•First review exclusively on the TBARS assay to measure antioxidant activity.•Literature surveyed on the TBARS test in food and physiological systems.•Methodology of the TBARS assay critically ...reviewed.•Steps needed to enhance use of the TBARS assay in screening studies outlined.
The thiobarbituric acid reactive substances (TBARS) assay is widely used to measure lipid oxidation and antioxidant activity in food and physiological systems. However, there has been no review (to our knowledge) that focuses exclusively on this test. This review presents an overview of the current use of the TBARS test in food and physiological systems, before looking at the various ways in which the assay is used in studies on antioxidant activity. As an antioxidant assay, the TBARS test may lack acceptable reproducibility, and long reaction times may preclude its adoption as a rapid screening method. Despite these potential limitations, there are features of the TBARS test that make it useful as a complement to popular screening tests such as Trolox equivalent antioxidant capacity. This review concludes with proposals for development of the TBARS test so that it can be used as a rapid and robust antioxidant assay.
Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic environmental pollutants that are extremely hydrophobic in nature and resistant to biological degradation. Extraction of PAHs from ...environmental matrices is the first and most crucial step in PAH quantification. Extraction followed by quantification is essential to understand the extent of contamination prior to the application of remediation approaches. Due to their non-polar structures, PAHs can be adsorbed tightly to the organic matter in soils and sediments, making them more difficult to be extracted. Extraction of PAHs can be achieved by a variety of methods. Techniques such as supercritical and subcritical fluid extraction, microwave-assisted solvent extraction, plant oil-assisted extraction and some microextraction techniques provide faster PAH extraction using less organic solvents, while providing a more environmentally friendly and safer process with minimum matrix interferences. More recently, more environmentally friendly methods for soil and sediment remediation have been explored. This often involves using natural chemicals, such as biosurfactants, to solubilize PAHs in contaminated soils and sediments to allow subsequent microbial degradation. Vermiremediation and microbial enzyme-mediated remediation are emerging approaches, which require further development. The following summarises the existing literature on traditional PAH extraction and bioremediation methods and contrasts them to newer, more environmentally friendly ways.
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•The fate of PAHs in contaminated soils and sediments was summarized.•Greener methods of PAH extraction for quantitative analysis were reviewed.•Sustainable approaches to remediate PAH contaminated soils/sediments were discussed.•Biosurfactant-mediated remediation efficiency and toxicity needs further research.
Biophenols have attracted increasing attention during the past few years due to their biological activities and natural abundance and are potential targets for the food and pharmaceutical industries. ...Olive mill waste (OMW) is rich in biophenols and typically contains 98% of the total phenols in the olive fruit, making value addition to OMW an attractive enterprise. The phenolic profile of OMW is complex, yet this complexity has not been fully exploited in the valorization of the waste. Most work on the bioactivity of OMW has focused on antioxidant and antimicrobial activities. The analytical techniques used to identify and quantify active biophenols are also reviewed.
and
are native plants of Australia, which were used by the First Peoples for medicinal purposes. In this study, 70% aqueous ethanol crude extracts were prepared from
bark and leaves,
leaves and
...leaves, and partitioned via sequential extraction with
-hexane, dichloromethane (DCM), ethyl acetate and ethanol. The crude extracts and fractions were screened for antioxidant activity using a novel, high-throughput lipid-based antioxidant assay, as well as the aqueous ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay and the Folin-Ciocalteu test for total phenols. In the lipid-based assay, non-polar
-hexane and DCM fractions showed higher antioxidant activity against the formation of peroxides and thiobarbituric acid reactive substances (TBARS) than the other fractions, whereas the non-polar fractions were not effective in aqueous assays. This illustrates that the high potential of the lipid-soluble
-hexane and DCM fractions as antioxidants would have been missed if only aqueous-based assays were used. In addition, the potent antioxidant compounds were putatively annotated using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-qTOF-MS). Gallic acid, (+)-catechin, (-)-epicatechin and tannins were found in most crude extracts.
Dissolved organic carbon (DOC) in aquatic environments represents one of the largest active organic carbon reservoirs in the biosphere. Current ideologies concerning the sources of DOC, how it is ...formed and utilized, and what determines the quality of DOC are examined. Humic substances can comprise a significant fraction of the DOC and developments in methods of analysis including the isolation and characterization of this fraction are reviewed.
The phenolic component of freeze-dried olive fruit was fractionated by high-performance liquid chromatography using ultraviolet, atmospheric pressure chemical ionisation (APCI) and electrospray ...ionisation (ESI) detection. The fractions together with several standards were tested for antioxidant activity in an aqueous and a lipid system. The negative ion mode of APCI and ESI showed less fragmentation than positive ion mode. The latter was generally more useful in obtaining fragmentation data and hence structural information. Some olive phenolics notably tyrosol exhibited a low ionisation efficiency in both APCI and ESI. There was no simple relationship between antioxidant activity and chemical structure. The ranking of antioxidant activity was strongly dependent on both the test system and on the substrate demonstrating the need to examine activity in both aqueous and lipid systems. Significant antioxidant activity was seen in most olive fractions and this was related to phenolic content. The kinetics of the oxidation process are complex and suggest that multiple pathways may be involved at different antioxidant concentrations.
•New method developed for simultaneous analysis of bioactives in canola oil.•Normal phase LC method suited to a non-polar sample matrix.•APCI-MS/MS offers enhanced selectivity over previous ...methods.•Minimal sample preparation and a short run time of 22min.•Individual free and bound sterols quantified, without need for saponification.
A normal phase high performance liquid chromatography (HPLC) method was developed to simultaneously quantify several prominent bioactive compounds in canola oil vis. α-tocopherol, γ-tocopherol, δ-tocopherol, β-carotene, lutein, β-sitosterol, campesterol and brassicasterol. The use of sequential diode array detection (DAD) and tandem mass spectrometry (MS/MS) allowed direct injection of oils, diluted in hexane without derivatisation or saponification, greatly reducing sample preparation time, and permitting the quantification of both free sterols and intact sterol esters. Further advantages over existing methods included increased analytical selectivity, and a chromatographic run time substantially less than other reported normal phase methods. The HPLC–DAD-MS/MS method was applied to freshly extracted canola oil samples as well as commercially available canola, palm fruit, sunflower and olive oils.
Phenolic compounds occur in all fruits as a diverse group of secondary metabolites. Hence, they are a component of the human diet although data for dietary intakes and metabolic fate are limited. ...Their role in oxidation processes, as either antioxidants or substrates in browning reactions, is examined. They are characterised by high chemical reactivity and this complicates their analysis.
