Correction: Ghani et al. Multi-Dimensional Antioxidant Screening of Selected Australian Native Plants and Putative Annotation of Active Compounds. Molecules 2023, 28, 3106.

In the original publication [...].

Multi-Dimensional Antioxidant Screening of Selected Australian Native Plants and Putative Annotation of Active Compounds.

Acacia implexa, Eucalyptus rossii and Exocarpos cupressiformis 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 A. implexa bark and leaves, E. rossii leaves and E. cupressiformis leaves, and partitioned via sequential extraction with n-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 n-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 n-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.

Differentiation of wood-derived vanillin from synthetic vanillin in distillates using gas chromatography/combustion/isotope ratio mass spectrometry for δ13 C analysis.

RATIONALE: Typical storage in oak barrels releases in distillates different degradation products such as vanillin, which play an important role in flavour and aroma. The addition of vanillin, as well as other aroma compounds, of different origin is prohibited by European laws. As vanillin samples from different sources have different δ13 C values, the δ13 C value could be used to determine whether the vanillin is authentic (lignin-derived), or if it has been added from another source (e.g. synthetic). METHODS: The δ13 C values for vanillin derived from different sources, including natural, synthetic and tannins, were measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), after diethyl ether addition and/or ethanol dilution. A method for analysing vanillin in distillates after dichloromethane extraction was developed. Tests were undertaken to prove the reliability, reproducibility and accuracy of the method with standards and samples. Distillate samples were run to measure the δ13 C values of vanillin and to compare them with values for other sources of vanillin. RESULTS: δ13 C values were determined for: natural vanillin extracts (-21.0 to -19.3‰, 16 samples); vanillin ex-lignin (-28.2‰, 1 sample); and synthetic vanillin (-32.6 to -29.3‰, 7 samples). Seventeen tannin samples were found to have δ13 C values of -29.5 to -26.7‰, which were significantly different (p < 0.05) from those of the natural and synthetic vanillins. The vanillin δ13 C values measured in distillates (-28.9 to -25.7‰) were mainly in the tannin range, although one spirit (-32.5‰) was found to contain synthetic vanillin. CONCLUSIONS: The results show that synthetic vanillin added to a distillate could be differentiated from vanillin derived from oak barrels by their respective δ13 C values. The GC/C/IRMS method could be a useful tool in the determination of adulteration of distillates.

Eucalyptus saponin- and sophorolipid-mediated desorption of polycyclic aromatic hydrocarbons from contaminated soil and sediment.

The potential for biosurfactant-mediated desorption of polyaromatic hydrocarbons (PAHs) was evaluated using PAH-spiked soil and sediment. PAH desorption behaviors and toxicity of novel saponin biosurfactant extracted from Eucalyptus camaldulensis leaves and sophoro-lipid biosurfactant were investigated. Their PAH desorption efficiencies were compared with rhamnolipid biosurfactant and the industrial-chemical surfactant, Tween 20. Based on the emulsification indices, the salt tolerance of surfactants up to 30 g/L NaCl followed the order of saponin > Tween 20 > sophorolipid > rhamnolipid, while the thermal stability over the range of 15 to 50 °C was in the order of sophorolipid > rhamnolipid > saponin > Tween 20. The saponin biosurfactant emulsion demonstrated the highest stability under a wide range of acidic to basic pHs. PAH extraction percentages of saponin and sophorolipid under the optimized surfactant concentration, volume, and incubation time were 30-50% and 30-70%, respectively. PAH desorption capacities of saponin and sophorolipid were comparable to that of rhamnolipid and Tween 20 for all matrices. Sophorolipid more efficiently desorbed low molecular weight PAHs in soil and sediment compared to the other three surfactants. Microbial respiration was used to determine biosurfactant toxicity to the soil/sediment microbiome and indicated no inhibition of respiration during 60 days of incubation, suggesting that sophorolipid- and saponin-mediated remediation may be sustainable approaches to remove PAHs from contaminated soils and sediments.

