玉米灵芝菌粮营养成分及加工特性变化研究

玉米作为主要的杂粮谷物,营养价值高,维生素、膳食纤维等含量丰富,可以预防多种亚健康疾病,受到市场追捧。但是玉米粉营养结构不均衡、加工性差,限制其应用。有研究表明,微生物发酵技术可以改善谷物的营养成分、大分子物质结构和加工特性。基于此,利用灵芝固态发酵玉米,得到玉米灵芝菌粮（简称菌粮）,从营养成分、大分子物质结构和加工特性3个方面对其进行评价。结果显示,与未发酵玉米相比,菌粮中碳水化合物、蛋白质含量分别提高了748%、28.00%,且蛋白质的氨基酸评分提高,而脂肪含量降低了52.56%;维生素C、核黄素和烟酸含量均显著提高（P<0.05）,分别提高了56.19%、73.91%和20.27%,且玉米中缺乏的硫胺素在菌粮中被检测到;菌粮中各类淀粉和纤维的含量也发生了显著变化（P<0.05）,淀粉、支链淀粉含量分别降低了11.17%、34.70%,直链淀粉含量提高了26.66%,粗纤维、不溶性膳食纤维含量分别降低了21.07%、21.47%,可溶性膳食纤维含量提高了13.57%;菌粮粉粘度降低,水溶性指数提高,吸水性指数和溶胀力降低;此外,与灵芝子实体相比,菌粮中灵芝三萜和灵芝酸含量均显著提高（P<0.05）,分别为灵芝子实体的1.68和2.07倍。灵芝固态发酵玉米得到的玉米灵芝菌粮,营养结构更加均衡,功能活性提高,具有更高的营养价值;大分子物质结构发生改变,加工特性得到改善,冲调特性更好。研究结果为食用菌发酵改良谷物特性的研究提供了参考和指导。     

双斑蟋营养成分分析及评价

由于具有较好的营养价值以及较高的食物转化效率,食用昆虫特别是蟋蟀受到普遍关注。在双斑蟋（Gryllus bimaculatus,GB）营养成分测定的基础上,对比家蟋（Acheta domesticus,AD）和黑蟋（Gryllus testaceus,GT）的营养及含量,分析评价了双斑蟋的使用价值。结果显示：双斑蟋水分含量71.0%、粗蛋白含量58.60%（干重）、粗脂肪含量28.90%（干重）、粗纤维含量7.23%（干重）、灰分4.93%（干重）;蛋白含量与黑蟋相当而高于家蟋,粗脂肪和灰分含量要高于家蟋和黑蟋;双斑蟋含有17种氨基酸,总氨基酸含量51.03%（干重）,必需氨基酸含量24.76%（干重）、占总氨基酸的48.3%,氨基酸含量低于其他两种蟋蟀;双斑蟋中常量元素含量最高的为钾（6 416 mg/kg,干重）、含量最低的是钙（92 mg/kg,干重）,微量元素中锌含量较高（241 mg/kg,干重）;双斑蟋油脂中不饱和脂肪酸的相对含量为65.33%,以亚油酸（37.05%）和油酸（25.86%）为主、饱和脂肪酸以棕榈酸（25.44%）和硬脂酸（8.74%）为主。双斑蟋的脂肪酸组成、含量与家蟋相近,而与黑蟋的脂肪酸组成差别较大,三种蟋蟀中含量最高的饱和脂肪酸为棕榈酸,而含量最高的不饱和酸为亚油酸。结果表明,双斑蟋的必需氨基酸组成符合FAO/WHO推荐的氨基酸构成比例的蛋白条件,具有较高的营养价值和食用价值。     

Neuroprotective effects of ginkgetin against neuroinjury in Parkinson's disease model induced by MPTP via chelating iron

Abstract

Disruption of neuronal iron homeostasis and oxidative stress are closely related to the pathogenesis of Parkinson's disease (PD). Ginkgetin, a natural biflavonoid isolated from leaves of Ginkgo biloba L, has many known effects, including anti-inflammatory, anti-influenza virus, and anti-fungal activities, but its underlying mechanism of the neuroprotective effects in PD remains unclear. The present study utilized PD models induced by 1-methyl-4-phenylpyridinium (MPP⁺) and 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) to explore the neuroprotective ability of ginkgetin in vivo and in vitro. Our results showed that ginkgetin could provide significant protection from MPP⁺-induced cell damage in vitro by decreasing the levels of intracellular reactive oxygen species and maintaining mitochondrial membrane potential. Meanwhile, ginkgetin dramatically inhibited cell apoptosis induced by MPP+ through the caspase-3 and Bcl2/Bax pathway. Moreover, ginkgetin significantly improved sensorimotor coordination in a mouse PD model induced by MPTP by dramatically inhibiting the decrease of tyrosine hydroxylase expression in the substantia nigra and superoxide dismutase activity in the striatum. Interestingly, ginkgetin could strongly chelate ferrous ion and thereby inhibit the increase of the intracellular labile iron pool through downregulating L-ferritin and upregulating transferrin receptor 1. These results indicate that the neuroprotective mechanism of ginkgetin against neurological injury induced by MPTP occurs via regulating iron homeostasis. Therefore, ginkgetin may provide neuroprotective therapy for PD and iron metabolism disorder related diseases.     

