Acetyl- and butyrylcholinesterase inhibitory activities of sterols and phlorotannins from Ecklonia stolonifera

ABSTRACT:   As part of this study on the isolation of cholinesterase inhibitors from natural marine products, the bioactivity of the ethanolic extracts from 27 Korean seaweeds were screened using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory assays. Ecklonia stolonifera exhibited promising inhibitory properties against both AChE and BChE. Bioassay-guided fractionation of the active n -hexane and ethyl acetate (EtOAc) soluble fractions, obtained from the ethanolic extract of E. stolonifera , resulted in the isolation of the sterols; fucosterol ( 1 ) and 24-hydroperoxy 24-vinylcholesterol ( 2 ), from the n -hexane fraction and the phlorotannins; phloroglucinol ( 3 ), eckstolonol ( 4 ), eckol ( 5 ), phlorofucofuroeckol-A ( 6 ), dieckol ( 7 ), triphlorethol-A ( 8 ), 2-phloroeckol ( 9 ) and 7-phloroeckol ( 10 ), from the EtOAc fraction. Of these, compounds 2 , 9 and 10 were isolated from E. stolonifera for the first time. Compounds 4 – 7 , 9 and 10 exhibited inhibitory potential against AChE, with 50% inhibition concentration (IC₅₀) values of 42.66 ± 8.48, 20.56 ± 5.61, 4.89 ± 2.28, 17.11 ± 3.24, 38.13 ± 4.95 and 21.11 ± 4.16 μM, respectively; whereas, compounds 1 , 2 , 4 and 6 were found to be active against BChE, with IC₅₀ values of 421.72 ± 1.43, 176.46 ± 2.51, 230.27 ± 3.52 and 136.71 ± 3.33 μM, respectively. It has been suggested that the inhibition of these enzymes by the sterols and phlorotannins derived from marine brown algae could be a useful approach for the treatment of Alzheimer's disease.     

Anti HSV-1 Activity of Halistanol Sulfate and Halistanol Sulfate C Isolated from Brazilian Marine Sponge Petromica citrina (Demospongiae)

The n-butanol fraction (BF) obtained from the crude extract of the marine sponge Petromica citrina, the halistanol-enriched fraction (TSH fraction), and the isolated compounds halistanol sulfate (1) and halistanol sulfate C (2), were evaluated for their inhibitory effects on the replication of the Herpes Simplex Virus type 1 (HSV-1, KOS strain) by the viral plaque number reduction assay. The TSH fraction was the most effective against HSV-1 replication (SI = 15.33), whereas compounds 1 (SI = 2.46) and 2 (SI = 1.95) were less active. The most active fraction and these compounds were also assayed to determine the viral multiplication step(s) upon which they act as well as their potential synergistic effects. The anti-HSV-1 activity detected was mediated by the inhibition of virus attachment and by the penetration into Vero cells, the virucidal effect on virus particles, and by the impairment in levels of ICP27 and gD proteins of HSV-1. In summary, these results suggest that the anti-HSV-1 activity of TSH fraction detected is possibly related to the synergic effects of compounds 1 and 2.     

雷竹笋总黄酮和总甾醇的抗氧化性与抑菌性

为给雷竹笋的深度开发提供参考依据,采用有机溶剂法从雷竹笋中提取总黄酮和总甾醇,就雷竹笋总黄酮与总甾醇对清除羟基自由基(·OH)与DPPH的能力和对油脂的抗氧化能力进行了测定、分析和评价,并就其对大肠杆菌、金黄色葡萄球菌及黑曲霉的抑制作用进行了试验研究。结果表明:雷竹笋总黄酮和总甾醇对羟基自由基(·OH)和DPPH均有一定程度的清除能力,总甾醇对这两者的清除能力均大于总黄酮;对羟基自由基(·OH)的清除能力,1 mg·mL~(-1)总黄酮与0.13 mg·mL~(-1)总甾醇的效力相当;而对DPPH的清除能力,1 mg·mL~(-1)总黄酮与0.60 mg·mL~(-1)总甾醇的效力相当。雷竹笋总黄酮和总甾醇对油脂的抗氧化作用均显著,其与VC、VE及柠檬酸的混合物具有协同抗氧化性,其与VC的协同抗氧化能力最强。雷竹笋总黄酮和总甾醇对金黄色葡萄球菌、大肠杆菌与黑曲霉均有一定的抑制作用,而总黄酮的抑菌效果比总甾醇的好。     

