3-羟基-6-O-甲基红霉素-9-肟基衍生物的合成及体外抗菌活性

目的　寻找并合成抗耐药菌活性的3位羟基红霉素衍生物。方法　以红霉素A为原料,经9位酮基肟化,9位肟羟基,2′位羟基和3′位二甲胺基同时苄基化,6位羟基甲基化,水解去3位克拉定糖,氢化还原脱苄基,对甲基苄基或邻氯苄基取代9位肟羟基等6步反应,制得3-羟基-6-O-甲基红霉素-9-肟基衍生物,其结构经¹³CNMR ,FAB MS确证。结果　共制得7个化合物,对其中4个(5 - 8)未见报道的化合物进行了体外抗菌活性测定。结论　5 ,7,8对部分红霉素诱导耐药菌有一定的活性     

9-肟基-3-酮基-6-O-甲基红霉素的合成

以红霉素为原料，经肟化、苄基化、甲基化、水解、氧化和氢化还原等6步反应，制得9-肟基-3-酮基-6-O-甲基红霉素。总收率41％。     

2′,4″-二乙酰基红霉素-9-O-杂环烷基肟衍生物的合成及体内抗菌活性

目的设计合成2′,4″-二乙酰基红霉素-9-O-杂环烷基肟衍生物,并对其体内抗菌活性进行评价。方法以红霉素为原料,经9位羰基肟化、肟羟基烷基化、2′,4″-二羟基乙酰化3步反应制得目标化合物;选取有代表性的8个化合物评价其对小鼠感染所致败血症的治疗作用。结果与结论共制得18个未见文献报道的目标化合物,经MS1、H-NMR确证结构;该类化合物具有较好的抗菌活性,其中化合物9n的活性优于对照药罗红霉素和克拉霉素。     

2',4″-二乙酰基红霉素-9-O-杂环烷基肟衍生物的合成及体内抗菌活性

目的 设计合成2',4"-二乙酰基红霉素-9-O-杂环烷基肟衍生物,并对其体内抗菌活性进行评价.方法 以红霉素为原料,经9位羰基肟化、肟羟基烷基化、2',4"-二羟基乙酰化3步反应制得目标化合物;选取有代表性的8个化合物评价其对小鼠感染所致败血症的治疗作用.结果与结论 共制得18个未见文献报道的目标化合物,经MS、1H-NMR确证结构;该类化合物具有较好的抗菌活性,其中化合物9 n的活性优于对照药罗红霉素和克拉霉素.     

2’，4＂-二乙酰基红霉素-9-O-杂环烷基肟衍生物的合成及体内抗菌活性

目的设计合成2’，4＂-二乙酰基红霉素-9-O-杂环烷基肟衍生物，并对其体内抗菌活性进行评价。方法以红霉素为原料，经9位羰基肟化、肟羟基烷基化、2’，4＂-二羟基乙酰化3步反应制得目标化合物；选取有代表性的8个化合物评价其对小鼠感染所致败血症的治疗作用。结果与结论共制得18个未见文献报道的目标化合物，经MS,^1H—NMR确证结构；该类化合物具有较好的抗菌活性，其中化合物9n的活性优于对照药罗红霉素和克拉霉素。     

大环内酯类药物研究进展

大环内酯类药物因其安全、有效 ,已在临床上应用 40余年 ,占据口服抗生素的主导地位 ,对感染性疾病有良好疗效 ,临床证实在一些非感染性疾病中用途广泛。大环内酯类药物是当今药理开发与临床研究最为活跃的一类药物。世界药学工作者不仅研制开发出了对酸稳定、改善了抗耐药性、扩展了抗菌谱、增强了抗菌活性的大环内酯类抗生素 ,而且发现了具有抑制细胞因子生成、抗癌、抗寄生虫等非抗菌活性的大环内酯类药物 ,为大环内酯类药物的广泛应用展示了远大的前景。现就大环内酯类药物的研究进展作一综述。1　通过改造修饰增强大环内酯类新药品种1 .1　耐酸型大环内酯类新药的研究　1 .1 .1　对 6 ,1 1 ,1 2 位羟基的改造　2 0世纪 80年代初 ,药物化学工作者将红霉素 6 羟基甲基化制得克拉霉素 ,即红霉素 6 Ｏ 甲基衍生物 ,成功应用于临床。由于羟基醚化 ,阻碍其酸性条件下形成螺缩酮 ,从而具有耐酸、口服血药浓度高且持久的特点 ,对大环内酯类抗生素传统敏感菌显示较强的抗菌活性 ,对部分细菌的体外活性强于红霉素。1 .1 .2　对 9 位酮基的改造　①将红霉素制得 9 肟化物后 ,对肟羟基进行醚化得到一系列化合物 ,经筛...     

(9S)-9-羟基-12-亚甲基红霉素A衍生物的合成

为了合成具有抗菌活性的红霉素衍生物,本文以红霉素A为原料,合成了6-位烯丙基取代中间体12,21-双键-2′-O,4″-O-二苯甲酰基-(9S)-9-O,11-O-异丙基-6-O-烯丙基红霉素A 12,得到(9S)-9-羟基-12-亚甲基衍生物6和6,7-去氢-(9S)-9-羟基-12-亚甲基衍生物11。经¹³C NMR,FAB-MS确证产物结构。所得化合物进行了体外抗菌活性测定。6和11均显示出较弱的抑菌活性。     

2-氨基异黄酮化合物的合成

本文报道了一系列2-氨基-3′-胺甲基-4′-羟基-6-取代异黄酮化合物(Ⅱ)的合成。中间体2-甲氧基-5-取代苯甲酸甲酯(Ⅲ)系用相转移催化技术同时进行醚化和酯化得到。Claisen缩合产物用三溴化硼脱甲基同时环化成2-氨基异黄酮化合物(Ⅵ)。利用Mannich反应在4′-羟基的邻位引入胺甲基制得目的物。药理筛选结果显示Ⅱbb′对小鼠具有明显的耐缺氧作用。     

C克拉霉素的合成

首先用邻氯氯苄保护红霉素A9—肟衍生物,其次用三甲基硅胺保护2′,4″-羟基,最后选择性甲基化6—羟基制得克拉霉素。     

4＂-0-取代红霉素衍生物的研究进展

随着大环内酯类抗生素广泛应用于临床,细菌耐药性的问题日趋严重,因此,开发对耐药菌有效的第3代红霉素衍生物成为目前的研究热点。综述红霉素分子上克拉定糖4＂位羟基结构修饰的研究进展,并介绍了若干个对耐药菌具有优良抗菌活性的新型4＂-0-取代红霉素衍生物。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.