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排序方式: 共有250条查询结果,搜索用时 31 毫秒
1.
Our purpose was to determine the effects of six cigarette toxicants (pyridine, nicotine, 2-ethylpyridine, 3-ethylpyridine, p-cresol, and pyrazine) on three types of cultured mammalian cells (human umbilical vein endothelial cells [HUVECs], human microvascular endothelial cells [HMVECs], and NIH 3T3 cells) using a cell proliferation/survival assay. Synchronized cells were cultured in proliferation or survival medium containing various doses (10(-18)M-10(-2)M) of the tested chemicals. After 48 h, cells were counted using a hemacytometer. The no observable adverse effect level (NOAEL), lowest observable adverse effect level (LOAEL), and the efficacy were determined for each compound in the cell proliferation and survival assays. Pyridine and p-cresol did not show significant effects with any cell types, except at high doses. Derivitization of the pyridine ring altered its potency, especially when an ethyl group or nitrogen was added. In survival medium, nicotine stimulated proliferation of all three cell types at doses found in smoker's serum (10(-8)M-10(-7)M). For HUVEC and HMVEC, 2-ethylpyridine, 3-ethylpyridine, and pyrazine inhibited proliferation in proliferation medium and induced cell death in survival medium at attomolar and femtomolar doses. All chemicals, except pyridine and pyrazine, stimulated NIH 3T3 cell proliferation at low doses and induced cell death at high doses. LOAELs and efficacies revealed that endothelial cells from a developing organ (umbilical cord) were more sensitive to these chemicals than endothelial cells from an adult organ (lung). 3-Ethylpyridine and pyrazine, which induced cell death at low doses, are added to consumer products and should be subjected to further toxicological testing.  相似文献   
2.
王冰倩  周瑾欣  魏星  于生  张丽  吴啟南  单鸣秋 《中草药》2023,54(17):5541-5549
目的 通过超声辅助大孔树脂对荆芥穗Schizonepetae Spica水提物中总黄酮和总酚类化合物进行富集并对比处理前后化合物含量及活性变化。方法 从7种不同类型树脂中筛选超声辅助最佳树脂型号,在吸附动力学和吸附热力学研究下,对超声温度、功率、上样质量浓度及解吸溶剂百分比等影响因素进行工艺优化。测定了优化处理前后各成分含量及活性变化。结果 动力学和热力学的研究表明,荆芥穗总黄酮适用于Langmuir模型,且吸附过程为自发吸热熵增,总酚则为自发放热熵减并适用于Freundlich模型,据此不同的吸附机制优化了2类成分同时富集的最佳工艺,在超声辅助AB-8大孔树脂,温度25 ℃、时间2.5 h,功率150 W,上样质量浓度0.1 g/mL,70%乙醇解吸附的过程下,荆芥穗水提物中总黄酮和总酚类化合物含量增加2~3倍,其单体成分的含量及抗氧化和神经氨酸酶抑制活性均显著增加。结论 超声辅助大孔树脂技术为荆芥穗总黄酮和总酚类成分的有效可行富集技术。  相似文献   
3.
干姜超临界CO2提取物质量控制的研究   总被引:3,自引:0,他引:3  
目的:建立干姜超临界CO2提取物的有效部位质量控制的方法。方法∶采用薄层色谱法,以石油醚(60~90℃)醋酸乙酯冰醋酸(8∶3∶0.2)为展开剂,5%香草醛硫酸溶液为显色剂,对本品进行鉴别;并采用紫外双波长分光光度法和高效液相色谱法对本品进行总酚及有效成分6姜酚的含量测定。结果∶总酚在9.668~38.67μg·mL-1呈良好线性关系(r=0.9999),平均回收率为97.7%,RSD1.96%;6姜酚在0.20~2.00μg呈良好线性关系(r=0.9999),平均回收率为97.9%,RSD0.33%。结论∶方法准确,灵敏、专属性强,可作为该原料的全面质量控制标准。  相似文献   
4.
