红光对紫色红曲霉生长及色素和桔霉素产量的影响

本文研究了红光对紫色红曲霉M9生长及色素和桔霉素产量的影响。采用高效液相色谱法对六种红曲色素,包括两种红色素：红斑红曲胺（rubropunctamine,RUM）和红曲玉红胺（monascorubramine,MOM）;两种黄色素：红曲素（monascin,MS）和红曲黄素（ankaflavin,AK）;两种橙色素：红斑红曲素（rubropunctatin,RUN）和红曲玉红素（monascorubrin,MON）以及桔霉素的产量进行测定。结果表明：持续红光照射促进了紫色红曲霉M9菌丝生长、色素合成积累以及孢子形成,尤其对于闭囊壳的产生有更显著促进作用。5种不同的红光照射条件促进了RUM、MOM、MS和AK的产生,抑制了RUN、MON和桔霉素的产生。在光照强度300 lux,光照时间30 min/d,光照节律12 h的最佳光照条件下,RUM、MOM的产量分别提高了53.8%和75.2%;MS和AK的产量分别提高了42.2%和59.4%;RUN和MON的产量分别降低了42.6%和54.5%;桔霉素的产量降低了42.5%。     

New Monascus metabolites: structure elucidation and toxicological properties studied with immortalized human kidney epithelial cells

Monascus sp. are used for the production of red yeast rice, which has been applied in Asian food and medicine for centuries. The fungi form several secondary metabolites, among others the monascopyridines A and B. We have now detected two new monascopyridines (named C and D) with similar UV absorption spectra and maxima at 306-307 nm in red rice fermented with M. purpureus. The new monascopyridines have the same chromophores as the already known and differ in a missing gamma-lactone ring only. Monascopyridine C has a hexanoyl side chain, whereas monascopyridine D is the higher homologue with an octanoyl side chain. The toxicological properties of monascopyridines were studied using immortalized human kidney epithelial cells, displaying cytotoxic effects in micromolar concentrations with median effective concentration values between 20.7 and 43.2 micromol/L, depending on the compound and method used. The monascopyridines C and D did not induce apoptosis. However, they caused a rise of the mitotic index from 3.21 +/- 0.27% (control) to maximum 8.14 +/- 0.89% (monascopyridine D) by an accumulation of cells in the metaphase with a simultaneous decrease of cells in the ana- and telophase. Monascopyridine-induced metaphase arrest is caused by a partial or complete loss of the spindle apparatus as indicated by the occurrence of abnormal metaphases and immunological staining of alpha-tubulin. These effects are indicating an aneuploidic potential and therefore the monascopyridines C and D might contribute to tumor formations.     

红曲色素的色调及发酵工艺条件对色调的影响

用扫描式分光光度计对 3种纯红曲色素及板层析分离的色素进行分析 ,得出了其特征性吸收峰及对应波长。安卡红曲黄素 (黄色 ) ,红曲玉红素 (橙色 )分别在 388nm ,464nm ,而红斑玉红胺 (紫色 )在 51 6nm和 41 8nm 2处有吸收峰。复合色素的主吸收峰在 490～ 50 0nm处。此外 ,板层析上还有深黄和米黄等色素。红曲米的色调取决于多种色素的相对比例。红曲米的发酵工艺条件对色素的相对比例具有重要的影响。锌离子对红曲霉产色素具有促进作用。培养过程中添加醋酸不利红曲霉产生橙色素 ,而有利黄色素的产生。     

Effect of ammonium nitrate on the production of PP-V and monascorubrin homologues by Penicillium sp. AZ

