藻类生物活性物质在化妆品中的应用

随着化妆品行业的迅猛发展以及人们对美的追求,天然温和、绿色安全的环境友好型化妆品已经成为广大消费者的诉求.消费者更青睐于以天然产物为基础的化妆品,而不是合成化学品.随着天然产物化学和海洋生物资源技术的迅速发展,藻类(包括大型藻和微藻)生物活性物质已得到了广泛的应用.许多研究已经证明藻类活性物质具有保湿补水、抗氧化、抗衰...     

Uncovering Plant Virus Species Forming Novel Provisional Taxonomic Units Related to the Family Benyviridae

Based on analyses of recent open-source data, this paper describes novel horizons in the diversity and taxonomy of beny-like viruses infecting hosts of the plant kingdom (Plantae or Archaeplastida). First, our data expand the known host range of the family Benyviridae to include red algae. Second, our phylogenetic analysis suggests that the evolution of this virus family may have involved cross-kingdom host change events and gene recombination/exchanges between distant taxa. Third, the identification of gene blocks encoding known movement proteins in beny-like RNA viruses infecting non-vascular plants confirms other evidence that plant virus genomic RNAs may have acquired movement proteins simultaneously or even prior to the evolutionary emergence of the plant vascular system. Fourth, novel data on plant virus diversity highlight that molecular evolution gave rise to numerous provisional species of land-plant-infecting viruses, which encode no known potential movement genetic systems.     

Antimicrobial effect of phlorotannins from marine brown algae

Marine organisms exhibit a rich chemical content that possess unique structural features as compared to terrestrial metabolites. Among marine resources, marine algae are a rich source of chemically diverse compounds with the possibility of their potential use as a novel class of artificial food ingredients and antimicrobial agents. The objective of this brief review is to identify new candidate drugs for antimicrobial activity against food-borne pathogenic bacteria. Bioactive compounds derived from brown algae are discussed, namely phlorotannins, that have anti-microbial effects and therefore may be useful to explore as potential antimicrobial agents for the food and pharmaceutical industries.     

The influence of humic acid on the toxicity of nano‐ZnO and Zn2+ to the Anabaena sp.

This study explored the effects of humic acid (HA) on the toxicity of ZnO nanoparticles (nano‐ZnO) and Zn²⁺ to Anabaena sp. Typical chlorophyll fluorescence parameters, including effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse‐amplitude modulated fluorometer. Results showed that nano‐ZnO and Zn²⁺ could inhibit Anabaena sp. growth with the EC₅₀ (concentration for 50% of maximal effect) of 0.74 ± 0.01 and 0.3 ± 0.01 mg/L, respectively. In the presence of 3.0 mg/L of HA, EC₅₀ of nano‐ZnO increased to 1.15 ± 0.04 mg/L and EC₅₀ of Zn²⁺ was still 0.3 ± 0.01 mg/L. Scanning electron microscopy observation revealed that HA prevented the adhesion of nano‐ZnO on the algae cells due to the increased electrostatic repulsion. The generation of intracellular reactive oxygen species and cellular lipid peroxidation were significantly limited by HA. Nano‐ZnO had more damage to the cell membrane than Zn²⁺ did, which could be proven by the malondialdehyde content in Anabaena sp. cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 895–903, 2015.     

Water oxidation by photosystem II is the primary source of electrons for sustained H2 photoproduction in nutrient-replete green algae

The unicellular green alga Chlamydomonas reinhardtii is capable of photosynthetic H₂ production. H₂ evolution occurs under anaerobic conditions and is difficult to sustain due to 1) competition between [FeFe]-hydrogenase (H₂ase), the key enzyme responsible for H₂ metabolism in algae, and the Calvin–Benson–Bassham (CBB) cycle for photosynthetic reductants and 2) inactivation of H₂ase by O₂ coevolved in photosynthesis. Recently, we achieved sustainable H₂ photoproduction by shifting algae from continuous illumination to a train of short (1 s) light pulses, interrupted by longer (9 s) dark periods. This illumination regime prevents activation of the CBB cycle and redirects photosynthetic electrons to H₂ase. Employing membrane-inlet mass spectrometry and H218O, we now present clear evidence that efficient H₂ photoproduction in pulse-illuminated algae depends primarily on direct water biophotolysis, where water oxidation at the donor side of photosystem II (PSII) provides electrons for the reduction of protons by H₂ase downstream of photosystem I. This occurs exclusively in the absence of CO₂ fixation, while with the activation of the CBB cycle by longer (8 s) light pulses the H₂ photoproduction ceases and instead a slow overall H₂ uptake is observed. We also demonstrate that the loss of PSII activity in DCMU-treated algae or in PSII-deficient mutant cells can be partly compensated for by the indirect (PSII-independent) H₂ photoproduction pathway, but only for a short (<1 h) period. Thus, PSII activity is indispensable for a sustained process, where it is responsible for more than 92% of the final H₂ yield.

