植物硒及其含硒蛋白的研究

硒是植物的有益元素,植物对硒的吸收与外源硒的有效性、硒的形态、植物的种类等有关;硒在植物中主要以有机硒形态存在,HPLC-ICP-MS联用已成为植物体内硒形态鉴定的最常用手段;含硒蛋白是植物体内最主要的有机大分子硒,具有抗肿瘤、抗氧化等多种生物活性。在环境安全和人类健康等方面,富硒植物具有很好的应用价值,所以利用分子生物学手段分析富硒植物的富硒机制,可以为富硒基因的筛选和利用提供理论依据。     

萝卜硫素的成药性及其在肿瘤和神经退行性疾病中的作用

萝卜硫素是一种来源于十字花科类蔬菜的天然活性物质,具有强大的抗氧化和抗癌能力。研究表明,萝卜硫素可通过调节Nrf2、NF-κB、HSF1-HSP信号通路和调控表观遗传,从而作用于II相解毒酶、HDAC和DNMT,影响癌症、神经退行性疾病等疾病的发生、发展。此外,由于萝卜硫素具有易吸收易代谢等特点,用纳米材料包裹萝卜硫素可提高其生物利用度和稳定性,更好发挥其疗效。近年来已有多项I/II期临床实验显示,萝卜硫素具有良好的成药性,这表明萝卜硫素在治疗癌症和神经退行性疾病方面有极高的药用潜力。本文主要针对萝卜硫素的药代动力学、作用靶点、安全性及其在肿瘤和神经退行性疾病中的研究进展进行综述,为萝卜硫素未来应用于肿瘤和神经退行性疾病的治疗提供参考。     

湖北省豆类植物种子硒含量的测定及赋存状态的研究

硒是人类必需的微量元素之一。我们对湖北省豆类植物种子的硒含量进行测定并对硒的赋存状态进行了研究。结果显示:大豆具有较强的富硒能力;大豆硒的赋存形态是含硒蛋白质,主要存在于白蛋白和球蛋白中;高硒地区的大豆含硒量比一般地区高近100倍。     

硒的生物活性与相关疾病

微量元素硒对人类有重要的生物学意义,硒在机体内发挥功能的主要形式是硒蛋白,特别是硒酶,其主要生物活性包括:防止自由基损伤、调节甲状腺激素和二十碳花生四烯酸代谢、增强免疫、促进生殖等。研究表明,缺硒与许多疾病如心血管系统疾病、癌症、病毒感染等有关。含硒活性物质具有良好的营养保健及医药应用前景。     

苹果对硒的吸收及其积聚特征研究

对秦冠苹果采用不同浓度的硒溶液进行了花期喷施、对干注射和土壤施加３种处理,研究了苹果树对硒的吸收,找到了生产富硒苹果的有效方法。研究表明,硒并不是苹果必需的微显元素;首次提出了苹果树属非积聚硒植物的新概念;同时也对食用富硒苹果的有效性与安全性进行了分析     

中国不同地区畜禽水产品硒含量分析

目的：检测中国不同地区普通和富硒猪肉、鸡肉、鱼肉中总硒含量,为评估居民硒摄入量以及指导富硒产业发展提供依据。方法：2017年7—9月采集中国10个地区代表城市普通和富硒样品共516份,采用原子荧光光谱法测定总硒含量。结果：普通和富硒产品中,鱼肉总硒含量最高,其次猪肉,鸡肉与猪肉接近;西安三种产品总硒水平最高,克山和安康总硒水平最低。富硒产品与普通相比,猪肉和鸡肉总硒水平显著提高,富硒鱼肉略高于普通鱼肉。结论：鱼肉是很好的居民膳食硒来源,但富硒作用不显著;富硒猪肉和鸡肉产业发展不平衡,亟需制定相应的科学技术与国家相关标准。     

