四川蜡瓣花、密花樫木、四川溲疏及云南豆腐柴的化学成分研究

本论文对四川蜡瓣花 (Corylopsis willmottiae Rehd. et Wils.)、密花樫木[Dysoxylum densiflorum (Blume) Miq.]、四川溲疏 (Deutzia setchuenensis Franch)及云南豆腐柴 (Premna yunnanensis W. W. Smith)的化学成分进行了研究。通过色谱分离得到44个化合物。主要基于波谱数据鉴定了它们的结构，其中1个为新化合物。 1．从四川蜡瓣花全株的95%乙醇提取物中共分离鉴定了13个化合物，它们是：1-O-(3-O-甲基没食子酸)-岩白菜素(1)、11-O-没食子酰基岩白菜素(2)、 11-O-紫丁香基岩白菜素(3) 、岩白菜素(4)、4-O-没食子酰基岩白菜素(5) 、4,11-O-二没食子酰基岩白菜素 (6)[14]、β-谷甾醇 (7)、acetyl aleuritolic acid (8)、(-)-表没食子儿茶素没食子酸酯(9)、对羟基苯甲酮 (10)、 11-香豆酸酰岩白菜素 (11)[19]、丁香酸 (12)和没食子酸 (13)。其中1为新化合物。 2．从密花樫木根的95%乙醇提取物中共分离纯化了13个化合物，它们是：β-白檀酮(14)、richenone (15)、β-谷甾醇 (7)、cabraleadiol (16)、β-香树脂醇 (17)、龙脑香醇酮 (18)、cabraleadiol monoacetate (19)、cabraleone (20)、3β-hydroxy-5 -pregnen-20-one (21)、3β-hydroxy-5α-pregnan-20-one (22)、cabraleahydroxylactone (23)、川楝子甾醇B (24)、表儿茶素 (25)。 3．从四川溲疏全株95%乙醇提取物中共分离11个化合物，鉴定了其中的9个化合物。它们是：β-谷甾醇 (7)、白桦酯醇(26)、齐墩果酸(27)、hydrangetin (28)、肉桂酸 (29)，齐墩果酸-3-O-β-D-吡喃葡萄糖醛酸苷(30)、β-胡萝卜苷 (31)、齐墩果酸-3-O-（β-D-吡喃葡萄糖醛酸-6-正丁酯）(32)、齐墩果酸-3-O-β-D-吡喃葡萄糖醛酸-28-O-β-D-吡喃葡萄糖苷 (33)。 4．从云南豆腐柴95%乙醇提取物中分离得到12个化合物，分别为白桦脂醇 (25)、7-羟基黄烷酮 (34)、松属素 (35)、2’,4’-羟基查儿酮 (36)、高良姜素-3-甲醚 (37) 、高良姜素-3,7-二甲醚 (38)、异甘草素-4-甲醚 (39)、豆蔻明 (40)、乔松酮 (41)、异甘草素 (42)、arjunolic acid (43)、槲皮素3-O-β-D-木糖苷(44)。 5．综述了1976年以来樫木属植物化学成分和活性研究的概况。 Phytochemical investigation on Corylopsis willmottiae, Dysoxylum densiflorum, Deutzia setchuenensis, and Premna yunnanensis, led to the isolation of 44 compounds, 1 of which was new one. 1. One new compound was isolated from 95% ehanolic extrat of the whole plants of C. willmottiae, identified as 11-O-(3-O-methylgalloyl)-bergenin (1). The twelve known compounds isolated were 11-O-galloylbergenin (2), 11-O-syringylbergenin (3), bergenin (4), 4-O-galloylbergenin (5), 4,11-di-O-galloylbergenin (6), β-sitosterol (7), acetyl aleuritolic acid (8), (-)-epigallocatechin 3-O-gallate (9), 1-(4-hydroxyphenyl) ethanone (10), 11-O-coumaroylbergenin (11), syringic acid (12), gallic acid (13). 2. Thirteen compounds were isolated from 95% ethanol extract from the roots of D. densiflorum and identified as β-amyrenone (14), richenone (15), β-sitosterol (7), cabraleadiol (16), β-amyrin (17), hydroxydammarenone-Ⅱ (18), cabraleadiol monoacetate (19), cabraleone (20), 3β-hydroxy-5-pregnen-20-one (21), 3β-hydroxy-5α-pregnan-20-one (22), cabraleahydroxylactone (23), toosendansterol B (24) and (-)-epicatechin (25). 3. Eleven compounds were isolated from ethanol extract of D. Setchuenensis. Nine were identified as β-sitosterol (7), betulin (26), oleanolic acid (27), hydrangetin (28), cinnamic acid (29), oleanolic acid 3-O-β-D-glucuronopyranoside (30), β-daucosterol (31), oleanolic acid 3-O-β-D-glucuronopyranoside-6-O-butyl ester）(32), oleanolic acid 3-O-β-D-glucuronopyranosyl-28-3-O-β-D-glucopyranoside (33). 4. Twelve compounds were isolated from ethanol extract of P. yunnanensis and identified as betulin (26), 7-hydroxyflavanone (34), pinocembrin (35), 2’,4’-dihydroxychalcone (36), galangin 3-methyl ether (37), galangin 3,7-dimethyl ether (38), isoliquiritigenin 4-methyl ether (39), cardamonin (40), pinostrobin (41), isoliquiritigenin (42), arjunolic acid (43), quercetin 3-O-β-D-lyxosopyranoside (44). 5. Chemical constituents and biological activities of the genus Dysoxylum (Meliaceae) were reviewed during 1976-2009.

