Toxic Metabolite Produced by Aspergillus wentii

Mycelial extracts of an Aspergillus wentii strain grown on yeast-extract sucrose medium and initially isolated from country-cured ham were highly toxic when inoculated into chicken embryos or fed to mice. Moldy corn and rice were less toxic when fed to mice. Water extracts of moldy corn or rice or culture filtrates from yeast-extract sucrose medium were not toxic. Purification by thin-layer chromatography followed by crystallization yielded orange-red crystals that showed high toxicity and had a melting point of 285 to 286 C. Chloroform solutions of the crystals had absorption maxima at 270, 295, and 452 nm. The smallest amount of this component necessary to have zero hatchability of fertile eggs was 50 mug/egg.     

Effect of culture phasing and a polysaccharide on production of xylanase by mixed culture of Trichoderma reesei D1-6 and Aspergillus wentii Pt 2804

A significant increase in extracellular xylanase activity was observed in the mixed culture fermentation of Trichoderma reesei D1-6 and Aspergillus wentii Pt 2804 when A. wentii inoculation was phased by 15 h. A. wentii produced a polysaccharide, chiefly consisting of glucose monomeric units, which was required for expression of maximum xylanase activity. Expression of high activity of xylanase in the A. wentii phased mixed culture compared to that in either T. reesei or A. wentii single cultures appeared to be controlled by the combined action of a polysaccharide produced by A. wentii and the relative growth of the two fungi in the mixed culture.     

Aflatoxin: A metabolic product of several fungi

Summary Culture extracts produced by 107 fungi isolated from corn grains were assayed by thin layer chromatography for aflatoxin. Certain isolates ofAspergillus flavus, A. niger, A. parasiticus, A. ruber, A. wentii, Penicillium citrinum, andP. variabile produced aflatoxin.Penicillium frequentans andP. puberulum elaborated this toxin only in trace amounts. Bioassays of extracts from 4 of these fungi showed that only the extract fromA. parasiticus was highly toxic.     

Cellular absorption of anthraquinones emodin and chrysophanol in human intestinal Caco-2 cells

The intestinal absorption characteristics of anthraquinones emodin and chrysophanol were observed by measuring the intracellular accumulation across Caco-2 cells by the reverse-phase high performance liquid chromatography. The intracellular accumulation of chrysophanol was much greater than that of emodin, the maximum absorption of emodin and chrysophanol being 414.02+/-15.28 and 105.56+/-11.57 nmol/l x mg x protein, respectively. The absorption of each anthraquinone was significantly lower at 4 degrees C than that of 37 degrees C. The effects of the transport inhibitors, verapamil, cyclosporine and phloridzin, on the intracellular accumulation were also examined. Verapamil and cyclosporine increased the absorption of emodin and chrysophanol, while phloridzin inhibited their absorption, all in a dose-dependent manner. These results suggest that the absorption characteristics of emodin and chrysophanol were closely related to their special structure with the hydroxy groups. It is also likely that a specific transport system mediated the intracellular accumulation of emodin and chrysophanol across the Caco-2 cells.     

Effect of culture phasing and mannanase on production of cellulase and hemicellulase by mixed culture of Trichoderma reesei D 1-6 and Aspergillus wentii pt 2804

Significant increase in extracellular cellulase and hemicellulase activities was observed in the biosynthesis of cellulase enzyme in mixed culture fermentation of Trichoderma reesei D 1-6 and Aspergillus wentii Pt 2804 when the A. wentii inoculation was phased by 15 h. The optimal conditions of fermentation by the mixed culture have been established. Presence of mannanase has been found to affect the release as well as activity of cellulase enzyme produced in mixed culture.     

温特曲霉HD_1的鉴定及其对氧蒽类染料脱色特性的研究

从土壤中分离到1株染料脱色真菌,经鉴定命名为温特曲霉HD1（aspergilluswentiiWehmerHD1）.该菌对氧蒽类染料虎红具有很强的脱色能力。温度在28～40℃之间,HD1对虎红的脱色率为93～99％,最适脱色温度为33℃;pH值在4.0～8．0之间,其脱色率为89．3～98．8％,最适脱色pH值为6．0。培养基、碳源、氮源及接种量对其脱色率均有影响。该菌对虎红的脱色酶为组成酶,主要分布在细胞内。染料的加入能改变脱色酶在胞内外的分配比例,加速胞内脱色酶的合成。虎红脱色产物的紫外可见光光谱分析表明,可见光区544．8nm处的吸收峰完全消失,而紫外光区的吸收峰则减弱、移位、消失（244～277nm）或稍有增加（242nm以下）。     

