甘草中异甘草素和甘草素含量测定方法研究

目的 建立同时测定甘草中异甘草素和甘草素含量的方法。方法 采用高效液相色谱（HPLC）等度洗脱和检测波长时间序列采样的方法,流动相为甲醇-水=（45∶55）,检测波长0~25min时为276nm,25~70min时为360mn,流速为0.8mL/min,同时测定甘草中异甘草素和甘草素的含量。结果 异甘草素和甘草素进样量线性范围分别为0.028~0.28μg和0.064~0.64μg,平均加样回收率分别为97.92%和98.27%,RSD分别为1.29%和1.67%。结论 该方法准确、灵敏度高、重现性好、操作简单,可为甘草药材的质量评价提供参考。     

异甘草素对胃癌 SGC7901 细胞侵袭能力的影响

目的 探讨异甘草素 （isoliquiritigenin） 对人胃癌 SGC7901 细胞侵袭能力的影响及其可能的分子机制。方法 取对数生长期人胃癌 SGC7901 细胞, 分为对照组（正常细胞培养液）, 异甘草素实验组(异甘草素溶于细胞培养液, 浓度分别为 10、 25、 50、 100 μmol/L), 每组 4 个复孔。培养 24、 48、 72 h 后采用 MTT 法检测异甘草素对细胞生长的抑制情况, 摸索后续实验药物浓度和作用时间; 采用 Transwell 小室侵袭实验检测各组细胞的侵袭能力; Western blotting 法检测基质金属蛋白酶-9（MMP-9）、 蛋白激酶 B（Akt）和磷酸化 Akt（P-Akt）的表达。结果 10 μmol/L 异甘草素不能抑制胃癌细胞株 SGC7901 的生长, 而 25、 50、 100 μmol/L 异甘草素可明显抑制其生长, 且呈时间和浓度依赖性,24、 48、 72 h 半数抑制浓度（IC50）分别为 52.48、 44.49、 32.50 μmol/L, 故选定后续实验药物浓度为 25、 50、 100 μmol/L,作用时间为 24 h。与对照组穿膜细胞数（个： 209.75±9.29）相比, 25 μmol/L 组（138.50±10.15）、 50 μmol/L 组（89.50±16.56）、 100 μmol/L 组（45.00±8.08）逐渐降低（F=267.948, P < 0.05）。各组间 Akt 蛋白水平差异无统计学意义（F=1.492）; 随异甘草素浓度的增加, P-Akt、 MMP-9 蛋白水平逐渐降低（F 分别为 359.219、 431.324, 均 P < 0.05）。结论 异甘草素能够抑制 SGC7901 细胞侵袭能力, 其机制可能与下调 PI3K/Akt信号转导通路蛋白及其下游的 MMP-9蛋白表达有关。     

HPLC法同时测定炙甘草汤中甘草苷、甘草素、异甘草素的含量

目的:建立同时测定炙甘草汤中甘草苷、甘草素、异甘草素含量的方法。方法:采用高效液相色谱法。色谱柱为Waters Sunfire C18(250mm×4.6mm,5μm),流动相为乙腈-0.5%冰醋酸(50:50,V/V),检测波长为278nm,流速为1.0mL·min-1。结果:甘草苷、甘草素、异甘草素的检测浓度分别在1.2～24.0、64.0～1280.0、50.0～1000.0μg·mL-1范围内与各自峰面积积分值呈良好的线性关系(r分别为0.9998、0.9999、0.9999);三者平均加样回收率分别为100.38%、99.45%、97.46%,RSD分别为0.45%、0.53%、0.96%(n=6)。结论:该方法准确、可靠,可为炙甘草汤的质量控制提供检测依据。     