Optimization and Comparison of Microwave-Assisted Extraction, Supercritical Fluid Extraction, and Eucalyptus Oil-Assisted Extraction of Polycyclic Aromatic Hydrocarbons from Soil and Sediment.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic compounds of major concern that mainly accumulate in soils and sediments, and their extraction from environmental matrices remains a crucial step when determining the extent of contamination in soils and sediments. The objective of the present study was to compare the extraction of PAHs (phenanthrene, pyrene, chrysene, and benzo[a]pyrene) from spiked soil and sediment using supercritical fluid extraction (SFE) with ethanol as the modifier, microwave-assisted extraction (MAE), and eucalyptus oil-assisted extraction (EuAE). Recoveries of PAHs were comparable between the three methods, and >80% of applied pyrene, chrysene and benzo[a]pyrene were recovered. The most efficient method of extracting PAHs from naturally incurred soils with different levels of contamination was SFE. A longer extraction time was required for the EuAE method compared with SFE and MAE under optimized conditions. However, EuAE required lower extraction temperatures (15-20 °C) compared with SFE (80 °C) and MAE (110-120 °C), and consumed less solvent than SFE and MAE. Compared with hexane/acetone used in MAE, the use of ethanol in SFE and eucalyptus oil in EuAE can be considered as more sustainable approaches to efficiently extract PAHs from spiked/naturally contaminated soils and sediments. And, although less efficient for matrices containing higher carbon content, EuAE offered a cheap, low-tech approach to extracting PAHs. Environ Toxicol Chem 2023;42:982-994. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Polycyclic aromatic hydrocarbon contamination in soils and sediments: Sustainable approaches for extraction and remediation.

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.

Suppression of reductive characters in white wine by Cu fractions: Efficiency and duration of protection during bottle aging.

Cu in wine can suppress sulfidic-odours, but the active forms and duration of protection are uncertain. Additions of 0, 0.3 or 0.6 mg/L Cu(II) were made to Chardonnay and Pinot Grigio at bottling. Throughout a 12- or 14-month storage period, Cu fractions were determined by colorimetry, and sulfhydryl compounds by gas chromatography with sulfur chemiluminescence detection. After Cu(II) addition, the dominant Cu fractions were associated with Cu(II)-organic acids (fraction I) and Cu(I)-thiol complexes (fraction II), and over 8-months their concentrations gradually fell below 0.015 mg/L. During this time, a fraction of Cu, predominantly attributed to sulfide-bound Cu, increased in concentration. Suppression of free hydrogen sulfide was assured when the combined Cu fractions I and II concentrations were above 0.015 mg/L, while free methanethiol suppression required Cu fraction I concentration above 0.035 mg/L. Decay rates for Cu fractions demonstrated that the duration that Cu can actively suppress sulfidic odours is wine-dependent.

Ascorbic acid: a review of its chemistry and reactivity in relation to a wine environment.

Extensive reviews of research are available on the use of ascorbic acid, and its consequent degradation pathways, in physiological conditions or food matrices. However, very little information can be found for wine-related systems. This review highlights the relevant chemistry and reactivity of ascorbic acid with a focus on its behavior and potential behavior in a wine environment. The review describes the use of ascorbic acid as a complementary antioxidant preservative to sulfur dioxide along with the metal-catalyzed and radical-dependent manner by which it achieves this role. The relevant degradation products of ascorbic acid in aerobic and anaerobic conditions are presented as well as the interaction of these degradation products with sulfur dioxide and other wine-relevant sulfur compounds. Limitations in existing knowledge, especially regarding the crossover between the antioxidant and pro-oxidant roles of ascorbic acid, are identified.

Should Red Wine Be Considered a Functional Food?

Functional foods may be regarded as foods that have nutritional value, but in particular, they also have beneficial effects on one or more body functions. Thus, functional foods may improve health and/or reduce the risk of developing certain diseases when taken in amounts that can be consumed in a normal diet. Based on nearly 2 decades of research since the term "French paradox" was first coined in 1992, wine would appear to fit this definition. Yet there seems to be reluctance to consider wine as a functional food. In this review, we present an overview of the accumulated evidence for the health benefits of wine-and its key phenolic components such as resveratrol, quercetin, catechin-and show that these alone are not enough to firmly establish wine as a functional food. What is required is to create clearly defined products based on wine that are targeted to consumers' needs and expectations when it comes to purchasing functional foods. Moreover, the crucial question of alcohol and health also needs to be addressed by the functional food industry. Suggestions are presented for working through this issue, but in many regards, wine is like any other food-it should be consumed sensibly and in amounts that are beneficial to health. Overindulgence of any kind does not promote good health.