富硒食品的研究进展与展望

介绍了富硒食品中硒元素的优点,总结了富硒产品的分类、国内外富硒食品的研究现状以及硒元素的检测方法,并对富硒食品的前景进行了展望。     

基于生态位理论的富硒土壤资源开发利用适宜性评价及分区方法

实施乡村振兴战略,产业兴旺是关键。立足区域富硒土壤资源禀赋优势,发展富硒农业特色经济,是振兴乡村产业的一条有效途径。以多维超体积生态位理论为指导,以区域富硒土壤资源禀赋和富硒农业发展要求为基础,从土壤自身条件、土地利用和生态保护3个方面明确了富硒土壤资源开发利用的主导因素、区位因素、限制因素;选择土壤硒含量、土壤有机质含量、地形坡度、土地利用类型、土地综合污染指数、生态保护建设等6个关键因子,构建了富硒土壤资源开发利用生态位适宜性评价指标体系;利用生态位适宜性评价相关模型,探讨了生态位适宜性单一指数和综合指数的计算方法;结合土壤利用改良分区、土壤利用功能分区、富硒农业生产分区等,分析了区域富硒土壤资源开发利用适宜性分区问题。研究可为富硒土壤资源开发利用适宜性评价提供科学可行的思路与方法,对于促进区域富硒土壤资源科学合理利用、实现富硒农业产业科学发展具有重要的指导意义和现实意义。     

三个不同省份富硒大蒜硒含量分析

目的：检测山东、黑龙江、江西三个省份富硒大蒜、普通大蒜、土壤及水源的硒含量,为当地富硒大蒜产业发展提供科学依据。方法：采集山东、黑龙江、江西三个省份富硒大蒜、普通大蒜、土壤及水源共120份,采用电感耦合等离子体质谱法测定总硒含量。结果：山东省富硒大蒜硒含量高于普通大蒜中硒的含量;黑龙江省来信子村富硒大蒜硒含量明显高于其他4个基地;江西省5个地区富硒大蒜硒的含量可以分为两个区间：硒含量较低的区间（11.660 0～31.984 0 μg/100 g）、硒含量较高的区间（86.530 0～97.224 0 μg/100 g）。结论：山东省的富硒大蒜富硒效果好,黑龙江省宝清县来信子村富硒大蒜的富硒效果好,江西省宜春县富硒大蒜均为超富硒农产品。     

富硒酵母中硒赋态的研究

硒是人体必需的一种微量元素,参与合成硒代半胱氨酸、硒代甲硫氨酸以及多种硒代蛋白(酶),具有抗肿瘤、抗氧化、增强人体免疫等多种生物学活性,与人体的健康有着密切关系.硒以不同的形式存在于自然界中,大致可分为无机硒和有机硒两种,其生物活性与毒性也各有不同.富硒酵母作为补充硒元素的主要形式之一,具有生物利用度高、食用安全、毒性低等优点.研究富硒酵母中的硒的赋态,对合理摄取硒元素,促进人体健康具有重要意义,因此成为近年来研究的热点.     

Changes in Sulforaphane and Selenocysteine Methyltransferase Transcript Levels in Broccoli Treated with Sodium Selenite

Broccoli (Brassica oleracea L. var. italica planck) has been highly valued because of its nutrient content, which has been attributed to both sulforaphane, a sulfur-containing compound, and selenium enrichment ability. The sulforaphane synthesis may be affected by Se/S metabolism because sulfate and selenate share the same initial pathway for uptake in plants. Selenocysteine methyltransferase (SMT) plays a critical role in the Se/S metabolism system. In the present work, we analyzed the SMT expression level and sulforaphane content in transgenic broccoli under the conditions of overexpression and RNAi knockdown of SMT under normal and selenium-stressed conditions. The relative expression value of SMT in the overexpression line is 13.93 % higher than that in the untransformed control. Interestingly, the sulforaphane content of the overexpression line was 14.09 % lower after selenium treatment, while that of the empty vector (pCAMBIA1301) transformed and untransformed plants was 59.04 and 66.56 % lower than that of the non-selenium-treated, respectively. In the SMT-RNAi line, which has a relative expression value for SMT 15.60 % lower than that of the untransformed, we cannot detect sulforaphane after selenium treatment. These results showed that SMT plays a key role in sulforaphane synthesis in a selenium-rich environment. Specifically, overexpression of SMT decreases the negative effect of selenium on sulforaphane synthesis, while knockdown of SMT by RNAi enhances the negative effect.     