异甘草素诱导人黑色素瘤A375细胞凋亡研究

目的研究异甘草素诱导人黑色素瘤(A375)细胞凋亡及其初步机制。方法采用硫氰酸盐B(SRB)法测定异甘草素对A375细胞生长的抑制效应,AO/EB和Hoechst33258荧光染色法观察细胞凋亡形态,流式细胞技术检测A375细胞凋亡率;荧光染料二乙酸-2’,7’-二氯荧光素(DCFH-DA)测定A375细胞内活性氧的变化。5,5',6,6'-四氯-1,1',3,3'-四乙基苯并咪唑羰花青碘化物(JC-1)测定线粒体膜电势的变化,利用试剂盒检测异甘草素处理后的A375细胞内ATP和培养液中的乳酸、葡萄糖含量。结果异甘草素能抑制A375细胞的增殖,并呈浓度依赖性;在荧光显微镜下发现,异甘草素处理后的A375细胞出现明显的凋亡形态;细胞凋亡率随异甘草素浓度的增加而升高;异甘草素处理后的细胞内活性氧有明显上升趋势,细胞线粒体膜电位明显下降;异甘草素作用后胞内ATP含量下降(P<0.05或P<0.01),培养液中的乳酸含量下降,葡萄糖含量上升(P<0.05或P<0.01)。结论异甘草素能够抑制A375细胞的恶性增殖,最终诱导细胞凋亡。推测异甘草素通过活性氧升高,引起线粒体膜电势下降,从而影响A375细胞的糖酵解途径而导致细胞凋亡。     

复方甘草片中甘草酸、异甘草苷、异甘草素的测定

目的：建立复方甘草片中甘草酸、异甘草苷和异苷草素的含量定量分析的高效液相色谱(HPLC)方法。方法：采用色谱柱ODS-C_(18)(4．6mm×250mm,5μm),甘草酸流动相为甲醇：冰醋酸：水(70：1：30)；检测波长254nm。异甘草苷与异甘草素在同一条件下检测,其流动相为甲醇：冰醋酸：水(50：2：50)；检测波长346nm；三者流速均为1ml /min；进样量为10μl；柱温为25℃。结果：复方甘草片中甘草酸的含量为7．51mg/g,异甘草苷和异甘草素的含量分别为3．01mg/g,0．448mg/g,上述3种组分的平均回收率分别为98．32%,99．57%和98．59%。结论：本方法可作为复方甘草片中的甘草酸、异甘草苷和异甘草素的含量质量控制的一种有效方法。     

甘草及其黄酮类化合物的神经保护作用

甘草及其黄酮类化合物对神经元有保护作用,能对抗缺血再灌注引起的脑损伤,也有改善学习记忆和抗抑郁作用。综述甘草粗提物及其异甘草素、甘草素、甘草查耳酮、光甘草定等黄酮类化合物的神经保护作用的研究进展文献,认为甘草及其黄酮类化合物的神经保护作用是其抗炎、抗氧化、抗细胞凋亡及抗胆碱酯酶、单胺氧化酶、环磷酸腺苷磷酸二酯酶等基本药理作用综合的结果。     

甘草素与异甘草素的合成

甘草素与异甘草素的合成杨立，沈凤嘉（兰州大学化学系，兰州７３００００）甘草（Ｇｌｙｃｙｒｒｈｉｚａｕｒａｌｅｎｓｉｓｆｉｓｃｈ．）为我国一项宝贵的中药资源，历来受到人们重视。甘草素（ｌｉｑｕｉｒｉｔｉｇｅｎｉｎ）和异甘草素（ｉｓｏｌｉｑｕｉｒｉｔｉｇ...     