Many species of green algae have [FeFe]-hydrogenases (H₂ases) (1) that catalyze the reversible reduction of protons to molecular hydrogen:2H++2e−⇄H2.[1]Since [FeFe]-H₂ases are extremely O₂-sensitive (2), reaction 1 typically proceeds under anoxic conditions. With respect to H₂ metabolism, Chlamydomonas reinhardtii is the most studied alga. This alga possesses two [FeFe]-H₂ases in the chloroplast, HYDA1 and HYDA2 (3, 4). In the light, they accept electrons from photosynthetically reduced ferredoxin (FDX1) (5), while in the dark electrons come from the activity of pyruvate ferredoxin oxidoreductase (PFR1) (6). PFR1 catalyzes the oxidation of pyruvate to acetyl-CoA, and its activity is linked to H₂ase via FDX1 (7). Since [FeFe]-H₂ases interact with the photosynthetic electron transport chain at the level of ferredoxin, they may accept electrons originating both from water oxidation via the photosystem II (PSII)-dependent pathway (“direct water biophotolysis”) and from the degradation of organic substrates via a PSII-independent mechanism (“indirect water biophotolysis” or “indirect pathway”) (8). In the latter case, the reductants are supplied to the plastoquinone (PQ) pool by the type II NADPH dehydrogenase (NDA2), thus bypassing PSII (9, 10).The release of H₂ leads to a loss of metabolic energy. In healthy, actively growing C. reinhardtii cultures, H₂ production is therefore only a temporal phenomenon observed during dark anoxia and upon subsequent onset of illumination (11). In contrast to dark fermentation, H₂ photoproduction is a very efficient process that proceeds for only a short period of time (from a few seconds to a few minutes). Two theories have been developed to explain the short duration. The first is based on the oxygen sensitivity of H₂ases (12, 13). In the light, algae accumulate O₂ that is produced by water oxidation at PSII (14). As a result, H₂ photoproduction may cease over time (14, 15), and the duration of this process is reported to shorten with increased light intensity (16). Because of the negative correlation between the rates of H₂ photoproduction and O₂ evolution, the inhibition of H₂ases by O₂ is frequently quoted as the primary reason for the rapid loss in H₂ photoproduction after the onset of illumination (17).Alternatively, the loss in the H₂ photoproduction efficiency during illumination could be explained by the light-induced induction of competitive pathways, which may drain reducing equivalents away from the [FeFe]-H₂ase enzyme (18, 19). Candidates for this role are the Mehler-like reaction driven by flavodiiron proteins (FDPs) (15, 20, 21) and the Calvin–Benson–Bassham (CBB) cycle (22). Compelling evidence for the competition between these two pathways and H₂ production has been accumulated in recent studies (23–25). As CO₂ fixation provides the strongest sink for photosynthetic reductants, it should play a major role in the cessation of H₂ photoproduction in algae when the CBB cycle is active (19, 22).For preventing competition between the [FeFe]-H₂ases and the CBB cycle, we recently devised a pulse-illumination protocol that allows H₂ production in nutrient-replete algal cultures for up to 3 d (23). To achieve this, we specifically selected the duration of light pulses in the light/dark sequence to avoid activation of the CBB cycle, thus allowing for the redirection of photosynthetic electrons toward the [FeFe]-H₂ases. Typically, a train of 1- to 6-s light pulses interrupted by 9-s dark periods is sufficient for sustained H₂ photoproduction in C. reinhardtii cultures (23, 25). Our protocol thus differs from earlier pulse-illumination approaches that aimed at preventing the accumulation of O₂ in the cultures (26).While we could demonstrate competition of [FeFe]-H₂ase with FDPs (25), the origin of reductants for H₂ photoproduction in the pulse-illuminated algae remained unclear. The relatively high efficiency of the process suggests the involvement of water oxidation by PSII, and consequently the simultaneous production of H₂ and O₂. Although widely proposed in the current literature (8, 24), the presence of the direct water biophotolysis in H₂-producing green algae has not yet been proven by direct experimental data.In the present study, we provide clear evidence for the presence of PSII-dependent oxidation of ¹⁸O-labeled water H218O with concomitant evolution of ¹⁶O₂ and ^16,18O₂ during H₂ photoproduction in the pulse-illuminated green alga C. reinhardtii under anoxic conditions. O₂ evolution is balanced by light-dependent and light-independent respiration that sustains the anoxic condition. We also demonstrate that the loss of PSII activity in algae can be partly compensated by the PSII-independent H₂ photoproduction pathway. Nevertheless, the activity of PSII is indispensable for the sustained process, where it contributes to more than 92% of the final H₂ yield.     

