玉米黄素转化为虾青素的工艺参数研究

本文通过氧化剂氧化玉米黄素得到虾青素,并对实验中的主要影响因素进行了筛选和优化。实验结果表明,以三氯甲烷做溶剂,溴酸钠为氧化剂,三氯甲烷/玉米黄素(v/m)为40,溴酸钠/玉米黄素为6,温度为30℃,pH为9.5,反应时间为12 h时,产物含量最高,达69%,产率为74%。通过液-质联用、核磁共振氢谱以及红外光谱确定了最终产物。     

叶黄素的抗癌作用及其研究现状

叶黄素是自然界广泛存在的类胡萝卜素,可以提高人体的免疫能力,也是一种抗氧化剂,对老年视黄斑退行性变化有很好的预防作用,但更重要的是研究表明,叶黄素对一些类型的癌症具有预防效果。本综述了近年来有关叶黄素预防癌症作用的流行病学调查、分析,以及与癌症关系的实验研究及作用机制等方面的研究进展。     

叶黄素酯的皂化工艺研究

本文研究了以金盏菊提取物为原料,通过皂化反应将其中叶黄素酯类衍生物转化为游离态叶黄素的皂化工艺。考察了溶剂类型、KOH浓度、反应时间、反应温度和KOH溶液加入量对衍生效果的影响。     

植物叶黄素循环的组成、功能和调节(综述)

对近几年来植物体内叶黄素循环的组成、功能、堇菜黄素脱环氧化酶和玉米黄素环氧化酶的结构、生化性质和调节,以及叶黄素的可转变性、定位等方面的研究进展作了综述。     

平菇转化叶黄素酯研究

目前针对有关天然产物的生物转化研究较少,首次报道了平菇转化叶黄素酯的研究。在对平菇在叶黄素酯培养基生长的观察中,发现对于固体培养基,菌丝体可利用叶黄素酯但不能增生,而孢子悬液不能生长,但在发酵液中两者生长良好,可见只有菌丝体可分泌水解酶,而且谊酶在溶液环境下效价高。同时利用高效液相色谱测定其降解效果发现,平菇首先将叶黄素酯转化为叶黄素,同时也可将叶黄素转化为其它物质,故控制发酵时间非常重要,这为今后的工业化提供了基础。     

叶黄素和叶黄素酯的护眼功能

综述了叶黄素和叶黄素酯在消除和减轻眼视网膜底中心的蓝光集中区对眼睛的伤害方面的研究进展。     

紫花苜蓿中叶黄素超声提取优选工艺条件的研究

采用L9（3^4）正交试验,以叶黄素含量为评价指标,用紫外可见分光光度法进行测定,考察了超声温度（A）、时间（B）、超声功率（C）、超声频率（D）对超声波提取苜蓿中叶黄素的影响。结果表明：优化工艺为提取温度55℃,提取时间45min,超声波功率50W,超声频率45kHz。该工艺合理,可大大缩短工时,提高收率。     

HPLC法测定甘薯叶片中的叶黄素

建立甘薯叶片中有效成分叶黄素含量的高效液相色谱测定方法,以寻求含量高的甘薯品种。采用Waters SunFire^TM C₁₈(150 mm×4.6 mm,5 μm )色谱柱;以甲醇—水为95:5(V/V)为流动相,流速为0.8 mL·min^-1;检测波长为445 nm;外标法定量。此色谱条件下,叶黄素含量在5~100 μg·mL^-1范围内时,与峰面积呈线性关系;样品平均回收率为99.5%;相对标准偏差 (RSD)为1.9%(n=5)。该方法灵敏、准确、专属性强,适用于甘薯叶片中叶黄素的测定;大部分供试品种间存在显著差异,其中以苏薯8号的含量最高。     

叶黄素持续补充对机体叶黄素水平及抗氧化能力影响研究

目的：探讨叶黄素持续补充对机体血浆叶黄素浓度、血浆氧化应激水平及氧化型低密度脂蛋白（Ox-LDL）水平的影响。方法：20名健康青年志愿者,随机分为2组,分别为叶黄素组和正常对照组,叶黄素组每天补充叶黄素20mg,连续补充20d,正常对照组未给予任何补充。试验前及首次口服后的12、24、72、144、240、480、720h分别留取清晨空腹静脉血5mL,分离血浆。HPLC检测血浆叶黄素浓度,测定血浆总超氧化物歧化酶（T-SOD）及谷胱甘肽过氧化物酶（GSH-Px）活性、丙二醛（MDA）含量、Ox-LDL浓度。结果：叶黄素组血浆叶黄素浓度呈稳定上升趋势,GSH-Px及T-SOD活性呈持续性上升趋势,MDA含量呈持续性下降趋势。叶黄素组血浆叶黄素浓度在口服72、144、240、480h后分别升高59%、115%、164%、214%（P均＜0.05）,且女性血浆叶黄素浓度在口服240h后显著高于男性（P＜0.05）;血浆GSH-Px活性在补充20d后升高42%（P＜0.05）,MDA含量下降23%（P＜0.05）。结论：每天补充叶黄素20mg,持续补充20d能有效提高机体血浆叶黄素浓度及机体抗脂质过氧化能力。     

