Application of electron paramagnetic resonance spectroscopy for determining the relative nanoenvironment fluidity of polymeric micelles

Polymeric micelles are nanocarriers for drug, protein and gene delivery due to their unique core/shell structure, which encapsulates and protects therapeutic cargos with diverse physicochemical properties. However, information regarding the micellar nanoenvironment's fluidity can provide unique insight into their makeup. In this study, we used electron paramagnetic resonance (EPR) spectroscopy to study free radical spin probe (5-doxylstearate methyl ester, 5-MDS, and 16-doxylstearic acid, 16-DS) behaviour in methoxy-poly(ethylene oxide)-poly(α-benzyl carboxylate-ε-caprolactone) (PEO-PBCL) and methoxy-poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) polymeric micelles. Spin probes provided information about the spectroscopic rotational correlation time (τ, s) and the spectroscopic partition parameter F. We hypothesized that spin probes would partition into the polymeric micelles, and these parameters would be calculated. The results showed that both 5-MDS and 16-DS spectra were modulated in the presence of polymeric micelles. Based on τ values, 5-MDS revealed that PEO-PCL (τ = 3.92 ± 0.26 × 10-8 s) was more fluid than PEO-PBCL (τ = 7.15 ± 0.63 × 10-8 s). The F parameter, however, could not be calculated due to the rotational hindrance of the probe within the micelles. With 16-DS, more probe rotation was observed, and although the F parameter could be calculated, it was not helpful to distinguish the micelles' fluidity. Also, doxorubicin-loading interfered with the spin probes, particularly for 16-DS. However, using simulations, we could distinguish the hydrophilic and hydrophobic components of the 16-DS probe. The findings suggest that EPR spectroscopy is a valuable method for determining core fluidity in polymeric micelles.

Effect of Plasma-Activated Water Bubbles on Fusarium graminearum, Deoxynivalenol, and Germination of Naturally Infected Barley during Steeping

Contamination of barley by deoxynivalenol (DON), a mycotoxin produced by Fusarium graminearum, causes considerable financial loss to the grain and malting industries. In this study, two atmospheric cold plasma (ACP) reactors were used to produce plasma-activated water (PAW) bubbles. The potential of PAW bubbles for the steeping of naturally infected barley (NIB) during the malting process was investigated. The PAW bubbles produced by treating water for 30 min using a bubble spark discharge (BSD) at low temperature resulted in the greatest concentration of oxygen-nitrogen reactive species (RONS). This treatment resulted in 57.3% DON degradation compared with 36.9% in the control sample; however, the same treatment reduced germination significantly (p < 0.05). Direct BSD ACP treatment for 20 min at low temperature and indirect treatment for 30 min increased the percentage of germinated rootlets of the seedlings compared with the control. Considering both the DON reduction and germination improvement of barley seeds, continuous jet ACP treatment for 30 min performed better than the other treatments used in this study. At higher temperature of PAW bubbles, the concentration of RONS was significantly (p < 0.05) reduced. Based on quantitative polymerase chain reaction (qPCR) analysis and fungal culture tests, the PAW bubble treatment did not significantly reduce infection of NIB. Nonetheless, this study provides useful information for the malting industry for PAW treatment optimization and its use in barley steeping for DON reduction and germination improvement.

Heating of consumer cannabis oils can lead to free radical initiated degradation, causing CBD and THC depletion

