Norisoprenoids from Ulva lactuca

Five norisoprenoids were isolated from the green marine alga Ulva lactuca. Two new compounds were assigned to (3R,5R,6R,7E)3,5,6-trihydroxy-7-megastigmen-9-one (1) and (3S,5R,6S,7E)3,5,6-trihydroxy-7-megastigmen-9-one (2). The structures and absolute configurations of the five compounds were determined by analyses of NMR, MS and circular dichroism (CD).     

中药石莼的生药学研究

目的对中药石莼进行生药学研究,为其质量控制提供依据。方法对石莼基原、采收期、采收加工方法进行考证,建立性状、薄层色谱鉴别方法对其进行定性鉴别。结果明确了石莼药材基原、采收期及采收加工方法;所建立的薄层色谱鉴别方法化学成分信息量丰富,专属性强。结论本研究为中药石莼的鉴别、开发利用及质量标准的制订奠定了基础。     

石莼的化学成分研究（Ⅱ）

目的研究绿藻石莼的化学成分。方法利用硅胶柱色谱、凝胶柱色谱、HPLC等方法进行分离纯化，并根据理化性质和波谱数据鉴定结构。结果从石莼中分离得到8个化合物，分别鉴定为3，6-二甲基-2，5-哌嗪二酮（1）、吡咯并哌嗪-2，5-二酮（2）、3-异丙基-6-甲基-2，5-哌嗪二酮（3）、邻苯二甲酸二丁酯（4）、邻苯二甲酸二（2-乙基-己基）酯（5）、单棕榈酸甘油酯（6）、苯丙氨酸（7）、亮氨酸（8）。结论所有化合物均从石莼中首次分离得到。     

Cadmium as an uncoupler of respiration in Ulva lactuca

The effect of cadmium on the respiration of Ulva lactuca was examined using an oxygen electrode. Discs of U. lactuca thallus in filtered seawater were either incubated in the dark for 24 h or treated with 20 μM 3(3,4-dichlorophenyl) 1,1-dimethylurea to inhibit photosystem II dependent noncyclic electron transfer. In both cases, the addition of cadmium, as sulphate, increased respiration, with maximum stimulation occurring at approximately 15 mM; above this concentration respiration declined and at >21 mM inhibitory effects were significant. Dinitrophenol (DNP, 50 μM) and carbonyl cyanide m-chlorophenylhydrazone (CCCP, 10 μM) also uncoupled respiration of U. lactuca, and when these compounds were used in conjunction with Cd the effects were found to be additive. Oligomycin (12.5 μ mL^?1), which inhibits the mitochondrial ATPase, inhibited U. lactuca respiration but subsequent Cd addition (to 6 mM) resulted in a 2.5 × increase in respiration over control values. DNP had a similar effect when used with oligomycin. DNP and CCCP had a negligible effect on the respiration of KCN-treated discs but the addition of Cd restored respiration to control values, probably because of the formation of insoluble Cd(CN)₂. These results demonstrate that Cd can act as a respiratory uncoupler in U. lactuca.     

石莼硫酸多糖的分离纯化及结构解析

目的:研究石莼硫酸多糖的分离纯化条件并对其结构进行解析。方法:对石莼水溶性硫酸多糖的分离、纯化条件进行优化,用苯酚-硫酸法测定粗多糖中多糖的含量;高效凝胶色谱测定多糖分子量;红外光谱和碳谱分析多糖结构。结果:石莼硫酸多糖最佳提取条件为材料粉碎20目,用20倍量水85℃煎煮3次,每次2h。多糖含量为22.64%,分子量为1156112。所得可溶性多糖结构中主要含有β-葡糖醛酸和鼠李糖2种单糖,且多糖中含有大量的硫酸根。结论:本方法操作简便、结果稳定,可为工业生产提供理论依据。     

绿藻石莼多糖的提取工艺

用正交设计法对绿藻石莼多糖成分提取工艺进行研究。采用苯酚-硫酸法测定石莼提取液中石莼多糖含量。结果显示在pH4、温度100℃条件下提取的提取液中石莼多糖含量最高，达55.19％。溶液pH和提取温度是提取石莼多糖的关键影响因素，提取次数和时间长短的影响不大。     