具有环氧化酶-2选择性抑制活性的多取代蒽醌的合成

1-甲基-2-甲氧羰基-3, 6, 8-三羟基-7-甲氧基蒽醌是从唐菖蒲干球茎中分离到的具有环氧化酶-2选择性抑制活性的多取代蒽醌类化合物。本文试图合成该化合物，实现了其类似物的合成，同时发现了几个未见报道的反应。 1．通过Diels-Alder 反应合成了关键中间体——3-甲基-5-羟基-1, 2, 4-苯三甲酸三甲酯，1-COOMe选择性水解产物与1, 2, 3-三甲氧基苯进行分子间Friedel-Crafts反应的产物再进行分子内Friedel-Crafts反应得到了目标产物的类似物1-甲基-2-甲氧羰基-3-羟基-6，7，8-三甲氧基蒽醌（路线1）。目标产物及其它类似物的合成正在进行中。 2．以乙酰乙酸甲酯和巴豆醛为原料，经过Michael加成、分子内的Aldol反应、芳香化、选择性甲酰化和还原反应，得到关键中间体2-甲基-3-羟甲基-6-甲氧基苯甲酸甲酯及其衍生物。通过该化合物与3，4，5-三甲氧基苯甲酸甲酯进行Friedel-Crafts烷基化反应得到了多取代的二苯基甲烷衍生物，拟进一步关环合成目标化合物（路线2）。 3．发现邻甲氧基苯甲酸甲酯中酯甲基可以被正丁基锂和仲丁基锂中烷基交换生成相应的酯，反应的机理不明确。当使用叔丁基锂时，得到的是邻甲氧基苯基叔丁酮，这个方法可以用来合成芳基叔丁酮类化合物。 4．以2-苄氧基-6-甲基苯甲酸甲酯为原料进行氯甲基化反应时，以苯和二氯乙烷作溶剂，发生了苄基的迁移和芳环的偶联，分别得到2，2'-二甲基-3，3'-二甲氧羰基-4，4'-二羟基联苯和2，2'-二甲基-3，3'-二甲氧羰基-4，4'-二羟基-5，5'-二苄基联苯。这是对称联苯合成的新方法。 5．水杨酸羟基邻对位的选择性甲酰化可以分别通过水杨酸和水杨酸甲酯用HMTA/CF3COOH来实现。 6．Lewis酸催化3，4，5-三甲氧基苄醇环化成1, 2, 3, 6, 7, 8, 11, 12, 13-nonamethoxyl-10,15-dihydro-5H-trbibenzo [a, d, g] cyclononene (NDTC)，产率(54%)高于已有方法（12%）。 Methyl 3,6,8-trihydroxy-7-methoxy-1-methylanthraquinone-2-carboxylate is a new COX-2 selective inhibitor isolated from Gladiolus gandavensis. Two strategies were investigated to synthesis this compound, in which some important reactions were discovered. 1. The key intermediate 5-hydroxy-3-methylbenzene-1,2,4-tricarboxylic acid 2,4-dimethyl ester was prepared via Diels-Alder reaction followed by selective hydrolysis of 1-COOMe. This compound was coupled with 1,2,3-trimethoxybenzene and the product undergo intramolecular Friedel-Crafts reaction to give methyl 3-hydroxy-5,6,7-trimethoxy-1-methylanthraquinone-2-carboxylate (1st route). The target compound and other analogues are being prepared with the same procedure. 2. The key intermediates methyl 3-hydroxymethyl-6-methoxy-2-methylbenzoate and its derivatives were prepared starting from crotonaldehyde and methyl acetoacetate via Michael addition, intramolecular aldol reaction, aromatization, formylation and reduction. The intermediates were coupled respectively with derivatives of gallic acid to give polysubstituted diphenylmethane. However, attempts to cyclize these compounds to the target compounds and analogues were not successful (2nd route). 3. In the process for ortho-lithiation of methyl 2-methoxybenzoate, the substrate converted respectively to n-butyl 2-methoxybenzoate and sec-butyl 2-methoxybenzoate when n-BuLi and sec-BuLi were used. However, tert-BuLi reacted with methyl 2-methoxybenzoate afford 2-methoxyphenyl tert-butyl ketone, which could be used to synthesize aryl tert-butyl ketones. 4. The transformtion of methyl 2-benzoxy-6-methylbenzoate to dimethyl 4,4'-dihydroxy-2,2'-dimethylbiphenyl-3,3'-dicarboxylate in benzene, and dimethyl 5,5'-dibenzyl-4,4'-dihydroxy-2,2'-dimethylbiphenyl-3,3'-dicarboxylate in 1,2-dichloroethane in the presence of ZnCl2 provides a new method for the synthesis of symmetric biphenyl. 5. The formylation of salicylic acid at C-5 and methyl 2-hydroxybenzoate at C-3 could be regioselectively realized by using HMTA/CF3COOH. 6. Racemic 1, 2, 3, 6, 7, 8, 11, 12, 13-nonamethoxyl-10, 15-dihydro-5H-trbibenzo [a, d, g] cyclononene was prepared via Lewis acids catalyzed trimerization of 3, 4, 5-trimethoxylbenzyl alcohol with yield (54%) higher than the reported procesure (12%).