Free radicals act as effectors in the growth inhibition and apoptosis of iron-treated Burkitt's lymphoma cells

The addition of ferric citrate to Burkitt's lymphoma (BL) cell lines inhibits growth, leads to the accumulation of cells in the phase G₂/M of the cell cycle and to the modulation of translocated c-myc expression. The increase in the labile iron pool (LIP) of iron-treated BL cells leads to cytotoxicity. Indeed, intracellular free iron catalyzes the formation of highly reactive compounds such as hydroxyl radicals and nitric oxide (NO) that damages macromolecular components of cells, eventually resulting in apoptosis. In this report, we have investigated the possible involvement of free radicals in the response of Ramos cells to iron. When added to Ramos cells, iron increased the intracellular levels of peroxide/peroxynitrite and NO. Moreover, the addition of free radicals scavengers (TROLOX^® and Carboxy-PTIO) neutralized the effects of iron on Ramos cells while addition of an NO donor or hydrogen peroxide (H₂O₂) to cells generated effects which partially mimicked those induced by iron addition. Collectively, our results suggest the involvement of free radicals as effectors in the iron specific growth inhibition of BL cells observed in vitro.     

Iron mobilization by succinylacetone methyl ester in rats. A model study for hereditary tyrosinemia and porphyrias characterized by 5-Aminolevulinic acid overload

Accumulation of 5-aminolevulinic acid (ALA) is an event characteristic of porphyrias that may contribute to their pathological manifestations. To investigate effects of ALA independent of porphyrin accumulation we treated rats with the methyl ester of succinylacetone, an inhibitor of 5-aminolevulinic acid dehydratase that accumulates in the porphyric-like syndrome hereditary tyrosinemia. Acute 2-day treatment of fasted rats with succinylacetone methyl ester (SAME) promoted a 27% increase in plasma ALA. This increase in plasma ALA was accompanied by augmentation of the level of total nonheme iron in liver (37%) and brain (20%). Mobilization of iron was also indicated by 49% increase in plasma iron and a 77% increase in plasma transferrin saturation. Liver responded with a mild (12%) increase in ferritin. Under these acute conditions, some indications of oxidative stress were evident: a 15% increase in liver reactive protein carbonyls, and a 42% increase in brain subcellular membrane TBARS. Brain also showed a 44% increase in CuZnSOD activity, consistent with observations in treatment with ALA. Overall, the data indicate that SAME promotes ALA-driven changes in iron metabolism that could lead to increased production of free radicals. The findings support other evidence that accumulation of ALA in porphyrias and hereditary tyrosinemia may induce iron-dependent biological damage that contributes to neuropathy and hepatoma.     

Reactions of Adriamycin with Microsomal Iron and Lipids

Iron plays a central role in oxidative injury, reportedly because it catalyzes superoxide- and hydrogen peroxide-dependent reactions yielding a powerful oxidant such as the hydroxyl radical. Iron is also thought to mediate the cardiotoxic and antitumour effects of adriamycin and related compounds. NADPH-supplemented microsomes reduce adriamycin to a semiquinone radical, which in turn re-oxidizes in the presence of oxygen to form superoxide and hence hydrogen peroxide. During this redox cycling membrane-bound nonheme iron undergoes superoxide dismutase- and catalase-insensitive reductive release. Membrane iron mobilization triggers lipid peroxidation, which is markedly enhanced by simultaneous addition of superoxide dismutase and catalase. The results indicate that : i) lipid peroxidation is mediated by the release of iron, yet the two reactions are governed by different mechanisms; and ii) oxygen radicals are not involved in or may actually inhibit adriamycin-induced lipid peroxidation. Microsomal iron delocalization and lipid peroxidation might represent oxyradical-independent mechanisms of adriamycin toxicity.     

Chemical reactivity of the carbon-centered free radicals and ferrous iron in coals: Role of bioavailable Fe2+ in coal workers' pneumoconiosis

