Poplar Propolis Improves Insulin Homeostasis in Non-Diabetic Insulin-Resistant Volunteers with Obesity: A Crossover Randomized Controlled Trial

Propolis, a natural resinous mixture rich in polyphenols, produced by bees from a variety of plant sources, has shown significant therapeutic effects and may prevent the development of certain chronic diseases like type 2 diabetes mellitus (T2DM). The objective of this study was to evaluate the effect of supplementation with standardized poplar propolis extract powder (PPEP) on insulin homeostasis in non-diabetic insulin-resistant volunteers with obesity. In this randomized, controlled, crossover trial, nine non-diabetic insulin-resistant volunteers with obesity, aged 49 ± 7 years, were subjected to two periods of supplementation (placebo and PPEP) for 3 months. Blood samples and anthropomorphic data were collected at baseline and at the end of each phase of the intervention. PPEP supplementation improved insulin sensitivity by significantly decreasing the percentage of insulin-resistant subjects and the insulin sensitivity Matsuda index (ISI-M). According to this study, supplementation with standardized PPEP for 3 months in non-diabetic insulin-resistant volunteers with obesity led to an improvement in insulin homeostasis by its effect on insulin resistance and secretion. This study suggests that poplar propolis has a preventive effect on the physiopathological mechanisms of T2DM and, therefore, that it can help to prevent the development of the disease

Antifungal activity of Brazilian red propolis extract and isolation of bioactive fractions by thin-layer chromatography-bioautography

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Development of a method to determine carotenoid composition of fresh forages

International audienceDevelopment of a method to determine carotenoid composition of fresh forages. Can. J. Plant Sci. 88: 1057-1064. Due to the limited interest in carotenoids in ruminant diets until recently, analyses of forages are often incomplete, focusing mainly on P-carotene and lutein. Carotenoid composition of green forage from middle mountain meadow was analyzed by HPLC after extraction and elimination of chlorophylls by mild saponification. This method Of analysis uses two C-18 columns in series with a quaternary gradient system. Our method allowed, for the first time, the identification and quantification of several xanthophylls other than lutein (i.e., violaxanthin, antheraxanthin, epilutein) in chlorophyll-free extracts from carotenoid-rich forage. The intra-day (3.5-7.5%) and inter-day (1.2-3.5%) coefficients of variation are Suitable for routine determination of carotenoids in green forage. This method Could also be used in metabolic studies of these micronutrients in ruminants

Purified low-density lipoprotein and bovine serum albumin efficiency to internalise lycopene into adipocytes

International audienceEpidemiological studies have suggested that lycopene has protective effects against various diseases including cardiovascular diseases. However, mechanistic studies to understand these effects are difficult due to the insolubility of lycopene in aqueous culture medium. The objective of the present study was to use LDL or BSA as physiological vehicles for lycopene and to compare them with various classical vehicles. Among tested vehicles, only LDL, BSA, THF/BHT, beadlets, and liposomes were able to solubilise lycopene. No cytotoxicity was observed with these vehicles. LDL and BSA allowed good stability of lycopene during incubation (52% and 43% for 2microM lycopene solutions), but remained less efficient than THF/BHT or beadlets (67% and 62%). Incubation of adipocytes (3T3-L1) with the different vehicles for 24 and 48h showed that beadlets best delivered lycopene to cells. Finally, whatever the vehicle used, intracellular localization of lycopene was the same: lipid droplets (32-51%), plasma membrane (32-37%) and nuclear membrane (19-29%). As a conclusion, LDL or BSA display comparable properties to THF/BHT or beadlets. It is the first time that lycopene carried by physiological vehicles is shown to reach different subcellular compartments supporting molecular effects in adipocyte, such as cell signaling or nuclear receptor interacting

Simple method for clinical determination of 13 carotenoids in human plasma using an isocratic high-performance liquid chromatographic method

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LDL-cholesterol-lowering effect of a dietary supplement with plant extracts in subjects with moderate hypercholesterolemia

