Primary Oxidation Research Articles

The combined effect of pulsed electric field treatment and brine salting on changes in the oxidative stability of lipids and proteins and color characteristics of sea bass (Dicentrarchus labrax)

A combined effect of pulsed electric field application and salting in a brine with 5 and 10% w/w NaCl on oxidative stability of lipids and proteins, as well as color characteristics of sea bass samples, was assessed in the study. The applied intensity of the current was set at 10 and 20 A corresponding to 300 and 600 V cm−1, respectively. Pulsed electric field (PEF) treatment led to a significant (p < 0.05) increase in primary and secondary lipid oxidation products expressed as peroxide value, conjugated dienes and 2-thiobarbituric acid reactive substances in PEF-treated samples compared to untreated ones. Conjugated dienes, as unstable primary oxidation products, correlated with b∗-value (p < 0.05, R = 0.789), suggesting their contribution to the yellowness of the fish flesh due to fast decomposition and conversion into secondary oxidation products yielding yellow pigmentation.However, none of the fish samples treated at the higher current intensity of 20 A exceeded the acceptable level of 5 meq active oxygen/kg lipid according to the requirements of the Standard for fish oils CODEX STAN 329–2017, suggesting acceptable oxidative status quality of sea bass samples after the treatment. PEF-treated fish samples also showed a significant increase in Schiff bases and total carbonyls on day 5 and day 8 of brine salting compared to non-treated samples, revealing a strong effect of electroporation on protein oxidation.

Pharmacokinetics of primary oxidative metabolites of thalidomide in rats and in chimeric mice humanized with different human hepatocytes

The approved drug thalidomide is teratogenic in humans, nonhuman primates, and rabbits but not in rodents. The extensive biotransformation of 5'-hydroxythalidomide after oral administration of thalidomide (250 mg/kg) in rats was investigated in detail using liquid chromatography-tandem mass spectrometry. Probable metabolites 5'-hydroxythalidomide sulfate and glucuronide were extensively formed, with approximately tenfold and onefold peak areas, respectively, to the primary 5'-hydroxythalidomide measured using authentic standards. As a minor metabolite, 5-hydroxythalidomide was also detected. The output of simplified physiologically based pharmacokinetic rat models was consistent with the observed in vivo data under a metabolic ratio of 0.05 for the hepatic intrinsic clearance of thalidomide to unconjugated 5'-hydroxythalidomide. The aggregate of unconjugated and sulfate/glucuronide conjugated 5'-hydroxythalidomide forms appear to be the predominant metabolites in rats. Two hours after oral administration of thalidomide (100 mg/kg) to chimeric mice humanized with four different batches of genotyped human hepatocytes, the plasma concentration ratios of 5-hydroxythalidomide to 5'-hydroxythalidomide were correlated with replacement indexes of human liver cells previously transplanted in immunodeficient mice. These results indicate that rodent livers mediate thalidomide primary oxidation, leading to extensive deactivation in vivo to unconjugated/conjugated 5'-hydroxythalidomide and suggest that thalidomide activation might be dependent on the humanized livers in mice transplanted with human hepatocytes.

Aerobic primary and secondary amine oxidation cascade by a copper amine oxidase inspired catalyst

A CAO inspired catalyst catalyzed the cascade aerobic oxidation of primary and secondary amines for the synthesis of quinazolin-4(3H)-one core in high yields. Like the natural CAOs, a copper ion improves the o-quinone cofactor's catalytic activity.

Light protection performance of wrapping films to prevent the photo-oxidation of extra virgin olive oil during storage in glass bottles

&lt;abstract&gt; &lt;p&gt;Packaging material plays an important role in minimizing food waste in the supply chain. This study evaluated the light-protective effects of wrapping films as a secondary packaging material on the deterioration of extra virgin olive oil after exposure to sunlight for 5 weeks. Milky white polyethylene terephthalate (MW-PET) and aluminum oxide vapor-deposited polyethylene terephthalate (AV-PET) were used on bottles of different transparency (clear or amber glass) as the primary packaging material. Wrapping the bottles with either PET film resulted in protection against fatty acid release and secondary oxidation of the oils upon exposure to sunlight, but no protection against the primary oxidation of the oils. Although sunlight exposure induced the degradation of minor components, including chlorophyll and carotenoid pigments, in oils stored in clear glass bottles with no film, in oils stored in clear and amber glass bottles with either type of PET film, these compounds were partially protected from degradation during storage. In addition, sunlight exposure induced a decrease in E2-hexenal, which has a positive olive aroma in oils stored in clear glass bottles with no film, but this decrease was not observed to the same extent in oils stored in clear and amber glass bottles with either PET film. The light-protective effects of the AV-PET film were significantly higher than those of the MW-PET film. These results showed that secondary packaging with these PET films provided more effective protection against sunlight-induced oxidative deterioration of extra virgin olive oil during storage in primary materials, such as glass bottles, compared with storage in glass bottles with no secondary packaging.&lt;/p&gt; &lt;/abstract&gt;

