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991.
Shao-Fang Xing Man Lin Yu-Rong Wang Tuo Chang Wei-Ye Cui 《Natural product research》2020,34(5):651-658
AbstractThree novel dammarane-type saponins, 2α,3β,12β,20(S),24(S)-pentahydroxydammar-25-ene-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-20-O-β-D-glucopyranoside (1, namely gypenoside J1), 2α,3β,12β,20(S),25-pentahydroxydammar-23-ene-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-20-O-β-D-glucopyranoside (2, namely gypenoside J2) and 2α,3β,12β,20(S)-tetrahydroxydammar-25-en-24-one-3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-20-O-β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside (3, namely gypenoside J3) along with one known gypenoside (gypenoside LVII) were isolated from the aerial parts of G. pentaphyllum using various chromatographic methods. Their structures were elucidated on the basis of IR, 1D- (1H and 13C), 2D-NMR spectroscopy (HSQC, HMBC and COSY), and mass spectrometry (ESI-MS/MS). Their activity was tested using CCK-8 assay. These four compounds showed little anti-cancer activity with IC50 values more than 100?μM against four types of human cancer lines. The effects of them against H2O2-induced oxidative stress in human neuroblastoma SH-SY5Y cells were evaluated and they all showed potential neuroprotective effects with 3.64–18.16% higher cell viability than the H2O2-induced model group. 相似文献
992.
Antibody drug conjugates are cytotoxic pharmaceuticals, designed to destroy malignant cells. A cytotoxic molecule is attached to an antibody that binds specific to a cancer‐cell surface. Given the high toxicity of the drugs, strict safety standards have to be kept. For this reason, an antibody drug conjugates model was developed with fluorescein 5‐isothiocyanate as the nontoxic payload surrogate. Due to the similar hydrophobicity, this model is used to establish a suitable purification process and characterization method for antibody drug conjugates. Because of the pH dependent solubility of fluorescein, the hydrophobicity of conjugates can be modulated by the pH value. Based on the complex heterogeneity and hydrophobicity of the conjugates a chromatographic purification is challenging. Hydrophobic interaction chromatography is used for analytical as well as for preparative separation. Because of the increased hydrophobicity of the conjugates compared to native antibody, hydrophobic interaction chromatography often suffer from resolution and recovery problems. Conjugates were separated differing on the number of payloads attached to the antibody. For this matter, the drug–antibody ratio is determined and used as a quantitative term. The conjugates are purified at high recoveries and resolution by step gradients using suitable resins, allowing the separation of the target drug–antibody ratio. 相似文献
993.
XuanLin Meng Yang Li Chongchong Lu Man Zhao Ming Li ShaoLi Wang ChangBao Zhao Bao Lin LuYue Shang Zhaohui Chu Xinhua Ding 《Journal of separation science》2020,43(12):2311-2320
In a recent study, anthocyanins, which have a strong free radical‐scavenging activity, were examined for their potential to effectively prevent cancer. However, clinical trials are limited by the purity of the anthocyanin. Multiple methods are used to extract and purify anthocyanins. Based on previous work on Solanum nigrum, which is a widely distributed plant, in this study, DM130 macroporous resin, Sephadex LH20, and a C18 column were used to separate cis–trans anthocyanin isomers. These anthocyanins constitute the majority of total S. nigrum anthocyanins. The results showed that this “DM130‐LH20‐C18 system” can be used to obtain a cinnamic acid‐derived cis–trans anthocyanin, petunidin‐3‐(p‐coumaroyl)‐rutinoside‐5‐glucoside, with a purity of 98.5%, for effective quantitation. In order to determine the antioxidant ability of the petunidin‐3‐(p‐coumaroyl)‐rutinoside‐5‐glucoside cis–trans isomers, three ordinary methods were adopted. The maximum antioxidant ability of the cis–trans anthocyanin was dozens of times higher than that of vitamin C. 相似文献
994.
Catalytic conversion of carbohydrates into value-added products and platform chemicals became a trend in recent years. Microwave activation used in the processes of carbohydrate conversion coupled with the proper choice of catalysts makes it possible to enhance dramatically the efficiency and sometimes the selectivity of catalysts. This mini-review presents a brief literature survey related to state-of-the-art methods developed recently by the world research community to solve the problem of rational conversion of carbohydrates, mostly produced from natural resources and wastes (forestry and agriculture wastes) including production of hydrogen, synthesis gas, furanics, and alcohols. The focus is made on microwave technologies used for processing carbohydrates. Of particular interest is the use of heterogeneous catalysts and hybrid materials in processing carbohydrates. 相似文献
995.