In the natural environment, bacteria predominantly exist in matrix‐enclosed multicellular communities associated with various surfaces, referred to as biofilms. Bacteria in biofilms are extremely resistant to antibacterial agents thus causing serious problems for antimicrobial therapy. In this study, we showed that different plant phenolic compounds, at concentrations that did not or weakly suppressed bacterial growth, increased the capacity of Pseudomonas aeruginosa PAO1 to form biofilms. Biofilm formation of P. aeruginosa PAO1 was enhanced 3‐ to 7‐fold under the action of vanillin and epicatechin, and 2‐ to 2.5‐fold in the presence of 4‐hydroxybenzoic, gallic, cinnamic, sinapic, ferulic, and chlorogenic acids. At higher concentrations, these compounds displayed an inhibiting effect. Similar experiments carried out for comparison with Agrobacterium tumefaciens C58 showed the same pattern. Vanillin, 4‐hydroxybenzoic, and gallic acids at concentrations within the range of 40 to 400 μg/mL increased the production of N–3‐oxo‐dodecanoyl‐homoserine lactone in P. aeruginosa PAO1 which suggests a possible relationship between stimulation of biofilm formation and Las Quorum Sensing system of this bacterium. Using biosensors to detect N‐acyl‐homoserine lactones (AHL), we demonstrated that the plant phenolics studied did not mimic AHLs.  相似文献   
5.
The stem, leaf, and root of Tinospora cordifolia (willd.) have been highly exploited for medicinal preparations; however, the nutritional and nutraceutical potential of its attractive red berries (fruits) have not so far been studied. Pigments, berberine (107.0 mg/100 g) and lycopene (50.8 mg/100 g), were identified in the deseeded fruit. Total phenol content in the fruit was 3.2 mg gallic acid equivalent/g. The IC50 of DPPH (82, and 468 ppm) and OH (100, and 1,000 ppm) scavenging activity, and the EC50 of reducing power (2,616, and 1,472 ppm) of hexane and methanol extracts, respectively, were observed. Oxygen radical absorbance capacities of the fruit extracts (150 and 300 ppm) were 1,107 and 2,614 μM trolox equivalent/g, respectively. Nutrient composition including carbohydrate (18.4%), proteins (1.5%), lipids (6%) of which ~62% was unsaturated fatty acids, vitamins like ascorbic acid (0.24 μg), niacin (0.7 mg), and tocopherols (2.4 mg) in 100 g fruits were determined. Potassium content was 1.2 g/100 g dry tissue of berries. These findings show that components of T. cordifolia fruit could be bioactive and used in food, pharmaceutical, and cosmetics.  相似文献   
6.
7.
Cauliflower (Brassica oleraceae L. var. Botrytis) is a good source of bioactive compounds, such as glucosinolates, phenolic compounds and vitamins. In this study, the effects of some processes (i.e. boiling, steaming) on the sinigrin bioaccessibility as a major glucosinolate found in cruciferous vegetables after in vitro digestion, also in vitro antimutagenic activities, total phenols and total antioxidant capacities of cauliflower were determined. The sinigrin content was reduced by approximately 9.6% and 29.1% in steamed and boiled cauliflower (p > 0.05), respectively. After in vitro simulated digestion, sinigrin content was decreased by 26.4% in raw samples, increased by 29.5% and 114.7% in steamed and boiled samples, respectively. In all samples, mutagenic effect to Salmonella typhimurium TA 100 was not seen. When samples were steamed, phenol content was increased by 14.83%. After boiling total phenol content of cauliflower was decreased by 1.8%. Total antioxidant capacities (TAC) measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were increased by 47% and 39%, respectively (p < 0.05) in steamed samples and decreased by 8% and 7% with boiling, respectively (p > 0.05). TAC in raw sample of cauliflower, which was investigated in phosphomolybdenum assays, was determined as 18.7 mg ascorbic acid equivalents (AAE)/100 g. In all cases, the highest antioxidant activity was determined in the steamed samples, while the lowest antioxidant activity was in boiled samples.  相似文献   
8.