The use of dietary chromium associated with vitamins and minerals (synthetic and natural source) to improve some quality aspects of broiler thigh meat reared under heat stress condition

The effect of chromium associated with vitamins and minerals (synthetic or natural ingredients) on broiler meat nutritional quality, subjected to heat stress conditions were evaluated. The 6-week feeding trial was conducted on 120 unsexed 1-day-old Cobb 500 broilers, assigned to 4 treatments and housed in digestibility cages at 32 °C constant temperature. Compared to the control diet (C), the experimental diets were supplemented with 200 µg/kg diet chromium picolinate (Cr), as follows: Cr-AA has 0.25 g ascorbic acid/kg diet; Cr-Zn has 0.025 g zinc/kg diet; Cr-WS has 10 g creeping wood sorrel/kg diet. The results of the study showed that essential amino acids concentrations determined in the thigh meat samples tend to increase in groups supplemented with chromium and ascorbic acid and chromium and zinc, especially sulphur containing amino acids (methionine and cystine) which increased for experimental groups (methionine: 1.25% (C) vs. 1.77% (Cr-AA); 1.58% (Cr-Zn); 1.64% (Cr-WS) and cystine: 0.46% (C) vs. 0.52% (Cr-AA); 0.54% (Cr-WS)). Among the compounds with biological value, vitamin E and lutein & zeaxanthin concentration registered the highest increase for chromium and zinc supplemented group (vitamin E: 35.49 mg/kg (C) vs. 59.05 mg/kg (Cr-Zn) and lutein & zeaxanthin: 0.66 mg/kg (C) vs. 1.36 mg/kg (Cr-Zn)). The peroxidation process was delayed under nutritional supplements influence, the primary oxidation parameters (peroxide value) from the Cr-WS group being significantly lower compared to the control group. The same trend was maintained for the secondary oxidation parameters, the Cr-WS group highlighting reduced values for p-anisidine and TBARS concentration compared to the C group (p-anisidine: 17.22 (C) vs. 9.29 (Cr-WS) and TBARS: 0.15 mg/kg (C) vs. 0.11 mg/kg (Cr-WS)). In conclusion, sulphur-containing amino acids (methionine and cysteine) concentrations increased for experimental groups, in the thigh meat samples, the liposoluble compounds (vitamin E, lutein & zeaxanthin) concentration registered the highest increase for chromium and zinc supplemented group and the peroxidation process was more pronounced delayed under chromium and wooden sorrel combination.

Pharmacokinetics of primary metabolites 5-hydroxythalidomide and 5'-hydroxythalidomide formed after oral administration of thalidomide in the rabbit, a thalidomide-sensitive species.

The teratogenicity of the chemotherapeutic drug thalidomide is species-specific and affects humans, non-human primates, and rabbits. The primary oxidation of thalidomide in previously investigated rodents predominantly resulted in the formation of deactivated 5'-hydroxythalidomide. In the current study, similar in vivo biotransformations to 5-hydroxythalidomide and 5'-hydroxythalidomide were confirmed by the analysis of blood plasma from male rabbits, a thalidomide-sensitive species, after oral administration of thalidomide (2.0 mg/kg). Similar levels of thalidomide in seminal plasma and in blood plasma were detected using liquid chromatography-tandem mass spectrometry at 4 hr and 7 hr after oral doses in male rabbits. Seminal plasma concentrations of 5-hydroxythalidomide and 5'-hydroxythalidomide were also seen in male rabbits in a roughly similar time-dependent manner to those in the blood plasma after oral doses of thalidomide (2.0 mg/kg). Furthermore, the values generated by a simplified physiologically based pharmacokinetic rabbit model were in agreement with the measured in vivo blood plasma data under metabolic ratios of 0.01 for the hepatic intrinsic clearance of thalidomide to both unconjugated 5-hydroxythalidomide and 5'-hydroxythalidomide. These results suggest that metabolic activation of thalidomide may be dependent on rabbit liver enzymes just it was for cytochrome P450 enzymes in humanized-liver mice; in contrast, rodent livers predominantly mediate biotransformation of thalidomide to 5'-hydroxythalidomide. A developmental toxicity test system with experimental animals that involves intravaginal exposures to the chemotherapeutic drug thalidomide via semen should be considered in the future.

