Steroid and triterpenoid distributions in bransfield strait sediments: Hydrothermally-enhanced diagenetic transformations

Recent sediments from Bransfield Strait, Antarctica have been analyzed for triterpenoid and steroid hydrocarbons, sterols and steroid ketones to consider the effects of hydrothermal fluids on the sedimentary organic matter. The steroid distributions in unaltered and altered sediments are controlled more by inputs from source organisms than by the effects of hydrothermal activity, which is suggested to be limited to low temperature alteration. Nevertheless, chemical reactions occurred in altered sediments and include dehydration of sterols to sterenes, isomerization of triterpenes and sterenes, rearrangement of sterenes to diasterenes and reductive processes leading to generation of phytane from phytol via phytenes.     

Biological marker compounds as indicators of the depositions! history of the Maoming oil shale

The Eocene Maoming oil shale from Guangdong Province occurs as a laterally uniform stratigraphic section, typically 20–25 m thick, from which the aliphatic hydrocarbon constituents of six representative samples were investigated using GC and C-GC-MS. The sediments evaluated included the basal lignite, a vitrinite lens from the overlying claystone, and four intervals from the massive oil shale bed. As expected, the lignite and vitrinite differ markedly from the oil shales. The lignite is dominated by bacterial hopanoids and components of higher plant origin, including C₂₉ steroids and triterpenoids such as oleanenes. Visually, the oil shale samples show corroded and degraded phytoclasts, spores, wispy particles of fluorescent organic material attributable to dinoflagellates and, especially in the uppermost sample, colonial algal bodies. The distributions of biological markers in the oil shales show many features in common, notably a dominance of dinoflagellate-derived 4-methylsteroids, and a significant proportion of higher-plant derived n-alkanes with marked odd-over-even carbon number predominance. Overall, they exhibit several features that resemble characteristics of the Messel shale. The hydrocarbons of the lowest shale horizon suggest that there may have been a gradual transition between deposition of the original peat and the subsequent oil shales. The aliphatic hydrocarbons of the uppermost shale are dominated by a number of C₃₁ and C₃₃ botryococcane homologues and other unusual branched alkanes possibly derived from green algae. All of the samples are immature. Overall, molecular and microscopic examination of the stratigraphic succession of the Maoming oil shale suggests a shallow, lacustrine environment within which peats were deposited. This lake subsequently deepened to support abundant algal populations, especially dinoflagellates, culminating in a dominance of botryococcoid algae.     

Steroids from green alga Chaetomorpha basiretorsa Setchell

Six steroids have been isolated from ethanolic extract of green alga Chaetomorpha basiretorsa Setehell by a combination of repeated normal phase silica gel and Sephadex LH-20 gel column chromatography as well as recrystallization. Using spectroscopic methods including MS and NMR, their structures were determined as β-lawsaritol (1), saringosterol (2), 24-hydroperoxy-24-vinyl-cholesterol (3), β-stigmasterol (4), stigmast-4-en-3α, 6β-diol (5), 29-hydroxystigmasta-5, 24 (28)-dien-3β-ol (6). All these compounds were obtained from this genus for the first time and they were inactive (IC5010 μg/ml) against KB, Bel-7402, PC-3M, Ketr 3 and MCF-7 cell lines.     