石莼的化学成分

目的研究绿藻石莼的化学成分。方法利用硅胶柱色谱、Sephadex LH 20、HPLC等方法进行分离纯化,并根据理化性质和波谱数据进行结构鉴定。结果得到6个化合物,分别鉴定为豆甾24R,28R环氧5烯3β醇(Ⅰ)、豆甾5,24(28)二烯3β醇(Ⅱ)、豆甾5,28(29)二烯3β醇(Ⅲ)、β谷甾醇(Ⅳ)、对羟基苯甲酸(Ⅴ)、琥珀酸(Ⅵ)。结论化合物除(Ⅱ)以外均为首次从石莼中分离得到。     

Interactions of silver nanoparticles with the marine macroalga, Ulva lactuca

The marine macroalga, Ulva lactuca, has been exposed for 48 h to different concentrations of Ag added as either silver nanoparticles (AgNP) or aqueous metal (AgNO₃) and the resulting toxicity, estimated from reductions in quenching of chlorophyll-a fluorescence, and accumulation of Ag measured. Aqueous Ag was toxic at available concentrations as low as about 2.5 μg l⁻¹ and exhibited considerable accumulation that could be defined by the Langmuir equation. AgNP were not phytotoxic to the macroalga at available Ag concentrations up to at least 15 μg l⁻¹ and metal measured in U. lactuca was attributed to a physical association of nanoparticles at the algal surface. At higher AgNP concentrations, a dose–response relationship was observed that was similar to that for aqueous Ag recorded at much lower concentrations. These findings suggest that AgNP are only indirectly toxic to marine algae through the dissolution of Ag⁺ ions into bulk sea water, albeit at concentrations orders of magnitude greater than those predicted in the environment.     

Sulfated polysaccharide isolated from Ulva lactuca attenuates d-galactosamine induced DNA fragmentation and necrosis during liver damage in rats

Context: Ulva lactuca Linnaeus (Chlorophyceae), a commonly distributed seaweed, is rich in polysaccharide but has not been studied extensively.

Objective: The present study investigated the effects of crude fraction of Ulva lactuca polysaccharide (ULP) on d-galactosamine (d-Gal)-induced DNA damage, hepatic oxidative stress, and necrosis in rats.

Materials and methods: The rats were treated with ULP (100?mg/kg, orally) for 4 weeks before a single intraperitoneal injection of d-Gal (500?mg/kg). In addition to liver cell necrosis and DNA damage, antioxidant parameters, such as lipid peroxide (LPO), superoxide dismutase, and catalase, and histopathology of liver tissue were evaluated.

Results: ULP pre-treatment significantly attenuated a d-Gal-induced decrease in DNA and RNA levels (3.67?±?0.38) and (5.42?±?0.46), respectively. Comet tail length and acridine staining confirmed the number of cells undergoing necrosis were relatively lower in ULP treated rats (30?µm and 8–10% of counted cells) compared to rats treated with d-Gal (60?µm and 16% of counted cells). Biochemical (LPO, SOD and CAT) and histological evaluation (p?d-Gal-induced elevation of LPO and infiltration of inflammatory cells into liver tissue.

Discussion and conclusion: Although our previous studies have reported on the protective role of ULP against liver toxicity, our present findings show that ULP improved the hepatic antioxidant defense system against d-Gal-induced DNA damage and necrosis in rats.     

正交试验优选苯酚-硫酸法测定石莼多糖的含量

目的 建立苯酚-硫酸法测定石莼多糖含量的方法.方法 用超声法提取石莼多糖,用苯酚-硫酸法进行含量测定,以葡萄糖为对照品,检测波长为480nm,用L9（34）正交试验设计优化测定条件.结果 1.0mL样液,加5%苯酚液0.8mL、硫酸5.0mL,100℃水浴保温15min结果最佳,测得石莼超声提取物中粗多糖含量为15.62%.结论 优化后的苯酚-硫酸法测定石莼多糖方法简单,重复性好,结果准确.     

Toxicity of the amphoteric surfactant, cocamidopropyl betaine, to the marine macroalga, Ulva lactuca

The degradation of the synthetic, amphoteric surfactant, cocamidopropyl betaine (CAPB) and its toxicity to the marine macroalga, Ulva lactuca, has been evaluated using several different physiological test end-points over different periods of exposure up to 120 h. Droplet surface angle measurements revealed that, following a period of acclimation of about 24 h, CAPB began to degrade and that primary degradation was complete within 120 h. Effective quantum yield (∆F/F_m′) and relative growth rates (RGRs) were the most sensitive measures of phytotoxicity, with CAPB concentrations at and above 10 mg l⁻¹ eliciting irreversible, time-dependent and/or dose-dependent responses. Cell membrane damage, estimated from measurements of ion leakage, was detected only at a concentration of 40 mg l⁻¹ after 48 h of exposure to CAPB but by 120 h damage was evident at all measured concentrations above 10 mg l⁻¹. These observations suggest that both CAPB and its metabolites are intrinsically toxic to U. lactuca. The findings of this study are discussed in terms of the environmental consequences of applying CAPB to control harmful algal blooms.     