Commercial cannabis oil products are widely available in Canada even though there is a significant gap in scientific information regarding them. Oils, such as vegetable oils, are known to undergo oxidative changes through free radical mechanisms when they are heated or aged, but the cannabis oils used in this study did not have expiry dates or best-before usage dates. This led to the question of how these products would be affected with time. We hypothesized that cannabis oils would produce increased concentrations of free radicals in aging-simulated conditions, which would be related to a decrease in cannabidiol (CBD) or Δ⁹-tetrahydrocannabinol (THC) content. Cannabis oils and their respective vehicles (oils) were heated using two protocols: One (moderate aging method) used a 2-day heating protocol at 50 °C, and the other (enhanced aging method) used a 14-day heating protocol at 70 °C. We used electron paramagnetic resonance (EPR) spectroscopy for free radical analysis using the spin trapping technique using 200 mM PBN and 0.02 mM CuCl₂ (for peroxide breakdown to free radicals). For active ingredient analysis (CBD, THC), we used LC/MS. Cannabis oils that contained unsaturated oils as their vehicles, such as olive or sunflower oil, all showed varying degrees of free radical formation. In both aged and unaged oils containing CBD or THC, less free radical formation was detected compared to the vehicle controls. Cannabis oils using medium-chain triglycerides (MCT) showed little or no free radical formation. The most significant decrease in CBD or THC was observed in the products using sunflower oil, to a lesser extent in MCT oil, and THC also decreased in olive oil. These findings are important for consumers and policymakers considering using such products in hot beverages or cooking and highlighting the importance of appropriate storage conditions.

Treatment of a mixture of pharmaceuticals, herbicides and perfluorinated compounds by powdered activated carbon and ozone: Synergy, catalysis and insights into non-free OH contingent mechanisms

Powdered activated carbon (PAC) is a strong adsorbent also capable of catalyzing ozonation processes. Ozone (O₃) and PAC were simultaneously applied to treat a mixture of 17 micropollutants (MPs) at low concentrations, including 13 compounds that were studied for the first time by simultaneous addition of O₃ and PAC system. Synergy and catalysis improved the removals and specific degradation rates of MPs in the first minute of the treatment. Radical probing experiments showed that scavenging hydroxyl radicals (OH) did not have a significant impact on the removals, while scavenging other reactive oxygen species was more influential. A detailed study by electron paramagnetic resonance spectroscopy ascertained that the decomposition of ozone in presence of PAC at neutral pH did not boost the generation of free OH. Instead, adsorbed OH was likely produced as PAC-HO along with other oxidizing species resulting from adsorbed singlet oxygen and superoxide radicals.

Myeloperoxidase-mediated oxidation of edaravone produces an apparent non-toxic free radical metabolite and modulates hydrogen peroxide-mediated cytotoxicity in HL-60 cells

Edaravone is considered to be a potent antioxidant drug known to scavenge free radical species and prevent free radical-induced lipid peroxidation. In this study, we investigated the effect of edaravone on the myeloperoxidase (MPO) activity, an enzyme responsible for the production of an array of neutrophil-derived oxidants that can cause cellular damage. The addition of edaravone to the reaction of MPO and hydrogen peroxide (H₂O₂) significantly enhanced the reduction of MPO Compound II back to native MPO. Interestingly, the MPO-mediated production of toxic hypochlorous acid exhibited a concentration-dependent biphasic effect, with the apparent optimal edaravone concentration at 10 μM. Oxidation of edaravone by MPO was examined by various analytical methods. An MPO-catalyzed product(s) of edaravone was identified at 350 nm by kinetic analysis of UV-Vis spectroscopy. Several MPO-catalyzed metabolites of edaravone were proposed from the LC-MS analyses, including oxidized dimers from edaravone radicals. Electron spin resonance (ESR) spin trapping detected a carbon-centred radical metabolite of edaravone. NMR studies revealed that there are two exchangeable hydrogens, one of which is on the α-carbon, justifying the carbon-centred edaravone radical produced from MPO. Despite the formation of an edaravone carbon-radical metabolite, it did not appear to effectively oxidize GSH (in comparison with phenoxyl radicals). Viability (ATP) and cytotoxicity (LDH release) assays showed a concentration-dependent effect of edaravone on HL-60 cells treated with either a bolus concentration of 30 μM H₂O₂ or a flux of H₂O₂ generated by 5 mM glucose and 10 mU/mL glucose oxidase. The H₂O₂-induced toxicity was ameliorated at high edaravone concentrations (100-200 μM). In contrast, low concentrations of edaravone (1-10 μM) exacerbated the H₂O₂-induced toxicity. However, the effect of edaravone at low concentration (0-10 μM) appeared more prominent with the LDH assay only. The cellular findings correlated with the biochemical studies with respect to hypochlorous acid formation. These findings provide interesting perspectives regarding the duality of edaravone as an antioxidant drug.