人用截短侧耳素类抗生素的研究现状与发展趋势

为了应对日益严重的细菌耐药性问题,人们不断研发具有新型作用机制的抗菌药物,其中截短侧耳素及其衍生物作为重要的一类兽用抗生素,具有独特的作用机制,其特点不易产生交叉耐药性.已经上市的泰妙菌素、沃尼妙林均具有抗菌谱广及较强的抗菌活性,而2007年4月批准的瑞他莫林是近二十年来首个新的局部应用的抗菌药物,被认为是第一个人用截短侧耳素衍生物,标志着截短侧耳素类从兽用跨越到人用领域.本文就截短侧耳素的作用机制、耐药机制、人用截短侧耳素的临床研究现状以及新型截短侧耳素衍生物研发等方面的最新进展做简要概述.     

截短侧耳素类抗生素及其耐药研究进展

截短侧耳素(Pleuromutilins)是从担子菌纲侧耳属Pleurotus mutilus和Pleurotus passeckerianus中分离得到的二萜类抗生素，对革兰阳性菌和支原体具有良好的抗菌活性。截短侧耳素类药物用途广泛，泰妙菌素(Tiamulin)和沃尼妙林(Valnemulin)作为兽用药用于防治由病原微生物引起的猪痢疾、支原体肺炎等疾病；人用批准的瑞他莫林(Retapamulin)和来法莫林(Lefamulin)主要用于治疗球菌感染和获得性细菌性肺炎。近年来，截短侧耳素类药物耐药监测表明，在病原微生物的rplC、rplD、23sRNA、Cfr和vga基因中报道了多种新的突变位点，导致侧耳素类药物敏感性降低。本文对已上市的截短侧耳素类药物进行回顾，并对近十年该类药物的耐药机制研究进行综述，以期为新型截短侧耳素类药物的创制提供参考。     

头孢菌素类抗生素结构修饰的研究

细菌的耐药性问题日益严峻,给临床治疗带来极大困难。研发新型抗耐药菌药物成为目前的研究热点。头孢菌素作为重要的抗生素药物,在筛选新抗生素困难重重的情况下,对其进行适当的结构修饰成为创制新药的有效途径。本文简单介绍了头孢菌素类构效关系,并对头孢菌素分子结构中的C-2、C-3、C-7等部位的修饰改造以及相关母核来源进行了综述。     

截短侧耳素及其衍生物的研究进展

截短侧耳素是重要的二萜类兽用抗生素.发现至今,针对其衍生物进行了深入研究,发现了抗菌活性更强、应用范围更广的泰妙菌素、沃尼妙林、retapamulin和一系列水溶性衍生物等.其中retapamulin是2007年4月FDA批准的近二十年来第一个新的局部应用的抗菌药物,同时作为第一个人用截短侧耳素衍生物,标志着此类抗生素实现了从兽用到人用的飞跃.本文就截短侧耳素的作用机制、生物合成及其衍生物应用等方面的最新进展做简要概述.     

大环内酯类抗生素抗菌机制及构效关系研究现状

大环内酯类抗生素在临床上的广泛应用导致其耐药性问题日益凸显,对其作用机制及构效关系进行深入研究,有助于设计出抗菌活性更强且不易诱导耐药性的新型抗生素。综述大环内酯类抗生素抗菌机制及构效关系的研究现状。     

截短侧耳素在醇-水复合溶剂体系溶解度的测定与关联

截短侧耳素是一种三环二萜类抗生素，因其抗菌机制独特，与一般抗菌药物不发生交叉耐药，而日益受到重视。本 研究测定了截短侧耳素在不同甲醇 ( 或乙醇 )- 水复合溶剂 ( 醇含量 0~50%) 中在 273.15~333.15K 溶解度，并采用多项式经验方程 和 Apelblat 方程进行关联。结果表明，随着温度的提高，随溶剂中甲醇或乙醇含量的增加，截短侧耳素的溶解度显著同步增加。 多项式经验方程和 Apelblat 方程都能很好拟合截短侧耳素溶解度数据，回归系数都在 0.993 以上。热力学分析表明，截短侧耳 素在甲醇 ( 或乙醇 )- 水复合溶剂中的溶解过程焓变都是正值，且随着溶剂中醇含量的增加而增加，是一吸热过程。溶解过程的 熵变在纯水中是负值，随着溶剂中醇含量的增加，熵变也随之增加并且成为溶解度大幅提升的主要驱动力。本论文的研究结果 可为截短侧耳素的提取工艺优化及制剂工艺开发提供重要的科学依据。     