Potential Role of Phenolic Extracts of Mentha in Managing Oxidative Stress and Alzheimer's Disease.

With an increase in the longevity and thus the proportion of the elderly, especially in developed nations, there is a rise in pathological conditions that accompany ageing, such as neurodegenerative disorders. Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive and memory decline. The pathophysiology of the disease is poorly understood, with several factors contributing to its development, such as oxidative stress, neuroinflammation, cholinergic neuronal apoptotic death, and the accumulation of abnormal proteins in the brain. Current medications are only palliative and cannot stop or reverse the progression of the disease. Recent clinical trials of synthetic compounds for the treatment of AD have failed because of their adverse effects or lack of efficacy. Thus, there is impetus behind the search for drugs from natural origins, in addition to the discovery of novel, conventional therapeutics. Mints have been used traditionally for conditions relevant to the central nervous system. Recent studies showed that mint extracts and/or their phenolic constituents have a neuroprotective potential and can target multiple events of AD. In this review, we provide evidence of the potential role of mint extracts and their derivatives as possible sources of treatments in managing AD. Some of the molecular pathways implicated in the development of AD are reviewed, with focus on apoptosis and some redox pathways, pointing to mechanisms that may be modulated for the treatment of AD, and the need for future research invoking knowledge of these pathways is highlighted.

Bulk and compound-specific stable isotope ratio analysis for authenticity testing of organically grown tomatoes.

Until now, there has been a lack of analytical methods that can reliably verify the authenticity of organically grown plants and derived organic food products. In this study, stable isotope ratio analysis of hydrogen (H, δ2H), carbon (C, δ13C), nitrogen (N, δ15N), oxygen (O, δ18O) and sulfur (S, δ34S) was conducted along the tomato passata production process using organic and conventionally grown tomatoes from two Italian regions over two years. A gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) based method was developed and applied for analysis of C and N isotope ratios in amino acids derived from tomatoes. Of the bulk isotope ratios, δ15N was the most significant parameter for discriminating organic from conventional products. The classification power was improved significantly by compound-specific isotope analysis regardless of the production years and regions. We conclude that isotope analysis of amino acids is a novel analytical tool for complementing existing certification and control procedures in the organic tomato sector.

Neuroprotective Activity of Mentha Species on Hydrogen Peroxide-Induced Apoptosis in SH-SY5Y Cells.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with an unclear cause. It appears that multiple factors participate in the process of neuronal damage including oxidative stress and accumulation of the protein amyloid ß (Aß) in the brain. The search for a treatment for this disorder is essential as current medications are limited to alleviating symptoms and palliative effects. The aim of this study is to investigate the effects of mint extracts on selected mechanisms implicated in the development of AD. To enable a thorough investigation of mechanisms, including effects on ß-secretase (the enzyme that leads to the formation of Aß), on Aß aggregation, and on oxidative stress and apoptosis pathways, a neuronal cell model, SH-SY5Y cells, was selected. Six Mentha taxa were investigated for their in vitro ß-secretase (BACE) and Aß-aggregation inhibition activities. Moreover, their neuroprotective effects on H2O2-induced oxidative stress and apoptosis in SH-SY5Y cells were evaluated through caspase activity. Real-time PCR and Western blot analysis were carried out for the two most promising extracts to determine their effects on signalling pathways in SH-SY5Y cells. All mint extracts had strong BACE inhibition activity. M. requienii extracts showed excellent inhibition of Aß-aggregation, while other extracts showed moderate inhibition. M. diemenica and M. requienii extracts lowered caspase activity. Exposure of SH-SY5Y cells to M. diemenica extracts resulted in a decrease in the expression of pro-apoptotic protein, Bax, and an elevation in the anti-apoptotic protein, Bcl-xL, potentially mediated by down-regulation of the ASK1-JNK pathway. These results indicate that mint extracts could prevent the formation of Aß and also could prevent their aggregation if they had already formed. M. diemenica and M. requienii extracts have potential to suppress apoptosis at the cellular level. Hence, mint extracts could provide a source of efficacious compounds for a therapeutic approach for AD.

Chemistry and bioactivity of olive biophenols in some antioxidant and antiproliferative in vitro bioassays.

