotonyl greater than OH [e.g., acetyl T-2 (OAc at C4) greater than iso T-2 (OH at C4); trichothecin (isocrotonoyl at C4) greater than trichothecolone (OH at C4)]; at C8 position, H greater than isovaleryl greater than OH [e.g., 3 alpha-acetyldiacetoxyscirpenol (H at C8) greater than acetyl T-2 (isovaleryl at C8); T-2 triol isovaleryl at C8) greater than T-2 tetraol (OH at C8); scirpentriol (H at C8) greater than T-2 tetraol (OH at C8)]. Among trichothecenes (without ester groups) with H and OH substituents, the toxicity was inversely related to the number of OH groups in the molecule: verrucarol (2 OHs) greater than scirpentriol (3 OHs) greater than T-2 tetraol (4 OHs). Zearalenone was about 3 times more toxic than its analogue zearalenol. The Tetrahymena cultures exposed 1 d to mycotoxins had protozoa counts/microliters inversely related to doses, and the % transmittance and pH values were directly related to doses.

The isolation and identification of several trichothecene mycotoxins from Fusarium heterosporum

An isolate of Fusarium heterosporum Nees ex Fr. that parasitizes the honeydew and immature sclerotia of Claviceps paspali was shown to be highly toxigenic to day-old chickens. The major toxicity of culture extracts of the fungus was due to the presence of several trichothecene mycotoxins. Six trichothecenes were isolated and chemically identified by spectroscopic methods as T-2 toxin (1), HT-2 toxin (2), T-2 tetraol (6), 3alpha,4beta,dihydroxy-15-acetoxy-8alpha-(3-hydroxy-3-methylbutyryloxy)-12,13-epoxytrichothec-9-ene (3), 3alpha,4beta,15-trihydroxy-8alpha-(3-hydroxy-3-methylbutyryloxy)-12,13-epoxytri chothec-9-ene (5), and 3alpha,4beta,8alpha-trihydroxy-15-acetoxy-12,13-epoxytrichothec-9-ene (4). The acute toxicities of the trichothecenes were compared to the effects of T-2 toxin in day-old chickens and on the back skins of rabbits. The comparative inhibitory effects of the trichothecene mycotoxins in the Triticum coleoptile bioassays were also determined.

Toxicity and plant growth regulator effects of cytochalasin H isolated from Phomopsis sp

A biologically active metabolite was found in crude extracts of an unidentified species of Phomopsis isolated from weevil-damaged pecans. Purified metabolite was toxic to day-old cockerels, with an LD50 of 12.5 mg/kg, and was markedly inhibitory to growth the floral development of tobacco plants at concentrations of 10(-2) to 10(-4) M. IR and 1H-nmr spectra indicated an alkylpheny moiety with a single nitrogen atom present as a secondary amide; and acetate ester, OH, CH3, and a trans-double bond function. Elemental and high-resolution mass-spectral analysis indicated a formula of C30H39NO5 and a molecular weight of 493.2886. The metabolite was identified as cytochalasin H.

Two toxic indole alkaloids from Penicillium islandicum

Two new isomeric metabolites, toxins A and B, were isolated from culture extracts of Penicillium islandicum. Both toxins had a molecular formula of C16H15O2N2Cl, and physical and chemical analyses indicated that they were indole alkaloids. LD50 of toxin A was about 75-125 mg/kg in day-old cockerels. Insufficient toxin B was available to determine accurate LD50 values. Toxin A moderately inhibited growth of wheat coleoptiles but did not inhibit growth of week-old intact corn and bean plants. Toxin B showed no plant-growth inhibition.

A Growth Inhibitor from Young Expanding Tobacco Leaves

Extracts of expanding tobacco leaves inhibit the growth of wheat coleoptiles. Infrared, ultraviolet, and mass spectroscopy show that the active component is neither abscisin nor an aromatic structure.