Identification of a functional dddD-Rh for dimethyl sulfide production in the Antarctic Rhodococcus sp. NJ-530

Dimethylsulfoniopropionate (DMSP) is widespread in the oceans, and its biological metabolite, dimethyl sulfide (DMS), plays an important role in the atmosphere. The Antarctic region has become a hotspot in DMS studies due to the high spatial and temporal variability in DMS(P) concentration, but the level of bacterial DMS production remains unclear. In this study, a bacterium isolated from Antarctic floating ice, Rhodococcus sp. NJ-530, was found to metabolize DMSP into DMS, and the rate of DMS production was measured as 3.96 pmol·mg protein⁻¹·h⁻¹. Rhodococcus sp. NJ-530 had a DddD-Rh enzyme containing two CaiB domains, which belonged to the CoA-transferase III superfamily. However, the DddD-Rh had a molecular weight of 73.21 kDa, which was very different from previously characterized DddD enzymes in sequence and evolution. In vitro assays showed that DddD-Rh was functional in the presence of acetyl-CoA. This was the first functional DddD from Gram-positive Actinobacteria. Moreover, a quantitative real-time polymerase chain reaction revealed that high temperature facilitated the expression of dddD-Rh, and changes of salinity had little effect on it. This study adds new evidence to the bacterial DMS production in the Southern Ocean and provides a basis for investigating the metabolic mechanism of DMSP in extreme environments.     

Saroclazines A–C,thio-diketopiperazines from mangrove-derived fungi <Emphasis Type="Italic">Sarocladium kiliense</Emphasis> HDN11-84

Three new diketopiperazine derivatives (DKPs), saroclazines A–C (1–3) along with three known DKPs (4–6) were isolated from mangrove-derived fungi Sarocladium kiliense HDN11-84. Saroclazines A–B (1 and 2) possessed a free amide structure, which was first found in sulfur-containing aromatic DKPs. Their structures were elucidated by NMR, HRESIMS and X-ray. The cytotoxic activity of new compounds (1–3) was tested against HeLa cell lines, among which compound 2 showed an IC₅₀ value of 4.2 µM.     

Trans fatty acids in the New Zealand food supply

Adverse health effects from the consumption of trans fatty acids (TFA) have led to efforts to decrease the consumption of these lipids. There is a need for up to date information on TFA levels in foods to support decision-making by regulators on labelling and health claims. This paper reports the results from a 2006 survey of New Zealand manufactured food items for fatty acid content, including TFA, determined using gas chromatography. The TFA levels in snack bars, margarines/table spreads, biscuits and cakes, pies and pastries were all below 10 g/100 g fatty acids (less than 3.5 g/100 g product). Also reported are results from a 1998 survey of margarines and table spreads which are compared with those from a previously published 1996 survey conducted by the same organisation. The conclusion is that the TFA content of foods in New Zealand has declined over the previous decade, with a likely decrease in consumption of these lipids by New Zealanders.     

Insights on the pathophysiology of Alzheimer's disease: The crosstalk between amyloid pathology,neuroinflammation and the peripheral immune system

Alzheimer's disease (AD) is the most common form of dementia, whose prevalence is growing along with the increased life expectancy. Although the accumulation and deposition of amyloid beta (Aβ) peptides in the brain is viewed as one of the pathological hallmarks of AD and underlies, at least in part, brain cell dysfunction and behavior alterations, the etiology of this neurodegenerative disease is still poorly understood. Noticeably, increased amyloid load is accompanied by marked inflammatory alterations, both at the level of the brain parenchyma and at the barriers of the brain. However, it is debatable whether the neuroinflammation observed in aging and in AD, together with alterations in the peripheral immune system, are responsible for increased amyloidogenesis, decreased clearance of Aβ out of the brain and/or the marked deficits in memory and cognition manifested by AD patients. Herein, we scrutinize some important traits of the pathophysiology of aging and AD, focusing on the interplay between the amyloidogenic pathway, neuroinflammation and the peripheral immune system.     