红霉素衍生物抗菌活性构效关系研究进展

为解决抗生素的耐药性问题，近年来在红霉素化学结构修饰方面开展了大量的研究，并发现了诸如酮内酯、酰内酯、双环内酯等多种具有良好抗耐药菌活性的新型大环内酯类化合物。该文对红霉素衍生物抗菌活性研究成果做一概括，并对构效关系研究的某些重要结论加以探讨。     

Lefamulin：一种新型人用截短侧耳素类抗菌药物的临床药学研究

摘要：Lefamulin是全球首个静脉和口服剂型的人用截短侧耳素类抗菌药物,具有独特的作用机制,与其他临床用抗菌 药物不易产生交叉耐药性。对社区获得性肺炎、皮肤软组织感染以及性传播疾病的常见病原体有良好的抗菌活性。本文就 lefamulin的作用机制、耐药机制、抗菌活性以及临床使用等方面进行综述。     

新一类β—内酰胺抗生素trinems研究进展

为了克服细菌对β-内酰胺类抗生素的耐药性,科学家们合成了新的一类β-内酰胺抗生素trinems.sanfetrinem是这一类化合物中的第一个,具有广谱抗菌活性,并且能耐受临床上几乎所有的β-内酰胺酶.本文就trinems这一类化合物的结构特点,构效关系及sanfetrinem的抗菌活性、药动学、药效学等方面作一阐述.     

恩诺沙星噁二唑硫乙酰腙类化合物的合成及抗肿瘤活性

目的寻找氟喹诺酮C-3羧基等排体的优化方法。方法噁二唑为恩诺沙星C-3羧基的等排体,硫醚酰腙作为修饰侧链,设计合成了C-3噁二唑硫醚酰腙类目标化合物7a~7l,其结构经元素分析和光谱数据确证,评价了目标化合物在体外对SMMC-7721、L1210和HL60 3种癌细胞的抗增殖活性。结果 12个新目标物被合成,它们对3种试验癌细胞的生长抑制活性强于母体恩诺沙星。初步的构-效关系表明,苯环带吸电子基化合物的活性强于其他取代基的化合物,对SMMC-7721细胞的活性与对照阿霉素相当。结论氟喹诺酮C-3羧基并非是抗肿瘤活性所必要的药效团,用功能化侧链修饰的唑杂环替代有利于提高抗肿瘤活性。     

Antibacterial activity and chemical modifications of PS-5 at the C-3 side chain

Using PS-5 as starting material, the effects of chemical modification at the C-3 side chain were studied on the antibacterial activity against Gram-positive and Gram-negative bacteria including beta-lactamase-producers. Among 35 side chains tested, 4-pyridylthio showed the highest antibacterial activity against the Gram-positive bacteria, and D-cysteinyl against the Gram-negative microbes. In general, compared with acetamidoethylthio in PS-5, basic side chains showed improved antibacterial activity against the staphylococci and pseudomonads, whereas the antibiotic activity against the Gram-negative bacteria decreased with bulky side chains. The introduction of 6-aminopenicillanate and 7-aminocephalosporanate to the C-3 side chain of carbapenem significantly reduced the antibacterial activity against the beta-lactamase-producing microbes.     

A click chemistry approach to pleuromutilin conjugates with nucleosides or acyclic nucleoside derivatives and their binding to the bacterial ribosome

Pleuromutilin and its derivatives are antibacterial drugs that inhibit protein synthesis in bacteria by binding to ribosomes. To promote rational design of pleuromutilin based drugs, 19 pleuromutilin conjugates with different nucleoside fragments as side chain extensions were synthesized by a click chemistry protocol. Binding was assessed by chemical footprinting of nucleotide U2506 in 23S rRNA, and all conjugates bind to varying degree reflecting their binding affinity to the peptidyl transferase center. The side chain extensions also show various protections at position U2585. Docking studies of the conjugates with the highest affinities support the conclusion that despite the various conjugations, the pleuomutilin skeleton binds in the same binding pocket. The conjugated triazole moiety is well accommodated, and the nucleobases are placed in different pockets in the 50S ribosomal subunit. The derivative showing the highest affinity and a significantly better binding than pleuromutilin itself contains an adenine-9-ylpropylene triazole conjugate to pleuromutilin C-22.     