生态条件和种质因素对初烤烟叶次生代谢产物含量的影响

【目的】分析生态条件和种质因素对烤烟次生代谢产物含量的影响,为低危害烟叶生产提供理论依据。【方法】从贵州道真县、威宁县、盘县和天柱县采集K326、云烟87和贵烟1号3个烟草品种的C3F和B2F等级烟叶初烤样品,测定不同烟叶样本有机酸类、生物碱、多酚类、甾醇类物质等主要次生代谢产物含量,分析烤烟次生代谢产物含量的品种和地区差异性。【结果】同一地区3个品种(系)间的有机酸和生物碱含量差异不显著;道真县和盘县不同品种间烟叶多酚类物质含量、威宁县和盘县不同品种间烟叶甾醇类物质含量的差异均不显著;威宁县、天柱县不同品种间烟叶多酚类物质含量和道真县、天柱县不同品种间烟叶甾醇类物质含量的差异达显著或极显著水平。不同地区不同品种烟叶间的有机酸、生物碱、多酚和甾醇类物质含量差异明显,地区间烟叶主要次生代谢产物总含量的差别明显大于品种间。【结论】生态条件对烟叶次生代谢产物含量影响明显,种质因素对烟叶次生代谢产物含量影响较小。     

菜籽油脱臭馏出物中甾醇分离的甲酯化过程优化研究

运用中心组合设计，以甾醇得率与纯度为考察指标，对菜籽油脱臭馏出物的甲酯化过程工艺进行了优化研究。通过甾醇回收率的响应曲面分析，考察了甲酯化时间、催化剂浓硫酸量与甲醇/物料比及其交互作用的影响，并建立了其数学回归模型，利用Matlab绘制出响应曲面图，揭示了内在关系。结果表明：甲酯化温度60℃，甲醇/物料比100 mL/(100 g)，甲酯化时间1.65 h，催化剂浓硫酸加量4.4%，将甲酯化产物通过结晶与冷冻高速离心，甾醇得到较高纯度与得率，维生素E也得到较好保留。二次重结晶甾醇纯度可以达到95％以上，总得率达到45％以上。     

Sterol Ring System Oxidation Pattern in Marine Sponges

The marine sponges (Porifera) are a unique group of sedentary organisms from which several novel natural products are reported, many of which have useful biological activities. In producing unusual sterols, they occupy a preeminent position among the various groups of organisms. The polar sterols of sponges reported as at the end of the year 2002 number about 250; their ring structure changing a hundred times. The oxidation pattern in the sterol ring system, from the point of view of biogenesis seems to be mainly of four types. Each sponge species is able to produce sterols fitting into one of the four main biogenetic pathways viz., (i) 3β-hydroxy-Δ⁵-sterol pathway, (ii) 3β-hydroxy-Δ⁷-sterol pathway, (iii) 3β-hydroxy-Δ^5,7-sterol pathway, and (iv) 3α-hydroxy sterol pathway.     

三种色型玛咖甾醇组分及含量分析

玛咖（Lepidium meyenii Walp.）为十字花科（Cruciferae）独行菜属（Lepidium）1年生或2年生草本植物,原产于秘鲁海拔4 000 m以上的安第斯山区,这些地区海拔高、土地贫瘠、岩石丛生、风强、气温常处于冰冻状态、气候恶劣,几乎没有其他农作物能生长[1];因此玛咖的引种栽培,对高寒贫困地区生态环境的改善及经济发展具有积极的促进作用.     