小麦长蠕孢菌毒素

小麦长蠕孢菌(Helminthosporium sativum)在21—25℃的Fries溶液中振荡培养时产生的毒素,易引起与病原菌感染小麦类似的特征性病状。培养滤液的浓缩物,经丙酮沉淀,正丁醇-氯仿萃取,二次硅胶柱层析等程序,将毒素部分纯化,毒素的硅胶TLC层析表明,毒素层离组分至少为6种,在紫外灯下和碘蒸气中观察,显蓝紫色光斑和棕黄色斑,它们的Rf值依次为0.12,0.16,0.25,0.36,0.43,0.54,并具有倍半萜类化合物特有的紫外吸收带,它们的最大吸收值(max)分别为270,285,287,290,287,287nm,与国外报道乙醚提取物的紫外吸收特性相近(sommereyns & Closset,1978)。生物检测结果表明,上述组分均为毒素活性部分,它除能溶于ε为10以上的溶剂外,对热和光稳定,最适pH 4—7,极端pH下,毒素活性被钝化,回调最适pH后,活性仍可恢复,即令高温蒸煮也不丧失活性。毒素对小麦叶组织伤害能力及其活性与温度,毒素浓度和剂量,作用时间的变化呈正相关。     

豆壳过氧化物酶的电子吸收光谱性质

应用电子吸收光谱技术研究了豆壳过氧化物酶 ( EC1 .1 1 .1 .7)的不同氧化态电子吸收光谱 ,并与其它来源的过氧化物酶作了比较研究 .天然态酶的特征吸收峰位为 40 4 nm的 Soret带 ,638nm的α带和 50 8nm的β带 ,与过氧化氢反应可生成三类复合物 .复合物 ( Com )在 40 8、580、61 8和 655nm处出现特征吸收 ;复合物 ( Com )在 41 9、52 9和 556nm处显示特征吸收 ;复合物 ( Com )则于 41 8、543和 578nm处显示特征吸收 .天然态酶经连二亚硫酸钠还原则出现 435和 558nm的特征峰 ,与氰化钾作用在 42 2和 544nm处显示特征吸收 .氰化钾对该酶的抑制为竞争性抑制 ,其 Ki 值为 2 .4μmol/L.     

Photochemical revelation of the stacking aggregation of thymine chromophores in water solutions of polythymidylic acid

The structure heterogeneity of water solutions of polyribothymidylic acid at T(room) was studied from changes caused in their absorption spectra by the photodimerization reaction. Three fractions of thymine chromophores were revealed from the differential absorption spectra: (a) the main fraction consisting of weakly interacting (isolated chromophores) chromophores with the absorption spectrum maximum at approximately 270 nm; (b) pair chromophores of the first type with the absorption spectrum maxima at 260 and 290 nm (exciton splitting 4000 cm(-1)); and (c) pair chromophores of the second type with the absorption spectrum maxima at 250 and 280 nm (exciton splitting 4300 cm(-1)). The revealed aggregates have a relatively high photochemical activity in the photodimerization reaction in comparison with the isolated chromophores. They contribute little to the total absorption spectrum of solutions but make a great contribution to its changes at the initial stages of the UV irradiation of solutions.     

Toxigenic Aspergillus and Penicillium Isolates from Weevil-Damaged Chestnuts

Aspergillus and Penicillium were among the most common genera of fungi isolated on malt-salt agar from weevil-damaged Chinese chestnut kernels (16.8 and 40.7% occurrence, respectively). Chloroform extracts of 21 of 50 Aspergillus isolates and 18 of 50 representative Penicillium isolates, grown for 4 weeks at 21.1 C on artificial medium, were toxic to day-old cockerels. Tweleve of the toxic Aspergillus isolates were identified as A. wentii, eight as A. flavus, and one as A. flavus var. columnaris. Nine of the toxic Penicillium isolates were identified as P. terrestre, three as P. steckii, two each as P. citrinum and P. funiculosum, and one each as P. herquei (Series) and P. roqueforti (Series). Acute diarrhea was associated with the toxicity of A. wentii and muscular tremors with the toxicity of P. terrestre, one isolate of P. steckii, and one of P. funiculosum.     

Sambutoxin, a new mycotoxin produced by toxic Fusarium isolates obtained from rotted potato tubers.