Selective photoelectrocatalytic tuning of benzyl alcohol to benzaldehyde for enhanced hydrogen production

Hydrogen production can be promoted by replacing sluggish oxygen evolution reaction (OER) with a thermodynamically more favorable reaction, the primary oxidation reaction of benzyl alcohol to benzaldehyde. On a Bi2MoO6@TiO2NTA photocathode, the conversion of benzyl alcohol to benzaldehyde is realized with the selectivity of 100 %. This is originated from enhanced adsorption and activation of benzyl alcohol on this photoanode, as confirmed from tested by in situ FTIR techniques. The electrons generated during such a controllable and selective primary oxidation reaction is then utilized as the source for synergistical hydrogen production. The amount of generated hydrogen is then 5.5 times higher than that when OER is used. The efficiency for such hydrogen production is as high as 85 %. The proposed strategy combines solar energy and biomass for the efficient production of the valuable raw material - benzaldehyde as well as green energy source - hydrogen.

Secondary oxidation of crushed coal based on free radicals and active groups

The secondary oxidation of active groups was studied for crushed coals with various particle sizes. Then, free radicals of these crushed coals were comparatively analyzed after primary and secondary oxidation. The secondary oxidation of active structures on the coal surface was studied by combining the theories of free radicals and functional groups. The coal oxidation reactivity was stronger in Particle 5#. Secondary oxidation had a stronger effect on the reactivity of high-rank coal. A relatively stable aliphatic chain structure was formed during the secondary oxidation of low-rank Coal 1#. The aliphatic hydrocarbon structure was relatively active in high-rank Coals 2# and 3#. Primary oxidation can improve the oxidizability of the aliphatic hydrocarbon structure and facilitate its secondary oxidation process. The OH group in Coal 1# possesses stronger oxidation reactivity and was consumed rapidly during secondary oxidation. In contrast, the consumption and generation rate of the OH group tended to reach a balance in Coal 2# and Coal 3#. CO and CO groups in Coal 1# experienced relatively violent secondary oxidation. The two groups in Coal 2# and Coal 3# experienced relatively gentle secondary oxidation.

1H–NMR fingerprinting and supervised pattern recognition to evaluate the stability of virgin olive oil during storage

Metabolomic fingerprinting of virgin olive oil (VOO) by 1H NMR spectroscopy was used to study its stability during storage simulating normal shelf life conditions during its commercialization. A representative set of VOOs covering the full range of possible chemical compositions were exposed to light (500 lux for 12 h/day) at 25 °C for 12 months or stored in the dark at 25 °C, 30 °C and 35 °C for 24 months. Multivariate data analysis of the 1H NMR spectra of the oil samples provided classification models to evaluate VOO freshness and to verify the light exposure of the VOO during storage, as well as regression models to determine VOO storage time and tentatively the best before date of a fresh VOO. These predictive models disclosed the chemical compounds responsible for the compositional changes in VOO due to hydrolytic and oxidative degradation taking place during its storage, and confirmed that light and increasing temperature enhance these processes. The presence of characteristic resonances of hydroperoxides (primary oxidation products) and the decrease of 1H signals assigned to phenolic compounds, mainly secoiridoid derivatives, and other minor compounds such as fatty acids, squalene and native (E)-2-hexenal present in fresh VOO revealed its oxidative degradation. Further, the emergence of low intensity 1H signals of saturated aldehydes meant that the secondary oxidation process has started at a low rate and yield. Moreover, the decrease of the 1H signals of triacylglycerides and sn-1,2-diacylglycerides, and the increase of sn-1,3-diacylglycerides indicated that hydrolytic degradation of VOO and diacylglyceride isomerisation was occurring. 1H NMR fingerprint of VOO together with pattern recognition techniques afford relevant information to assess the quality of VOOs taking into consideration legal, sensory and health-promoting aspects.