植物甾醇对泌乳前期奶牛产奶量及乳成分的影响

根据年龄、胎次、泌乳时间和产奶量选择24头泌乳奶牛,随机分为对照组、试验Ⅰ组和试验Ⅱ组。对照组饲喂奶牛场配制的全混合饲料,试验Ⅰ和Ⅱ组每头奶牛日粮中分别添加40 g/d和80 g/d植物甾醇,研究植物甾醇对奶牛生产性能的影响。结果表明,与对照组相比,试验Ⅰ和Ⅱ组奶牛的产奶量分别提高了2.07 kg/d(5.64%,P0.05)和1.74 kg/d(4.75%,P0.05);试验Ⅰ和Ⅱ组奶牛乳脂率分别提高了8.22%(P0.01)和2.97%(P0.05);乳蛋白率分别提高了2.45%(P0.05)和1.05%(P0.05);非脂固形物分别提高了1.29%(P0.05)和0.23%(P0.05),体细胞数分别下降了37.31%和19.34%,但差异均不显著(P0.05);牛奶中乳尿素氮含量分别降低了5.29%(P0.05)和7.58%(P0.01)。结果表明泌乳前期奶牛补饲一定量的植物甾醇能够提高产奶量和改善乳成分。     

The mechanism of resistance to sterol 14α demethylation inhibitors in a mutant (Erg 40) of Ustilago maydis

Resistance to DMI fungicides is a problem in both agriculture and medicine. Several mechanisms of resistance exist, but, as yet, few have been characterised in field resistant strains of plant pathogens. One approach to evaluating the role of mutations in the sterol 14α demethylase (14DM) target site requires cloning this gene and confirming its identity by complementation in an appropriate mutant. The azole‐resistant mutant, Erg 40, of Ustilago maydis which is totally blocked at the 14α demethylation step in sterol biosynthesis seems to be suitable for such expression studies. Transformation of Erg 40 with a plasmid containing the yeast 14α demethylase (CYP51A1) gene removed the block in sterol biosynthesis and generated azole‐sensitive transformants. Detailed analysis of these transformants failed to detect the presence of the yeast gene and suggested, instead, that changes in sterol biosynthesis resulted simply from the transformation protocol and not from the incorporation of extracellular DNA. Subsequent sequence analysis has revealed a mutation in the 14α demethylase gene of Erg 40. The results suggest that azole resistance in Erg 40 is not simply controlled by this mutation but involves some additional regulatory function, and consequently Erg 40 is not suitable for complementation studies with CYP51A1 genes. © 2000 Society of Chemical Industry     

Multiple Beneficial Lipids Including Lecithin Detected in the Edible Invasive Mollusk Crepidula fornicata from the French Northeastern Atlantic Coast

The invasive mollusk Crepidula fornicata, occurring in large amounts in bays along the French Northeastern Atlantic coasts, may have huge environmental effects in highly productive ecosystems where shellfish are exploited. The present study aims at determining the potential economic value of this marine species in terms of exploitable substances with high added value. Lipid content and phospholipid (PL) composition of this mollusk collected on the Bourgneuf Bay were studied through four seasons. Winter specimens contained the highest lipid levels (5.3% dry weight), including 69% of PLs. Phosphatidylcholine (PC) was the major PL class all year, accounting for 63.9% to 88.9% of total PLs. Consequently, the winter specimens were then investigated for PL fatty acids (FAs), and free sterols. Dimethylacetals (DMAs) were present (10.7% of PL FA + DMA mixture) revealing the occurrence of plasmalogens. More than forty FAs were identified, including 20:5n-3 (9.4%) and 22:6n-3 (7.3%) acids. Fourteen free sterols were present, including cholesterol at 31.3% of the sterol mixture and about 40% of phytosterols. These data on lipids of C. fornicata demonstrate their positive attributes for human nutrition and health. The PL mixture, rich in PC and polyunsaturated FAs, offers an interesting alternative source of high value-added marine lecithin.