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Transient receptor potential cation channel subfamily M member 8 (TRPM8) is a Ca2+ non-selective ion channel implicated in a variety of pathological conditions, including cancer, inflammatory and neuropathic pain. In previous works we identified a family of chiral, highly hydrophobic β–lactam derivatives, and began to intuit a possible effect of the stereogenic centers on the antagonist activity. To investigate the influence of configuration on the TRPM8 antagonist properties, here we prepare and characterize four possible diastereoisomeric derivatives of 4-benzyl-1-[(30-phenyl-20- dibenzylamino)prop-10-yl]-4-benzyloxycarbonyl-3-methyl-2-oxoazetidine. In microfluorography assays, all isomers were able to reduce the menthol-induced cell Ca2+ entry to larger or lesser extent. Potency follows the order 3R,4R,20R > 3S,4S,20R =3R,4R,20S > 3S,4S,20S, with the most potent diastereoisomer showing a half inhibitory concentration (IC50) in the low nanomolar range, confirmed by Patch-Clamp electrophysiology experiments. All four compounds display high receptor selectivity against other members of the TRP family. Furthermore, in primary cultures of rat dorsal root ganglion (DRG) neurons, the most potent diastereoisomers do not produce any alteration in neuronal excitability, indicating their high specificity for TRPM8 channels. Docking studies positioned these β-lactams at different subsites by the pore zone, suggesting a different mechanism than the known N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)-benzamide (AMTB) antagonist., This research was funded by the Spanish Ministerio de Ciencia y Universidades (MICYUFEDER, RTI2018-097189-C2-1 to A.F.-M. and A.F.-C., and RTI2018-097189-C2-2 to R.G.M.), Comunidad de Madrid (IND2017/BMD7673 to R.G.-M.) and the Spanish National Research Council (CSIC, 201980E030 to R.G.-M.).

Background: The effect of freezing (in liquid nitrogen at -196 °C , at -80 °C and at -20 °C) on the food matrix structure and the consequent effect on the bioaccessibility of total polyphenol content (TPC) and antioxidant activity (AA) of beetroot was investigated by an in vitro digestion method. The in vitro digestion involved incubation in simulated saliva followed by incubation in simulated gastric juice. Bioaccessibility of bioactive compounds was evaluated by measuring the TPC and the AA during in vitro digestion in both the beetroot matrix and the gastric juice.; Results: Release of TPC and AA of beetroot was higher in frozen samples (55 ± 5% for TPC and 68 ± 5% for AA) than in the fresh beetroot sample (∼46% for TPC and ∼53% for AA). The mass transfer kinetics were described by using a Weibull model with mean relative errors lower than 8.5% contributing to a better understanding of the influence of freezing on the bioaccessibility of bioactive compounds.; Conclusions: From the treatments tested in this study, freezing with liquid nitrogen resulted in the greatest increase in bioaccessibility of the antioxidant and phenolic compounds of beetroots. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

The effect of freezing (in liquid nitrogen at -196 °C , at -80 °C and at -20 °C) on the food matrix structure and the consequent effect on the bioaccessibility of total polyphenol content (TPC) and antioxidant activity (AA) of beetroot was investigated by an in vitro digestion method. The in vitro digestion involved incubation in simulated saliva followed by incubation in simulated gastric juice. Bioaccessibility of bioactive compounds was evaluated by measuring the TPC and the AA during in vitro digestion in both the beetroot matrix and the gastric juice.Release of TPC and AA of beetroot was higher in frozen samples (55 ± 5% for TPC and 68 ± 5% for AA) than in the fresh beetroot sample (∼46% for TPC and ∼53% for AA). The mass transfer kinetics were described by using a Weibull model with mean relative errors lower than 8.5% contributing to a better understanding of the influence of freezing on the bioaccessibility of bioactive compounds.From the treatments tested in this study, freezing with liquid nitrogen resulted in the greatest increase in bioaccessibility of the antioxidant and phenolic compounds of beetroots. © 2018 Society of Chemical Industry.

The effects of ultrasound assistance during a predrying treatment (soaking) on water mobility, polyphenoloxidase activity, microstructure, and the drying kinetics of apple (var. Granny Smith) have been studied. Predrying treatments were carried out using three different soaking media, distilled water, apple juice, and citric acid, at 25 °C during 5 min, without the assistance of ultrasound (S) and then with two acoustic densities: 2.1 W/cm2 (U1), and 12.9 W/cm2 (U2). Transverse relaxation times (T2) of vacuole and cytoplasm water of treated samples were longer than those in untreated samples (fresh apples) especially when the soaking assisted by ultrasound was used, resulting in greater mobility of internal water and easier water removal during convective drying. SEM observation showed that the ultrasound assistance promoted changes in the apple microstructure of treated samples regardless of the soaking medium. The polyphenoloxidase activity was affected by the soaking medium and the use of ultrasound during treatment, being higher reduction in samples treated with apple juice and citric acid, when the highest acoustic density was used (40 and 58 %, respectively). The effective water diffusion during hot air-drying (50 °C, 1 m/s) was higher in apples treated with and without power ultrasound than that in the fresh ones, causing a significant decrease in the drying time. This figure was higher when the soaking was carried out using citric acid and at an acoustic density of 12.9 W/cm2.