极端生物降解沥青中8,14- 开环藿烷系列及其地球化学意义

借助色谱- 质谱（GC- MS）和色谱- 质谱- 质谱（GC- MS- MS）分析,对黔南坳陷凯里残余油藏凯棠和洛棉剖面上储层沥青中的烃类组成进行了系统分析,以判断其所遭受生物降解作用的程度,探寻在极端降解原油中是否还存在原生生物标志物,为这类原油的油源研究开拓新的途径和方法。结果表明：凯棠剖面上的储层沥青中尽管仍可检测到较为完整的C19- 30三环萜烷和C27- 35藿烷系列,但C19- 29脱甲基三环萜烷系列和C26- 34 25- 降藿烷系列丰富而完整,甾烷系列中C21- 22低分子量甾烷和重排甾烷优势明显,这一系列特征表明这些沥青遭受了剧烈生物降解作用的改造。但三芳甾类仍保存完好,依据原油生物降解程度的评判标准,判断其生物降解级别介于8~9级之间。洛棉剖面上的储层沥青中藿烷系列基本消失殆尽,三环萜烷系列及其脱甲基产物和25- 降藿烷系列的分布因极端生物降解作用而发生显著变异,某些化合物如C23T、C24T、C23NTE和C28- 29NH成为优势成员;甾烷系列中C21- 22低分子量甾烷占绝对优势,三芳甾类完全消失,据此判断该剖面上沥青的生物降解级别已达到10级或更严重。由于这两个剖面上的沥青遭受了极端生物降解作用的改造,常用的甾、萜类生物标志物完全失去了实用价值。但是,在所分析的这些沥青中都检测到三个系列的C27- 35 8,14- 开环藿烷系列,它们与塔里木盆地塔中地区海相端元油中存在的同类标志物的分布特征相似。正常海相端元油和极端生物降解沥青中同时检测到这三个系列的8,14- 开环藿烷,这一事实表明这类生物标志物在成因上具有原生性,而与生物降解作用无关。此外,在极端生物降解作用沥青中的完好保存,表明它们具有极强的抗生物降解能力,因而它们在此类原油的油源研究中可能具有潜在的实用价值。     

Kinetics of the aromatisation of rearranged ring-C monoaromatic steroid hydrocarbons

The kinetics of the aromatisation of both rearranged and non-rearranged monoaromatics have been investigated in the laboratory under free radical conditions. These studies have indicated that the aromatisation rate constant for the non-rearranged is greater than that for the rearranged isomers at any one particular temperature. Since the members of the rearranged series coelute with their non-rearranged counterparts when both series are present in geological extracts, these results suggest that care needs to be exercised when assessing extents of maturation using monoaromatic and triaromatic steroid hydrocarbons.     

一株海绵共附生真菌Pleosporaceae sp.中甾体类化合物及其生物活性

在生物活性测定指导下,综合运用硅胶柱层析、凝胶柱层析以及半制备HPLC等方法,从南海海绵Xestospongiatestudinaria来源的一株共附生真菌Pleosporaceae sp.发酵液的乙酸乙酯提取物中分离鉴定出5个甾体类化物,通过NMR,MS等波谱技术鉴定其结构分别为:(22E,24R)-5α,8α-epidioxy-ergosta-6,22-dien-3β-ol(1),(22E,24R)-5α,8α-epidioxy-ergosta-6,9,22-trien-3β-ol(2),(22E)-ergosta-5,7,22-trien-3β-ol(3),ergosta-6α-hydroxy-4,22-dien-3-one(4),(22E)-5α-cholesta-7,22-diene-3β,5α,6β-triol(5)。这些化合物均为首次从Pleosporaceae属真菌中分离获得。化合物1,4和5具有较强的卤虫Ar-temia salina致死活性,化合物1还显示强的抗藤壶Balanus amphitrite附着活性,其EC50为0.85μg/mL。     