糖原酸酯合成方法的研究以及二环糖胺的合成

在糖化学中，糖原酸酯是一类重要的合成中间体，广泛运用于1,2-反式糖苷的合成，尤其对于寡糖的立体选择性合成具有重要的价值。目前文献报道的制备糖原酸酯的方法大多存在对环境不友好的问题。本文对传统的糖原酸酯制备方法进行了改进，通过研究发现无机碱也能够有效地催化合成糖原酸酯。以溴代糖和醇（或糖基受体）为原料，在无机碱、四丁基溴化铵、乙腈的体系中，合成了一系列简单醇糖原酸酯和糖-糖原酸酯。 聚乙二醇及其衍生物作为有机反应的溶剂和催化剂在有机化学中有广泛的应用。本文阐述了一种以溴代糖和醇（或糖基受体）为原料，在无机碱和聚乙二醇二甲醚反应体系中合成糖原酸酯的方法。该方法中，聚乙二醇二甲醚即作为绿色溶剂又作为催化剂，反应条件温和、环保、高效。 糖胺是一类重要的糖苷酶抑制剂，已在糖尿病和其他代谢紊乱等疾病的治疗中发挥了极其重要的作用。本文提供了一种合成一类具有潜在的糖苷酶抑制活性、结构新颖的二环糖胺的途径。该合成思路是以1-叠氮基-2-C-乙酰甲基-3,4,6-三-O-苄基-2-脱氧-β-D-葡萄糖为原料，经二环糖亚胺中间体，通过二环糖亚胺还原或加成得到一类二环糖胺。 Sugar orthoesters as one of the most important intermediates in carbohydrate chemistry, are used extensively in the synthesis of sugar 1,2-trans-glycosides, especially oligosaccharide. These methods in the literature are mostly eco-unfriendly. Herein we described a modified protocol for the preparation of sugar orthoesters using inorganic base, by improving the conventional method. Our method involves the treatment of peracetylated or perbenzotlated glycosyl bromides with alcohols in the presence of a quaternary ammonium salt and an inorganic alkali in acetonitrile solvent, affording both simple sugar orthoesters and sugar-sugar orthoesters. Polyethylene glycol and their derivatives as solvents or catalysts play a significant role in the organic reaction. We developed a novel and environmentally benign methodology towards the synthesis of sugar orthoesters, which are prepared by the reaction of peracetylated or perbenzotlated glycosyl bromides and alcohols in the presence of dimethyl ether of polyethylene glycol as either the reaction medium or catalyst. Glycosylamines and pseudo-glycosylamines have been tested against various glycosidases, and applied to the treatment of diabetes and other metabolic disorders. We presented a route of the synthesis of a bicyclic glycosylamine as a potential glycosidases inhibitor with unique structure. Reduction of 2-C-acetlymethyl-β-glucopyranosyl azide derivative firstly produced a bicyclic glycosylimine intermediate, and subsequently the bicyclic glycosylamine and its derivatives would be prepared through the selective reduction or addition the C=N double bond of the bicyclic glycosylimine intermediate.

