HZ818树脂在紫杉醇初分离工艺中的应用

采用HZ818大孔吸附树脂对红豆杉浸膏中的紫杉醇成分进行吸附和洗脱试验，同时利用液质联用进行分析检测，确定了其最佳工艺参数。结果表明，HZ818树脂对紫杉醇有良好的吸附分离效果。优化工艺条件为：样品溶于体积分数40％甲醇，以1．5mL／min过柱，体积分数75％甲醇淋洗，体积分数85％甲醇以0．5mL／min洗脱，紫杉醇的质量分数从原浸膏中的1．02％提高到8．1％，回收率达98．6％。     

对数期继代对南方红豆杉细胞培养动力学的影响

目的 解决南方红豆杉细胞生长缓慢及代谢水平低下的问题。方法 对对数期(20d)和静止期(30d)的红豆杉细胞分别进行继代，在整个生长周期中测定了培养基中的碳源、氮源、磷酸盐的变化并分析了红豆杉细胞生长及紫杉醇的合成情况。结果 对数期继代细胞吸收碳源和硝态氮早于静止期继代的细胞，且前者的比生长速度是后者的1．5倍，紫杉醇含量提高了近4倍。结论 对数期继代有利于生物量的积累及紫杉醇的合成。     

紫杉醇诱导HL—60细胞凋亡的研究

目的：观察抗微管药紫杉醇对急性白血病细胞株HL－60是否具有凋亡诱导作用,并进一步研究bcl－2基因在此过程中的作用。方法：（1）以紫杉醇处理HL－60细胞,观察细胞生长抑制作用的时间效应和剂量效应,在光镜和电镜下观察细胞形态变化;（2）用流式细胞仪检测药物孵育前后细胞凋亡率（AP）的变化;（3）用RT－PCR法检测药物孵育前后bcl-2基因的表达水平。结果：（1）在一定剂量和时间范围内紫杉醇能抑制HL－60细胞生长;（2）紫杉醇能诱导HL－60细胞凋亡,并显示剂量效应：（3）在紫杉醇诱导HL－609细胞凋亡过程中,bcl－2基因表达水平下调。结论：紫杉醇能诱导HL－60细胞凋亡;bcl-2基因参与了紫杉醇诱导HL－60细胞凋亡的调控。     

Estrogen increases intracellular p26Bcl-2 to p21Bax ratios and inhibits taxol-induced apoptosis of human breast cancer MCF-7 cells

Recent studies have demonstrated that following estrogen ablation, estrogen responsive breast cancer cells undergo apoptosis. In addition, estrogen receptor (ER) expression has been strongly correlated with the expression of the bcl-2 gene product, p26Bcl-2 protein, which is known to inhibit apoptosis. In the present studies, we investigated whether estrogen affects the intracellular levels of p26Bcl-2 and thereby modulates taxol-induced apoptosis of estrogen responsive human breast cancer MCF-7 cells. Transfer of MCF-7 cells to a culture-medium without estrogens reduced their intracellular p26Bcl-2 levels by 50%. Inclusion of 0.1 M estradiol in the medium produced approximately a four-fold increase in p26Bcl-2, but not p29Bcl-xL or p21Bax levels; the expression of the c-myc and mdr-1 genes remained unchanged. Estradiol-induced four-fold increase in the ratio of the p26Bcl-2 to p21Bax levels caused a significant decline in the lethal, kilobase size DNA fragments of apoptosis, which had resulted when MCF-7 cells were cultured in a medium without estrogen. In addition, in MCF-7 cells, estradiol-induced increase in the intracellular p26Bcl-2 to p21Bax ratios was associated with a significant reduction in the large-sized DNA fragmentation induced by treatment with taxol. The increased ratios also protected MCF-7 cells against taxol-mediated cytotoxicity as assessed by the MTT assay. These results suggest that by modulating p26Bcl-2 levels, estrogens may affect the antitumor activity of taxol and potentially of other anti-breast cancer drugs against estrogen responsive human breast cancer cells.     

X-Ray Structure and Crystal Lattice Interactions of the Taxol Side-Chain Methyl Ester

A colorless, parallelepiped crystal of methyl (2R,3S)-N-benzoyl-3-phenylisoserinate belonging to the space group P2_l with a = 5.414(4), b = 7.813(1), c = 17.802(7) , = 90.87(4)°, Z = 2, V = 752.9 ³, D _calc = 1.32 g cm^–3, and µ_calc = 1.02 cm^–1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [F _o 5(F_o)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the crystal lattice of this compound.     