In-situ electrochemical generation of permanganate for the treatment of atrazine

A novel process involving the simultaneous electrochemical oxidation and electrosynthesis of permanganate oxidant has been explored for the treatment of the triazine organic herbicide, atrazine. The electrochemical synthesis of permanganate in neutral pH conditions using low concentration manganese (Mn2+), analogous to levels found in some raw groundwater sources, and their subsequent effect on atrazine degradation were studied in bench-scale experiments. Permanganate synthesis was found to be largely unaffected by the operating current density (10, 40 and 80 mA cm−2) during electrolysis, indicating as mass transport controlled process. Under the same operating conditions, hydroxyl radical mediated oxidation was observed to degrade atrazine from an initial concentration of 9.27 µM (2 mg L−1), to 6.22, 4.88 and 2.36 µM after 120 min of electrolysis for 10, 40 and 80 mA cm−2 conditions. When 55 µM (3.0 mg L−1) Mn2+ was added to the water matrix, atrazine degradation increased, yielding final concentrations of 5.80, 3.66 and 2.17 µM, respectively. Atrazine degradation was found to be accurately described by pseudo-first-order reaction kinetics, with and without the enhanced oxidation by permanganate generation, as the concentration of hydroxyl radicals remained constant and comparatively high throughout electrolysis. Finally, the yielded second-order reaction rate constants of electrochemically generated permanganate, and dosed potassium permanganate, with atrazine were 9.79 and 8.35 M−1 s−1, respectively, whereby the latter degradation mechanism was kinetically limited and the former was under mass transfer control due to an extremely low permanganate-atrazine ratio. Finally, four primary oxidation by-products were observed to form in the reactions, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine.

Enhancing the oxidative stability of algal oil powders stabilized by egg yolk granules/lecithin composites

This study reported a powder formulation containing omega-3-rich algal oil emulsions stabilized by egg yolk granules (EYGs)/lecithin composites. The improved physical stability of the algal oil samples due to increasing pH and lecithin addition was beneficial to the oxidative stability through analysis of free radical scavenging activities, metal ion chelating activities, and the release of primary and secondary oxidation products during accelerated storage (12 days, 60 °C). In addition, the effect of three antioxidants, i.e. ascorbic acid (VC), ascorbyl palmitate (AP), and α-tocopherol (VE), on lipid oxidation was investigated. Results showed that antioxidant partitioning at different regions of the emulsion system influenced its ability to prevent oxidation with the effectiveness of AP (at the O/W interface) > VE (in the oil phase) > VC (in the aqueous phase). This study developed a new powder-based emulsion formulation for algal oils with superior oxidative stability as an alternative source of omega-3.

Effect of Cold Plasma on Meat Cholesterol and Lipid Oxidation.

Cold atmospheric plasma (CAP) is a novel non-thermal technology with potential applications in inactivating microorganisms in food products. However, its impact on food quality is not yet fully understood. The aim of this research is to study the impact of in-package plasma technology on the stability of cholesterol and total lipid in four different types of meat (beef, pork, lamb and chicken breast). Additionally, any changes in the primary or secondary lipid oxidation, which is undesirable from a health perspective, is investigated. CAP was not found to have any impact on the cholesterol or lipid content. However, higher peroxide and thiobarbituric acid reactive substances (TBARS) values were found for the treated samples, indicating that plasma can induce the acceleration of primary and secondary lipid oxidation. Finally, color was not affected by the treatment supporting the suitability of the technology for meat products.

Oxidative stability of breast meat from broilers fed diets supplemented with synbiotic and organic acids

Abstract The purpose of this study was to investigate the effect of synbiotic and organic acids on oxidative stability of breast broiler meat. The experiment consists on 120, 2 days old Ross 308 chicks, housed in metabolic cages (6 chicks/cage). A 2 x 2 factorial arrangement was considered with 4 treatments and 5 replicates (30 animals per group). Two different levels of synbiotic (0 and 10 g/kg) and two different levels of organic acids (0 and 1.5 g/kg) were added to the standard diets in order to constitute the four experimental diets. For further analysis, breast meat from 6 animals per group were collected in 42nd experimental day. No significant differences were noticed for any oxidative parameter measured in breast samples except TBARS (significant decreased values for OA supplemented groups), at the end of experiment. After 4 days of refrigeration (4°C), the secondary oxidative products (panisidine, TBARS) were significant smaller for E groups, compared to C. After 7 days of refrigeration (4°C), the OA groups had significant smaller values for primary (CD) and secondary oxidation products. Synbiotic and organic acids supplements presented positive effect on meat quality by increasing oxidative stability of breast meat during storage.