白腐菌选择性降解木质素的研究

对15株白腐真菌进行了以玉米秸秆为基质的初步筛选，从中获得一株选择性系数较高的菌株Y10，并对其降解玉米秸秆的情况进行了研究。结果表明，在30天的培养过程中菌株Y10对玉米秸秆降解的选择性系数都大于1，第15天选择性系数最高为3.88。对未经降解和降解过的玉米秸秆分别作了紫外光谱和红外光谱分析，结果表明，经该菌降解后玉米秸秆的化学成分发生了很大变化，且木质素的降解程度要大于纤维素的降解程度。对菌株Y10进行了ITS-5.8S rDNA序列鉴定，初步判定其为Cerrena sp.。 为了考查不同的外源添加物对菌株Y10降解玉米秸秆的影响，在以玉米秸秆为基质的固态发酵培养基中分别添加了7种金属离子、8种碳源、6种氮源。结果显示，这7种金属离子均能促进木质素的降解，并且一定浓度的某些离子明显抑制纤维素的降解；其中添加0.036%的MnSO4·H2O和0.36%的MgSO4·7H2O对纤维素降解的抑制作用比较强，降解率分别为0.96%和1.31%，木质素的选择性系数分别达到了34.40和20.17。8种碳源中除麦芽糖外都能促进木质素的降解，除微晶纤维素外都明显促进纤维素的降解。6种氮源中酒石酸铵、硫酸铵、草酸铵和氯化铵的添加都会使该菌生长变慢，而且氮源浓度越高菌丝生长越慢。外加碳源和金属离子对半纤维素降解和选择性系数的影响不大。 同时对菌株Y10在液态培养下产木质素降解酶的条件和培养基做了优化。结果表明，在初始产酶培养基中，菌株Y10的漆酶酶活在第10d达到最高，锰过氧化物酶酶活在第11d达到最高，基本上检测不到木质素过氧化物酶。菌株Y10产漆酶的最适温度为32℃，最适PH为6.0；产锰过氧化物酶的最适温度为32℃，最适PH为6.5。菌株Y10产漆酶的最佳碳源为甘露糖，最佳氮源为酒石酸铵，最适诱导剂VA浓度为3 mmol/L，最适表面活性剂TW-80浓度为1%。 利用响应面法对其产漆酶的培养基进行优化，优化后的培养基配方为葡萄糖10.00 g/L，酒石酸铵0.50 g/L，大量元素296.50 ml/L，微量元素100.00 ml/L，NTA 1.40 g/L，VA 5.00 mmol/L，吐温-80加入量为0.10%。进行了菌株Y10产漆酶的验证实验，实测酶活为5282.56 U/L，与预测酶活5162.73 U/L接近。在优化后培养基中，菌株Y10在第14 d达到生长的最高峰，第20 d时，漆酶酶活最高，为11325.00 U/L；第16 d时，锰过氧化物酶酶活最高，为30.77 U/L。 对菌株Y10的漆酶酶学性质做了初步的研究，结果显示，酶反应的最适温度为40℃-65℃，最适PH为3.0。在40℃，PH=3.0时，漆酶催化ABTS反应的米氏方程为 。 Fifteen white-rot fungi based on corn stalk were screened. One white-rot fungus Y10 with high selectivity value was obtained. The degradation of corn stalk was initially studied. The results indicated that the selectivity value was above 1 during the 30 day-cultivation and the highest was 3.88 after 15 days. The composition of untreated and treated stalk was analyzed through ultraviolet spectroscopy and infrared spectroscopy. It was found that the composition of treated stalk was greatly altered and the degree of the degradation of lignin is greater than the cellulose. Y10 was identified as Cerrena sp. by ITS -5.8S rDNA sequence analysis. The influence of metal ions, carbon sources and nitrogen sources on corn stalk degradation by white-rot fungus was studied. While all seven metal ions could promote lignin degradation, the cellulose degradation was best inhibited at certain ion concentrations. Notably, when 0.036% MnSO4·H2O and 0.36% MgSO4·7H2O were added into the medium, the cellulose degradation was restrained to the extents that the coefficients of lignin selectivity rose to 34.40 and 20.17 respectively. It was also found that all carbon sources except maltose can promote lignin degradation. The addition of carbon sources other than microcrystalline cellulose significantly promoted cellulose degradation. The addition of the nitrogen sources, ammonium tartrate, ammonium sulfate, oxalate, ammonium chloride, resulted in remarkable inhibition to mycelium growth; the larger the concentrations of nitrogen sources are, the slower the mycelium grew. The addition of carbon sources and metal ions had less impact on the degradation of hemicellulose and selectivity value. Meanwhile, we optimized the conditions and culture medium of the lignin-degrading enzyme production of strain Y10. The results showed that in the initial culture medium, the Lac activity was highest at the 10th day, the MnP activity was highest at the 11th day and the LiP could not be detected. The optimum condition of Lac was at temperature 32 and PH =6.0 and the optimum condition of MnP was at temperature 32 and PH =6.5. The optimum carbon source for Lac was seminose, the optimum nitrogen source was ammonium tartrate, the optimum content of VA was 3 mmol/L, the optimum content of TW-80 was 1%. PB and RSM were used to optimize the culture medium of laccase by white-rot fungus Y10. The optimum culture medium was consist of glucose 10.00 g/L, ammonium tartrate 0.50 g/L, macro elements 296.50 ml/L, trace elements 100.00 ml/L, NTA 1.40 g/L, VA 5.00 mmol/L, TW-80 0.10%. Under the optimal conditions, the activity of laccase was 5282.56 U/L and the experimental value agreed with the predicted value 5162.73 U/L. The biomass was highest at the 14th day, the Lac activity was highest at the 20th day, the MnP activity was highest at the 16th day. The results of the studies on the characteristics of Lac showed that the optimum temperature for Lac activity is 40℃-65℃ ; the optimum PH for Lac activity is 3.0 and under 40℃，PH=3.0, the Michaelis-menten equation of Lac catalized ABTS oxidation was .

