气相色谱-质谱定量检测水产品腐败菌群体感应DKPs信号分子

【目的】为了分析水产品腐败菌群体感应的新型信号分子二酮哌嗪(DKPs)化合物,建立一种简便、灵敏的气相色谱-质谱(GC-MS)定量检测方法。【方法】通过优化气相色谱和质谱条件、培养基和提取溶剂建立定量检测方法,确定Cyclo-(L-Pro-L-Gly)、Cyclo-(L-Pro-L-Leu)、Cyclo-(L-Leu-L-Leu)和Cyclo-(L-Pro-L-Phe)4种DKPs标准品的特征离子,并检测水产品腐败菌荧光假单胞菌(Pseudomonas fluorescens)和波罗的海希瓦氏菌(Shewanella baltica)中的DKPs。【结果】4种DKPs化合物在1-200 mg/L范围内线性良好,检测限为0.06、0.10、0.06和0.04 mg/L,定量限为0.16、0.18、0.14和0.12 mg/L,回收率为51.8%-88.5%,标准偏差为1.4%-8.3%。以LB培养基为细菌培养基,氯仿作为萃取溶剂,检测的DKPs含量较高。两种水产品腐败菌都检测到DKPs活性,主要种类为Cyclo-(L-Pro-L-Leu)和Cyclo-(L-Pro-L-Phe)。随着两种细菌的生长,培养上清中DKPs含量显著增加,在12 h达到最高。【结论】建立了检测细菌DKPs的GC-MS定量方法,具有较高精密度、准确度,能够准确定量分析4种DKPs的含量。为探究水产品特定腐败菌DKPs的调控机制奠定基础。     

Diketopiperazines from two strains of South China Sea sponge-associated microorganisms

The paper reports the isolation and structural elucidation of seven diketopiperazines from the title microorganisms. Although all isolates are known, three of which were isolated from the actinomycetes for the first time. And this is also the first report to isolate four DKPs from the D. avara-associated microorganism.     

Stereoselective ring contraction of 2,5-diketopiperazines: An innovative approach to the synthesis of promising bioactive 5-membered scaffolds

Ring contraction of 2,5-diketopiperazines by TRAL-alkylation led us to the stereoselective synthesis of original pyrrolidine-2,4-diones, a novel series of promising molecules with moderate anti-proliferative activity on breast cancer cells.     

海洋微生物中二酮哌嗪类化合物的研究进展

二酮哌嗪类化合物的基本结构是由两个氨基酸缩合而成的环二肽, 因其骨架具有稳定的六元环结构, 且有两个氢键给体和两个氢键受体, 使得DKPs具有较强的生物活性和药理活性, 在药物化学中成为一个重要的药效团。近年来从海洋微生物中发现一系列环二肽类化合物, 研究表明其功能不局限于抗菌、细胞毒活性等方面,在群体感应调控机制中也充当着信号分子的重要角色, 已成为化学生态学的研究热点。本文综述了近年来二酮哌嗪类化合物在海洋微生物代谢产物中的研究进展, 并对其研究方向进行了讨论和展望。     

污损生物膜细菌Pseudoalteromonas issachenkonii YT1305-1的鉴定及其代谢物化学成分分析

【目的】对污损生物膜细菌YT1305-1进行菌种鉴定;研究其作为污损生物膜优势菌之一的代谢产物。【方法】通过16S rRNA基因序列分析,结合系统进化树和细菌生理生化实验对菌种进行鉴定,通过硅胶柱层析分离方法和核磁共振检测技术分析其代谢物的化学成分。【结果】发现生物膜中存在明显的优势菌株,假交替单胞菌属为优势菌属之一。16S rRNA序列比对分析表明Pseudoalteromonas issachenkonii为优势菌种之一,将目标菌种命名为Pseudoalteromonas issachenkonii YT1305-1,对其代谢物化学成分进行分析,共得到10个化合物,其中包括5个二酮哌嗪(DKPs)类信号分子,环(甘氨酸-丙氨酸)(1)、环(脯氨酸-甘氨酸)(2)、环(脯氨酸-酪氨酸)(3)、环(4-羟基-脯氨酸-亮氨酸)(4)和环(4-羟基-脯氨酸-丙氨酸)(5),以及尿嘧啶(6)、胸腺嘧啶(7)、胸腺嘧啶脱氧核苷(8)、己二酸二(2-乙基己)酯(9)和邻苯二甲酸二(2-乙基己)酯(10)。【结论】污损生物膜中存在明显的优势菌,其中之一为P.issachenkonii YT1305-1,在其代谢产物中发现了疑似信号分子的物质DKPs,有研究表明该物质能调控生物膜的形成,进而影响生物污损的形成,为探究生物污损现象奠定了物质基础。     