异甘草素对人宫颈癌细胞增殖的抑制作用

目的鉴于异甘草素(ISL)对不同肿瘤细胞系的不同作用,研究ISL对人宫颈鳞状上皮癌细胞(CaSki)癌细胞的影响及有关机制。方法体外研究采用MTT法测定细胞增殖;流式细胞仪检测细胞周期;逆转录聚合酶链反应(RT-PCR)分析细胞周期蛋白B1(cyclin B1)mRNA表达;Western免疫印迹分析cyclin B1,P34cdc2和磷酸化P34cdc2(phospho-cdc2,酪氨酸15)蛋白表达;体内研究通过建立人宫颈癌CaSki细胞裸鼠移植瘤模型观察抑瘤率。结果ISL浓度依赖性(10~80μmol.L-1)抑制CaSki细胞增殖,IC50为(19.3±3.3)μmol.L-1,且呈时间依赖性。ISL 20μmol.L-1作用3 d对细胞抑制率为82.3%;ISL浓度依赖性(10~80μmol.L-1)干扰CaSki细胞周期,细胞周期阻滞于S和G2/M期,S和G2/M期的百分率分别从23.1%和8.2%上升到43.2%和32.1%;同时G0/G1期细胞百分率从68.7%下降到24.7%;RT-PCR分析显示,ISL(10~80μmol.L-1)显著抑制cyclin B1 mRNA表达,抑制率最高可达61.7%,且呈时间依赖性;Western免疫印迹分析显示,ISL作用24 h cyclin B1蛋白表达开始不同程度下降,48 h下降明显,P34cdc2变化较小,ISL作用16 h后磷酸化P34cdc2(酪氨酸15)蛋白水平明显改变;ISL(20~500 mg.kg-1.d-1)剂量依赖性抑制CaSki细胞裸鼠皮下移植瘤的生长,抑瘤率分别为36.8%,51.2%和84.6%,且对动物体重和外周血白细胞数均无明显影响。结论ISL可以显著抑制人宫颈癌细胞体内外增殖,其机制与将细胞周期阻滞于S和G2/M期及影响细胞周期因子cyclin B1的表达和改变P34cdc2的磷酸化水平有关。     

大鼠肝微粒体CYP3A1/2和CYP2C9/10参与甘草次酸羟化代谢

目的:对参与18α-甘草次酸(GA)羟化代谢的细胞色素P450(cytochromeP450,CYP)亚型进行研究。方法:采用大鼠肝微粒体体外代谢GA的孵育方法和高效液相色谱(HPLC)技术,通过分析甘草次酸在肝微粒体中形成的单羟化代谢物的酶促动力学,分析其酶学模型,然后用不同的CYP同工酶选择性抑制剂和底物进行抑制实验,初步选出介导甘草次酸单羟化代谢所涉及的CYP同工酶。结果:大鼠肝微粒体羟化代谢GA呈反应时间(10～40min),底物浓度(25～200μmol/L)和蛋白浓度(0.25～1.0g/L)依赖性。GA代谢为22α-羟-GA和24-羟-GA的Vmax分别为(7.9±1.4)μmol.min-1.g-1和(3.4±1.0)μmo1.min-1.g-1,Km分别为(33±9)μmol/L和(68±18)μmol/L。抑制性研究可见:TAO和Ery剂量依赖性抑制22α-羟-GA形成,最大抑制率分别为82.4%和45.7%,而Sul无显著抑制作用;Sul剂量依赖性抑制24-羟-GA形成,抑制率依次为26.8%、45.3%和69.5%,而TAO和Ery的抑制作用不显著。红霉素N-脱甲基酶活性与22α-羟化代谢速率高度相关(r=0.864,P<0.01,n=10),与24-羟化代谢速率无明显相关(r=0.310,P>0.05,n=10)。结论:大鼠肝微粒体CYP3A1/2和CYP2C9/10分别参与了GA的C-22α和C-24羟化代谢。     

HPCE法测定甘草中甘草素的含量

目的研究HPCE法测定甘草中甘草素的含量。方法采用未涂层弹性石英毛细管柱(75μm×50 cm,有效长度42.5 cm),以40mmol/L四氢硼钠-10%甲醇(pH)为运行缓冲液;运行电压:20kV;毛细管温度:25℃;二极管阵列检测器,测定波长λs=320nm,λR=380nm。结果以葛根素为内标,甘草素在0.6125~0.9800mg/L范围内有良好的线性关系,r=0.9999;平均加样回收率:98.72%,RSD为2.43%(n=6)。结论该方法操作简便,结果可靠,回收率及重现性好,可作为甘草质量控制的方法。     