叶黄素与叶酸的研究

叶黄素（Lutein）又名植物黄体素,分子式C40H50O2,易溶于氯仿、CO2,微溶于醇、醚,被认为是维生素的一个新品种。在复合维生素中加入一定比例的叶黄素对人体的保健起着重要作用。特别是在抗视力疲劳方面显现出一定的功效。在人的视网膜中除了特有的视紫红质（rhodopsin）之外,还含有叶黄素,一旦缺乏叶黄素必将引起视黄斑退化,损害视力,其致病机理和缺乏维生素A引起夜盲症类似。在美国,65岁以上的老人视黄斑退化占10％以上。除此之外,叶黄素在防病、抗癌和增强免疫力方面的作用也不可小视。它是人血液中主要类胡萝b素之一,对直肠癌、皮肤癌等多种癌症有抑制作用,例如它可保护皮肤不受紫外线照射的损伤,能大大减少皮肤癌的发生率,机体免疫力增强了。在膳食中摄入叶黄素不仅可以抑制肿瘤,还能预防肿瘤的发生。叶黄素还有利于预防心血管病的发生,延缓早期动脉硬化。这些充分显示了叶黄素对人体保健方面的重要价值。     

Sex and age differences in reflectance and biochemistry of carotenoid‐based colour variation in the great tit Parus major

The plumage coloration in great tits (Parus major) is the subject of much behavioural and ecophysiological research, yet there is a lack of analyses of the natural colour variation and its mechanisms. We used reflectance spectrometry and high‐performance liquid chromatography to explore individual, sexual and age‐related variation in carotenoid coloration and pigmentation, paramount to the often presumed, but rarely substantiated, costs and ‘honesty’ of carotenoid displays. In adults, we found that sex was the strongest predictor of ‘brightness’ (higher in males) and of ‘hue’ (longer wavelength in females). There was no sex difference in ‘carotenoid chroma’ or carotenoid content of feathers which also was unrelated to adult age (1 or 2+ years) and condition. Similar patterns were revealed for nestlings. Regarding the biochemical ‘signal content’, ‘carotenoid chroma’, but not ‘hue’, was significantly related to the carotenoid content (lutein and zeaxanthin) of feathers. These results refute the previously assumed exaggeration of carotenoid pigmentation in male great tits, and question the condition‐dependence of carotenoid coloration in this species. However, the sexual dimorphism in total reflectance or ‘brightness’, most likely due to melanins rather than carotenoids, may have implications for signalling or other adaptive explanations that need to be explored. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 758–765.     

CAROTENOID COMPOSITION OF MARINE RED ALGAE1

Photosynthetic organisms possess carotenoids that function either as accessory, photoprotective, or structural pigments. Therefore, the carotenoid profile provides information about certain photoacclimation and photoprotection responses. Carotenoids are also important chemosystematic markers because specific enzymes mediate each step of carotenoid biosynthesis. For red algae, diverse and often contradictory carotenoid compositions have been reported. As a consequence, it is difficult to infer the physiological importance of carotenoids in Rhodophyta. To characterize the relationship between carotenoid composition, rhodophycean phylogeny, and the presence of potentially photoprotective pigments, we analyzed the carotenoid composition of 65 subtropical species from 12 orders and 18 rhodophyte families. Our results showed that red algae do not present a unique carotenoid profile. However, a common profile was observed up to the level of order, with exception of the Ceramiales and the Corallinales. The main difference between profiles is related to the xanthophyll that represents the major carotenoid. In some species lutein is the major carotenoid while in others it is substituted by zeaxanthin or antheraxanthin. The presence of this epoxy carotenoid together with the presence of violaxanthin that are xanthophyll cycle (XC)‐related pigments was found in four of the 12 analyzed orders. The carotenoid pigment profiles are discussed in relation to Rhodophyta phylogeny, and it is suggested that the xanthophyll cycle‐related pigments appeared early in the evolution of eukaryotic phototrophs.     