目的建立基于药物体系的肉桂特征图谱质量表征关联分析方法,全面评价肉桂饮片质量。方法采用HPLC-PDA法建立肉桂饮片特征图谱,筛选7个特征峰并通过相对保留时间表征其质的关联性;同时测定6个主要有效指标性成分(原儿茶酸、表儿茶素、香豆素、肉桂醇、肉桂酸、肉桂醛)的含量并表征主要酚类成分和主要苯丙素类成分的含量,通过关联度等概念表征其量的关联性。结果以批号13为基准,基于质的表征模式及关联分析,肉桂饮片特征图谱中筛选的7个特征峰中有酚类成分2个、苯丙素类成分5个,15批肉桂饮片色谱图中均含有此7个特征峰。基于量的表征模式及关联分析,批号14有效指标性成分总体含量高于基准批号13,批号4、6、8、10含量与基准批号13关联性较高,综合评价得出批号14、13、4、6、8、10优良度居前。结论在定性的基础上进行定量表征,可全面评价肉桂饮片质量优次,为肉桂饮片资源筛选、药物原料质量控制及应用提供依据,同时为中药质量评价提供新的方法。  相似文献   
9.
目的基于多巴胺D2受体(DRD2),考察小剂量麦芽4个化学部位的催乳作用,初步探讨小剂量麦芽生物碱对产后缺乳模型大鼠泌乳素(PRL)分泌的调节机制。方法采用ig甲磺酸溴隐亭方法制备缺乳大鼠模型,造模成功后,各给药组均ig给予相应的药物,应用ELISA法检测各组大鼠血清PRL、雌二醇(E_2)、孕酮(P)水平;HE染色观察各组大鼠乳腺组织病理改变;采用实时荧光定量PCR(qRT-PCR)法检测各组大鼠脑垂体中泌乳素受体及DRD2 mRNA表达。结果与对照组比较,模型组大鼠血清中PRL、P及E_2水平、脑垂体PRL mRNA表达水平显著降低;脑垂体DRD2 mRNA表达水平显著升高。与模型组比较,麦芽总生物碱组大鼠乳腺小叶体积明显增加,导管明显扩张,且导管及腺泡内含有大量乳汁。麦芽总生物碱明显增加模型大鼠血清中PRL、P、E_2水平及脑垂体PRL mRNA表达水平,降低脑垂体DRD2 mRNA表达水平。结论麦芽催乳的主要药效物质为总生物碱,其作用机制可能与促进PRL分泌,增加脑垂体PRL受体、降低DRD2 mRNA表达水平有关。  相似文献   
10.
目的探讨天麻酚类成分对脑缺血大鼠海马NO和一氧化氮合酶(NOS)的影响。方法采用双侧颈总动脉永久性结扎法,造成大鼠脑缺血模型。造模6周后,SD大鼠40只随机分为5组,假手术组、模型组、尼莫地平组、天麻酚类成分高剂量组(高剂量组)和天麻酚类成分低剂量组(低剂量组),每组8只。给药3周后,比色法检测海马NO含量和NOS活性,免疫印记法检测大鼠海马NOS 3种亚型(nNOS,iNOS,eNOS)的表达。结果与假手术组比较,模型组大鼠海马NO含量、NOS活性及nNOS和iNOS表达明显升高,eNOS表达明显降低;与模型组比较,尼莫地平组和高剂量组大鼠海马NO含量、NOS活性及nNOS和iNOS表达明显降低,eNOS表达明显升高;低剂量组大鼠NOS活性和iNOS表达明显降低,差异有统计学意义(P<0.05,P<0.01)。结论天麻酚类成分对脑缺血大鼠海马NO损伤有保护作用。  相似文献   
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