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The effect of treatment with 5 g/L chitosan (CTS), 100 μmol/L melatonin (MT) and their combination on the storage quality and chlorophyll metabolism of fresh-cut broccoli (Brassica oleracea L. var. italica Planch.) during storage at (15 ± 1) ℃ and relative humidity (RH) of 85%–90% were investigated through sensory evaluation, physiological and biochemical characterization, and texture analysis. The results showed that separate and combined treatment with CTS and MT effectively maintained the sensory quality of fresh-cut broccoli, and the sensory scores of the samples treated with CTS, MT and their combination were 3.36, 2.83 and 5.17 times higher than that of the control group on the 7th day of storage, respectively. Compared with the control group, the combined treatment could significantly inhibit the activity of chlorophyll-degrading enzymes in broccoli (P < 0.05), thereby inhibiting chlorophyll degradation, while significantly reducing the rate of mass loss and respiratory intensity of fresh-cut broccoli (P < 0.05). Furthermore, it was found that the combined treatment increased chlorophyll content by 83.80%, reduced chlorophyllase (CLH), Mg-dechelatase (MDcase), pheophyllase (PPH) and pheophyllase a oxygenase (PAO) activities by 5.78%, 26.76%, 18.59% and 34.87%, respectively, and decreased mass loss rate and respiratory intensity by 24.82% and 45.28%, respectively on the 5th day of storage. Also, the combined treatment better maintained the texture properties of fresh-cut broccoli, such as hardness and chewiness, as well as the contents of soluble solids, soluble protein, total phenols and flavonoids. These findings suggest that combined treatment with CTS and MT can effectively delay the yellowing and maintain the quality of fresh-cut broccoli.

We performed this study in order to evaluate the control effect and mechanism of the biosurfactant rhamnolipids (RLS) on black spot disease caused by Alternaria alternata in pear fruit. The results showed that RLS treatment at a mass concentration of 20 mg/mL effectively enhanced resistance to A. alternata, and the lesion diameter was only 64.29% of that of the control group at 12 days following the treatment. Furthermore, it was shown that compared to the control group, RLS treatment significantly increased the activities of phenylalanine ammonia lyase (PAL), cinnamate acid 4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD), as well as the contents of total phenols and flavonoids in pear fruit tissue. The activities of chitinase and β-1,3-glucanase were significantly induced. The activities of NADPH oxidase (NOX), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and the contents of H2O2 and superoxide anion radical in the early and middle stages of storage were also increased by RLS treatment. Meanwhile, the ascorbate-glutathione (ASA-GSH) cycle was activated to maintain the dynamic balance of reactive oxygen species (ROS) production and scavenging in pear fruit tissue, and the membrane permeability and the content of malondialdehyde (MDA) were reduced. Collectively, this study suggested that post-harvest rhamnolipid treatment can enhance black spot disease resistance in pear fruit by regulating phenylpropane metabolism, ROS metabolism and pathogenesis-related proteins.

Photonic crystals are extensively explored to replace inorganic pigments and organic dyes as coloring elements in printing, painting, sensing, and anti-counterfeiting due to their brilliant structural colors, chemical stability, and environmental friendliness. However, most existing photonic-crystal-based pigments can only display monochromatic colors once made, and generating multicolors has to start with designing different building blocks. Here, a novel photonic pigment featuring highly tunable structural colors in the entire visible spectrum, made by the magnetic assembly of monodisperse nanorods into body-centered-tetragonal photonic crystals, is reported. Their prominent magnetic and crystal anisotropy makes it efficient to generate multicolors using one photonic pigment by magnetically controlling the crystal orientation. Further, the combination of angle-dependent diffraction and magnetic orientation control enables the design of rotation-asymmetric photonic films that display distinct patterns and encrypted information in response to rotation. The efficient multicolor generation through precise orientational control makes this novel photonic pigment promising in developing high-performance structural-colored materials and optical devices.

The neuroprotective role of 5-hydroxymethyl-2-furfural (5-HMF) has been demonstrated in a variety of neurological diseases. The aim of this study is to investigate the effect of 5-HMF on multiple sclerosis (MS). IFN-γ-stimulated murine microglia (BV2 cells) are considered a cell model of MS. With 5-HMF treatment, microglial M1/2 polarization and cytokine levels are detected. The interaction of 5-HMF with migration inhibitory factor (MIF) is predicted using online databases. The experimental autoimmune encephalomyelitis (EAE) mouse model is established, followed by a 5-HMF injection. The results show that 5-HMF facilitates IFN-γ-stimulated microglial M2 polarization and attenuates the inflammatory response. According to the network pharmacology and molecular docking results, 5-HMF has a binding site for MIF. Further results show that blocking MIF activity or silencing CD74 enhances microglial M2 polarization, reduces inflammatory activity, and prevents ERK1/2 phosphorylation. 5-HMF inhibits the MIF-CD74 interaction by binding to MIF, thereby inhibiting microglial M1 polarization and enhancing the anti-inflammatory response. 5-HMF ameliorates EAE, inflammation, and demyelination in vivo. In conclusion, our research indicates that 5-HMF promotes microglial M2 polarization by inhibiting the MIF-CD74 interaction, thereby attenuating inflammation and demyelination in EAE mice.