The major biophenols in olives and the crude extract and ethyl acetate fraction from olive mill waste were studied for their ability to counteract different stages of oxidative damage, that is, hydrogen peroxide, superoxide radical (SOR), and hydroxyl radical in vitro. Antiproliferative activity on colon cancer (HT-29) and gastric cancer (AGS) cell lines was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide bioassay. Emphasis was given to how the observed in vitro activity is controlled by the structural feature of biophenols and possible synergism and antagonism. While in some bioassays, for example, 2,2'-diphenyl-1-picrylhydrazyl, the nonphenolic moiety had minimal affect, it had a significant role in the SOR scavenging bioassay. Verbascoside was more active than caffeic acid or hydroxytyrosol evaluated individually or in equimolar mixtures in some bioassays. Mixtures of biophenols were more active than individual biophenols as antiproliferative agents. Overall, the mixture of hydroxytyrosol/caffeic acid and the biophenol extracts were more effective in protecting DNA from oxidative damage and inhibiting the growth of cancer cells.

Zero effect of multiple dosage of olive leaf supplements on urinary biomarkers of oxidative stress in healthy humans.

OBJECTIVE: We determined the effect of dietary supplementation with an olive leaf capsule or liquid extract on oxidative status of young and healthy male and female subjects. METHODS: This was a single-center, randomized, single-blinded, prospective pilot comparison of the effect of dietary supplementation with olive leaf extracts. Healthy young adult male and female subjects (n = 45) were randomized into three groups and received daily doses of control, capsule, or liquid extract of olive leaf. Urinary F(2 alpha)-isoprostane, 8-hydroxy-2'-deoxyguanosine, and Folin-Ciocalteu total reducing power were measured to assess the impact of supplementation. RESULTS: Baseline values (mean +/- standard deviation) of the biomarkers were 0.24 +/- 0.13 microg, 9.16 +/- 2.94 microg, and 424.9 +/- 121.4 mg of gallic acid equivalents per gram of creatinine, respectively, for the control group. Using these markers, supplementation with liquid or capsule did not alter oxidative status compared with the control group. Possible reasons for the lack of an observed correlation are presented. CONCLUSION: Dietary supplementation with olive leaf extract did not alter the oxidative status of healthy young adults.

Different Processing Practices and the Frying Life of Refined Canola Oil.

Refined expeller-pressed (RCanO-I and RCanO-II) and expeller-pressed and solvent-extracted blended (RCanO-III and RCanO-IV) canola oils were compared to determine the effect of processing (extraction) practice on the frying life of canola oil. Samples were from the 2016/2017 and 2017/2018 production seasons and were used to fry potato chips for 36 to 48 cycles. Frying life was assessed by the total polar compounds, retention of tocopherols, antioxidant activity, and other quality indices. RCanO-II exhibited significantly, the longest frying life as compared with the other three oils and this correlated with tocopherol retention and antioxidant activity (p < 0.05). The extraction practice influenced the frying life of canola oil, but this was dependent on other processing practices employed by the individual processors. Variations in initial oil quality dictated the rates of chemical reactions occurring in the oils during frying and influenced oil stability.

Development of a Method Suitable for High-Throughput Screening to Measure Antioxidant Activity in a Linoleic Acid Emulsion.

An improved system for measuring antioxidant activity via thiobarbituric acid reactive substances and ferric thiocyanate assays is reported, on the basis of oxidation of a linoleic acid (LA) emulsion. Oxidation times were reduced from 20 h to 5 h by increasing the reaction temperature from 37 °C to 50 °C and with an acceptable precision of <10% coefficient of variation (CV). Antioxidants varying in polarity and chemical class-250 µM Trolox, quercetin, ascorbic acid and gallic acid-were used for method optimisation. Further reductions in reaction time were investigated through the addition of catalysts, oxygen initiators or increasing temperature to 60 °C; however, antioxidant activity varied from that established at 37 °C and 20 h reaction time-the method validation conditions. Further validation of the method was achieved with catechin, epicatechin, caffeic acid and α-tocopherol, with results at 50 °C and 5 h comparable to those at 37 °C and 20 h. The improved assay has the potential to rapidly screen antioxidants of various polarities, thus making it useful in studies where large numbers of plant extracts require testing. Furthermore, as this assay involves protection of a lipid, the assay is likely to provide complementary information to well-established tests, such as the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.