辐射诱导的HeLa细胞旁效应信号通路研究

随着肿瘤认识的不断深入，肿瘤外科学、肿瘤放射治疗学、肿瘤化学治疗学构成了现代肿瘤治疗学的三大支柱，而放射治疗学的研究对于肿瘤的治疗有重要的临床意义。本文通过对HeLa进行辐射来观察其产生的旁效应信号通路，从而对临床工作的起到一定的帮助。辐照过的细胞通过释放信号分子引起周围未辐照细胞产生一系列的生物学反应的现象，称之为辐射诱导的旁效应。活性氧（Reactive oxygen species, ROS）和一氧化氮（Nitric oxide, NO）是辐射诱导的旁效应信号通路中的两个重要信号分子。本文研究了这两种重要的信号分子在辐射诱导的HeLa细胞旁效应信号通路中的关系。通过微核实验，我们发现X射线以及12C6+ 辐照过的HeLa细胞及其旁观者细胞的微核形成明显增加，而1%的二甲亚砜（Dimethyl sulfoxide，DMSO，ROS清除剂）预处理X射线辐照的细胞则显著抑制了受辐照细胞及其旁观者细胞的微核形成。1 Gy的X射线辐照能够抑制细胞的增殖速率而0.5%和1%的DMSO预处理则能减少X射线的增殖抑制作用，并且DMSO预处理的效果与浓度有关：1%的DMSO比0.5%的DMSO处理更大程度的恢复了受辐照细胞的增殖速率。另一方面，接受条件培养基（Conditioned medium）的旁观者细胞的增殖速率增加，而DMSO预处理产生条件培养基的受辐照细胞则使旁观者细胞的增殖速率降低，且DMSO预处理的效果同样与其浓度相关：浓度越高，条件培养基的刺激生长作用越小。Western blotting和DAF-FM DA荧光探针检测分别显示了辐照过后细胞的诱导型一氧化氮合酶（Inducible nitric oxide synthase, iNOS）和NO水平均升高，而DMSO预处理则降低其水平。因此，我们推测在X射线辐照的HeLa细胞旁效应信号通路当中ROS是NO的上游信号。另外，我们采用培养基转移后立即加DMSO或BMS－345541（IKK/NF-κB抑制剂）的方法研究了旁观者细胞当中的旁效应信号通路。我们发现DMSO和BMS－345541均显著抑制了旁观者细胞的NO水平。因此，在旁观者细胞当中ROS与NF-κB均为NO的上游信号

