星期三, 三月 29, 2006 

Consumption of purple sweet potato leaves modulates human immune response: T-lymphocyte functions, lytic activity of natural killer cell and antibody

ISSN 1007-9327 CN 14-1219/R World J Gastroenterol 2005 October 7;11(37):5777-5781
Consumption of purple sweet potato leaves modulates human immune response: T-lymphocyte functions, lytic activity of natural killer cell and antibody production
Chiao-Ming Chen, Sing-Chung Li, Ya-Ling Lin, Ching-Yun Hsu, Ming-Jer Shieh, Jen-Fang Liu

Chiao-Ming Chen, Graduate Institute of Pharmacy, Graduate Institute of Nutrition and Health Sciences, Taipei Medical University; Department of Dietetics, Taipei Medical University Hospital, Taipei, Taiwan, ChinaSing-Chung Li, Ya-Ling Lin, Ming-Jer Shieh, Jen-Fang Liu, School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan, ChinaChing-Yun Hsu, Chang-Gung Institute of Technology, Taoyuan, Taiwan; Graduate Institute of Pharmacy, Taipei Medical University, Taipei, Taiwan, ChinaSupported by the Grant From the Taipei Medical University, No. TMU91-Y05-A110, TMU92-AE1-B33Correspondence to: Dr. Jen-Fang Liu, School of Nutrition and Health Sciences, Taipei Medical University, 250 Wu-Shing Street, Taipei 110, Taiwan, China. liujenfa@tmu.edu.tw
Telephone: +886-2-27361661-6551 Fax: +886-2-27373112
Received: 2004-12-10 Accepted: 2005-01-05

AbstractAIM: To study the immunological effects of physiological doses of purple sweet potato leaves (PSPL).
METHODS: The randomized crossover study (two periods, each lasting for 2 wk) involved 16 healthy non-smoking adults of normal weight. The 6-wk study consisted of a run-in (wk 1) PSPL diet (daily consumption of 200 g PSPL) or a control diet (low polyphenols, with the amount of carotenoids adjusted to the same level as that of PSPL) (wk 2-3), washout diet (wk 4), and switched diet (wk 5-6). Fasting blood was collected weekly in the morning. T-lymphocyte function was assessed via the proliferation and secretion of immunoreactive cytokines. Salivary IgA secretion and the specific cytotoxic activities of cytotoxic T lymphocytes and natural killer (NK) cells were determined.
RESULTS: The plasma b-carotene level increased with time in both groups, while the plasma polyphenol level decreased in the control group, and no significant difference was detected between the two groups. Although plasma polyphenol levels did not significantly increase in the PSPL group at the end of the study, they were significantly elevated in urine. PSPL consumption produced a significant increase in proliferation responsiveness of peripheral blood mononuclear cells (PBMC) and their secretion of immunoreactive IL-2 and IL-4. As well, lytic activity in NK cells was elevated in a time-dependent fashion. Salivary IgA secretion significantly decreased in control group after 2 wk, and returned to baseline following dietary switch to PSPL.
CONCLUSION: Consumption of PSPL modulates various immune functions including increased proliferation responsiveness of PBMC, secretion of cytokines IL-2 and IL-4, and the lytic activity of NK cells. The responsible determinants of PSPL remain to be elucidated, as does the biological significance of the present observations.
© 2005 The WJG Press and Elsevier Inc. All rights reserved.
Key words: Purple sweet potato leaves; Polyphenol; Immune functionChen CM, Li SC, Lin YL, Hsu CY, Shieh MJ, Liu JF. Consumption of purple sweet potato leaves modulates human immune response: T-lymphocyte functions, lytic activity of natural killer cell and antibody production. World J Gastroenterol 2005; 11(37): 5777-5781

9:03 上午 | |

 

Stereoisomerism


Stereoisomerism is the arrangement of atoms in molecules whose connectivity remains the same but their arrangement in space is different in each isomer.
The two main types of stereoisomerism are:
cis-trans isomerism
optical isomerism

Cis-trans Isomerism
For example a geometrical isomerism occurs when a double bond is present, because the pi bond involved prevents that bond from being "twisted" the same way that a single bond can be. A good example is 1,2-dichloroethene: C2H2Cl2. Consider the two examples below:


The two molecules shown above are cis-1,2-dichloroethene and trans-1,2-dichloroethene. This is more specifically an example of cis-trans isomerism. These two molecules are geometrical isomers because the two carbon atoms cannot be rotated relative to each other, due to the rigidity caused by the pi bond between them. Therefore, they are not "superimposeable" - they are not identical, and cannot take each other's place. Geometrical isomers have different chemical and physical properties and can exhibit dramatically different biological activity.
Optical Isomerism
Optical isomers are stereoisomers formed when asymmetric centers are present, for example, a carbon with four different groups bonded to it. Enantiomers are two optical isomers that are reflections of each other. Every stereocenter in one has the opposite configuration in the other. Compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different optical isomers of other compounds. In nature, most biological compounds, such as amino acids, occur as single enantiomers. As a result, different enantiomers of a compound may have substantially different biological effects. When a molecule has more than one source of asymmetry, two optical isomers may be neither perfect reflections of each other nor superimposeable: some but not all stereocenters are inverted. These molecules are called they are diastereomers, not enantiomers. Diastereomers seldom have the same physical properties.

8:27 上午 | |

 

叶黄素的提取与分离

科学家们对叶黄素化学结构的研究表明：它具有3个属性中心，8种立体异构体(实际上自然界中只存在一种异构体)。因为工艺太复杂，在化学上人工合成单一异构体的叶黄素至今尚未成功。目前只有从天然植物中提取出的叶黄素才含具有抗氧化作用的生物活性物质。国外一些公司正在探索新的叶黄素生产途径。
富含叶黄素的天然植物主要有：万寿菊、金盏花、羽衣甘蓝、蚕沙、猕猴桃、菠菜、南瓜、苜蓿、蛋黄、黄色玉米等。其中万寿菊、金盏花中叶黄素含量较高。提取溶剂有环己烷、石油醚、丙酮、乙醇、四氢呋喃等。

2．1 国外公司研究现状
国外专利报道的提取方法和检测方法较多：a)从金盏花中同时用四氢呋喃提取和皂化叶黄素酯。b)从绿色植物中分离类胡萝卜素。c)从蚕沙中用丙酮和石油醚提取叶黄素。

意大利Fabio等人采用浓缩富集、离心分离、冷冻干燥等工艺，从苜蓿中分离得到富含胡萝卜素和叶黄素的浓缩物，而后联用CO2萃取工艺，在不同的萃取工艺下，分别得到胡萝卜素和叶黄素。美国凯明(Kemin)食品公司发明了生产叶黄素的新工艺，使叶黄素成为一种新型保健食品添加剂。该公司从大量野生的金盏花中提取叶黄素成品结晶。另据报道，该公司正在计划生产富含叶黄素的“超视力饮料”。美国食品和药物管理局1995年即已批准叶黄素作为食品补充剂用于食品饮料，以提高其营养价值；德国巴斯夫维生家公司开发出含有叶黄素的鸡饲料添加剂，其产品在我国的上海、广州、香港都有销售；南美洲的Henkle公司已从资源丰富的南瓜和榨汁后的桶渣中提取出叶黄素酯(Xangold)。由于叶黄素酯在人体内可自动转化成为叶黄素，因此叶黄素酯的成功提取大大拓展了叶黄素的来源。

2．2 国内研究现状
叶黄素的应用在我国尚未引起食品和医药行业的重视，有关国内开发叶黄素及富含叶黄素的保健品未见有报道。下面是作者了解到的一些信息：山西恒康乳业公司下属天成生物公司从万寿菊中提取含有叶黄素的类胡萝卜素产品，用于鸡饲料中做添加剂，并在吕梁地区广泛栽培万寿菊(形成当地的观赏旅游型农业)设厂生产；华北工学院化学工程系对于从蚕沙中提取叶黄素的工艺研究取得了一定的进展；青岛大学天然色素研究所经过大量科研人员的多年研究，对于叶黄素的分离纯化、降解等方面取得了一些成果，生产出比较纯的叶黄素产品，但未形成大批量生产。叶黄素在我国烟草行业也有一定的应用，但对于提取叶黄素的工业化生产企业的产品和含有叶黄素的保健食品在我国市场上还未见有销售。

8:14 上午 | |