β-胡萝卜素立体异构体对环磷酰胺处理小鼠免疫功能的比较研究

就β-胡萝卜素立体异构体对环磷酰胺处理小鼠的免疫功能影响进行了比较研究。结果显示β-胡萝卜素立体异构体对外磷酰胺造成的免疫功能低下具有不同程度的改善作用，提高胸腺和脾脏指数，增强脾脏细胞对刀豆素A（ConA）的反应性和NK活性，血清溶菌酶含量也有所增加。综合各项指标，9-顺式和全反式混合物的作用最明显，提示一定浓度的9-顺式对于提高β-胡萝卜素对机体的总体作用是有一定意义的。     

Blood retinol and β-carotene levels in rural Guatemalan preschool children

Plasma retinol and -carotene levels were measured in 502 preschool Guatemalan children from five rural hamlets. Their ages ranged from 6 to 78 months (mean: 42.9±19.2 months); 45% males and 55% females. The mean retinol value in the whole group was 0.9±0.4 µmol/1 (range: 0.1 to 8.4 µmol/1). There was no significant difference between sexes in retinol mean values nor in the incidence of retinol values less than 0.7 µmol/1 (22% in males, 18% in females). When grouped by age and community, significant low retinol mean values were found in two hamlets in the youngest age group (12 to 23 months) as compared to the other age-groups (p<0.05). In the other two hamlets, there were no significant differences among retinol means by age-group. The highest prevalence of deficient retinol values by age-group was in the 12 to 23 months group (40%), and decreased as age increased. The mean value for -carotene in the whole group was 0.13±0.18 µmol/1 (range: 0.01 to 2.23 µmol/1). There were no significant differences in -carotene means between sexes in the whole group. Stratifying the -carotene data by age-groups and community, values were significantly higher in the 48–59 months and 72–83 months groups, as compared with the other age groups in two of the communities (p<0.05). Significant differences across communities for -carotene were found only in the 12 to 23 months group.     

Cucurbita moschata Duch. and its active component, β-carotene effectively promote the immune responses through the activation of splenocytes and macrophages

Cucurbita moschata Duch. has long been used for traditional health food in many countries. However, to enhance the immune system of Cucurbita moschata Duch. and its major component, β-carotene is not clear. Here, we determined the immune enhancement effect of Cucurbita moschata Duch. and β-carotene in mouse splenocytes and RAW 264.7 macrophage cell line. We prepared baked Cucurbita moschata Duch. (Sweetme Sweet Pumpkin^TM, SSP) and steamed Cucurbita moschata Duch. (SC). Splenocytes isolated from the spleen of BALB/c mice were treated with SSP, SC, and β-carotene for 24?h. RAW 264.7 cells were stimulated with recombinant interferon-γ (rIFN-γ) for 6?h before treatment with SSP, SC, or β-carotene. SSP, SC and β-carotene significantly up-regulated the proliferation of splenocyte and mRNA expression of KI-67. The levels of interleukin-2 and IFN-γ were up-regulated by SSP, SC, or β-carotene in the splenocytes. SC and β-carotene also increased the levels of tumor necrosis factor-α (TNF-α) in the splenocytes. In addition, SSP, SC, or β-carotene significantly increased the levels of TNF-α through the nuclear translocation of the nuclear factor-κB and phosphorylation of IκBα in the rIFN-γ-primed RAW 264.7 cells. These data indicate that Cucurbita moschata Duch. and β-carotene may have an immune-enhancing effect through the production of Th1 cytokines by activation of splenocytes and macrophages.     

Can Diet Prevent Urological Cancers? An Update on Carotenoids as Chemopreventive Agents

Urological cancers, namely prostate, bladder, kidney, testicular, and penile cancers, are common conditions that constitute almost one-quarter of all malignant diseases in men. Urological cancers tend to affect older individuals, and their development is influenced by modifiable metabolic, behavioral, and environmental risk factors. Phytochemicals may have cancer-fighting properties and protect against cancer development, slow its spread, and reduce the risk of cancer deaths in humans. This paper aims to review the current literature in regard to the effects of carotenoids in reducing urological cancer risk.     