Inhibition of monoamine oxidases A and B by simple isoquinoline alkaloids: racemic and optically active 1,2,3,4-tetrahydro-, 3,4-dihydro-, and fully aromatic isoquinolines

A series of 1,2,3,4-tetrahydro-, 3,4-dihydro-, and fully aromatic isoquinolines were tested as substrates and/or inactivators of highly purified human monoamine oxidase A and B (MAO A and B). None were found to be a substrate for either enzyme, but many of these isoquinolines could selectively inhibit either MAO A or B. Stereoselective competitive inhibition of MAO A was found with the R enantiomer of all the stereoisomers tested, including salsolinol (Ki = 31 microM), salsoline (Ki = 77 microM), salsolidine (Ki = 6 microM), and carnegine (Ki = 2 microM). As a class, the 3,4-dihydro-isoquinolines were the most potent inhibitors tested (Ki = 2-130 microM), and the fully aromatic isoquinolines had intermediate activity (Ki = 17-130 microM) against MAO A. In contrast, only a few of these compounds markedly inhibited MAO B. 1,2,3,4-Tetrahydroisoquinoline, its 2-methyl derivative, and o-methylcorypalline gave apparent Ki values of 15, 1, and 29 microM, respectively, and two 3,4-dihydroisoquinolines (compounds 22 and 25) showed substantial inhibition of MAO B (Ki = 76 and 15 microM, respectively). These results support the concept that the topography of the inhibitor binding site differs in MAO A and B.     

Inhibition of rat brain monoamine oxidase activities by psoralen and isopsoralen: implications for the treatment of affective disorders

Psoralen and isopsoralen, furocoumarins isolated from the plant Psoralea corylifolia L., were demonstrated to exhibit in vitro inhibitory actions on monoamine oxidase (MAO) activities in rat brain mitochondria, preferentially inhibiting MAO-A activity over MAO-B activity. This inhibition of enzyme activities was found to be dose-dependent and reversible. For MAO-A, the IC50 values are 15.2 +/- 1.3 microM psoralen and 9.0 +/- 0.6 microM isopsoralen. For MAO-B, the IC50 values are 61.8 +/- 4.3 microM psoralen and 12.8 +/- 0.5 microM isopsoralen. Lineweaver-Burk transformation of the inhibition data indicates that inhibition by both psoralen and isopsoralen is non-competitive for MAO-A. The Ki values were calculated to be 14.0 microM for psoralen and 6.5 microM for isopsoralen. On the other hand, inhibition by both psoralen and isopsoralen is competitive for MAO-B. The Ki values were calculated to be 58.1 microM for psoralen and 10.8 microM for isopsoralen. These inhibitory actions of psoralen and isopsoralen on rat brain mitochondrial MAO activities are discussed in relation to their toxicities and their potential applications to treat affective disorders.     

Liquiritigenin isolated from Glycyrrhiza uralensis stimulates osteoblast function in osteoblastic MC3T3-E1 cells

Liquiritigenin is one of the flavonoids present in Glycyrrhizae radix. In the present study, the effects of liquiritigenin on the function of osteoblastic MC3T3-E1 cells were studied. Liquiritigenin caused a significant elevation of cell growth, alkaline phosphatase activity, collagen synthesis, mineralization, and glutathione content in the cells (P<0.05). Moreover, liquiritigenin significantly decreased the production of reactive oxygen species (ROS) and osteoclast differentiation inducing factors such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and receptor activator of nuclear factor-κB ligand (RANKL) in the presence of antimycin A, which inhibits mitochondrial electron transport and has been used as a ROS generator. These results demonstrate that liquiritigenin may have positive effects on skeletal structure.     