Sensitive Method for the Identification of Potential Sensitizing Impurities in Reaction Mixtures by Fluorescent Nitrobenzoxadiazole-Labeled Glutathione.

Allergic contact dermatitis is a critical issue in the development of new chemicals. Minor impurities with strong skin-sensitizing properties can be generated as byproducts. However, it is very difficult to identify these skin sensitizers in product mixtures. In this study, fluorescent nitrobenzoxadiazole-labeled glutathione (NBD-GSH) was synthesized to identify small amounts of skin sensitizers in reaction mixtures. Twelve known skin sensitizers and three nonsensitizers were reacted with NBD-GSH. Adducts formed only with the skin sensitizers, which allowed for their detection by a fluorescence detector. Liquid chromatography-mass spectrometry (LC-MS) analyses showed that NBD-GSH reacted with the skin sensitizers via its thiol and amino groups. An adduct of NBD-GSH with the strong skin sensitizer 1-chloro-2,4-dinitrobenzene was detected with a limit of detection of 6 × 10-8 mol/L by high-performance liquid chromatography with fluorescence detection. When a reaction mixture from primary alcohol oxidation was incubated with NBD-GSH, a NBD-GSH adduct formed with skin-sensitizing aldehyde impurities and could be specifically detected by LC-MS with fluorescence detection. This method will be useful for detection and identification of small amounts of skin sensitizers in raw materials, intermediates, reaction mixtures, and end products in the chemical industry.

Improving wholegrain product quality by selecting lipid-stable wheat varieties

Lipid oxidation is one of the major quality issues of wholegrain wheat flour and products, despite their rich endogenous antioxidants. Diverse wheat germplasm resources are available for industrial production and breeding selection. Therefore, to improve the stability qualities of wholegrain, it is important to study lipid stability of wheat varieties, together with their endogenous antioxidant contents. In this study, 65 wheat varieties were evaluated for their oxidative stabilities under accelerated conditions. Primary and secondary oxidation products, radical scavenging activities, and tocol contents were analyzed to obtain a comprehensive understanding of lipid oxidation in wholegrain flour. The results showed significant diversity of lipid stability in the wheat varieties, with a 30-fold difference in hexanal content after 19 weeks of storage. Varieties, such as ‘Velocity’ and ‘Arina’, with high stability and high antioxidant contents, are potentially better suited for stable wholegrain products. The findings will benefit consumers with better quality wholegrain products.

Fabrication and characterization of whey protein isolates- lotus seedpod proanthocyanin conjugate: Its potential application in oxidizable emulsions

Emulsified ω-3 polyunsaturated fatty acid have expanding application in different food matrix with improved water solubility while still prone to oxidation. Lotus seedpod proanthocyanidin (LSPC) was grafted to whey protein isolate (WPI) to create nature-derived antioxidant emulsifiers. 1HNMR, SDS-PAGE and multiple spectrometry showed that the structure of protein was changed after grafting. DPPH and FRAP measurements showed that WPI-LSPC conjugate (90.53 ± 1.48% of DPPH scavenging, 691.85 ± 4.54 μg/mL for FRAP assay) possessed a much better antioxidant ability than WPI (17.06 ± 3.34% of DPPH scavenging, 10.43 ± 0.26 μg/mL for FRAP assay). Ultrasonic emulsification and DSC experiments showed that WPI-LSPC conjugate were more effective at forming and stabilizing the flaxseed oil emulsions than pure WPI, with higher thermostability. Likewise, low levels of primary and secondary oxidation products were formed for the conjugate than the pure protein in O/W systems after storage, again suggesting WPI-LSPC could be used as fine antioxidant emulsifiers in oxidizing delivery systems.

NMR and Computational Studies as Analytical and High-Resolution Structural Tool for Complex Hydroperoxides and Diastereomeric Endo-Hydroperoxides of Fatty Acids in Solution-Exemplified by Methyl Linolenate.

A combination of selective 1D Total Correlation Spectroscopy (TOCSY) and 1H-13C Heteronuclear Multiple Bond Correlation (HMBC) NMR techniques has been employed for the identification of methyl linolenate primary oxidation products without the need for laborious isolation of the individual compounds. Complex hydroperoxides and diastereomeric endo-hydroperoxides were identified and quantified. Strongly deshielded C–O–O–H 1H-NMR resonances of diastereomeric endo-hydroperoxides in the region of 8.8 to 9.6 ppm were shown to be due to intramolecular hydrogen bonding interactions of the hydroperoxide proton with an oxygen atom of the five-member endo-peroxide ring. These strongly deshielded resonances were utilized as a new method to derive, for the first time, three-dimensional structures with an assignment of pairs of diastereomers in solution with the combined use of 1H-NMR chemical shifts, Density Functional Theory (DFT), and Our N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) calculations.