Carotenoids, β-Apocarotenoids,and Retinoids: The Long and the Short of It

Naturally occurring retinoids (retinol, retinal, retinoic acid, retinyl esters) are a subclass of β-apocarotenoids, defined by the length of the polyene side chain. Provitamin A carotenoids are metabolically converted to retinal (β-apo-15-carotenal) by the enzyme β-carotene-15,15′-dioxygenase (BCO1) that catalyzes the oxidative cleavage of the central C=C double bond. A second enzyme β-carotene-9′-10′-dioxygenase cleaves the 9′,10′ bond to yield β-apo-10′-carotenal and β-ionone. Chemical oxidation of the other double bonds leads to the generation of other β-apocarotenals. Like retinal, some of these β-apocarotenals are metabolically oxidized to the corresponding β-apocarotenoic acids or reduced to the β-apocarotenols, which in turn are esterified to β-apocarotenyl esters. Other metabolic fates such as 5,6-epoxidation also occur as for retinoids. Whether the same enzymes are involved remains to be understood. β-Apocarotenoids occur naturally in plant-derived foods and, therefore, are present in the diet of animals and humans. However, the levels of apocarotenoids are relatively low, compared with those of the parent carotenoids. Moreover, human studies show that there is little intestinal absorption of intact β-apocarotenoids. It is possible that they are generated in vivo under conditions of oxidative stress. The β-apocarotenoids are structural analogs of the naturally occurring retinoids. As such, they may modulate retinoid metabolism and signaling. In deed, those closest in size to the C-20 retinoids—namely, β-apo-14′-carotenoids (C-22) and β-apo-13-carotenone (C-18) bind with high affinity to purified retinoid receptors and function as retinoic acid antagonists in transactivation assays and in retinoic acid induction of target genes. The possible pathophysiologic relevance in human health remains to be determined.     

β-胡萝卜素包合物的制备及稳定性研究

目的:制备β-胡萝卜素包合物并考察其稳定性。方法:用改进的饱和水溶液法,制备了β-胡萝卜素与β-环糊精的固体包合物,并用紫外分光光度法考察了包合物的稳定性,测定了包合物中β-胡萝卜素的含量。结果:包合物中β-胡萝卜素的含量为5.54%,其被包合后在加热、光照和氧化剂存在条件下稳定性得到改善,β-胡萝卜素的保留率分别提高了34.4%、1.8%和64.2%。结论:β-胡萝卜素被β-环糊精包合后可以提高稳定性。     

Plasma concentration response to drinks containing beta-carotene as carrot juice or formulated as a water dispersible powder

Summary. Background: Bioavailability of β-carotene is highly variable and depends on the source, the formulation and other nutritional factors. Objective: It was the aim of the study to compare β-carotene plasma response to b-carotene dosing with two commercially available drinks, containing β-carotene from carrot juice or as water dispersible β-carotene powder. Design In a randomized, parallel group study design, 4 volunteers per group received daily β-carotene doses of 6–7 or 18–22 mg of either drink over 6 weeks. Blood samples for determination of carotenoid and vitamin A plasma concentrations were collected before supplementation and over the dosing period. Results: Apparent steady-state β-carotene concentrations were attained after 40 days of supplementation. Consumption of the beverage containing β-carotene as a water dispersible powder resulted in a higher response of β-carotene plasma concentrations with increments of 3.84 ± 0.60 μmol/L (p < 0.05, dose: 7.2 mg/d) and 5.04 ± 0.72 μmol/L (p < 0.05, dose: 21.6 mg/d), respectively, in comparison to the carrot juice-based drink with increments of 0.42 ± 0.33 μmol/L (dose: 6 mg/d) and 1.71 ± 0.55 μmol/L (dose: 18 mg/d), respectively. β-carotene was cleared from the plasma with an apparent half-life of 6–11 days. Plasma concentrations of α-carotene, β-cryptoxanthin, lutein, zeaxanthin, and lycopene remained almost unchanged, whereas retinol plasma concentrations increased slightly. By contrast, with the exception of elevated 13-cis-retinoic acid in one group (21.6 mg/d, water dispersible powder), the concentrations of all-trans-retinoic acid, and the oxo-derivatives or retinoic acid were not significantly affected by b-carotene supplementation. Conclusions: The results confirm that the relative bioavailability of β-carotene depends largely on the source of b-carotene and demonstrate the superior bioavailability of β-carotene powder in comparison to that in carrot juice. Received: 7 May 2002, Accepted: 22 August 2002 This work was supported by a grant from F. Hoffmann-La Roche Ltd., Vitamins and Nutrition Research, Basle, Switzerland. Correspondence to: Prof. Dr. med. Petra A. Thürmann     

Prospective study of serum retinol, β-carotene, β-cryptoxanthin, and lutein/zeaxanthin and esophageal and gastric cancers in China