Ninety-nine isolates of Fusarium species were obtained from rotted potato tubers from various parts of Korea. Of these isolates, 80 were identified as Fusarium oxysporum, F. solani, or F. sambucinum. The isolates of these species were grown on autoclaved wheat grains and examined for toxicity in a rat-feeding test. A total of 8 of 57 F. oxysporum isolates, 3 of 14 F. solani isolates, and 5 of 9 F. sambucinum isolates caused the death of the rats. Of the 16 toxic isolates, 1 isolate of F. oxysporum produced a substantial amount of moniliformin, which could account for its toxicity. None of the other 15 isolates produced trichothecenes, moniliformin, fusarochromanone, fumonisin B1, or wortmannin. F. sambucinum PZF-4 produced an unknown toxin in wheat culture. This new toxin, given the trivial name sambutoxin, caused toxic effects in rats, including body weight loss, feed refusal, hemorrhage in the stomach and intestines, and, finally, death when rats were fed diets supplemented with 0.05 and 0.1% sambutoxin. The toxin was also toxic to chicken embryos, and the 50% lethal concentration was 29.6 micrograms per egg. Sambutoxin formed as white crystals that turned purple when combined with reagents such as sulfuric acid and p-anisaldehyde. It exhibited a green color immediately after treatment with potassium ferricyanide-ferric chloride. Its UV spectrum had absorption maxima at 213, 233, and 254 nm, and its infrared spectrum showed an amide group at 1,650 and 1,560 cm-1 and a hydroxy group at 3,185 cm-1. Mass spectrometry showed that the molecular weight of the toxin was 453 and the molecular formula was C28H39NO4.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies on the toxin of Aspergillus fumigatus. VII. Purification and some properities of hemolytic toxin (asp-hemolysin) from culture filtrates and mycelia.

A hemolytic toxin has been obtained from mycelia and culture filtrates of Aspergillus fumigatus by the procedures that included precipitation with ammonium sulfate, chromatography of DEAE-Sephadex, affinity chromatography on Concanavalin A-Sepharose and gell filtration on Sephadex G-50, G-100 AND G-150. The purified homolytic toxin was homogeneous on immunological and disk electrophoretic analysis, and the toxin from culture filtrates was identical with that from mycelia by the immunodiffusion technique. The hemolytic toxin was obtained for the first time from fungi and designated as Asp-hemolysin. The molecular weight of Asp-hemolysin was estimated to be appoximately 30,000 by the gel-filtration technique and its isoelectric point was found to be around pH 4.0. This Asp-hemolysin contained large amounts of protein and very small amounts of carbohydrate. The UV absorption spectrum of Asp-hemolysin showed a maximum absorption at 280 nm and minimum absorption at 251 nm. The extinction coefficient at 280 nm and minimum absorption at 251 nm. The extinction coefficient at 280 nm, E 1% 1CM, was 12.4 and the ratio of absorbance at 280 nm to that at 260 nm was 2.3. The optimum pH for the hemolytic activity of the toxin toward chicken erythrocytes was 5.0 at room temperature and it was active in the pH range of 3.5 to 10.5. The optimum temperature was 21 C and about 50% of the activity was lost by incubation at 50 C for 5 min or 45 C for 23 min. The hemolytic activity was remarkably inhibited by Hg2+, Cu2+, Fe2+, Ag1+, iodine and p-CMB, but enhanced slightly by Zn2+ and Co2+.     

Cleavage of cardiac steroid glucosides by pure beta-glucosidase from Aspergillus ventii.

Electrophoretically pure beta-glucosidase (beta-glucoside glucohydrolase, EC 3.2.1.21) A3 from Aspergillus wentii was shown to deglucosylate cardiac steroid biosides, triosides and tetraosides with a terminal beta-D-glucoside residue linked to the aglycon sugar in 1 leads to 6 or 1 leads to 4 position. In dependence on the structure and conformation of the aglycon, the deglucosylation rate may vary by six orders of magnitude.     