A micromethod for the determination of the activities of kininases in rat plasma. Kinetics and inhibitory characteristics.

Kininase II (EC 3.4.15.1) (KII) and kininase I (KI) (EC 3.4.12.7) activities of rat plasma were characterized by the hydrolysis of hippuryl-L-histidyl-L-leucine (HHL), hippuryl-L-arginine (HLA) [expressed as carboxypeptidase N1 (CN1) activity] and hippuryl-L-lysine (HLL) [expressed as carboxypeptidase N2 (CN2) activity]. Using a spectrophotometric assay, biochemical characteristics of the three enzymes were investigated. The Michaelis-Menten constants were as follows: KII: Km 2.55 +/- 0.22 mM, Vmax 0.357 +/- 0.017 mumol/min/mL; CN1: Km 6.93 +/- 0.32 mM, Vmax 0.748 +/- 0.019 mumol/min/mL; and CN2: Km 35.8 +/- 1.52 mM, Vmax 13.11 +/- 0.40 mumol/min/mL. EDTA and O-phenanthroline inhibited the three enzyme assays at the same Ki, whereas captopril and 2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MERGETPA), allowed for the demonstration of the specificity of each assay. Furthermore, Ki values of MERGETPA against both CN1 (4.75 microM) and CN2 (2.36 microM) activities do not support the hypothesis that KI activity may be accounted for by the presence of isoenzymes in rat plasma.     

In vitro and in vivo antiallergic effects of Glycyrrhiza glabra and its components

Licorice (Glycyrrhiza glabra L., Leguminosae) is frequently used in traditional medicine to treat inflammatory and allergic diseases. In this study, the main components (glycyrrhizin, 18beta-glycyrrhetinic acid, isoliquiritin, and liquiritigenin) were isolated from licorice, and their anti-allergic effects, such as antiscratching behavior and IgE production-inhibitory activity, were evaluated both in vitro and in vivo. Liquiritigenin and 18beta-glycyrrhetinic acid most potently inhibited the degranulation of RBL-2H3 cells induced by IgE with the antigen (DNP-HSA) and rat peritoneal mast cells induced by compound 48/80. Liquiritigenin and 18beta-glycyrrhetinic acid potently inhibited the passive cutaneous anaphylactic reaction as well as the scratching behavior in mice induced by compound 48/80. These components inhibited the production of IgE in ovalbumin-induced asthma mice but liquiritigenin had little effect. This suggests that the antiallergic effects of licorice are mainly due to glycyrrhizin, 18beta-glycyrrhetinic acid, and liquiritigenin, which can relieve IgE-induced allergic diseases such as dermatitis and asthma.     

Inhibition of monoamine oxidase A-form and semicarbazide-sensitive amine oxidase by selective and reversible monoamine oxidase-A inhibitors, amiflamine and FLA 788(+)

In vitro studies demonstrated that two selective monoamine oxidase (MAO)-A inhibitors, amiflamine and FLA 788(+), have been shown to inhibit semicarbazide-sensitive amine oxidase (SSAO) in rat testis and lung homogenates in a concentration-dependent way. The inhibition was not greatly influenced by pretreatment of the preparations with either clorgyline (10(-3) mol/l), l-deprenyl (10(-3) mol/l) or SKF 525A (10(-4) mol/l). The two compounds showed a time-dependent inhibition of SSAO, and for the initial phase of the inhibition, amiflamine is a competitive inhibitor with a Kislope of 135 mumol/l, but FLA 788(+) is a noncompetitive inhibitor with a Ki value of 180 mumol/l. After preincubation for 60 min at 37 degrees C, however, inhibition by amiflamine was found to be essentially irreversible whereas that produced by FLA 788(+) was still noncompetitive and reversible. These two compounds also reversibly and competitively inhibited rat testis MAO-A with FLA 788(+) being much more selective towards this MAO (Kislope = 0.26 mumol/l for FLA 788(+) and 7 mumol/l for amiflamine, respectively). The present results indicate that both MAO-A-selective inhibitors also inhibit SSAO in vitro, but their properties as SSAO inhibitors differ from those as MAO-A inhibitors.     