Studies on cephalosporin antibiotics. V. Synthesis, antibacterial activity and oral absorption of new 3-[(Z)-2-methoxycarbonylvinylthio]-7 beta- [(Z)-2-(2-aminothiazol-4-yl)-2-(oxyimino)acetamido]cephalosporins.

A series of new 3-[(Z)-2-methoxycarbonylvinylthio]-7 beta-[(2- aminothiazol-4-yl)acetamido]-cephalosporins (1) having various oxyimino groups (Z-form) at the alpha position of the C-7 side chain was synthesized and evaluated for antibacterial activity and oral absorption in rats. Of these, the cephalosporin (1a) with a hydroxyimino group in the C-7 side chain showed a potent antibacterial activity against Gram-negative bacteria and Gram-positive Staphylococcus aureus as well as good oral absorption in rats. The structure-activity relationships of 1 are also presented.     

Synthesis and structure-activity relationships of a new series of cephalosporins, E1040 and related compounds.

The synthesis and in vitro antibacterial activity of a series of 7-[(Z)-2-aminoaryl-2-oxyiminoacetamido]-3-ammoniomethyl++ +-3-cephems are described. Variation of an oxyimino moiety with aminoaryl at the C-7 side chain and a quaternary ammonium moiety at the C-3 side chain were examined and structure-activity relationships were studied. E1040, the 3-(4-carbamoylquinuclidinio)methyl derivative of the 7-alpha-methoxyimino series of aminothiadiazolyl cephalosporins, exhibited excellent activity against both Gram-positive and Gram-negative bacteria, particularly against Pseudomonas aeruginosa, and possessed high stability to beta-lactamases.     

Synthesis and conformational analysis of fusidic acid side chain derivatives in relation to antibacterial activity.

Novel fusidic acid type antibiotics having flexible side chains are described. Saturation of the double bond between C-17 and C-20 of fusidic acid produces four stereoisomers differing in the configuration at C-17 and C-20. The structure-activity relationship of the stereoisomers was studied using computer-assisted analyses of low-energy conformations and crystallographic data. Only one of the four stereoisomers showed potent antibiotic activity comparable with that of fusidic acid, whereas the other three stereoisomers retained little or no activity. The orientation of the side chain is crucial, and there is only a limited space for bioactive side chain conformations. This investigation demonstrates the essential role of the side chain conformations in relation to antibacterial activity and contradicts earlier assumptions that the Delta17(20) bond is an essential feature in the molecule.     

Studies on monocyclic beta-lactam antibiotics. II. Synthesis and antibacterial activity of 3-acylamino-2-azetidinone-1-oxysulfonic acids

The synthesis and in vitro antibacterial and beta-lactamase inhibitory activity of the 2-azetidinone-1-oxysulfonic acids having a substituent at C-4 position of the beta-lactam ring are described. The influence of C-4 substituents on the antibacterial activity was examined for the compounds having alpha-ureidoacetyl or alpha-oxyiminoacetyl group as acyl side chain at C-3 position. The antibacterial activity is correlated with the C-4 substituents and acyl side chain. Especially, 4(R)-methyl substituted derivatives exhibited excellent activity against Gram-negative bacteria and 4-dimethyl substituted derivatives exhibited strong activity against resistant Gram-negative bacteria except for Pseudomonas aeruginosa. 39 and 40 showed strong inhibitory activity against cephalosporinase of Enterobacter cloacae H-27.     