A fungal strain, Penicillium sp. AZ, has been found to produce the monascorubramine homologues, PP-V [(10Z)-3-(9a-methyl-3-octanoyl-2,9-dioxo-2,7,9,9a-tetrahydro-furo[3,2-g]isoquinolin-6-yl)-acrylic acid] and PP-R [(10Z)-7-(2-hydroxyethyl)-monascorubramine] when cultured in a medium composed of soluble starch, ammonium nitrate, yeast extract, and citrate buffer, pH 5.0. When ammonium nitrate was omitted from the culture medium, PP-V and PP-R production was replaced by orange (PP-O) and yellow-orange (PP-Y) pigment production. The structures of these pigments were determined by FAB-MS and 1H and 13C NMR to be novel compounds, (10Z)-3-(9a-methyl-3-octanoyl-2,9-dioxo-9,9a-dihydro-2H-furo[3,2-g]isochromen-6-yl)-acrylic acid and (10Z)-monascorubrin, respectively.     

高效液相色谱法测定红曲莫纳可林及桔霉素——如何防治色素的干扰

红曲产品存在的色素对桔霉素和莫纳可林K的高效液相色谱分析有干扰作用 ,并造成色谱柱负担过重。消除色素的副面影响显得尤为重要。采用甲苯 /乙酸乙酯 /甲酸为溶剂萃取固态红曲样品 ,可在萃取较少色素的同时最大程度萃取桔霉素。对于液态发酵的红曲样品 ,采用 2倍于发酵液体积的乙醇萃取桔霉素的方法也优于其他方法。在HPLC分析中 ,用红曲的 3种色素与莫纳可林K(酸型和内酯型 )分别进样或混合后进样 ,发现当流动相中的乙腈浓度较高时 ,内酯型莫纳可林K与黄色素有相当接近的出峰时间。同时 ,紫色素、橙色素与酸型莫纳可林K也有相当接近的出峰时间 ,无法完全分离。如果不预先去除红曲色素 ,也可通过降低流动相中乙腈的比例 ,有效分离色素与莫纳可林K ,以提高分析结果的准确性。     

散囊菌产次级代谢物及其生物活性研究进展

散囊菌广泛分布于自然环境,也是传统发酵食品的重要发酵剂,例如它们是日本鲣鱼发霉工艺和中国茯砖茶发花工艺的优势菌。本文总结了散囊菌的主要类群和生态分布,散囊菌产生的次级代谢物的种类和生物活性功能。研究表明散囊菌的次级代谢物主要包括蒽醌衍生物类和苯甲醛衍生物类色素以及二酮哌嗪类霉菌毒素,并图示了38种次级代谢物的化学结构式。次级代谢物的生物活性涉及抗微生物、抗氧化和抗肿瘤等多个方面。      

Application of various methods for determination of the color of cocoa beans roasted under variable process parameters

Cocoa beans of Forastero variety from Togo were subjected to roasting under either constant or variable process parameters. The variable process parameters were roasting air flow rate, temperature and relative humidity. The color of roasted cocoa beans was determined by pigment extraction under various conditions followed by either their spectrophotometric assays or CIE L*a*b measurements. Also the Maillard compounds index and total polyphenols content correlated with progress of the browning of beans were determined. It was found that an increase in the roasting air relative humidity stimulated formation of brown pigments, while elevated temperature caused worsening of color parameters of roasted cocoa beans. The most suitable method of color characterization of roasted cocoa beans was found to be pigments extraction combined with either separation of their fractions or CIE L*a*b measurements. These assays revealed that cocoa beans roasted under variable roasting air flow rate were characterized by improved color parameters. The relatively simple and inexpensive CIE L*a*b measurements ensured fast analysis of color parameters, while total polyphenols in roasted cocoa beans were quickly estimated by using F–C reagent. Furthermore, quantification of melanoid pigments in roasted cocoa beans can be based on determination of the index of nonenzymatic browning products content, which is relatively simple and inexpensive.     