褐藻来源硫酸岩藻聚糖的化学组成与结构的研究进展

褐藻硫酸岩藻聚糖是来源于褐藻的结构复杂的1类海洋硫酸多糖,主要由岩藻糖、半乳糖、甘露糖和葡萄糖醛酸组成,并含有少量的木糖、葡萄糖、鼠李糖、阿拉伯糖和氨基葡萄糖.研究表明,褐藻硫酸岩藻聚糖的主链是由α(1→3)或α(1→3)、α(1→4)交替连接的硫酸化L-岩藻糖构成,还嵌有半乳糖、葡萄糖醛酸等,而厚叶解曼藻和羊栖菜等褐...     

Primary Shewanella algae Bacteremia Mimicking Vibrio Septicemia

Shewanella algae infections are rare in humans. Previously reported cases of S. algae have mainly been associated with direct contact with seawater. We report a case of primary S. algae bacteremia occurring after the ingestion of raw seafood in a patient with liver cirrhosis that presented a fulminent course of necrotizing fasciitis.     

Repression of proinflammatory gene expression by lipid extract of Nostoc commune var sphaeroides Kützing,a blue-green alga,via inhibition of nuclear factor-κB in RAW 264.7 macrophages

We investigated whether lipid extract from a blue-green alga, N commune, modulates proinflammatory gene expression in RAW 264.7 macrophages. The cells were incubated with N commune lipid extract (0-100 μg/mL) and subsequently activated by LPS (100 ng/mL). Quantitative real-time PCR analysis showed that mRNA abundance of proinflammatory mediators, including TNF-α, COX-2, IL-1β, IL-6, and iNOS, was significantly reduced by N commune lipid extract in a dose-dependent manner. Secretion of TNF-α and IL-1β into cell culture medium was also significantly decreased by N commune lipid extract. Thin-layer chromatography–densitometry analysis showed that N commune lipid extract contained approximately 15% of fatty acids. To determine whether the inhibition of proinflammatory mediator production by N commune lipid extract is primarily conferred by fatty acids in the lipid extract, macrophages were incubated with 100 μg/mL of N commune lipid extract or 15 μg/mL of a fatty acid mixture, which was formulated to reflect the fatty acid composition of N commune lipid extract. The fatty acid mixture significantly reduced RNA abundance of TNF-α and COX-2, but to a lesser extent than did the N commune lipid extract, suggesting the presence of additional bioactive compounds with an antiinflammatory property in the lipid extract. As NF-κB is a major regulator for the proinflammatory gene expression, we measured its DNA-binding activity. DNA-binding activity of NF-κB was significantly reduced by N commune lipid extract. In conclusion, our study suggests that N commune lipid extract represses the expression of proinflammatory genes in RAW 264.7 macrophages, at least in part, by inhibiting the activation of NF-κB pathway.     

细基江篱的化学成分

目的研究红藻细基江篱(Gracilaria tenuistipitata)中的化学成分。方法细基江篱用甲醇冷浸提取,浓缩成浸膏,分别用石油醚、乙酸乙酯萃取,所得石油醚部分和乙酸乙酯部分利用反复硅胶柱色谱、凝胶柱色谱等方法进行分离纯化,并根据其理化性质和光谱(NMR及MS等)数据进行化学结构鉴定。结果从细基江篱的石油醚和乙酸乙酯部分共分离得到了8个化合物,经鉴定分别为胆甾醇(1)、3β羟基胆甾5烯7酮(2)、胆甾5烯3β,7α二醇(3)、β谷甾醇(4)、胡萝卜苷(5)、胸腺嘧啶(6)、尿嘧啶(7)、棕榈酸(8)。结论上述化合物均为首次从该种海藻中分离得到。