Sulforaphane inhibits pancreatic cancer through disrupting Hsp90–p50Cdc37 complex and direct interactions with amino acids residues of Hsp90

Sulforaphane [1-isothiocyanato-4-(methyl-sulfinyl) butane)], an isothiocyanate derived from cruciferous vegetables, has been shown to possess potent chemopreventive activity. We analyzed the effect of sulforaphane on the proliferation of pancreatic cancer cells. Sulforaphane inhibited pancreatic cancer cell growth in vitro with IC₅₀s of around 10–15 μM and induced apoptosis. In pancreatic cancer xenograft mouse model, administration of sulforaphane showed remarkable inhibition of tumor growth without apparent toxicity noticed. We found that sulforaphane induced the degradation of heat shock protein 90 (Hsp90) client proteins and blocked the interaction of Hsp90 with its cochaperone p50^Cdc37 in pancreatic cancer cells. Using nuclear magnetic resonance spectroscopy (NMR) with an isoleucine-specific labeling strategy, we overcame the protein size limit of conventional NMR and studied the interaction of sulforaphane with full-length Hsp90 dimer (170 kDa) in solution. NMR revealed multiple chemical shifts in sheet 2 and the adjacent loop in Hsp90 N-terminal domain after incubation of Hsp90 with sulforaphane. Liquid chromatography coupled to mass spectrometry further mapped a short peptide in this region that was tagged with sulforaphane. These data suggest a new mechanism of sulforaphane that disrupts protein–protein interaction in Hsp90 complex for its chemopreventive activity.     

Physiological effects of broccoli consumption

Epidemiological studies suggest that broccoli can decrease risk for cancer. Broccoli contains many bioactives, including vitamins C and E, quercetin and kaempferol glycosides and, like other members of the Brassicaceae, several glucosinolates, including glucobrassicin (3-indolylmethyl glucosinolate) and glucoraphanin (4-methylsulphinylbutyl glucosinolate). A key bioactive component responsible for much of this activity may be sulforaphane (1-isothiocyanato-4-methylsulfinylbutane), a hydrolysis product of glucoraphanin. Sulforaphane not only upregulates a number of phase II detoxification enzymes involved in clearance of chemical carcinogens and reactive oxygen species, but has anti-tumorigenic properties, causing cell cycle arrest and apoptosis of cancer cells. The bioequivalency of sulforaphane and whole broccoli have not been fully evaluated, leaving it unclear whether whole broccoli provides a similar effect to purified sulforaphane, or whether the presence of other components in broccoli, such as indole-3-carbinol from glucobrassicin, is an added health benefit. Dietary indole-3-carbinol is known to alter estrogen metabolism, to cause cell cycle arrest and apoptosis of cancer cells and, in animals, to decrease risk for breast cancer. Recent research suggests that both dietary broccoli and the individual components sulforaphane and indole-3-carbinol may offer protection from a far broader array of diseases than cancer, including cardiovascular and neurodegenerative diseases. A common link between these oxidative degenerative diseases and cancer may be aggravation by inflammation. A small body of literature is forming suggesting that both indole-3-carbinol and sulforaphane may protect against inflammation, inhibiting cytokine production. It remains to be seen whether cancer, cardiovascular disease, dementia and other diseases of aging can all benefit from a diet rich in broccoli and other crucifers.     