紫杉醇、三尖杉宁碱和7-表-10-去乙酰基紫杉醇的分离及7-表-紫杉醇的转化研究

目的 探索从云南红豆杉树皮提取物中分离紫杉醇、三尖杉宁碱和7-表-10-去乙酰基紫杉醇3种纯化合物以及7-表-紫杉醇转化成紫杉醇的高效方法。方法 用乙酸叔丁酯为单漉动相。硅胶为填充柱的正相色谱系统分离。使用碱性氧化铝，在40℃对7-表-紫杉醇进行催化而转化成紫杉醇。结果与结论 分离得到紫杉醇、三尖杉宁碱和7-表-10-去乙酰基紫杉醇3个纯化合物。7-表-紫杉醇转化率可达30％。     

KP544, a nerve growth factor amplifier: Pharmacokinetics,safety, and efficacy in the rat

In cultured cells, KP544 [2‐amino‐5‐(4‐chlorophenylethynyl)‐4‐(4‐trans‐hydroxycyclohexyl amino) pyrimidine] amplifies differentiation initiated by nerve growth factor (NGF) or cAMP. This report describes the pharmacokinetics, safety, and neuroprotective efficacy of KP544 in rats. After an oral dose of 10 mg/kg KP544 was 25% bioavailable with a plasma half‐life of 1.3 h and brain levels 6‐fold higher than plasma levels at 4 and 8 h post‐dose. In a safety study, daily oral dosing for 30 days at 10 and 100 mg/kg was well tolerated. The favorable pharmacokinetic and safety profiles, together with its amplification of NGF in vitro, prompted evaluation of KP544 in two models involving NGF deficiencies. In the first model, brains were lesioned with intrastriatal injections of quinolinic acid. KP544 at oral doses of 0.02 to 1.0 mg/kg/day almost completely prevented the resulting learning deficits as evaluated using a radial‐arm‐water maze. At the lowest dose, there was a slower onset of functional improvement. These effects were accompanied by reductions (16–34%) in the striatal lesion size that were greatest at the highest dose and comparable to those seen with NGF therapy. The second model involved a peripheral neuropathy induced by taxol that is associated with decreases in NGF. KP544 at oral doses of 0.1–10 mg/kg/day decreased the severity of the neuropathy as measured by caudal nerve conduction velocities (30–70% return to control values). In both models, KP544 had a large therapeutic index suggesting its potential as a new approach for treating clinical disorders involving deficiencies in NGF. Drug Dev. Res. 62:60–70, 2004. © 2004 Wiley‐Liss, Inc.     

10-去乙酰基-7-表紫杉醇转化为紫杉醇的研究

目的将天然紫杉烷类物质10-去乙酰基-7-表紫杉醇高效地转化为抗癌药物紫杉醇.方法首先将10-去乙酰基-7-表紫杉醇中的2'-OH选择性保护、7-OH乙酰化、去保护3步一锅反应获得7-表紫杉醇,再在DBU的催化下差向异构化为紫杉醇.结果本方法以10-去乙酰基-7-表紫杉醇为起始原料,以40%的总收率制备得到紫杉醇.结论建立了一条将天然紫杉烷类物质以较高的化学选择性以及良好的收率转化为紫杉醇的途径.     

Drug target interaction of tubulin-binding drugs in cancer therapy

Microtubules and their component protein, tubulin, constitute a popular target for the treatment of cancer. Many drugs that are presently used in clinics or in clinical trials and drugs that show promise as anticancer drugs bind to tubulin and microtubules. There are three conventional binding sites on β-tubulin where many of these drugs bind. The binding properties, conformational changes upon binding, association constants and thermodynamic parameters for the drug–tubulin interaction on these three sites are discussed. The antiproliferative activities of these drugs and the possible correlation with the binding properties are also described.     

Nobiletin and its derivatives overcome multidrug resistance (MDR) in cancer: total synthesis and discovery of potent MDR reversal agents

Our recent studies demonstrated that the natural product nobiletin (NOB) served as a promising multidrug resistance (MDR) reversal agent and improved the effectiveness of cancer chemotherapy in vitro. However, low aqueous solubility and difficulty in total synthesis limited its application as a therapeutic agent. To tackle these challenges, NOB was synthesized in a high yield by a concise route of six steps and fourteen derivatives were synthesized with remarkable solubility and efficacy. All the compounds showed improved sensitivity to paclitaxel (PTX) in P-glycoprotein (P-gp) overexpressing MDR cancer cells. Among them, compound 29d exhibited water solubility 280-fold higher than NOB. A drug-resistance A549/T xenograft model showed that 29d, at a dose of 50 mg/kg co-administered with PTX (15 mg/kg), inhibited tumor growth more effective than NOB and remarkably increased PTX concentration in the tumors via P-gp inhibition. Moreover, Western blot experiments revealed that 29d inhibited expression of NRF2, phosphorylated ERK and AKT in MDR cancer cells, thus implying 29d of multiple mechanisms to reverse MDR in lung cancer.