Effect of processing conditions, prestorage treatment, and storage conditions on the phenol content and antioxidant activity of olive mill waste.

The impact of two- and three-phase processing systems and malaxation conditions on phenol content (both total and individual phenols) and antioxidant capacity of laboratory-generated olive mill waste (OMW) was assessed. Two-phase olive processing generated a waste with higher phenol content and antioxidant capacity. Using the two-phase system, both malaxation time and temperature affected the phenol content and antioxidant capacity. The effects of different prestorage drying treatments on phenol content and antioxidant capacity were also compared. Air drying and drying at 60 degrees C resulted in a substantial decrease in the phenol content and antioxidant capacity. Drying at 105 degrees C and freeze-drying produced less degradation. The phenol content and antioxidant capacity of OMW stored at 4 degrees C and of OMW preserved by 40% w/w ethanol and 1% w/w acetic acid and stored at 4 degrees C were monitored for 30 days and compared with those of OMW stored at room temperature. None of these storage conditions could prevent the rapid decrease in phenolic concentrations and antioxidant capacity, which happened within the first 24 h.

Changes in virgin olive oil quality during low-temperature fruit storage.

'Frantoio' olive fruits were stored at low temperature (4 +/- 2 degrees C) for 3 weeks to investigate the effect of postharvest fruit storage on virgin olive oil quality. Volatile compounds and phenolic compounds explained the changes in sensory quality that could not be explained with quality indices (FFA, PV, K232, and K270). Increases in concentrations of ( E)-2-hexenal and hexanal corresponded to positive sensory quality, whereas increases in ( E)-2-hexenol and (+)-acetoxypinoresinol were associated with negative sensory quality. Volatile and phenolic compounds were also indicative of the period of low-temperature fruit storage. Oleuropein and ligstroside derivatives in olive oil decreased with respect to storage time, and their significant ( p < 0.05) change corresponded to changes in bitterness and pungency. ( Z)-2-Penten-1-ol increased during low-temperature fruit storage, whereas 2-pentylfuran decreased. Changes in volatile compounds, phenolic compounds, quality indices, and sensory notes indicated that virgin olive oil quality was lost within the first week of low-temperature fruit storage and regained at 2 weeks. This research suggests that low-temperature olive fruit storage may be beneficial, with a possibility of increasing oil yield and moderating the sensory quality of virgin olive oils. This study demonstrates that deeper insights into virgin olive oil quality changes during low-temperature fruit storage may be gained by studying volatile and phenolic compounds in addition to quality indices and physical appearance of the fruit.

Nutritional methodologies and their use in inter-disciplinary antioxidant research.

There has been a significant increase in the volume of research relating to antioxidants and health. The very nature of this research is inter-disciplinary, yet the full potential of such an approach, whereby nutritionists (clinicians), chemists, pharmacists and others all bring their expertise to bear in a concerted way, is rarely achieved. This is perhaps due to a lack of understanding of the methodology and terminology of the various disciplines. In this review, the terminology and features of nutritional studies are examined with particular emphasis on the confounders that may often be ignored by laboratory-based researchers. Attention is drawn to the potential role that ethics approval processes may have in directing outcomes.

Isolation and seasonal effects on characteristics of fulvic acid isolated from an Australian floodplain river and billabong.

Fulvic acids from an Australian floodplain river and billabong were isolated using DEAE and DAX-8 resins, and characterised with the use of size exclusion chromatography and solid-state CP-MAS (13)C NMR spectroscopy. Differences between the two resin isolates were evident. Fulvic acids isolated using DEAE-cellulose had higher apparent M(n) and M(w) values, while the DAX-8 resin showed a slight preference for aliphatic components. Fulvic acids from the river and billabong had the same functional groups present, however, the river fulvic acids had higher apparent M(n) (number average molecular weight) and M(w) values (weight average molecular weight), and were more polydisperse than the billabong fulvic acid. There were no significant changes in the characteristics of the fulvic acid isolated from the river at four sampling times: summer, autumn, winter and spring. In contrast, fulvic acids isolated from a billabong displayed seasonal variation in molecular weights. This work emphasizes the importance in ecological studies of isolation procedure for the operationally defined fulvic acids.