池养乌苏里拟鲿雌雄鱼生长及周年性激素与性腺发育研究

乌苏里拟鲿(Pseudobagrus ussuriensis)的种质资源保护和商品鱼养殖正在我国悄然兴起。本文首次研究了乌苏里拟鲿雌、雄鱼在池塘养殖条件下的生长规律以及性成熟鱼周年性腺发育与性激素变化特性。研究结果表明,乌苏里拟鲿随着年龄的增长,雌鱼和雄鱼之间的体质量、体长差异逐渐明显,雌鱼体长与体质量的关系式为:W=0.182 5L1.964 6(R2=0.944 5);雄鱼体长与体质量的关系式为:W=0.188 1L2.0059(R2=0.961 8)。在12月份(2龄鱼)至翌年10月份(3龄鱼)期间,雌、雄鱼丰满度呈下降趋势,成熟度、血清雌二醇(E2)和睾酮(T)水平均呈先升高后下降的变化规律。雌鱼的E2和T在5月份达到最高值,分别为(1 624.23±331.4)pg/mL和(1 320.85±279.12)pg/mL;雄鱼的E2在5月份达到最高值(323.17±147.36)pg/mL,而T的最高值则出现在4月份,为(758.33±100.47)pg/mL。雌、雄鱼性腺发育和成熟度基本同步,从外观和组织学观察对性腺的分期显示,2龄乌苏里拟鲿在12月份的精巢和卵巢已发育至第Ⅲ期,在次年6月份均达到第Ⅴ期。     

An examination by GC×GC-TOFMS of organic molecules present inhighly degraded oils emerging from Caribbean terrestrial seeps of Cretaceous age

For our ancestors, oil seeps were both a fascination and a resource but as the planet's reserves of high quality low density oil becomes increasingly depleted, so there is now a renewed interest in heavier,biodegraded oils such as those encountered in terrestrial seeps. One such seep is Pitch Lake in the Caribbean island of Trinidad, which is the largest natural deposit of asphalt in the world. At the northern end of the Caribbean, oil emerges along a tectonic contact on the island on Cuba. The sources of the oils from these seeps are relatively recent and both are subject to intense weathering due to the tropical conditions. When analysed by gas chromatography(GC) both oils appear as unresolved complex mixtures(UCM) and show a very high degree of biodegradation thus presenting an analytical challenge. In this case study, these two Caribbean seep oils were analysed by comprehensive two dimensional GC with time of flight mass spectrometry(GC×GC-TOFMS) to expose many thousands of the individual compounds that comprise the UCM. The high chromatographic resolution of the GC×GC-TOFMS produced good quality mass spectra allowing many compounds including molecular fossil ‘biomarkers' to be identified. Compound classes included diamondoid hydrocarbons, demethylated hopanes and secohopanes, mono-and tri-aromatic steroids. D-ring aromatised structures of the 8,14-seco-hopanes,including demethylated forms were present in both oils but further demethylation, probably at position C-25 during biodegradation, was only observed in the Pitch Lake oil. Many polycyclic aromatic hydrocarbons(PAHs) were absent although the fungal-derived pentacyclic PAH perylene was present in both oils. The presence of the angiosperm biomarker lupane in the Pitch Lake oil constrained the age to the Late Cretaceous. The higher degree of biodegradation observed in the Cuban oil was likely due to relatively slow anaerobic processes whereas oil within Pitch Lake was probably subject to additional more rapid aerobic metabolism within the lake.     

塔里木盆地北部隆起原油混合作用半定量评价

塔里木盆地北部隆起油气类型非常复杂，多期充注和储层内的混合作用极为普遍，早期充注原油遭受过生物降解作用的强烈改造，油质非常重，烃类含量和组成发生很大变化，表现为正烷烃和类异戊二烯烃完全消失，甾烷和藿烷被严重破坏，形成大量25－降藿烷，三芳甾相对富集。后期充注的正常原油油质较轻，正烷烃和类异戊二烯烃完整分布，25－降藿烷和三芳甾含量极低。两期充注原油在储层内不同的混合程度造成原油物性和分子组成复杂多变，其变化受控于混合比。根据混合油中正烷烃和25－降藿烷的绝对含量以及三芳甾的相对含量，对油藏内两期充注油的贡献进行了半定量计算，结果表明塔河油田4号构造早期充注的残留油与新近充注的正常油含量相当，塔河3号构造除沙47原油中含20％左右的早期充注油外，基本属晚期充注的产物；哈得逊油田早期充注的残留油含量在5％－15％之间，表明该油田的形成期很晚；乡3井原油中早期充注的残留油约占1／4，羊屋2井主要是晚期充注的贡献。