UV-C treatment inhibits browning, inactivates Pseudomonas tolaasii and reduces associated chemical and enzymatic changes of button mushrooms.

BACKGROUND: Button mushrooms with completely white appearance are popular with consumers. However, button mushrooms are susceptible to infection with Pseudomonas tolaasii, which results in browning. This study evaluates the effects of ultraviolet-C (UV-C) treatment on the inactivation of P. tolaasii in vitro and in vivo and on the physiological and chemical changes of button mushrooms during storage for 21 days at 4 °C. RESULTS: UV-C doses of 0.5 to 9.0 kJ m-2 resulted in 3.91-6.26 log CFU mL-1 reduction of P. tolaasii populations in vitro, and UV-C treatment reduced P. tolaasii populations inoculated on mushroom cap surfaces and browning severity. Moreover, P. tolaasii increased polyphenol oxidase (PPO) activity, and decreased phenylalanine ammonia-lyase (PAL) activity, the accumulation of phenolics and contents of brown melanin precursors, including γ-l-glutaminyl-4-hydroxybenzene (GHB), γ-l-glutaminyl-3,4-dihydroxybenzene (GDHB), and tyrosine in button mushrooms. UV-C treatment was found to reduce the negative changes due to P. tolaasii infection. CONCLUSION: These results indicated that the application of UV-C treatment inhibited browning, inactivated P. tolaasii and reduced P. tolaasii - associated chemical and enzymatic changes of button mushrooms. © 2021 Society of Chemical Industry.

Nobiletin Attenuates DSS-Induced Intestinal Barrier Damage through the HNF4α-Claudin-7 Signaling Pathway.

The intestinal epithelium barrier functions to protect human bodies from damages such as harmful microorganisms, antigens, and toxins. In this study, we evaluated the protective effect and molecular mechanism of a dominant polymethoxyflavone nobiletin (NOB) from tangerine peels on intestinal epithelial integrity. The results from transepithelial electrical resistance (TEER) suggested that NOB pretreatment counteracts epithelial injury induced by inflammatory cytokines (TEER value in 48 h: vehicle, 135.6 ± 3.9 Ω/cm2; TNF-α + IL-1ß, 90.7 ± 0.5 Ω/cm2; 10 µM NOB + TNF-α + IL-1ß, 126.1 ± 0.8 Ω/cm2; 100 µM NOB + TNF-α + IL-1ß, 125.3 ± 0.5 Ω/cm2. P < 0.001). Clinical and pathological test results suggested that administration of NOB effectively alleviates intestinal barrier injury induced by dextran sulfate sodium (DSS) as evidenced by the length of colon villi on day 7 (control, 253.7 ± 4.8 µm, DSS 131.6 ± 4.6 µm, NOB + DSS, 234.5 ± 5.1 µm. P < 0.001). Interestingly, when screening tight junction molecules for intestinal barrier integrity, we observed that independent treatment with NOB sharply increased claudin-7 levels (ratio of claudin-7 over GAPDH: control, 1.0 ± 0.06; DSS, 0.02 ± 0.001; NOB + DSS, 0.3 ± 0.07. P < 0.001), which was previously suppressed upon DSS stimulation. Furthermore, hepatocyte nuclear factor 4α (HNF-4α) transcriptional regulation of claudin-7 contributed to intestinal barrier homeostasis. Therefore, our study suggests potential intestinal protective strategies based on polymethoxyflavones of aged tangerine peels.

Effects of Selected Resveratrol Analogues on Activation and Polarization of Lipopolysaccharide-Stimulated BV-2 Microglial Cells.

Increasing health-promoting effects of resveratrol and its molecular structural analogues have been discovered, and the acting mechanism has been explored. However, the activity comparison of such compounds in targeting macrophage-related inflammation associated with neurodegenerative diseases remains untouched. In this study, we evaluated the activation and polarization transition of lipopolysaccharide (LPS)-stimulated BV-2 mouse microglial macrophages exposed to resveratrol (RES) and its analogues pterostilbene (PTE), oxyresveratrol (ORES), acetyl-trans-resveratrol (ARES), and trans-2,3,5,4'-tetrahydroxystilbene-2-O-glucopyranoside (TSG). At 10 µM, all of the five stilbene compounds have effectively suppressed the LPS-stimulated BV-2 cell release of proinflammatory mediators such as NO, TNF-α, iNOS, IL-1ß, and IL-6. Mechanism study elucidated that they exert anti-inflammatory effects through MAPKs (ERK1/2, JNK, and p38) and NF-κB signaling pathways. Further investigation in treating BV-2 cells with resveratrol and its analogues revealed the reversal of LPS-induced phenotype molecules from M1 (iNOS, IL-1ß, IL-6, and CD86) to M2 (Arg1, CD163, and IL-10) subtypes, manifesting that these five stilbenes suppressed inflammation through modulating the polarized phenotypes of BV-2 microglia. Most importantly, PTE demonstrated the most potent inhibitory activity among these five stilbene compounds. Therefore, this study not only highlights microglia-induced inflammatory responses as a potential therapeutic target but also suggests future insights in considering the options of nutraceutical development for resveratrol and its analogues.

