Analysis of carotenoids and tocopherols in plant matrices and assessment of their in vitro antioxidant capacity

Exploring the Lipidome: Current Lipid Extraction Techniques for Mass Spectrometry Analysis

In recent years, high-throughput lipid profiling has contributed to understand the biological, physiological and pathological roles of lipids in living organisms. Across all kingdoms of life, important cell and systemic processes are mediated by lipids including compartmentalization, signaling and energy homeostasis. Despite important advances in liquid chromatography and mass spectrometry, sample extraction procedures remain a bottleneck in lipidomic studies, since the wide structural diversity of lipids imposes a constrain in the type and amount of lipids extracted. Differences in extraction yield across lipid classes can induce a bias on down-stream analysis and outcomes. This review aims to summarize current lipid extraction techniques used for untargeted and targeted studies based on mass spectrometry. Considerations, applications, and limitations of these techniques are discussed when used to extract lipids in complex biological matrices, such as tissues, biofluids, foods, and microorganisms.

Extraction and Analysis by HPLC-DAD of Carotenoids in Human Faeces from Spanish Adults

Carotenoids are bioactive compounds with widely accepted health benefits. Their quantification in human faeces can be a useful non-invasive approach to assess their bioavailability. Identification and quantification of major dietary carotenoids in human faeces was the aim of the present study. Faeces and dietary intake were obtained from 101 healthy adults (45-65 years). Carotenoid concentrations were determined by HPLC in faeces and by 3-day food records in dietary intake. Carotenoids quantified in faeces (µg/g dry weight, median) were: β-carotene (39.5), lycopene (20), lutein (17.5), phytoene (11.4), zeaxanthin (6.3), β-cryptoxanthin (4.5), phytofluene (2.9). α-carotene (5.3) and violaxanthin were found 75.5% and 7.1% of the faeces. The carotenoids found in the highest concentrations corresponded to the ones consumed in the greatest amounts (µg/d): lycopene (13,146), phytoene (2697), β-carotene (1812), lutein+zeaxanthin (1148). Carotenoid concentration in faeces and in dietary intake showed correlation for the total non-provitamin A carotenoids (r = 0.302; p = 0.003), phytoene (r = 0.339; p = 0.001), phytofluene (r = 0.279; p = 0.005), lycopene (0.223; p = 0.027), lutein+zeaxanthin (r = 0.291; p = 0.04) and β-cryptoxanthin (r = 0.323; p = 0.001). A high proportion of dietary carotenoids, especially those with provitamin A activity and some of their isomers, reach the large intestine, suggesting a low bioavailability of their intact forms.

Effect of Natural Food Antioxidants against LDL and DNA Oxidative Changes

Radical oxygen species formed in human tissue cells by many endogenous and exogenous pathways cause extensive oxidative damage which has been linked to various human diseases. This review paper provides an overview of lipid peroxidation and focuses on the free radicals-initiated processes of low-density lipoprotein (LDL) oxidative modification and DNA oxidative damage, which are widely associated with the initiation and development of atherosclerosis and carcinogenesis, respectively. The article subsequently provides an overview of the recent human trials or even in vitro investigations on the potential of natural antioxidant compounds (such as carotenoids; vitamins C and E) to monitor LDL and DNA oxidative changes.

A Review of the Structure, Biosynthesis, Absorption of Carotenoids-Analysis and Properties of their Common Natural Extracts

Carotenoids are a class of natural pigments familiar to all through the orange-red colours of popular foods like oranges, tomatoes and carrots and the yellow colour of many flowers. They have been studied for a number of years because of their diverse roles in photobiology, photochemistry and photo medicine. Carotenoids are also added as colorants to many manufactured foods, drinks, and animal feeds, either in the forms of natural extracts (e.g annatto, paprika or marigold extracts) or as pure compounds manufactured by chemical synthesis. Carotenoids are often described as provitamins A, as this particular vitamin is a product of carotenoid metabolism. The distribution of carotenoids among the different plant groups shows no obvious pattern. b-Carotene is the most abundant in leafy vegetables, though the colour is masked by its co-existence with chlorophyll, and this carotenoid has the highest vitamin A activity. Zeaxanthin, a-carotene and antheraxanthin are also present in small amounts. In the tomato, lycopene is the major carotenoid, while fruits contain varying proportions of cryptoxanthin, lutein and antheraxanthin. In this review paper the natural occurrence of carotenoids (with focus on certain natural extracts) is described along with its structure and physicochemical properties. The biosynthesis - industrial synthesis and absorption of carotenoids is also discussed. Finally, a brief overview of analysis and properties of commonly available natural carotenoid extracts (annato, paprika, xanthophylls, lycopene) are also reported.