Structural elucidation and analysis of thermal degradation products of the Fusarium mycotoxin nivalenol

The major class of mycotoxins produced by Fusarium moulds are trichothecenes, a large group of sesquiterpenes sharing the same basic chemical structure, a 12,13-epoxytrichothec-9-ene ring system. Their toxic effects range from causing diarrhoea, vomiting and gastro-intestinal inflammation to noncompetitive inhibition of the biosynthesis of proteins in eukaryotic cells. Trichothecenes in general are relatively stable compounds, their degradation is observed only at high temperatures and prolonged heating time. In order to investigate the stability of the trichothecene nivalenol (NIV) under food processing conditions such as cooking or baking, we performed model heating experiments and screened the residue for degradation products using gas chromatography-mass spectrometry (GC-MS). Heating of nivalenol, especially under mild alkaline conditions, gave a mixture of four compounds (norNIV A, norNIV B, norNIV C, and NIV lactone), which where isolated and identified by nuclear magnetic resonance (NMR) and MS experiments. Although their formation was also demonstrated in heating experiments with spiked flour samples, only norNIV B was detectable in a screening of several commercially available samples, possibly due to the very low contamination with nivalenol. Furthermore, cell culture experiments using immortalized human kidney epithelial (IHKE) cells showed that the four compounds are less cytotoxic (formazan dye cytotoxicity assay) compared to nivalenol. Whereas nivalenol revealed an EC50 at 0.9 micromol, all other compounds did not show any significant effect up to 100 micromol.     

基于HepG2细胞模型研究普洱茶茶色素的抗氧化作用

采用正常培养和油酸诱导培养的HepG2细胞为模型,通过测定普洱茶茶色素对HepG2细胞外谷胱甘肽(glutathione,GSH)含量,过氧化氢酶(catalase,CAT)活力和细胞内丙二醛(malondialdehyde,MDA)含量的影响,以研究普洱茶茶色素的抗氧化作用。结果显示,普洱茶茶色素对正常培养的HepG2细胞的抗氧化作用影响不显著,而对油酸诱导的HepG2细胞模型抗氧化作用有显著的提高。抗氧化作用提高的程度依赖于普洱茶茶色素的质量浓度。当400μg/m L普洱茶茶色素作用HepG2油酸诱导模型24 h,细胞外GSH含量由0.004 4 g/L增加到0.010 3g/L,CAT活力由0.136 U/m L提高至1.174 U/m L,细胞内MDA含量由15.146 nmol/mg减少到7.635 nmol/mg,从而使这些指标接近正常培养HepG2细胞模型水平。因此,普洱茶茶色素的抗氧化作用是通过提高清除活性氧的酶活力和促进合成还原性物质来干预细胞的氧化应激。     

Beneficial biofilm formation by industrial bacteria Bacillus subtilis and related species

Biofilms are densely packed multicellular communities of microorganisms attached to a surface or interface. Bacteria seem to initiate biofilm formation in response to specific environmental cues, such as nutrient and oxygen availability. Biofilms undergo dynamic changes during their transition from free-living organisms to sessile biofilm cells, including the specific production of secondary metabolites and a significant increase in the resistivity to biological, chemical, and physical assaults. Bacillus subtilis is an industrially important bacterium exhibiting developmental stages. It forms rough biofilms at the air-liquid interface rather than on the surface of a solid phase in a liquid, due to the aerotaxis of the cells. Biofilm formation by B. subtilis and related species permits the control of infection caused by plant pathogens, the reduction of mild steel corrosion, and the exploration of novel compounds. Although it is obviously important to control harmful biofilm formation, the exploitation of beneficial biofilms formed by such industrial bacteria may lead to a new biotechnology.     

Strawberry Polyphenoloxidase: Its Role in Anthocyanin Degradation

Two purified fractions of strawberry polyphenoloxidase (PPO) were used in model systems containing D-catechin alone or in combination with either pelargonin or cyanin. Km values using D-catechin were 0.5 mM and 0.41 mM and Vmax 82,700 and 18,800 nmoles O²/min/ mg protein, respectively, for each isozyme. Reaction of PPO with D-catechin led to the formation of yellow-brown pigments with maximum absorbance at 390 nm. Little PPO activity could be detected using cyanin as a substrate and no activity with pelargonin. PPO and D-catechin together caused the loss of 50 to 60% of the anthocyanin pigments after 24 hr at room temperature with the formation of a precipitate.     