Synthesis of 5-amino-5-deoxy-D-mannopyranose and 1,5-dideoxy-1,5-imino-D-mannitol, and inhibition of alpha- and beta-D-mannosidases

The title compounds and the corresponding L-gulo derivatives were synthesised in 6 steps from benzyl 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranoside. The Ki values, determined from inhibition studies with alpha-D-mannosidases from jack beans, almonds, and calf liver, and beta-D-mannosidase from Aspergillus wentii, ranged from 70 to 400 microM for the mannitol derivative and from 1.2 to 20 microM for 5-amino-5-deoxy-D-mannopyranose, i.e., inhibition is 10(2)-10(4)-fold stronger than with D-mannose. Marked enhancement of inhibition with increasing pH is ascribed to the ionisation of a carboxyl group at the active site, forming an ion pair with the protonated inhibitor. The inhibition equilibrium between the jack-bean enzyme and the mannose derivative was approached slowly with kapp 2.0 X 10(5) M-1 X min-1. The mannose-derived inhibitor was also inhibitory against beta-D-glucosidases from almonds and Asp. wentii, with Ki values only 20-150-times larger than those for the inhibition of these enzymes by 5-amino-5-deoxy-D-glucopyranose. This moderate discrimination in binding of D-gluco and D-manno derivatives is in marked contrast to the high specificity shown by the glucosidase in catalysing the hydrolysis of mannosidases. A similar low specificity with respect to binding, combined with highly specific catalysis, was also seen with the mannosidases acting on inhibitors and substrates with the D-gluco configuration.     

Studies on toxigenic fungi in roasted foodstuff (Salted seed) and halotolerant activity of emodin-producingAspergillus wentii

Commercial roasted salted peanuts (3% NaCl), popcorn (1% NaCl), summer-squash (9% NaCl), sunflower (3% NaCl) and wild-melon (3% NaCl) seeds are polluted with fungi, mostlyAspergillus flavus, A. niger, Penicillium chrysogenum, P. corylophilum andRhizopus stolonifer. Contamination of popcorn with the fungi is about 10 times higher than in the other foods. These fungi, common also on unsalted seeds, are significantly inhibited in seeds (30% moisture content) treated with 9–21% NaCl. The halotolerantA. wentii represents the main fungus recovered from seeds treated by 15–21% NaCl. 9% NaCl stimulated emodin production byA. wentii on peanut and citrinin production byP. chrysogenum on popcorn and sunflower. Aflatoxin, citrinin and emodin production on popcorn persisted up to 15% NaCl. Popcorn is thus strongly susceptible to fungal invasion and toxin pollution. The halotolerance ofA. wentii was confirmed by its strong permanent growth in liquid medium at up to 15% NaCl. At 3% NaCl the mycelial growth and nitrogen content increased while the level of emodin and lipid production decreased. CO₂ evolution strongly increased at 9–15% NaCl as a characteristic ofA. wentii salt tolerance. Emodin inhibited seed viability and the inhibition dose for 50% reduction (LD₅₀) was 65 mg/L for popcorn and 45 mg/L for sunflower.     

Immune reponses in human mesangial cells regulated by emodin from Polygonum hypoleucum Ohwi

In the hope of identifying agents of therapeutic value in glomerulonephritis from Chinese herbs, we found that methanolic extracts of Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) inhibit human mesangial cells proliferation activated with interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) previously. This study was designed to identify bioactive components from P. hypoleucum Ohwi and elucidate their action mechanisms. We tested four anthraquinones emodin, emodin 1-O-beta-D-glucoside (49A), physcion (62A), and physcion 1-O-beta-D-glucoside (50A) purified from P. hypoleucum Ohwi for their effects on human mesangial cell proliferation and cytokines production in vitro. On a percentage basis, emodin had the highest suppressing activity on the human mesangial cells proliferation activated by IL-1beta and IL-6. The IC50 of emodin on human mesangial cells proliferation were 17.9+/-1.2 microM. In contrast to 49A, 50A, and 62A, emodin also decreased IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha) production in human mesangial cells activated with IL-1beta and IL-6. The IC50 of emodin on IL-1beta, IL-6 and TNF-alpha production in activated human mesangial cells were 16.6+/-1.8 microM, 8.2+/-1.3 microM, and 9.5+/-1.6 microM, respectively. Moreover, IL-1beta and TNF-alpha mRNA expression in activated human mesangial cells was impaired by emodin. The intracellular free Ca2+ concentration ([Ca2+]i) in IL-1beta and IL-6 activated human mesangial cells was decreased by emodin. It is unlikely that cytotoxicity was involved because no cell deaths were observable. We hypothesize that the inhibitory mechanisms of emodin on activated human mesangial cells proliferation may be related to the impairments of gene expression and production of cytokines and [Ca2+]i in the cells.     

