Design and optimization of a novel method for extraction of genistein

Genistein, an isoflavone, has been demonstrated to promote the health of human beings by reducing the incidence of specific chronic diseases, namely, cancer and atherosclerosis. The present investigation explores a novel method of extraction of genistein from soy source which consists of a bioconversion reaction using fermentation by microorganism namely Streptomyces roseolus NRRL B-5424. In situ bioconversion of genistein glycoside to aglycone was carried out by the microbe. Such methodology has not been reported hitherto. Optimization of upstream and downstream parameters was done for maximum extraction of genistein. Genistein was isolated in a powder form by column chromatography and preparative thin layer chromatography and was characterized using massspectrometry, nuclear magnetic resonance and infrared spectroscopy and its purity determined using high performance liquid chromatography. Genistein was extracted with 91.04% purity and extraction efficiency was 67.01%.     

Genistein potentiates activity of the cation channel TRPC5 independently of tyrosine kinases

Background and purpose:

TRPC5 is a Ca²⁺-permeable channel with multiple modes of activation. We have explored the effects of genistein, a plant-derived isoflavone, on TRPC5 activity, and the mechanism(s) involved.

Experimental approach:

Effects of genistein on TRPC5 channels were investigated in TRPC5-over-expressing human embryonic kidney 293 (HEK) cells and bovine aortic endothelial cells (BAECs) using fluorescent Ca²⁺ imaging and electrophysiological techniques.

Key results:

In TRPC5-over-expressing HEK cells, genistein stimulated TRPC5-mediated Ca²⁺ influx, concentration dependently (EC₅₀= 93 µM). Genistein and lanthanum activated TRPC5 channels synergistically. Effects of genistein on TRPC5 channels were mimicked by daidzein (100 µM), a genistein analogue inactive as a tyrosine kinase inhibitor, but not by known tyrosine kinase inhibitors herbimycin (2 µM), PP2 (20 µM) and lavendustin A (10 µM). Action of genistein on TRPC5 channels was not affected by an oestrogen receptor inhibitor ICI-182780 (50 µM) or a phospholipase C inhibitor {"type":"entrez-nucleotide","attrs":{"text":"U73122","term_id":"4098075","term_text":"U73122"}}U73122 (10 µM), suggesting genistein did not act through oestrogen receptors or phospholipase C. In BAECs, genistein (100 µM) stimulated TRPC5-mediated Ca²⁺ influx. In patch clamp studies, both genistein (50 µM) and daidzein (50 µM) augmented TRPC5-mediated whole-cell cation current in TRPC5 over-expressing HEK cells. Genistein stimulated TRPC5 channel activity in excised inside-out membrane patch, suggesting that its action was relatively direct and did not require cytosolic factors.

Conclusions and implications:

The present study is the first to demonstrate stimulation of a TRP channel by isoflavones. Genistein is a lipophilic compound able to stimulate TRPC5 activity in TRPC5-over-expressing HEK cells and in native vascular endothelial cells.     

Prolonged treatment of cells with genistein modulates the expression and function of the cystic fibrosis transmembrane conductance regulator

BACKGROUND AND PURPOSE: Cystic fibrosis (CF) is caused by dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. In the search for new CF therapies, small molecules have been identified that rescue the defective channel gating of CF mutants (termed CFTR potentiators). Here, we investigate the long-term effects of genistein, the best-studied CFTR potentiator, on the expression and function of CFTR. EXPERIMENTAL APPROACH: We pre-treated baby hamster kidney (BHK) cells expressing wild-type or F508del-CFTR (the most common CF mutant) with concentrations of genistein that potentiate (30 microM) or inhibit (100 microM) CFTR function for 2 or 24 h at 37 degrees C before examining CFTR maturation, expression and single-channel activity. KEY RESULTS: Using the iodide efflux technique, we found that genistein pre-treatment failed to restore function to F508del-CFTR, but altered that of wild-type CFTR. Pre-treatment of cells with genistein for 2 h had little effect on CFTR processing, whereas pre-treatment for 24 h either augmented (30 microM genistein) or impaired (100 microM genistein) CFTR maturation. Using immunocytochemistry, we found that all genistein pre-treatments increased the localization of CFTR protein to the cell surface. However, following the incubation of cells with genistein (100 microM) for 2 h, individual CFTR Cl(-) channels exhibited characteristics of channel block upon channel activation. CONCLUSIONS AND IMPLICATIONS: Genistein pre-treatment alters the maturation, cell surface expression and single-channel function of CFTR in ways distinct from its acute effects. Thus, CFTR potentiators have the potential to influence CFTR by mechanisms distinct from their effects on channel gating.     