Modulation of thioredoxin reductase-2 expression in EAhy926 cells: Implications for endothelial selenoprotein hierarchy

Background

We examined the expression of the mitochondrial selenoenzyme TrxR2 in the endothelial cell line EAhy926 under conditions known to modify its cytoplasmic counterpart TrxR1.

Methods

Cells were cultured with varying concentrations of selenite, sulforaphane or the Ca²⁺ ionophore A23187 for 72-h, prior to assay of TrxR concentration and activity. Further cultures underwent prolonged (7-day) Se-depletion before selenoprotein measurement.

Results

In Se-deficient cultures, neither Se, A23187 or sulforaphane affected TrxR2 concentration, while these treatments induced TrxR1 concentration (p < 0.05). When co-incubated, optimal concentrations of Se (40 nM) and sulforaphane (4 μM) only modestly increased TrxR2 protein (∼ 1.3-fold), compared with TrxR1 (∼ 4-fold). In Se-deficient cells, TrxR activity was unaffected by sulforaphane or A23187. Prolonged Se-depletion caused a comparatively small reduction in TrxR2 (66% TrxR2 retained) against TrxR1 and glutathione peroxidase-1 activity (38% and 17% retained, respectively).

Conclusions

The relative resistance of TrxR2 to Se-deprivation and induction by sulforaphane and A23187 suggests TrxR2 lies near the top of the selenoprotein hierarchy in EAhy926 cells and exhibits near maximum expression under a range of culture conditions. In Se deficiency an inactive (possibly truncated) TrxR1 is produced in response to stimulus by sulforaphane and A23187.

General significance

These observations underpin a likely critical antioxidant role for TrxR2 and TrxR1 in the endothelium.     

Sulforaphane controls TPA-induced MMP-9 expression through the NF-κB signaling pathway,but not AP-1, in MCF-7 breast cancer cells

Sulforaphane [1-isothiocyanato-4-(methylsulfinyl)-butane] is an isothiocyanate found in some cruciferous vegetables, especially broccoli. Sulforaphane has been shown to display anti-cancer properties against various cancer cell lines. Matrix metalloproteinase-9 (MMP-9), which degrades the extracellular matrix (ECM), plays an important role in cancer cell invasion. In this study, we investigated the effect of sulforaphane on 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced MMP-9 expression and cell invasion in MCF-7 cells. TPA-induced MMP-9 expression and cell invasion were decreased by sulforaphane treatment. TPA substantially increased NF-κB and AP-1 DNA binding activity. Pre-treatment with sulforaphane inhibited TPA-stimulated NF-κB binding activity, but not AP-1 binding activity. In addition, we found that sulforaphane suppressed NF-κB activation, by inhibiting phosphorylation of IκB in TPA-treated MCF-7 cells. In this study, we demonstrated that the inhibition of TPA-induced MMP-9 expression and cell invasion by sulforaphane was mediated by the suppression of the NF-κB pathway in MCF-7 cells. [BMB Reports 2013; 46(4): 201-206]     

Sulforaphane-mediated induction of a phase 2 detoxifying enzyme NAD(P)H:quinone reductase and apoptosis in human lymphoblastoid cells

The effect of sulforaphane on human lymphoblastoid cells originating from a patient of a high cancer risk was studied. Sulforaphane (SFN) is a naturally occurring substance of chemopreventive activity. In our study, changes in cell growth, induction of apoptosis and phase 2 enzymes as well as glutathione level were examined. Apoptosis was tested by confocal microscopy at three stages: change in mitochondrial membrane potential, caspase activation and phosphatidylserine externalization. We show that SFN increases the activity of the detoxification system: it increases quinone reductase activity at low concentration (0.5-1 microM) and raises glutathione level in a dose-dependent manner. At higher doses (2.5-10 microM) sulforaphane is a cell growth modulator, as it caused cell growth cessation (IC50 = 3.875 microM), and apoptosis inducer. The results obtained suggest that sulforaphane acts as a chemopreventive agent in human lymphoblastoid cells.