Striking differences in the prevalence of coal workers' pneumoconiosis (CWP) exist between different coal mine regions. The major factors responsible for the observed regional differences in CWP have not yet been identified. In the present study, chemical reactivity of the carbon-centered free radicals in coals and lung tissues, as well as ferrous iron in the coals, were studied by ESR techniques. The ESR spectra clearly demonstrated the presence of at least two types of carbon-centered free radical species, which might respectively attribute to the macromolecular phase and the molecular phase of coal. Grinding produced free radicals in coals. Exposure of freshly ground coal to air for 28 h induced a slight increase of free radicals for most of the coals, and a slight decrease after 4 months' exposure. The lung tissue samples of coal workers deceased of CWP showed similar ESR spectra as coal samples, and these radicals were highly stable in the lung. After incubation of coals with glutathione, hydrogen peroxide, sodium formate or oxygen, the coal sample from the Gardanne mine which has never induced CWP, and thus is the least hazardous coal, showed the most significant change in the carbon-centered free radical concentration. No significant changes were observed among other coals reported to induce CWP. On the other hand, we found that the coals released different amounts of Fe²⁺ in an acidic medium. Interestingly, the prevalence of CWP correlates positively with the released Fe²⁺ content in these coals and with the amount of oxygen radicals produced by the interaction of Fe²⁺ with O₂ in the acidified coal filtrates. Our studies indicate that the carbon-centered free radicals may not be biologically relevant to coal dust-induced pneumoconiosis, whereas the acid soluble Fe²⁺, which may be dissolved in the phagolysosomes of macrophages, can then lead to Fe²⁺-induced oxidative stress and eventual CWP development.     

Redox regulation and oxidant activation of heme oxygenase-1

The ultraviolet A (UVA, 320–400 nm) component of sunlight has the potential to generate an oxidative stress in cells and tissue so that antioxidants (both endogenous and exogenous) strongly influence the biological effects of UVA. The expression of several genes (including heme oxygenase-1, HO-1; collagenase; the CL100 phosphatase and the nuclear oncogenes, c-fos and c-jun) is induced following physiological doses of UVA to cells and this effect can be strongly enhanced by removing intracellular glutathione or enhancing singlet oxygen lifetime. We have observed that heme is released from microsomal heme-containing proteins by UVA and other oxidants and that activation of HO-1 expression by UVA correlates with levels of heme release. UVA radiation also leads to an increase in labile iron pools (either directly or via HO-1) and eventual increases in ferritin levels. The role of heme oxygenase in protection of skin fibroblasts is probably an emergency inducible defense pathway to remove heme liberated by oxidants. The slower increase in ferritin levels is an adaptive response which serves to keep labile iron pools low and thereby reduce Fenton chemistry and oxidant-induced chain reactions involving lipid peroxidation. In keratinocytes, the primary target of UVA radiation, heme oxygenase levels are constitutively high (because of HO-2 expression). Since there is a corresponding increase in basal levels of ferritin the epidermis appears to be well protected constitutively against the oxidative stress generated by UVA.     

Metabolism of Ethanol to 1-Hydroxyethyl Radicals in Rat Liver Microsomes: Comparative Studies with Three Spin Trapping Agents

Metabolism of ethanol to 1-hydroxyethyl radicals by rat liver microsomes was studied with three nitrone spin trapping agents (POBN, PBN, and DMPO) under essentially comparable conditions. The data indicate that POBN was the superior spin trapping agent for 1-hydroxyethyl radicals, and that DMPO was least efficient. Addition of deferoxamine completely prevented detection of 1-hydroxyethyl radicals with PBN or DMPO, but caused only 50% decrease in EPR signals when POBN was the spin trap. However, superoxide dismutase only decreased 1-hydroxyethyl radical formation when POBN was the spin trap. Other experiments demonstrated that POBN was the most effective of these nitrones for reduction of Fe(III) in aqueous solutions. Furthermore, 1-hydroxyethyl radical adducts were formed when POBN was added to mixtures of ethanol, phosphate buffer, POBN and FeCl₃, but this effect did not occur with either PBN or DMPO. Thus, these data indicate that undesirable effects of POBN on iron chemistry may influence results of spin trapping experiments, and complicate interpretation of the resulting data.     

DNA-breaking versus DNA-protecting activity of four phenolic compounds in vitro

Given the paradoxical effects of phenolics in oxidative stress, we evaluated the relative pro-oxidant and antioxidant properties of four natural phenolic compounds in DNA nicking. The phenolic compounds differed dramatically in their ability to nick purified supercoiled DNA, with the relative DNA nicking activity in the order: 1,2,4-benzenetriol (100% nicking) > gallic acid > caffeic acid > gossypol (20% nicking). Desferrioxamine (0.02 mM) decreased DNA strand breakage by each phenolic, most markedly with gallate (85% protection) and least with caffeic acid (26% protection). Addition of metals accelerated DNA nicking, with copper more effective (～5-fold increase in damage) than iron with all four phenolics. Scavengers revealed the participation of specific oxygen-derived active species in DNA breakage. Hydrogen peroxide participated in all cases (23–90%). Hydroxyl radicals were involved (32–85%), except with 1,2,4-benzenetriol. Superoxide participated (81–86%) with gallic acid and gossypol, but not with caffeic acid or 1,2,4-benzenetriol. With 1,2,4-benzenetriol, scavengers failed to protect significantly except in combination. Thus, in the presence of desferrioxamine, catalase or superoxide dismutase inhibited almost completely. When DNA breakage was induced by Fenton's reagent (ascorbate plus iron) the two catechols (caffeic acid and gossypol) were protective, whereas the two triols (1,2,4-benzenetriol and gallic acid) exacerbated damage.