Potential benefits of polysaccharides derived from marine alga Ulva lactuca against hepatotoxicity and nephrotoxicity induced by thiacloprid,an insecticide pollutant

The present study aimed to evaluate the potential protective and antioxidant effect of polysaccharides (PS) extracted from Ulva lactuca against thiacloprid (THC) induced nephrotoxicity and hepatotoxicity. The antioxidant capacity of PS was tested in vitro using ABTS radical scavenging activity and plasmid DNA cleavage assays andin vivo on adult male rats treated for 30 days. Animals were allocated into four groups: control; THC (22.5 mg/kg); THC (22.5 mg/kg) + PS1 (100 mg/kg diet); and THC (22.5 mg/kg) + PS2 (200 mg/kg diet). The structural features of PS were determined by Fourier transformed infrared (FT‐IR), UV absorption peak detection, high performance liquid chromatography (HPLC) and gel permeation chromatography, and also functional properties were investigated. Overall, results indicated that THC increased significantly malondialdehyde, advanced oxidation protein products, glutathione levels, which is correlated with severe histological and plasmatic biochemical injuries in both liver and kidney tissues. However, cotreatment PS induced a significant protective and healing affects against the nephrotoxicity and hepatotoxcity induced by THC.     

石莼、网地藻多糖含量与藻际微生物丰度关系研究

目的：研究石莼、网地藻藻际微生物丰度对多糖含量的影响。方法：通过实时荧光定量PCR(Real-time PCR)技术对石莼、网地藻所附着的藻际微生物丰度进行研究(细菌16S rDNA以及真菌18S rDNA丰度)。结果：石莼多糖含量、藻际微生物总DNA含量均显著高于网地藻(p <0.05)。石莼藻际微生物丰度(细菌1.04×1010-1.42×1010拷贝数/g干样,真菌1.01×107-1.38×107拷贝数/g干样) 显著高于网地藻(细菌2.05×108-6.9×108拷贝数/g干样、真菌2.59×105-4.79×105拷贝数/g干样)(p<0.01)。典型对应分析(CCA分析)表明石莼、网地藻多糖含量与藻际微生物(细菌、真菌)丰度显著相关。结论：石莼、网地藻藻际微生物丰度对多糖含量有一定影响。     

Toxic effects of imidazolium ionic liquids on the green seaweed Ulva lactuca: oxidative stress and DNA damage

The green credentials of ionic liquids (ILs) are being increasingly questioned due to the growing evidence of their toxicity to aquatic ecosystems, although the mechanisms of toxicity are unknown. This study provides insights into the mechanism of toxicity and biological effects of 1-alkyl-3-methylimidazolium bromide [C(n)mim]Br (n = 4 to 16) on the marine macroalga Ulva lactuca. The cell viability of this alga during IL exposure was found to be negatively correlated to the chain length of the alkyl group. The IL ([C(12)mim]Br) exposure triggers the generation of reactive oxygen species (ROS viz. O(2)(?-), H(2)O(2), and OH(?)), damage of the membrane and DNA, and inhibition of antioxidant systems in the alga. The enhanced production of ROS and lipid peroxidation in the alga subjected to LC(50) concentration for 4 days was largely attributed to lipoxygenase (LOX) activity coupled with the induction of two LOX isoforms (~80 kDa and ~55 kDa). Pretreatment of the algal thallus with enzyme inhibitors such as diphenylene iodonium, sodium azide, cantharidin, and oxadiazoloquinoxalin-1-one, prior to [C(12)mim]Br exposure showed the regulation of ROS by the activation of membrane bound NADPH-oxidase and cytochrome oxidase. The IL exposure resulted in the accumulation of n-3 and n-6 fatty acids at 0.5 LC(50) concentration indicating the induction of desaturase enzymes. Furthermore, antioxidant enzyme activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) were enhanced by 1.3-2.0-fold, while glutathione peroxidase (GSH-Px) diminished, together with a higher regeneration rate of reduced ascorbate and glutathione. The isoforms of antioxidant enzymes, namely, Mn-SOD (~85 kDa), APX (~125 and 45 kDa), and GR (~135 kDa) regulated differentially to IL exposure. The comet assay performed for the first time for seaweeds revealed the significant induction of DNA damage (>50-70% increase in % tail DNA over control) in alga exposed to ≥ LC(50) concentration.     