Recent progress in the discovery of Akt inhibitors as anticancer agents

Akt, also referred to as protein kinase B (PKB) or Related to A and C (RAC), is one of the major direct downstream targets of phosphoinositide 3-kinase (PI3K). As it plays a central role in promoting cancer cell proliferation and survival through a growing list of key substrates, intense efforts are underway to find inhibitors of Akt for the treatment of cancer. Discovery of potent and novel inhibitors of Akt has been facilitated greatly by the availability of the X-ray structure of the active form of Akt and by its structural similarity with other serine/threonine kinases. In this review, new Akt inhibitors for the treatment of cancer are comprehensively reviewed, with emphasis on small molecule inhibitors that bind to the ATP-binding site, allosteric sites and the PH domains. Inhibitors of pseudosubstrates and antisense oligonucleotides, as well as Akt inhibitors with unknown mechanism of actions, are also reviewed. Results of clinical trials of several Akt drug candidates are briefly discussed. A brief summary of Akt structure and regulation and the evidences supporting Akt as a cancer target is provided as well. The patent literature is surveyed through July 2007.     

Application of Box-Behnken design in understanding the quality of genistein self-nanoemulsified drug delivery systems and optimizing its formulation

The purpose of the present study was to understand the effect of formulation variables of self- nanoemulsified drug delivery systems (SNEDDS) on the rapid dissolution of a model drug, genistein (GN). A three-factor, three-level Box-Behnken design was used to explore the main and interaction effect of several independent formulation variables including the amount of Maisine 35-1 and Labrafac Lipophile WL 1349 (1:1, w/w) (X₁), Cremophor EL and Labrasol (3:1, w/w) (X₂), and Transcutol P (X₃). Droplet size (Y₁), turbidity (Y₂), and dissolution percentage of GN after 5 (Y₃) and 30 (Y₄) min were the dependent variables. A mathematical relationship, Y₃?=???89.3447?+?5.9524X₁?+?1.0683X₂?+?0.462X₃???0.0825X₁²???0.0075X₂²???0.0009X₃²?+?0.0104X₁X₂ ??0.0113X₁X₃?+?0.0009X₂X₃ (r2?=?0.9604), was obtained to explain the effect of all factors and their co-linearities on the dissolution of GN at 5?min. Formulation optimization was then performed to maximize dissolution percentage of GN at 5?min (Y₃). The optimized formulation was predicted to dissolution 93.34% of GN at 5?min, when X₁, X₂ and X₃ values were 37.1, 101.7 and 77.3?mg, respectively. A new batch was prepared according to the optimized formulation, and the observed and predicted values of Y₃ were in close agreement. In conclusion, the Box-Behnken experimental design allowed us to understand the effect of formulation variables on the rapid dissolution of GN from SNEDDS, and optimize the formulation to obtain a rapid drug dissolution at 5?min.     