Hui-Na Wang Qiu-An Xiang Hao-Hui Lin Jie-Ning Chen Wen-Jie Guo Wan-Meng Guo Xiang-Ning Yue Zhen-Fu Zhao Kunmei Ji Jia-Jie Chen 《Molecules (Basel, Switzerland)》2022,27(5)
Mast cells (MCs) are an important treatment target for high-affinity IgE Fc receptor (FcεRI)-mediated allergic diseases. The plant-derived molecule 4-methylumbelliferone (4-MU) has beneficial effects in animal models of inflammation and autoimmunity diseases. The aim of this study was to examine 4-MU effects on MC activation and probe the underlying molecular mechanism(s). We sensitized rat basophilic leukemia cells (RBLs) and mouse bone marrow-derived mast cells (BMMCs) with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated them with exposure to DNP-human serum albumin (HSA), and then treated stimulated cells with 4-MU. Signaling-protein expression was determined by immunoblotting. In vivo allergic responses were examined in IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) mouse models. 4-MU inhibited β-hexosaminidase activity and histamine release dose-dependently in FcεRI-activated RBLs and BMMCs. Additionally, 4-MU reduced cytomorphological elongation and F-actin reorganization while down-regulating IgE/Ag-induced phosphorylation of SYK, NF-κB p65, ERK1/2, p38, and JNK. Moreover, 4-MU attenuated the PCA allergic reaction (i.e., less ear thickening and dye extravasation). Similarly, we found that 4-MU decreased body temperature, serum histamine, and IL4 secretion in OVA-challenged ASA model mice. In conclusion, 4-MU had a suppressing effect on MC activation both in vitro and in vivo and thus may represent a new strategy for treating IgE-mediated allergic conditions. 相似文献
996.
以表面活性剂十六烷基三甲基溴化铵(CTABr)为模板剂,在水热体系对水蒸气处理后的超稳Y型(USY)沸石进行晶化处理,获得高酸量和高水热稳定性的USY-c-w样品。利用X射线衍射、扫描电子显微镜、透射电子显微镜、固态核磁共振、N2吸附-脱附、NH3-程序升温脱附、傅里叶变换红外光谱及吡啶红外对所制备催化剂的物化性质进行详细表征。选用1,3,5-三异丙苯(TIPB)催化裂化作为探针反应,研究制备的催化剂的催化性能,并与工业USY沸石进行对比。结果表明,再次水热晶化后,样品的硅铝骨架局部重构,非骨架铝重新进入沸石骨架,合成样品的硅铝比(nSi/nAl)由10降至3.0;再晶化后的USY沸石,不仅具有丰富的介孔结构,并且具有更多的弱酸和中强酸位点。在TIPB裂解反应中,再晶化后的USY沸石表现出比原样品更优异的催化性能。 相似文献
997.
998.
999.
荧光光谱法研究磷酰化5,7-二羟基黄酮与ctDNA的相互作用 总被引:1,自引:0,他引:1
以溴化乙锭(EB)为荧光探针,研究了磷酰化5,7-二羟基黄酮与ctDNA的相互作用。实验结果表明,磷酰化5,7-二羟基黄酮与ctDNA间存在相互作用。随着温度的升高,磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数降低,磷酰化5,7-二羟基黄酮可与ctDNA形成复合物,此猝灭过程为静态猝灭。根据Stern-Volmer方程,算出25℃及37℃下磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数分别为Kq1=30 860 L/mol及Kq2=27 760 L/mol,并且算出它与ctDNA结合的平衡常数为KM=2.39×107L/mol。 相似文献
1000.
在胶束电动色谱模式下考察了影响生物胺分离的几个因素(如缓冲溶液及SDS浓度、pH、表面活性剂、分离温度及外加电压等)并优化了分离条件,建立了一种简单快速的利用毛细管胶束电动色谱DAD检测器分离分析生物胺的新方法。当缓冲溶液为40mmol/L硼酸缓冲液(pH8.5)、68mmol/LSDS,分离电压为25kV、分离温度为25℃时,5种生物胺在7min内实现了令人满意的基线分离。在优化的条件下,对其线性范围、检出限和重现性进行了测定。结果表明,生物胺的迁移时间的重现性<0.8%,面积的重现性<4%。 相似文献