二酮哌嗪类化合物生物合成研究进展

二酮哌嗪类化合物(Diketopiperazines,DKPs)的特征结构是由两个氨基酸通过肽键缩合而成的环二肽(Cyclic dipeptides),稳定的六元环骨架结构使DKPs在药物化学中成为一个重要的药效团,表现出多种生物活性与药理活性,日益引起人们的极大关注。随着现代生物技术和高通量测序技术的飞速发展,人们对DKPs生物合成的分子机制与酶学机理的认识不断深入,DKPs中氨基酸缩合的分子机制主要有两种:非核糖体肽合成酶(Non-ribosomal peptide synthases,NRPSs)途径和环二肽合成酶(Cycliodipeptide synthases,CDPSs)途径。本文就近年来DKPs的生物合成相关研究进展进行了综述。     

Chiral Piperazine‐2,5‐dione Derivatives as Effective α‐Glucosidase Inhibitors. Part 4

The potential to inhibit α‐ and β‐glucosidases of a series of chiral piperazine‐2,5‐dione derivatives was investigated. Three of the seven compounds tested, viz., 1, 5b , and 5c , showed to be non competitive inhibitors of α‐glucosidase, whereas they exhibited very low inhibitory activity towards β‐glucosidase. The most active compound, 5c (K_I of α‐glucosidase=5 μm), had a 100‐fold α‐glucosidase/β‐glucosidase inhibitor selectivity.     

Antifouling diketopiperazines produced by a deep-sea bacterium,Streptomyces fungicidicus

Abstract

Modern antifouling coatings use heavy metals and toxic organic molecules to prevent biofouling, the undesirable growth of marine organisms on man-made substrata. In an ongoing survey of deep-sea microorganisms aimed at finding low toxic antifouling metabolites, an actinomycete bacterium was isolated from the Pacific sediment at the depth of about 5000 m. The bacterium was closely related to Streptomyces fungicidicus (99% similarity) according to 16S ribosomal RNA sequence information. The spent culture medium of this bacterium inhibited barnacle larval attachment. Bioassay-guided fractionation was employed to isolate antifouling compounds. The ethyl acetate extract was fractionated by using an open silica gel column. Active fractions were further purified on a HPLC C₁₈ column. Five diketopiperazines, cyclo-(L-Leu-L-Pro), cyclo-(L-Phe-L-Pro), cyclo-(L-Val-L-Pro), cyclo-(L-Trp-L-Pro), and cyclo-(L-Leu-L-Val) were isolated for the first time from a deep sea bacterium, and the structures of the compounds were elucidated by nuclear magnetic resonance spectroscopy and mass spectrometry. The pure diketopiperazines were tested for antilarval activity using the barnacle Balanus amphitrite. Effective concentrations that inhibited 50% larval attachment (EC₅₀) after 24 h ranged from 0.10 – 0.27 mM. The data suggest that diketopiperazines and other compounds from deep-sea bacteria may be used as novel antifoulants.     

浙贝母内生真菌菌株FTJZZJ09及其抑菌活性成分

根据菌株的形态学特征和ITS序列分析结果,将一株来源于浙贝母新鲜鳞茎的内生真菌菌株FTJZZJ09鉴定为产黄青霉(Penicillium chrysogenum),其在优化后的改良查氏培养基(3g/L麦芽糖,3g/L蛋白胨,0.1g/LK2HPO4,0.05g/LKCl,0.3g/LNaNO3,0.05g/LMgSO4·7H2O,0.001g/LFeSO4·7H2O,pH6.5)中28°C、160r/min振摇培养7d,获得的发酵液具有抑菌活性。利用正相硅胶、SephadexLH-20柱层析以及重结晶等方法,从发酵液乙酸乙酯提取物中分离到3个具有抑菌活性的化合物,利用质谱和核磁共振等技术将其分别鉴定为环(脯氨酸-甘氨酸)、环(脯氨酸-缬氨酸)和2-乙酰基-4(3H)喹唑酮,它们对枯草芽孢杆菌的生长均具有较为明显的抑制作用,MIC分别为0.8、0.8和0.4g/L,但对革兰氏阴性菌的生长无明显的影响。