Thermodynamic studies of monuron

Monuron (C9H11ClN2O; N,N-dimethyl-N'-(4-chlorophenyl) urea, CAS 150-68-5) was synthesized and the heat capacities of the compound were measured in the temperature range from 79 to 385 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The enthalpy and entropy data of the compound relative to the reference temperature 298.15 K were derived based on the heat capacity data. The thermodynamic properties of the compound were further investigated through DSC and TG analysis. The melting point, the molar enthalpy, and entropy of fusion were determined to be 447.6 +/- 0.1 K, 29.3 +/- 0.2 kJ mol(-1), and 65.4 J K-1 mol(-1), respectively. (C) 2004 Elsevier B.V. All rights reserved.

Monolithic column with zwitterionic stationary phase for capillary electrochromatography

A capillary electrochromatography (CEC) monolithic column with zwitterionic stationary phases was prepared by in situ polymerization of butyl methacrylate, ethylene dimethacrylate, methacrylic acid, and 2-(dimethyl amino) ethyl methacrylate in the presence of porogens. The stationary phases have zwitterionic functional groups, that is, both tertiary amine and acrylic acid groups, so the ionization of those groups on the zwitterionic stationary phase was affected by the pH values of the mobile phase, and further affects the strength and direction of the electroosmotic flow (EOF). Separations of alkylbenzenes and polycylic aromatic hydrocarbons based on the hydrophobic mechanism were obtained. Separation of various types of polar compounds, including phenols, anilines, and peptides, on the prepared column were performed under CEC mode with anodic and cathodic EOF, and different separation selectivities of those polar analytes were observed on the monolithic capillary column by using mobile phases with different pH values.

Highly enantioselective conjugate addition of diethylzinc to acyclic enones with fine-tunable phosphite-pyridine ligands

A new series of fine-tunable phosphite-pyridine (P,N) ligands derived from (S)-2-amino-T-hydroxy-6,6'-dimethyl-1,1'-biphenyl and (S)-2-amino-2'-hydroxy-4,4',6,6'-tetramethyl-1,1'-biphenyl was employed in Cu(I)-catalyzed conjugate addition of diethylzinc to acyclic enones. Excellent enantioselectivities (up to 98% ee) and highly catalytic activities were achieved for a variety of acyclic enones.

Cyclopropanation on a highly active heterogeneous catalyst: CuO/TiO2-Al2O3

Some heterogeneous catalysts, cupric oxide supported on different supports, were prepared and employed to catalyze the cyclopropanation of styrene and 2,5-dimethyl-2,4-hexadiene with ethyl diazoacetate (EDA). The catalytic performance for cyclopropanation strongly depends on the nature of the support. A novel catalyst, CUO/TiO2-Al2O3, in which Al2O3 is modified with a monolayer TiO2, is found to be most active and selective for the cyclopropanation reaction. The yields of 93 and 94% cyclopropanes are obtained for styrene and 2,5-dimethyl-2,4-hexadiene at 40 degreesC as the substrates, respectively. The activity and selectivity in cyclopropanes are optimized with a monolayer dispersion of cupric oxide on the corresponding supports. (C) 2002 Elsevier Science B.V. All rights reserved.

The study on a PVC membrane electrode for gemfibrozil

In this paper, a poly(vinyl chloride) (PVC) membrane electrode is prepared for gemfibrozil, 2, 2-dimethyl-5(2,5-xylyloxy) valeric acid, based on its ion pair complexes with hexadecyltrioctyl ammonium iodide (HTOA). The membrane composition of the electrode was optimized by using the sequential level elimination method for orthogonal experimental design. The electrode has a Nernstian response range from 2.5 X 10(-5) to 0.1 mol/l with an average slope of 55.3 mV/decade. The limit of detection is 7.1 X 10(-6) mol/l. The electrode responses were not affected by pH in the range 10.0-12.3. A Na2B4O7-Na2CO3 buffer of pH = 11.0 was selected as the background electrolyte solution for potentiometric measurements. The electrode was used for determining gemfibrozil in pharmaceutical preparations with satisfactory results.