Combined transcriptomic and proteomic analysis of cold stress induced sugar accumulation and heat shock proteins expression during postharvest potato tuber storage.

Plant species differ greatly in their ability to acclimatise to and survive, cold stress. Normally, potato tubers are stored at low temperatures (below 10 °C) to delay sprouting. In this research, combined transcriptomic and proteomic analysis was conducted on potato tubers stored at 15 °C, 4 °C and 0 °C to investigate the mechanism of cold responses during postharvest storage. Results showed that soluble sugars were accumulated under low temperatures, regulating by granule-bound starch synthase 1, beta-amylase, invertase inhibitor and fructokinase. In addition, fifteen heat shock proteins (Hsps), including three Hsp70s, two Hsp80s, one Hsp90, one Hsp100 and eight small Hsps, were induced by low temperatures, which may act individually or synergistically to prevent physiological or cellular damage from cold stress in postharvest potato tubers. This research provided general information of sugar accumulation and defense response in potato tuber under cold storage.

Effect of citronella essential oil fumigation on sprout suppression and quality of potato tubers during storage.

Effect of citronella essential oil (CEO) fumigation on sprout suppression and quality of potato tubers during storage was investigated. Potato tubers were treated under conditions of single-phase (30 µL L-1, 0-10 d) and dual-phase (30 µL L-1, 0-10 d; 30 µL L-1, 35-90 d) fumigation. Changes in germination rate, weight loss, starch, reducing sugar, gibberellins (GA3), and α-solanine were measured. The results showed that CEO fumigation could control sprouting and improve the quality of potato tubers during storage compared to the non-treated tubers. CEO treatments inhibited the degradation of starch and the increase of reducing sugar content. The production of gibberellins (GA3) was suppressed, and the levels of α-solanine in the skin and flesh of potato tubers were decreased by CEO fumigation. Dual-phase CEO fumigation had a better effect on sprout suppression than single-phase fumigation, and possesses potential for postharvest application.

UV-C treatment on physiological response of potato (Solanum tuberosum L.) during low temperature storage.

The storage of potato tuber (Solanum tuberosum L.) at low temperatures minimizes sprouting and disease but can cause cold-induced sweetening (CIS), which leads to the production of the cancerogenic substance acrylamide during the frying processing. The aim of this research was to investigate the effects of UV-C treatment on CIS in cold stored potato tuber. 'Atlantic' potatoes were treated with UV-C for an hour and then stored at 4 °C up to 28 days. The UV-C treatment significantly prevented the increase of malondialdehyde content (an indicator of the prevention of oxidative injury) in potato cells during storage. The accumulation of reducing sugars, particularly fructose and glucose, was significantly reduced by UV-C treatment possibly due to the regulation of the gene cascade, sucrose phosphate synthase, invertase inhibitor 1/3, and invertase 1 in potato tuber, which were observed to be differently expressed between treated and untreated potatoes during low temperature storage. In summary, UV-C treatment prevented the existence of oxidative injury in potato cells, thus, lowered the amount of reducing sugar accumulation during low temperature storage of potato tubers.

Effects of UV-C treatment and cold storage on ergosterol and vitamin D2 contents in different parts of white and brown mushroom (Agaricus bisporus).

Effects of ultraviolet-C (UV-C) treatment (0.5, 1.0 and 2.0kJ/m(2)) and cold storage on ergosterol and vitamin D2 content in different parts of white and brown button mushrooms (Agaricus bisporus) were investigated. UV-C treatment did not significantly affect ergosterol content in the caps and stems of the two mushrooms, but ergosterol content increased significantly during 14days cold storage. Vitamin D2 content in the caps and stems of two mushrooms significantly increased as UV-C dose increased, and 2.0kJ/m(2) UV-C showed the best result. During cold storage, vitamin D2 content in the caps of the two mushrooms decreased from day 1 to day 7, and then kept stable until day 14, but vitamin D2 content in the stems of brown mushrooms kept increasing for the whole 14days period. UV-C could increase vitamin D2 contents in both caps and stems of white and brown mushrooms without significantly affecting ergosterol content.