Pleuromutilin and its derivatives-the lead compounds for novel antibiotics

Due to the rapid onset of resistance to most antibacterial drugs, research efforts are focusing on new classes of antibacterials with different mechanisms of action from clinically used antibacterials. Pleuromutilin derivatives have received more and more scientific attention for their unique mechanism of action. Two pleuromutilin derivatives, tiamulin and valnemulin have been successfully developed as antibiotics for veterinary use. Retapamulin, another pleuromutilin derivative has been approved for use in humans in April 2007 by Food and Drug Administration (FDA). It has been shown that there is rarely cross-resistance between pleuromutilin derivatives and other antimicrobial agents, and the development of resistance bacterial is still low. This review will demonstrate mechanism of action of pleuromutilin derivatives and reveal the structure-activity relationship (SAR) of pleuromutilin derivatives. Additionally, the pleuromutilin antibacterial derivative agents in the market, such as tiamulin, valnemulin and retapamulin, will be discussed. It is proposed that new antibacterial agents might be developed from pleuromutilin derivatives in the future.     

新型14β-侧链紫杉醇衍生物的合成及构效关系研究

以生物合成得到的紫杉烷 sinenxan A为起始原料,合成一系列新的紫杉醇衍生物,以寻找高效低毒、抗瘤谱广、综合性能好的新一代紫杉醇类抗癌药,并进行构效关系研究。从半合成的紫杉烷中间体7出发,分别经5步和6步反应成功地合成了4位羟基和4位乙酸酯两类共8个新的14β 侧链紫杉醇衍生物,2位基团为苯甲酸酯、间氯苯甲酸酯、正戊酸酯和苯乙酸酯。将目标化合物连同已合成的2个14β-侧链紫杉醇衍生物进行了微管聚合试验和体外肿瘤细胞抑制试验。所有化合物在浓度为10μmol·L^-1时对微管无作用。在体外肿瘤细胞抑制试验中,大部分化合物显示边缘细胞毒活性。14β-侧链紫杉醇衍生物的构效关系与13α-侧链紫杉醇衍生物有所不同,2位脂肪酸酯与2位芳香酸酯活性相当,表明2位基团的改变对活性无明显影响。4位羟基衍生物的活性好于4位乙酸酯。     

Design, synthesis, and antibacterial activity of novel pleuromutilin derivatives bearing an amino thiazolyl ring

A series of novel pleuromutilin derivatives containing the amino thiazolyl ring were designed, synthesized, and evaluated for their antibacterial activities in vitro against Gram-positive clinical bacteria. All the target compounds showed better aqueous solubility compared with the lead compound (10). Most compounds displayed strong antibacterial activities against both susceptible and resistant bacteria, particularly for the compound (12f) which showed extraordinary antibacterial properties superior to amoxicillin and tiamulin. Molecular docking studies revealed that the amino thiazolyl ring, the side chains of the pleuromutilin derivatives, can be adopted in the binding pocket of the 50S ribosomal subunit near the mutilin core. Therefore, our novel findings may provide new insights into the design of novel pleuromutilin derivatives and lay the basis for further studies on these promising antibiotics for human clinical use.     

Synthesis and Antimicrobial Activity of the Hybrid Molecules between Sulfonamides and Active Antimicrobial Pleuromutilin Derivative

A series of novel hybrid molecules between sulfonamides and active antimicrobial 14‐o‐(3‐carboxy‐phenylsulfide)‐mutilin were synthesized, and their in vitro antibacterial activities were evaluated by the broth microdilution. Results indicated that these compounds displayed potent antimicrobial activities in vitro against various drug‐susceptible and drug‐resistant Gram‐positive bacteria such as Staphylococci and streptococci, including methicillin‐resistant Staphylococcus aureus, and mycoplasma. In particular, sulfapyridine analog ( 6c ) exhibited more potent inhibitory activity against Gram‐positive bacteria and mycoplasma, including Staphylococcus aureus (MIC = 0.016–0.063 μg/mL), methicillin‐resistant Staphylococcus aureus (MIC = 0.016 μg/mL), Streptococcus pneumoniae (MIC = 0.032–0.063 μg/mL), Mycoplasma gallisepticum (MIC = 0.004 μg/mL), with respect to other synthesized compounds and reference drugs sulfonamide (MIC = 8–128 μg/mL) and valnemulin (MIC = 0.004–0.5 μg/mL). Furthermore, comparison between MIC values of pleuromutilin‐sulfonamide hybrids 6a–f with pleuromutilin parent compound 3 revealed that these modifications at 14 position side chain of the pleuromutilin with benzene sulfonamide could greatly improve the antibacterial activity especially against Gram‐positives.