PHOTOINHIBITION IN RED ALGAL SPECIES WITH DIFFERENT CAROTENOID PROFILES1

Members of the Rhodophyta present different carotenoid profiles. In a majority of the species, lutein constitutes >50% of the total carotenoid content, while in other species, it is replaced by zeaxanthin or antheraxanthin. Given that carotenoids have specific roles in photoprotection, different carotenoid profiles of red algae species could be related to their capacity to cope with photoinhibitory stress. Therefore, in the present work, the sensitivity to light stress of red algal species with different carotenoid profiles was investigated. Photoinhibition of photosynthesis induced by high‐light stress and the subsequent recovery in dim‐light conditions was measured using maximal PSII quantum efficiency (F_v/F_m). The degree of decrease and recovery of F_v/F_m and their respective kinetics were related to the carotenoid profile of the species. Although no relationship between sensitivity to high‐light stress and the carotenoid profile was observed, there were clear carotenoid profile‐related differences in the decrease and recovery kinetics. In species with zeaxanthin or antheraxanthin as the major carotenoid, F_v/F_m reduction and recovery was principally associated with slowly activated and relaxed processes. In contrast, in species with lutein as the major carotenoid, rapidly activated processes appear to play a major role in the down‐regulation of photosynthesis during light‐stress conditions. In these species, the repair of D1 is also important during light‐stress conditions. This finding could imply differential expression of mechanisms involved in photoprotection in red algae that seems to be related to the carotenoid profile of the species.     

微胶囊叶黄素理化性质及其稳定性研究

本文研究了微胶囊叶黄素产品的理化性质及其在光、热、pH值及氧气条件下的稳定性。结果表明,微胶囊叶黄素含水率为3．0％、密度0．39g／cm^3、粒径8—10μm、溶解度90s;叶黄素经微胶囊化后可明显提高叶黄素的光稳定性和热稳定性,减弱了pH值的影响和氧气对叶黄素的氧化降解。     

Influence of carbon and nitrogen sources on Flavobacteriumgrowth and zeaxanthin biosynthesis

Growth and production of zeaxanthin by Flavobacterium sp were studied using different carbon and nitrogen sources in a chemically defined medium. The best growth was supported by sucrose, but glucose yielded similar carotenoid concentrations. Both asparagine and glutamine stimulated growth and pigment formation. Carotenoid production and glucose consumption increased as a function of asparagine concentration. In the presence of asparagine, high glucose concentrations decreased pigment production without affecting biomass formation. In the absence of glucose, asparagine could not support growth and zeaxanthin production. When compared to the effect of 55 mM glucose, 10 mM oxaloacetate increased growth and carotenoid production. Pyruvate and other intermediates of the citric acid cycle showed a similar stimulatory effect. The intermediates of glycolysis: glucose 6-phosphate and fructose 1,6-diphosphate did not support growth. These results suggest that Flavobacterium sp utilizes asparagine primarily as a nitrogen source for growth and production of zeaxanthin. Received 29 September 1998/ Accepted in revised form 23 April 1999     

A Double-Blind,Placebo-Controlled Study on the Effects of Lutein and Zeaxanthin on Neural Processing Speed and Efficiency

Lutein and zeaxanthin are major carotenoids in the eye but are also found in post-receptoral visual pathways. It has been hypothesized that these pigments influence the processing of visual signals within and post-retina, and that increasing lutein and zeaxanthin levels within the visual system will lead to increased visual processing speeds. To test this, we measured macular pigment density (as a biomarker of lutein and zeaxanthin levels in brain), critical flicker fusion (CFF) thresholds, and visual motor reaction time in young healthy subjects (n = 92). Changes in these outcome variables were also assessed after four months of supplementation with either placebo (n = 10), zeaxanthin only (20 mg/day; n = 29) or a mixed formulation containing 26 mg/day zeaxanthin, 8 mg/day lutein, and 190 mg/day mixed omega-3 fatty acids (n = 25). Significant correlations were found between retinal lutein and zeaxanthin (macular pigment) and CFF thresholds (p<0.01) and visual motor performance (overall p<0.01). Supplementation with zeaxanthin and the mixed formulation (considered together) produced significant (p<0.01) increases in CFF thresholds (∼12%) and visual motor reaction time (∼10%) compared to placebo. In general, increasing macular pigment density through supplementation (average increase of about 0.09 log units) resulted in significant improvements in visual processing speed, even when testing young, healthy individuals who tend to be at peak efficiency.     

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF PHYTOPLANKTON PIGMENTS USING A POLYMERIC REVERSED-PHASE C18 COLUMN1

A high-performance liquid chromatographic (HPLC) method is described that allows improved resolution of several chemotaxonomically significant phytoplankton pigments. The protocol, which employs two pumps and a modified Mantoura and Llewellyn (1983) solvent system, can be easily adapted for many HPLC systems currently in use. The most unique aspect of the method is the use of a polymeric C₁₈ reversed phase HPLC column (VYDAC 201TP). In comparison to the monomeric C₁₈ columns typically used in the characterization of phytoplankton pigments, polymeric C₁₈ columns offer superior selectivity for structurally similar compounds. The protocol was evaluated for the ability to resolve most of the phytoplankton pigments of diagnostic importance using algal cultures from nine classes. Pigment pairs that were resolved by the method include a) lutein and zeaxanthin, b) neoxanthin and 19′-hexanoyloxyfucoxanthin, and c) α-carotene and β-carotene, and partial resolution of chlorophyll c₁ and chlorophyll c₂.