Objective: This study examined the relationship between pretrial serum concentrations of retinol, -carotene, -cryptoxanthin, and lutein/zeaxanthin and the subsequent risk of developing esophageal squamous cell carcinoma and gastric cardia or non-cardia adenocarcinoma in subjects selected from a randomized nutritional intervention trial in Linxian, China, a region with epidemic rates of esophageal and gastric cardia cancer. Methods: We used a stratified case–cohort design to select cohort members for inclusion in this study. In all we measured serum concentrations of the above vitamins in 590 esophageal, 395 gastric cardia, and 87 gastric non-cardia case subjects as well as in 1053 control subjects. Relative risks (RRs) were estimated using Cox proportional hazards models. Results: Median values in our cohort were low for serum retinol (33.6 g/dl), -carotene (4.3 g/dl), and -cryptoxanthin (3.5 g/dl) , but were high for lutein/zeaxanthin (40.0 g/dl). Gastric cardia cancer incidence fell 10% for each quartile increase in serum retinol (RR = 0.90, 95% CI = 0.83–0.99). For esophageal cancer, an inverse association with retinol levels was found only in male non-smokers (RR = 0.79 per quartile increase, 95% CI = 0.63–0.99). For gastric non-cardia cancer, an inverse association was limited to subjects 50 years old or younger (RR = 0.58 per quartile, 95% CI = 0.31–0.96). For -cryptoxanthin there was a borderline significant protective association for gastric non-cardia cancer (RR = 0.88 per quartile, 95% CI = 0.76–1.0). In contrast, we found the incidence of gastric non-cardia cancer increased (RR = 1.2 per quartile, 95% CI = 1.0–1.3) with increasing concentration of serum lutein/zeaxanthin. Conclusions: In this population, we found that low retinol and high lutein/zeaxanthin concentrations increased the risks of gastric cardia and gastric non-cardia cancer respectively. We found that there were no strong associations between any of the other analytes and any of the cancer sites.     

β-carotene bioavailability from differently processed carrot meals in human ileostomy volunteers

Summary. Background: Carotenoids contribute to the beneficial effects of fruits and vegetables consumption; however, the bioavailability of these compounds from fresh or processed foods is not well established. Aim of the study: We evaluated the bioavailability of -carotene (15 mg) from a single meal composed of cooked, pureed carrots and compared it to raw, chopped carrots. Methods: Test meals were given to overnight-fastedileostomy volunteers (n = 8) along with skimmed-milk yogurt containing 40 g of added sunflower oil. Blood and complete ileal effluent samples were collected over a 24 h period. Samples were solvent-extracted and the -carotene content measured by HPLC. Results: Kinetics of excretion of cis and trans -carotene were similar. More -carotene was absorbed from puree as compared to raw carrots. Carotenoid mass-balance calculations indicated that 65.1 ± 7.4% of the -carotene was absorbed from cooked pureed carrot meals, vs. 41.4 ± 7.4 % from raw, chopped carrot meals. Gastrointestinal transit parameters did not differ significantly among the volunteers. As expected, the calculated lag phase was five times longer for raw vs. cooked carrots. Mean t-end, t-1/2 and rate of mass transit resulted in similar values for both raw and cooked carrot meals. A moderate response in carotenoid plasma profile was observed for cooked carrot test meals. Conclusions: Significantly more -carotene was absorbed from meals containing cooked, pureed carrots than from meals containing the raw vegetable. Moderate carotenoid plasma response was detected within 6 h following the administration of cooked processed carotenoid-containing single meal.     

镁和β-胡萝卜素对2型糖尿病大鼠糖脂代谢影响

目的 通过补充镁、β-胡萝卜素及其联合制剂,探讨其对实验2型糖尿病大鼠糖脂代谢的影响及其作用机制.方法 利用链脲佐菌素(STZ)建立2型糖尿病大鼠动物模型,将其随机分为糖尿病模型组、镁组、β-胡萝卜素组及镁+β-胡萝卜素组、正常对照组.实验期8周,检测大鼠血糖(Glu)、甘油三酯(TG)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL)含量,并计算胰岛素抵抗指数(HOMA-IR).结果 8周干预后,镁组、β-胡萝卜素组以及镁+β-胡萝卜素组血糖值分别为(7.57±5.61),(7.85±4.11)和(6.09±3.43),较模型组(13.28±4.11)明显降低(P＜0.05);镁+β-胡萝卜素组TG、LDL分别为(1.63±0.64),(0.29±0.08),较模型组(2.65±0.67),(0.45±0.16)明显降低(P＜0.05);HDL(11.1±0.31)较模型组(0.81±0.10)明显升高(P＜0.05);HOMA-IR与模型组(11.94±2.96)比较,镁组(6.64±4.54)明显降低(P＜0.05),镁+β-胡萝卜素组(4.95±3.36)明显降低(P＜0.01).结论 镁可以明显降低糖尿病大鼠的血糖、改善胰岛素抵抗;β-胡萝卜素可以明显降低血糖;镁和β-胡萝卜素联合补充可以明显改善糖脂代谢、减轻胰岛素抵抗.