Isolation and identification of 5-carboxy-pyranoanthocyanins in beverages from cherry (Prunus cerasus L.)

Novel pyranoanthocyanins were identified by HPLC–ESI-MSⁿ in fermented and unfermented fruit juices from cherry (Prunus cerasus L.). The two major compounds, namely 5-carboxy-pyranocyanidin 3-O-(2^G-glucosylrutinoside) and 5-carboxy-pyranocyanidin 3-O-rutinoside were isolated by a combination of high-speed countercurrent chromatography with semi-preparative HPLC. Their structures were fully elucidated by means of NMR spectroscopy and mass spectrometry. As minor compounds 5-carboxy-pyranocyanidin 3-glucoside, 5-carboxy-pyranopeonidin-3-glucoside, and 5-carboxy-pyranopeonidin 3-rutinoside could be identified.These compounds are formed during storage of the juice through the reaction of pyruvic acid with the respective genuine anthocyanins.Industrial relevanceFor the consumers the color of fruit juices is one of the most important quality markers. However due to a fast degradation of anthocyanins, changes in color from purple/red hues to orange/brown hues can be observed during storage. The main objective of this study was the isolation, structural characterization and evaluation of pigments that are formed during aging of fruit juices. Pyranoanthocyanins were reported to possess a color stabilizing effect. In the present study it could be demonstrated that the color contribution of these newly formed pigments to the overall color of fruit juice was overestimated. Instead, the formation of polymeric pigments yields the highest impact (> 80%) on the color of aged fruit juices.     

Metabolism of curcumin and induction of mitotic catastrophe in human cancer cells

In cultured cells, curcumin (CUR) causes cell death by interfering with mitosis and leading to fragmented nuclei and disrupted microtubules, a process named mitotic catastrophe. In order to clarify the role of the known CUR metabolites hexahydro-CUR (HHC) and CUR-glucuronide (CUR-gluc) in mitotic catastrophe, the effects of CUR were studied in three human cancer cell lines with different metabolism of CUR. In Ishikawa and HepG2 cells, CUR was metabolized to HHC and small amounts of octahydro-CUR (OHC), whereas the only metabolism in HT29 cells was the formation of CUR-gluc. Despite their different metabolism, all three cell systems responded to CUR with arrest in G2/M phase and mitotic catastrophe. Fractionation of the cells showed that concentrations of CUR were higher in the ER and cytosol than in the incubation medium by a factor of up to about 150 and 8, respectively. In contrast to CUR, the metabolite HHC and the products of spontaneous degradation did not elicit any effects in Ishikawa cells. These results imply that the causative agent of mitotic catastrophe is the parent CUR molecule, whereas reductive metabolism and chemical degradation render CUR inactive.     

Evaluation of the Genotoxicity of Chitosan Nanoparticles for Use in Food Packaging Films

Abstract: The use of nanoparticles in food packaging has been proposed on the basis that it could improve protection of foods by, for example, reducing permeation of gases, minimizing odor loss, and increasing mechanical strength and thermal stability. Consequently, the impacts of such nanoparticles on organisms and on the environment need to be investigated to ensure their safe use. In an earlier study, Moura and others (2008a) described the effect of addition of chitosan (CS) and poly(methacrylic acid) (PMAA) nanoparticles on the mechanical properties, water vapor, and oxygen permeability of hydroxypropyl methylcellulose films used in food packaging. Here, the genotoxicity of different polymeric CS/PMAA nanoparticles (size 60, 82, and 111 nm) was evaluated at different concentration levels, using the Allium cepa chromosome damage test as well as cytogenetic tests employing human lymphocyte cultures. Test substrates were exposed to solutions containing nanoparticles at polymer mass concentrations of 1.8, 18, and 180 mg/L. Results showed no evidence of DNA damage caused by the nanoparticles (no significant numerical or structural changes were observed), however the 82 and 111 nm nanoparticles reduced mitotic index values at the highest concentration tested (180 mg/L), indicating that the nanoparticles were toxic to the cells used at this concentration. In the case of the 60 nm CS/PMAA nanoparticles, no significant changes in the mitotic index were observed at the concentration levels tested, indicating that these particles were not toxic. The techniques used show promising potential for application in tests of nanoparticle safety envisaging the future use of these materials in food packaging.     

