Effects of hydrogen peroxide treatment on pulp breakdown, softening, and cell wall polysaccharide metabolism in fresh longan fruit.

Longan (Dimocarpus longan Lour.) is prone to pulp softening and pulp breakdown, leading to a loss of its nutrients including polysaccharides. ROS is one main factor affecting fruit quality. This work intended to explicate the influences of hydrogen peroxide, acting as a ROS, on pulp softening, pulp breakdown, and cell wall polysaccharides metabolism in longan fruit during storage. Contrasted to the control group, hydrogen peroxide-treated samples exhibited lower firmness, lower amounts of CWM, ISP, CSP, hemicellulose and cellulose, but higher breakdown index, WSP amount, expression levels of DlPG, DlPE, Dlß-Gal, DlCx and DlXET and activities of their corresponding enzymes (PG, PE, ß-Gal, Cx, XET). These results suggested that hydrogen peroxide reduced longan pulp firmness due to the increased gene expression levels and enzymes activities related to cell wall polysaccharide degradation to boost their decomposition, thereby led to the accelerated pulp softening and the expedited pulp breakdown of harvested longans.

A novel chitosan alleviates pulp breakdown of harvested longan fruit by suppressing disassembly of cell wall polysaccharides.

Longan pulp is an excellent source of polysaccharides and other nutrients that have many health benefits. However, longans is susceptible to pulp breakdown after harvest and loses its nutrition values. To solve this problem, this study aimed to study the effects of a novel chitosan, Kadozan, on pulp breakdown index, contents of pectin, cellulose and hemicelluloses, and activities of enzymes in longan pulp relating to disassembly of polysaccharides (XET, PE, PG, ß-Gal, and cellulase). The data illustrated that, compared to the control longans, chitosan-treated longans contained higher amounts of CWM, CSP, ISP, cellulose and hemicelluloses, but exhibited lower pulp breakdown index, lower activities of cell wall-disassembling enzymes, and contained lower WSP amount. These results suggested that Kadozan with a dilution of 1:500 (VKadozan: VKadozan + Water) could significantly decrease activities of disassembling-enzymes and depolymerization of polysaccharides in cell wall, and subsequently alleviate pulp breakdown and prolong storage-life of postharvest longans.

A novel chitosan formulation treatment induces disease resistance of harvested litchi fruit to Peronophythora litchii in association with ROS metabolism.

This study aimed to investigate the effects of a novel chitosan formulation (Kadozan) treatment on disease development, response of disease resistance, metabolism of reactive oxygen species (ROS) in Peronophthora litchii-inoculated "Wuye" litchis. Compared with P. litchii-inoculated litchis, Kadozan-treated P. litchii-inoculated litchis exhibited lower fruit disease index, higher lignin content, higher activities of disease resistance-related enzymes (CHI, GLU and PAL), lower O2- generating rate and malondialdehyde content, higher activities of ROS scavenging enzymes (SOD, CAT and APX), higher contents of ascorbic acid and glutathione, and higher levels of reducing power and DPPH radical scavenging activity. These results suggest that Kadozan can be used to inhibit the growth of P. litchii in harvested litchis owning to the enhancement of disease resistance and ROS scavenging capacity, and decreases in O2- accumulation and membrane lipid peroxidation. Kadozan treatment can be used as a facile and novel method for suppressing postharvest pathogenic disease of litchis.

Effects of paper containing 1-MCP postharvest treatment on the disassembly of cell wall polysaccharides and softening in Younai plum fruit during storage.

Disassembly of cell wall polysaccharides accompanied with softening is very common in harvested fruits. To develop a facile postharvest approach, which can be used at ambient temperature, for suppressing softening and maintaining higher nutritive cell wall polysaccharides of Younai plums, influences of paper containing 1-methylcyclopropene (1-MCP) on firmness, activities of cell wall-degrading enzymes, and contents of cell wall polysaccharide in Younai plums during storage at 25 ±â€¯1 °C were investigated. As compared to the control plums, 1.2 µL·L-1 1-MCP-treated plums exhibited higher firmness, lower activities of cell wall-degrading enzymes (pectinesterase, polygalacturonase, cellulase and ß-galactosidase), higher contents of cell wall polysaccharides (sodium carbonate-soluble pectin, chelate-soluble pectin, cellulose, and hemicelluloses), and lower content of water-soluble pectin. The results suggested that paper containing 1-MCP, which was convenient to apply under ambient temperature, could significantly inhibit activities of cell wall degrading-enzymes and decrease disassembly of cell wall polysaccharides, and subsequently retard softening in Younai plums.

Effects of a novel chitosan formulation treatment on quality attributes and storage behavior of harvested litchi fruit.

The effects of Kadozan (a novel chitosan formulation) treatment on physiological attribute, nutritional quality and storage behavior of harvested "Wuye" litchi fruit were studied. Compared with control litchis, Kadozan treatment significantly decreased fruit respiration rate, retarded the increase of pericarp cell membrane permeability, maintained higher contents of anthocyanins and flavonoids and higher values of L∗, a∗ and b∗ in litchi pericarp, and reduced the decreases of titratable acidity, total soluble solids, total soluble sugars, and vitamin C contents in litchi pulp, maintaining better quality of litchis. Furthermore, Kadozan treatment decreased browning index and disease index of litchis, kept higher rate of commercially acceptable fruit, and reduced fruit weight loss, showing better storage behavior of litchis under ambient temperature. The optimal Kadozan treatment for litchis was the 1:100 (VKadozan: VKadozan + Water) dilution, which might be a promising method for keeping quality and prolonging shelf-life of harvested "Wuye" litchi fruit.

Stimuli-Responsive "Cluster Bomb" for Programmed Tumor Therapy.

In this paper, mesoporous silica nanoparticle (MSN) loaded with doxorubicin (DOX) and capped with tumor-homing/-penetrating peptide tLyP-1-modified tungsten disulfide quantum dots (WS2-HP) was designed and applied as a stimuli-responsive "Cluster Bomb" for high-performance tumor suppression. The peptide tLyP-1 on the surface can both facilitate the homing of DOX@MSN-WS2-HP to 4T1 tumor and greatly enhance the penetration of WS2-HP in tumor. The benzoic-imine bonds as the linkers between "bomblets" and "dispenser" are stable under normal physical conditions and quite labile at pH 6.8. After arriving at the mild acidic tumor microenvironment, the nanoplatform can rapidly break into two parts: (1) electropositive DOX@MSN-NH2 for efficient chemotherapy on surface tumor cells and (2) small-sized WS2-HP with improved tumor penetrating ability for near-infrared (NIR)-light-triggered photothermal therapy (PTT) among deep-seated tumor cells. Having killed the tumor cells in different depths, DOX@MSN-WS2-HP exhibited significant antitumor effect, which will find great potential in clinical trials.