Absorption and fluorescence spectra of chlorophyll-proteins isolated from Euglena gracilis

A spectroscopic study of chlorophyll-protein complexes isolated from Euglena gracilis membranes was carried out to gain information about the state of chlorophyll in vivo and energy transfer in photosynthesis. The membranes were dissociated by Triton X-100 and separated into fractions by sucrose gradient centrifugation and hydroxyapatite chromatography. Four different types of chlorophyll-protein complexes were distinguished from each other and from detergent-solubilized chlorophyll in these fractions by examination of their absorption, fluorescence excitation (400–500 nm) and emission spectra at low temperature. These types were: (1). A mixture of antenna chlorophyll a- and chlorophyll ab-proteins with an absorption maximum at 669 and emission at 682 nm; (2) a P-700-chlorophyll a-protein (chlorophyll: P-700 = 30 : 1), termed CPI with an absorption maximum at 676 nm and emission maxima at 698 and 718 nm; (3) a second chlorophyll a-protein (CPI-2) less enriched in P-700, with an absorption maximum at 676 nm and emission maxima at 680, 722 and 731 nm; (4) a third chlorophyll a-protein (CPa₁) with no P-700, absorption maxima at 670 and 683 nm, and an unusually sharp emission maximum at 687 nm. Treatment of CPa₁ with sodium dodecyl sulfate drastically altered its spectroscopic properties indicating that at least some chlorophyll-proteins isolated with this detergent are partially denatured. The results suggest that the complex absorption spectra of chlorophyll in vivo are caused by varying proportions of different chlorophyll-protein complexes, each with different groups of chlorophyll molecules bound to it and making up a unique entity in terms of electronic transitions.     

Molecular spectroscopic studies on the interactions of rhein and emodin with thioglycolic acid‐capped core/shell CdTe/CdS quantum dots and their analytical applications

Water‐soluble thioglycolic acid (TGA)‐capped core/shell CdTe/CdS quantum dots (QDs) were synthesized. The interactions of rhein and emodin with TGA‐CdTe/CdS QDs were evaluated by fluorescence and ultraviolet‐visible absorption spectroscopy. Experimental results showed that the high fluorescence intensity of TGA‐CdTe/CdS QDs could be effectively quenched in the presence of rhein (or emodin) at 570 nm, which may have resulted from an electron transfer process from excited TGA‐CdTe/CdS QDs to rhein (or emodin). The quenching intensity was in proportion to the concentration of both rhein and emodin in a certain range. Under optimized conditions, the linear ranges of TGA‐CdTe/CdS QDs fluorescence intensity versus the concentration of rhein and emodin were 0.09650–60 µg/mL and 0.1175–70 µg/mL with a correlation coefficient of 0.9984 and 0.9965, respectively. The corresponding detection limits (3σ/S) of rhein and emodin were 28.9 and 35.2 ng/mL, respectively. This proposed method was applied to determine rhein and emodin in human urine samples successfully with remarkable advantages such as high sensitivity, short analysis time, low cost and easy operation. Based on this, a simple, rapid and highly sensitive method to determine rhein (or emodin) was proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

大黄蒽醌衍生物对酪氨酸酶的抑制作用

大黄素对酪氨酸酶有显著的竞争性抑制作用,K_i值为1.51×10~(-4)mol,50％抑制的药物浓度为36.6μg/ml;大黄酸的抑制作用较弱,芦荟大黄素几乎无抑制作用。氯化铜(3.3×10~(-7)mol/L)、半胱氨酸(3.3×10~(-7)mol/L)和牛血清白蛋白(1.0mg/ml)对大黄素抑制酪氨酸酶有较强的拮抗作用,恢复率分别为60.0％、45.7％和61.1％。大黄素能与牛血清白蛋白非特异性结合形成复合物,引起吸收光谱红移55毫微米。大黄蒽醌衍生物对酪氨酸酶的抑制作用可能是大黄抗黑色素瘤的作用机制之一。     

Isolation and Characterization of Stemphylin, a Chromone Glucoside from Stemphylium botryosum

A phytotoxic compound was isolated from a liquid culture medium of Stemphylium botryosum, a pathogen of lettuce. The toxin is an amorphous yellow solid with absorbance maxima at 218, 268, and 427.5 nm and exhibits a bathochromic shift in alkaline pH. It has a molecular weight of 370 and an empirical formula of C(17)H(22)O(9). Glucose and aromatic pigments are detected after acid hydrolysis. Based on its spectral and chemical properties, the proposed structure of the toxin is 3-hydroxy- 2,2-dimethyl-5-alpha-d-glucopyranoside-2,3-dihydrochromone, and it has been given the trivial name stemphylin. A linear relationship exists between lesion area and amount of toxin applied to a young lettuce leaf. The relationship between toxin production and the development of disease symptoms is discussed.