福建红曲中红曲菌的分离鉴定及菌株特性研究

采用选择性培养基分离纯化福建各地区红曲样品中的红曲菌,得到17株红曲菌纯菌株。经菌落形态特征观察,生理生化试验以及分子生物学鉴定手段,17株红曲菌被鉴定为变红红曲菌(M.serorubescens Sato)、橙色红曲菌(M.aurantiacus)、新月红曲菌(M.lunisporas)、血红色红曲菌(M.sanguineus)和高粱红曲菌(M.kao-liang)五大类。通过液态发酵法研究红曲菌产糖化酶,产色素以及产生理活性物质莫纳可林(Monacolin K)能力,结果表明不同红曲菌菌株特性存在显著性差异,其中被鉴定为高粱红曲菌的B6菌株具有最高的产色素能力和产莫那可林K(Monacolin K)能力,其醇溶性总色价为3373.12U/g,酸式和内酯式莫那可林K产量分别为25.928mg/L和12.114mg/L,产淀粉酶酶活力为543.21U/g。B6菌株是可用于红曲黄酒酿造的优良红曲菌菌株。     

Antioxidant properties of anthocyanidins,anthocyanidin-3-glucosides and respective portisins

The study of the antioxidants properties of three classes of pigments, namely anthocyanidins (cyanidin-Cy, delphinidin-Dp and malvidin-Mv), anthocyanidin-3-glucosides (Cy-3-gluc, Dp-3-gluc and Mv-3-gluc), and portisins (Cy-pt, Dp-pt and Mv-pt) was carried out. The aim was to evaluate the relationship between the structure antioxidant properties of individual anthocyanins and respective derivative pigments. The ability of these compounds to inhibit lipid peroxidation in a liposome membrane system was examined by monitoring oxygen consumption and the antiradical and reducing capacities were determined using the DPPH and FRAP assay, respectively. All compounds tested showed antiradical and reducing properties. These features seemed to increase with the presence of catechol and pyrogallol groups in ring B of anthocyanidin-3-glucosides and respective aglycones. The results obtained for portisins are very likely to be related with their unique structural features. The flavanol moiety of the compounds structure seems to be crucial for the antiradical properties, whilst their reducing ability was only evident for the portisin derived from malvidin. This outcome could be due to some of the structural features of these pigments as they are complex structures and may have several different conformations in solution. The antioxidant protection towards lipid peroxidation increased with the overall hydrophobicity of the compounds. This feature is related to the location of the antioxidant on the liposome surface vs. water phase. Among the pigments tested, portisins showed the higher effect in preventing lipid peroxidation of soybean phosphatidylcholine liposomes, especially the portisin derived from Cy. This outcome could be due to the presence of two o-catechol groups in the structure of this compound.     

Chlorosis induced by substituted benzoic acids and related compounds

A number of derivatives of 4-hydroxy-3-nitrobenzoic acid and 4-methoxy-3-nitrobenzoic acid and related compounds have been prepared, and their ability to produce chlorosis in six different species of plants has been examined. This series of compounds caused white and yellow areas to appear in the young tissues of the plants. A representative ester, ethyl-4-methoxy-3-nitrobenzoate, which caused this effect in barley was shown to affect the iron content and to reduce the quantity of pigments significantly. The structural requirements within this series of compounds for producing the type of chlorosis concerned are briefly discussed.