International audienceRed yeast rice (RYR), sugar cane-derived policosanols (SCdP) and artichoke leaf extracts (ALEs) are currently incorporated alone or in combination into dietary supplements for their potential low-density-lipoprotein cholesterol (LDL-cholesterol)-lowering effects. Yet, there is no information supporting the efficacy of this association on the reduction in LDL-cholesterol. The main objective of this study was to investigate the effects of a new dietary supplement (DS) with RYR, SCdP and ALEs on LDL-cholesterol. In a double-blind, randomized, parallel controlled study, 39 subjects from 21 to 55 years with moderate hypercholesterolemia without drug treatment were assigned to 2 groups and then consumed either a DS containing RYR, SCdP and ALEs or a placebo over a 16-week period. Plasma concentrations of lipids [LDL-cholesterol, total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-cholesterol), triacylglycerols (TG)] and plasma levels of vitamins C and E, total polyphenols and malondialdehyde were determined at baseline and after 4, 8, 12 and 16 weeks. LDL-cholesterol and TC were reduced by, respectively, 21.4 % (95 % CI, -13.3 to -24.9 %, p < 0.001) and 14.1 % (95 % CI, -10.1 to -18.0 %, p < 0.001) at week 16 in the DS group compared with baseline. Similar results were obtained at weeks 4, 8 and 12. TG decreased by 12.2 % after 16 weeks in the DS group (95 % CI: -24.4 to -0.1 %, p < 0.05). For the vitamin E/TC ratio, a difference was observed between groups at week 16 (p < 0.05). Other parameters were not modified. Daily consumption of this new DS decreased LDL-cholesterol and TC and is therefore an interesting, convenient aid in managing mild to moderate hypercholesterolemia

Lycopene but not lutein nor zeaxanthin decreases in serum and lipoproteins in age-related macular degeneration patients

International audienceBACKGROUND: Epidemiological studies have established that a low serum concentration of carotenoids was associated with risk of Age-Related Macular Degeneration (ARMD). The aim of this study was to determine carotenoid levels in serum and in different lipoprotein fractions in patients diagnosed for ARMD and in matched control group. METHOD: Thirty-four ARMD patients and 21 control subjects from Brest area (France) have been included to this study. Lipoproteins have been separated from serum by gradient density ultracentrifugation. We measured concentration of carotenoids and tocopherols in serum and in different lipoprotein fractions by HPLC. RESULTS: No difference was observed between ARMD patients and control subjects in total serum carotenoids. Individual carotenoid levels showed that only lycopene was decreased significantly in serum, LDL and HDL fractions in patients (P<0.05). Concentrations in serum and lipoparticle fractions of lutein and zeaxanthin, the major pigments present in macula were not modified between both groups. CONCLUSIONS: Lycopene, as liposoluble antioxidant nutrient, is the only carotenoid altered in ARMD patients. It cannot be excluded that this effect is related to different dietary habits, but we hypothesise that lower lycopene status could result also from specific antioxidant protection of lutein and zeaxanthin by lycopene

Vegetable-borne lutein, lycopene, and beta-carotene compete for incorporation into chylomicrons, with no adverse effect on the medium-term (3-wk) plasma status of carotenoids in humans

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Comparison of the postprandial chylomicron carotenoid responses in young and older subjects

International audienceBackground:. The plant carotenoids may contribute to the beneficial health effect of fruits- and vegetables-rich diet. Epidemiological studies consistently associated high plasma carotenoids status with reduced age-related diseases. However, the data concerning the bioavailability of carotenoids in the elderly are scarce. Objective:. To test whether there is an age effect on carotenoid bioavailability. Design:. Eight young (20-35 y) and eight older (60-75 y) healthy adults ingested three different meals containing 40 g triacylglycerols (TG) and vegetable sources of carotenoids. These sources were either 188 g carrot puree which provided 30 mg betacarotene as the main carotenoid, or 61 g tomato puree providing 30mg lycopene, or 260 g cooked chopped spinach providing 30 mg lutein. TG and carotenoids were assayed in chylomicrons (CM) collected for 9 h postprandially. Results:. There was no major effect of age on the postprandial CM/TG response (0-9 h area under the curve (AUC)). There was no major effect of age on the postprandial CM all-trans beta-carotene, cis betacarotene, alpha-carotene, and lutein responses.Adjustment of these responses by the CM TG responses did not reveal any age effect. While there was no significant effect of age on the CM lycopene response, the CM TG-adjusted lycopene response was significantly lower (-40 %) in the older than in the younger subjects (P < 0.04). The cis-trans ratios of CM betacarotene were not significantly different between the old and the young subjects. There was no significant effect of age on the ratio of CM retinyl-palmitate to the sum of alpha-carotene and beta-carotene measured after the carrot meal. Conclusions:. The bioavailability of lycopene is apparently impaired in the old,while there is no major difference in the bioavailability of beta-carotene, alpha-carotene and probably lutein. There is also no major effect of age on the cis-trans isomerization of beta-carotene during absorption, and in the intestinal conversion of provitamin A carotenoids into vitamin A