Antioxidant properties of blueberry extract in different oleogel systems

The oxidation properties of peanut oil and soybean oil oleogels (POO and SOO), which were used to load acid or alkaline blueberry extracts (AC or AL) and resveratrol (R), were investigated. A chemical method was employed to assess the superimposed or synergistic antioxidant activities of resveratrol. We detected functional group changes in oleogels during the course of oxidation by nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and identified a suitable base oil for AC, AL, and R. R and AC containing 235 mg/kg resveratrol could inhibit primary oxidation products. Soybean oil oleogel with resveratrol (SOOR, 0.001–0.063 mg/100 g) showed the best inhibition rate. Thiobarbituric acid (TBA) values showed that AC, AL, and R were more suitable for inhibiting the secondary oxidation products in POO from 0 to 30 days. Furthermore, we discovered additional esters, alcohols, and conjugated groups of primary oxidation products by analysing the functional group changes in SOO and POO.

Laminar flame structure of ethyl pentanoate at low and atmospheric-pressure: Experimental and kinetic modeling study

Ethyl pentanoate (EPE) or ethyl valerate is considered a surrogate for biodiesel fuels and a potential fuel for spark ignition engines. Knowledge of its combustion chemistry is of great importance for the development of high-performance and environmentally friendly combustion devices fueled with biofuels. In this work, a detailed chemical kinetic mechanism for the combustion of EPE is developed on the basis of a well-validated kinetic model proposed earlier for short ethyl esters up to ethyl propionate (by Sun et al.). The Sun et al. mechanism was augmented with primary oxidation reactions of ethyl butanoate and ethyl pentanoate and specific intermediates involved in these reactions. The proposed kinetic mechanism was validated against the new experimental data reported in this work on the chemical speciation of laminar premixed flames of stoichiometric EPE/O2/Ar mixtures at low (50 Torr) and atmospheric pressures. The mechanism provided a good predictive capability for experimental mole fraction profiles of many flame intermediates. The new mechanism was also shown to predict well literature experimental data on laminar flame speeds of EPE/air mixtures in a range of equivalence ratios and pressures. The reported flame data can be used for validation of kinetic models for ethyl ester-based biofuels.

Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products.

Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome®), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O2 in air-equilibrated aqueous solutions were identified, isolated, and structurally characterized. An HPLC method coupled with diode-array detection (DAD) and mass spectrometry (MS) was developed and validated to monitor the Ech A degradation process and identify the appearing compounds. Five primary oxidation products were detected and their structures were proposed on the basis of high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 7-ethyl-2,2,3,3,5,7,8-heptahydroxy-2,3-dihydro-1,4-naphthoquinone (2), 6-ethyl-5,7,8-trihydroxy-1,2,3,4-tetrahydronaphthalene-1,2,3,4-tetraone (3), 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (4), 2,3,4,5,7-pentahydroxy-6-ethylinden-1-one (5), and 2,2,4,5,7-pentahydroxy-6-ethylindane-1,3-dione (6). Three novel oxidation products were isolated, and NMR and HR-ESI-MS methods were used to establish their structures as 4-ethyl-3,5,6-trihydroxy-2-oxalobenzoic acid (7), 4-ethyl-2-formyl-3,5,6-trihydroxybenzoic acid (8), and 4-ethyl-2,3,5-trihydroxybenzoic acid (9). The known compound 3-ethyl-2,5-dihydroxy-1,4-benzoquinone (10) was isolated along with products 7–9. Compound 7 turned out to be unstable; its anhydro derivative 11 was obtained in two crystal forms, the structure of which was elucidated using X-ray crystallography as 7-ethyl-5,6-dihydroxy-2,3-dioxo-2,3-dihydrobenzofuran-4-carboxylic acid and named echinolactone. The chemical mechanism of Ech A oxidative degradation is proposed. The in silico toxicity of Ech A and its degradation products 2 and 7–10 were predicted using the ProTox-II webserver. The predicted median lethal dose (LD50) value for product 2 was 221 mg/kg, and, for products 7–10, it appeared to be much lower (≥2000 mg/kg). For Ech A, the predicted toxicity and mutagenicity differed from our experimental data.