中国南海蜂海绵Haliclona cymae formis的化学成分研究

目的研究中国南海蜂海绵属Haliclona cymaeformis的化学成分。方法运用正相硅胶、反相硅胶(ODS)和凝胶(Sephadex LH-20)等多种柱色谱手段对化合物进行分离纯化;通过理化性质和波谱数据,结合文献对照,鉴定化合物的结构。结果从海绵H.cymaeformis的乙醇提取物中共分离鉴定了11个单体化合物:24-亚甲基胆甾醇(1),5α,8β-epidioxy-cholesta-6-en-3-ol(2),cholesta-7-en-3β,5α,6β,9α-tetraol(3),胆甾醇(4),3-吲哚甲酸(5),尿嘧啶(6),胸腺嘧啶(7),尿嘧啶核苷(8),胸腺嘧啶核苷(9),尿嘧啶脱氧核苷(10)和胸腺嘧啶脱氧核苷(11)。结论化合物1~11均为首次从该海绵中分离得到。细胞毒活性测试结果表明,化合物3对慢性髓原白血病细胞(K562)和人肝癌细胞(SMMC-7721)的增殖显示了较强的生长抑制活性。     

中国南海聚裂丛柳珊瑚化学成分研究

目的研究聚裂丛柳珊瑚Rumphella aggregata的化学成分。方法利用硅胶色谱、Sephadex LH-20凝胶色谱、HPLC等手段对化学成分进行分离纯化;通过理化性质、波谱分析方法结合文献对照,鉴定化合物的结构。结果从聚裂丛柳珊瑚甲醇提取物中,共分离鉴定了15个单体化合物:胆甾醇(1)、(22E)-胆甾-5,22-二烯-3β-醇(2)、(22E)-麦角甾-5,22-二烯-3β-醇(3)、麦角甾-5,24(28)-二烯-3β-醇(4)、豆甾-5,24(28)-二烯-3β-醇(5)、柳珊瑚甾醇(6)、胆甾-7-烯-3β,5α,6β-三醇(7)、(22E)-胆甾-7,22-二烯-3β,5α,6β-三醇(8)、麦角甾-7-烯-3β,5α,6β-三醇(9)、(22E)-麦角甾-7,22-二烯-3β,5α,6β-三醇(10)、豆甾-7-烯-3β,5α,6β-三醇(11)、(22E)-豆甾-7,22-二烯-3β,5α,6β-三醇(12)、尿嘧啶(13)、咖啡因(14)、hydratoperidinin(15)。结论化合物1～15均为首次从该属柳珊瑚中分离得到,并首次对化合物hydratoperidinin(15)的1HNMR及13 CNMR信号进行了全归属。化合物12在10μg.mL-1浓度水平,对K562肿瘤细胞株的抑制率为39.17%。     

中国南海软体动物及其食源生物的化学、化学生态学和生物活性研究

海洋软体动物色彩艳丽、行动缓慢,主要依赖次生代谢产物形成的化学防御机制对抗天敌的捕食.多数软体动物可以通过选择适当的食物并将其中有用的代谢物质经过进一步的生物转化或积累到身体的特定部位而用作化学防御物质,以保护自己不受天敌的捕食;少数软体动物能够生物合成自身所需要的化学物质,从而建立起化学防御体系.研究软体动物及其食源生物的化学组成可以揭示它们之间的食物链关系,并进一步阐明这些化学物质的生态学作用.同时,这种进化的化学防御体系也能为我们提供一种从自然界寻找生物活性物质的新方法.近年来,我们研究小组对中国南海软体动物及其相关食源生物海绵、珊瑚和海藻等常见海洋生物物种之间的食物链关系进行了系统研究,获得了这些海洋生物的化学及生物学等方面的知识,并对这些化学物质的药理活性进行了系统考察,为更加系统、深入地开展中国海洋天然产物研究、开发具有自主知识产权的海洋新药打下了坚实的基础.     

抗多药耐药紫杉烷类抗肿瘤药物研究进展

目的介绍紫杉烷类活性分子与多药耐药肿瘤的构效关系及其临床研究进展。方法综述了近年来国内外相关报道,对紫杉醇6大区域的相关改造分别进行讨论,并就其临床研究及开发上市状况进行概述。结果发现了许多对敏感肿瘤和多药耐药肿瘤抑制活性相当的紫杉烷类药物候选分子。结论熟悉紫杉烷类活性分子与多药耐药肿瘤的构效关系,对开发新一代紫杉烷类抗肿瘤药物具有深远意义。