4-Fluoro-3-nitrophenyl azide, a selective photoaffinity label for type B monoamine oxidase

The effects of 4-fluoro-3-nitrophenyl azide (FNPA) on types A and B monoamine oxidase in rat brain cortex were studied using serotonin and phenylethylamine as substrates respectively. FNPA competitively inhibited the oxidative deamination of both serotonin (Ki = 3 microM) and phenylethylamine (Ki = 0.78 microM) in the dark. Upon photoirradiation in the presence of FNPA, a photodependent inhibition of type B MAO activity resulted. This photodependent inhibition was apparently irreversible since there was no recovery of activity upon washing of the photolyzed FNPA-enzyme mixture. Additional evidence for the photoinduced covalent binding of FNPA to type B MAO is that non-competitive inhibition kinetics resulted after photolysis. The specificity of the photodependent incorporation of FNPA to type B MAO was shown by the protective effect of phenylethylamine and by decreased [3H]pargyline labeling after the enzyme was photolyzed with FNPA. Under the same experimental conditions, only minimal photodependent inhibition of type A MAO by FNPA was found. The observed difference in the efficiencies of the photodependent inactivation of the two types of MAO by FNPA suggests that there is a conformational or a structural difference in the active sites of the two types of MAO. The active site of type B MAO could be characterized by utilizing FNPA as a photoaffinity labeling probe.     

Inhibition of xanthine and monoamine oxidases by stilbenoids from Veratrum taliense

The bioassay guided refractionation of the methanol extract of roots and rhizomes of Veratrum taliense (Liliaceae) yielded five stilbenoids: veraphenol, resveratrol, piceid, isorhapontin, and mulberroside E, all inhibiting xanthine oxidase (XO, EC 1.2.3.2.) in vitro in a dose-dependent manner with IC50 values of 11.0, 96.7, 66.1, 70.0, and 78.4 microM, respectively. Veraphenol and mulberroside E were found to be mixed XO inhibitors with the Ki and Ki data of the former being 32.8 and 239.3 microM, and those of latter 32.5 and 13.8 microM, respectively. However, the inhibition on the enzyme by resveratrol, isorhapontin, and piceid was shown to be competitive with their Ki values of 9.7, 19.1, and 14.3 microM, respectively. Among the five stilbenoids, veraphenol and resveratrol were also revealed to inhibit competitively monoamine oxidase A (MAO, EC 1.4.3.4) with IC50 values at 38.0 and 26.6 microM, and Ki data 36.4 and 47.3 microM, respectively. However, none of the stilbenoids was inhibitory on MAO B in our assay. The structure-activity relationship examination showed that glycosylation of the stilbenoids could reduce the inhibition on XO and diminish the activity against MAO A, indicating that the free phenolic hydroxy group of the compounds was most likely essential for these bioactivities.     

CYP3A4 inhibitors isolated from Licorice

The extract of licorice (Glycyrrhiza uralensis FISHER, Leguminosae) showed CYP3A4 inhibitory activity with the IC50 value of 0.022 mg/ml. Bioassay-guided purification afforded nine compounds, 3-(p-hydroxyphenyl)propionic acid (1), isoliquiritigenin (2), (3R)-vestitol (3), licopyranocoumarin (4), 4-hydroxyguaiacol apioglucoside (5), liquiritin (6), liquiritigenin 7,4'-diglucoside (7), liquiritin apioside (8), and glucoliquiritin apioside (9). Among these compounds, 3, 7, and 5 showed potent CYP3A4 inhibitory activities with IC50 values of 3.6, 17, and 20 microM, respectively. Glycyrrhizin (10), a main constituent of licorice, however, was inactive for CYP3A4 inhibition.