UPLC法检测染料木黄酮在Caco-2单细胞层模型上的吸收特征

目的 研究染料木黄酮在Caco-2单细胞层模型上的吸收特征。方法 将染料木黄酮的细胞样品经高速离心后取上清液,以乙腈-醋酸铵水溶液为流动相,以睾丸酮为内标,采用超高效液相色谱（ultra performance liquid chromatography,UPLC）法检测。考察时间、pH值等因素对染料木黄酮吸收的影响,测定透过Caco-2单细胞层的染料木黄酮浓度并计算其表观渗透系数（P_app）。结果 Caco-2细胞对染料木黄酮的吸收在1 h内呈线性,药物摄取时间定为1 h;pH值对染料木黄酮的吸收没有显著影响。染料木黄酮的线性范围为0.625～40 μmol/L,日间、日内精密度均小于15%。P_app从基顶侧（apical,AP）到基底侧（basolateral,BL）为1.51×10^?5 cm/s,从BL侧到AP侧为1.84×10^?5 cm/s,其渗透系数P_app（BL-AP）/P_app（AP-BL）为1.22。结论 染料木黄酮在肠道的吸收主要以被动扩散为主,UPLC检测方法简单、灵敏度高,可用于研究染料木黄酮在Caco-2单细胞层模型上的吸收特征。     

Analysis of soy isoflavone plasma levels using HPLC with coulometric detection in postmenopausal women

A reliable chromatographic method for the determination of soy isoflavones (genistein, daidzein and glycitein) using a coulometric detection has been developed and applied to analyse plasma of postmenopausal women. The chromatographic separation was performed on a C18 reversed phase column with a mobile phase composed of acetonitrile–phosphate buffer mixture. Coulometric detection was carried out at +0.500 V. A careful and rapid solid phase extraction procedure on hydrophilic/lipophilic cartridges was chosen for plasma sample purification with and without hydrolysis obtaining good extraction yield values for all the analytes (>90.0%). The enzymatic hydrolysis step was necessary for the determination of the total amount of soy isoflavones. The limit of quantitation was 0.5 ng mL⁻¹ for genistein and 0.25 ng mL⁻¹ for daidzein and glycitein. The method was found to be precise and accurate. Thus, the proposed method is suitable for the analysis of soy isoflavones (free and total amounts) in plasma of postmenopausal women under treatment with the SoymenGN^® dietary supplement.     

蒙古黄芪的化学成分研究

目的研究蒙古黄芪Astragalus membranaceus var.mongholicus的化学成分。方法利用硅胶柱色谱、Sephadex LH-20柱色谱、大孔树脂柱色谱、ODS柱色谱及制备高效液相等色谱技术对蒙古黄芪70%乙醇提取物进行分离纯化,根据理化数据和波谱数据鉴定化合物的结构。结果共分离得到16个化合物,分别鉴定为芒柄花素(1)、毛蕊异黄酮(2)、(6aR,11aR)-3-羟基-9,10-二甲氧基紫檀烷(3)、染料木素(4)、芒柄花苷(5)、毛蕊异黄酮苷(6)、7,2′-二羟基-3′,4′-二甲氧基异黄烷-7-O-β-D-葡萄糖苷(7)、(6aR,11aR)-9,10-二甲氧基紫檀烷-3-O-β-D-葡萄糖苷(8)、红车轴草素-7-O-β-D-葡萄糖苷(9)、黄芪甲苷(10)、异黄芪皂苷II(11)、黄芪皂苷VIII(12)、腺嘌呤(13)、鸟嘌呤核苷(14)、尿嘧啶核苷(15)、胡萝卜苷(16)。结论化合物13、14为首次从该属植物中分离得到。     

Using DNA microarray analyses to elucidate the effects of genistein in androgen-responsive prostate cancer cells: identification of novel targets

Many studies have correlated the consumption of soy-rich diets with a decreased risk of developing hormone-dependent cancers, including prostate cancer. Genistein is a candidate prostate cancer preventive phytochemical found at high levels in soybean and soy foods. To better understand the molecular mechanisms underlying the beneficial effects of genistein on prostate cancer prevention, we used a DNA microarray approach to examine the effects of genistein at concentrations in the physiologic range on global gene expression patterns in androgen-responsive cancer cells. Microarray analyses were performed on androgen-responsive LNCaP human prostate cancer cells exposed to 0, 1, 5, or 25 microM genistein. We found a concentration-dependent modulation of multiple cellular pathways that are important in prostate carcinogenesis. Interestingly, the androgen receptor (AR)-mediated pathways, in particular, appeared to be modulated by genistein at the lowest concentrations. Based on these results, we propose that the regulation of AR-mediated pathways is potentially the most relevant chemopreventive mechanism for genistein administered at physiologic levels.