Stimulation of respiration in Ulva lactuca by high concentrations of cadmium and zinc: Evidence for an alternative respiratory pathway

The effect of zinc on respiration of Ulva lactuca (previously incubated in filtered seawater, in the dark, for 18 h) was investigated using an oxygen electrode. When exposed to zinc (as sulphate) at concentrations up to 25 mM, zinc stimulated respiration with maximum stimulation occurring at 1.5 mM, and above 5 mM respiration was inhibited. When zinc was used in conjunction with the uncoupler DNP (dinitrophenol, 50 μM), the stimulatory effects were cumulative. Oligomycin (6 mM) reduced O₂ uptake by ∼42% but the addition of zinc to oligomycin-treated alga restored respiration to near normal values, indicating that zinc did not achieve its uncoupling effect via the mitochondrial ATPase. When zinc was added to cyanide-treated U. lactuca, respiration was partially restored to normal rates. These results were similar to those obtained previously, which showed that cadmium (but not uncouplers such as DNP) increased respiration in cyanide-treated U. lactuca. Cadmium-stimulated respiration was abolished only when cyanide was used in conjunction with salicylhydroxamic acid (SHAM), which indicated the presence of an alternative oxidative, cyanide-resistant pathway that has not been reported previously for U. lactuca. It is suggested that Zn (or Cd) stimulated O₂ uptake via the alternative oxidative pathway. © 1996 by John Wiley & Sons, Inc.     

孔石莼(Ulva pertusa Kjellm)凝集素提取工艺的研究

目的 为抑制肿瘤细胞增殖和防治有关病害提供基础理论依据。方法 通过研究各因素(缓冲液、料液比、浸泡时间、烘干温度)对孔石莼(Ulva pertusa Kjellm)凝集素(lectin)(UPL)提取液凝集活性的影响,得出每个因素的最佳提取效果。从各个单因素中选出提取的最适条件及与最适条件相临的2 个水平(共3个水平)进行4因素3水平的正交试验。结果 温度为50℃、缓冲液为pH 7.2 PBS、料液比为1:15 、浸泡时间为15h。结论 相比较其它的情况,这一组合对孔石莼提取效果最好。     

Comparative study of the insecticidal activity of a high green plant (Spinacia oleracea) and a chlorophytae algae (Ulva lactuca) extracts against Drosophila melanogaster fruit fly

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孔石莼多糖对小鼠免疫功能的影响

目的观察孔石莼多糖对小鼠免疫功能的影响。方法应用水煮醇沉法从海洋生物孔石莼中获得孔石莼多糖,观察孔石莼多糖对小鼠免疫功能的调节作用。结果200 mg/(kg.d)孔石莼多糖能明显促进小鼠的胸腺指数和脾指数。100,200 mg/(kg.d)剂量能显著促进ConA诱导的小鼠脾淋巴细胞转化能力,增强小鼠的迟发性超敏反应,提高小鼠的血清溶血素水平,增强小鼠的碳廓清能力,提高小鼠NK细胞的杀伤活性。结论孔石莼多糖能明显调节机体的细胞免疫与体液免疫功能,促进NK细胞的杀伤活性及巨噬细胞的吞噬能力。     

孔石莼多糖的分离分析

研究孔石莼中多糖的提取分离方法，并对多糖进行了灰分、总糖、水解硫酸根含量、特性粘度等测定，以及元素分析、单糖气相色谱分析、氨基酸分析、红外光谱和核磁共振光谱等仪器分析。     

孔石莼多糖降血脂活性的初步研究

为开发我国的孔石莼资源，在研究了其多糖化学组成的基础上，进行了孔石莼多糖对高脂血症的活性研究。结果表明：3个剂量的多糖样品组均有显著的降甘油三酯作用；中、高剂量组可显著降低血清中总胆固醇(TC)、低密度脂蛋白胆固醇(LDL—C)，升高高密度脂蛋白胆固醇(HLD-C)从而增加HDL—C／TC的比值；高剂量组的降脂活性与阳性对照药烟酸肌醇酯相近；血清中脂蛋白胆固醇的改善状况有明显的剂量依赖性。并对孔石莼多糖降血脂活性的机理进行了讨论。