3,5-Dicaffeoylquinic Acid Disperses Aspergillus Fumigatus Biofilm and Enhances Fungicidal Efficacy of Voriconazole and Amphotericin B.

BACKGROUND The aim of this study was to evaluate the dispersal effects of 3,5-dicaffeoylquinic acid (3,5-DCQA) against the preformed biofilm of Aspergillus fumigatus and to investigate its potential mechanism. MATERIAL AND METHODS Aspergillus fumigatus biofilms of laboratory strain AF293 and clinical strain GXMU04 were generated in 24- or 96-well polystyrene microtiter plates in vitro. Crystal violet assay and XTT reduction assay were performed to evaluate the effects of 3,5-DCQA on biofilm biomass, extracellular matrix, and metabolic activity alteration of cells in biofilms. Real-time PCR was performed to quantify the expression of hydrophobin genes. The cytotoxicity of 3,5-DCQA on human erythrocytes was evaluated by a hemolytic assay. RESULTS The results indicated that 3,5-DCQA in subminimum inhibitory concentrations (256 to 1024 mg/L) elicited optimal A. fumigatus biofilm dispersion activity and improved the efficacy of VRC and AMB in minimal fungicidal concentrations (MFCs) to combat fungal cells embedded in biofilms. The results of scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM) revealed 3,5-DCQA facilitated the entry of antifungal agents into the A. fumigatus biofilm through eliminating the hydrophobic extracellular matrix (ECM) without affecting fungal growth. Real-time PCR indicated that 3,5-DCQA down-regulated the expression of hydrophobin genes. Hemolytic assay confirmed that 3,5-DCQA exhibited a low cytotoxicity against human erythrocytes. CONCLUSIONS Subminimum inhibitory concentrations of 3,5-DCQA can disperse A. fumigatus biofilm and enhance fungicidal efficacy of VRC and AMB through down-regulating expression of the hydrophobin genes. The study indicated the anti-biofilm potential of 3,5-DCQA for the management of A. fumigatus biofilm-associated infection.

Osteoblasts proliferation and differentiation stimulating activities of the main components of Fructus Psoraleae corylifoliae.

Osteoporosis is a disease of bones that leads to an increased risk of fracture. Fructus of Psoralea corylifolia L. (scurfpea fruit) is commonly utilized for treating bone fractures and joint diseases for thousands of years in China. This study was aimed to screen active principles, which might have the potency to stimulate osteoblasts proliferation and differentiation from scurfpea fruit. A HPLC method was established to analyze the main components in scurfpea fruit. Totally 11 compounds have been identified by comparing their retention time with correspondent standard substances. The MTT and ALP methods were utilized for the assay of osteoblasts proliferation and differentiation activity. Icariin, a prenylated flavonoid glycoside was treated as the positive control. Bavachin and isobavachin significantly stimulated cell proliferation, while bakuchiol exhibited stronger effect to enhance osteoblasts differentiation. All these compounds were found with a characterized structure that in each of their molecule backbones, a prenylated side chain was attached. These results lead to a hypothesis that prenyl group might be crucial to exhibit the activity. The structure-effect relationship of these compounds with prenyl group in mouse primary calvarial osteoblasts needs to be explored in further research.

Characterization of xanthatin: anticancer properties and mechanisms of inhibited murine melanoma in vitro and in vivo.

Anti-cancer investigations on Xanthatin mainly focus on in vitro experiments. We herein reported the anti-tumor effects of Xanthatin both in vitro and in vivo. MTS assay results showed that Xanthatin had a remarkable anti-proliferative effect on B16-F10 cells. Moreover, the expression of ß-catenin was up-regulated both in vitro and in vivo. Animal studies further revealed that Xanthatin killed the tumor cells around the blood vessels which contributes to reduce microvascular density extremely. All these results indicate that Xanthatin inhibited murine melanoma B16-F10 cell proliferation possibly associated with activation of Wnt/ß-catenin pathway and its activity against melanoma tumor might also be relevant to inhibition of angiogenesis.

Photosynthesis of young apple trees in response to low sink demand under different air temperatures.

Gas exchange, chlorophyll fluorescence, photosynthetic end products and related enzymes in source leaves in response to low sink demand after girdling to remove the root sink were assessed in young apple trees (Malus pumila) grown in two greenhouses with different air temperatures for 5 days. Compared with the non-girdled control in the low-temperature greenhouse (diurnal maximum air temperature <32 degrees C), low sink demand resulted in lower net photosynthetic rate (P(n)), stomatal conductance (g(s)) and transpiration rate (E) but higher leaf temperature on Day 5, while in the high-temperature greenhouse (diurnal maximum air temperature >36 degrees C), P(n), g(s) and E declined from Day 3 onwards. Moreover, gas exchange responded more to low sink demand in the high-temperature greenhouse than in the low-temperature greenhouse. Decreased P(n) at low sink demand was accompanied by lower intercellular CO(2) concentrations in the low-temperature greenhouse. However, decreased maximal photochemical efficiency, potential activity, efficiency of excitation capture, actual efficiency and photochemical quenching, with increased minimal fluorescence and non-photochemical quenching of photosystem II (PSII), were observed in low sink demand leaves only in the high-temperature greenhouse. In addition, low sink demand increased leaf starch and soluble carbohydrate content in both greenhouses but did not result in lower activity of enzymes involved in metabolism. Thus, decreased P(n) under low sink demand was independent of a direct effect of end-product feedback but rather depended on a high temperature threshold. The lower P(n) was likely due to stomatal limitation in the low-temperature greenhouse, but mainly due to non-stomatal limitation in the high-temperature greenhouse.

Photosynthetic response to low sink demand after fruit removal in relation to photoinhibition and photoprotection in peach trees.

Diurnal variations in photosynthesis, chlorophyll fluorescence, xanthophyll cycle, antioxidant enzymes and antioxidant metabolism in leaves in response to low sink demand caused by fruit removal (-fruit) were studied in 'Zaojiubao' peach (Prunus persica (L.) Batch) trees during the final stage of rapid fruit growth. Compared with the retained fruit treatment (+fruit), the -fruit treatment resulted in a significantly lower photosynthetic rate, stomatal conductance and transpiration rate, but generally higher internal CO(2) concentration, leaf-to-air vapor pressure difference and leaf temperature. The low photosynthetic rate in the -fruit trees paralleled reductions in maximal efficiency of photosystem II (PSII) photochemistry and carboxylation efficiency. The midday depression in photosynthetic rate in response to low sink demand resulting from fruit removal was mainly caused by non-stomatal limitation. Fruit removal resulted in lower quantum efficiency of PSII as a result of both a decrease in the efficiency of excitation capture by open PSII reaction centers and an increase in closure of PSII reaction centers. Both xanthophyll-dependent thermal dissipation and the antioxidant system were up-regulated providing protection from photo-oxidative damage to leaves during low sink demand. Compared with the leaves of +fruit trees, leaves of -fruit trees had a larger xanthophyll cycle pool size and a higher de-epoxidation state, as well as significantly higher activities of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase and a higher reduction state of ascorbate and glutathione. However, the -fruit treatment resulted in higher hydrogen peroxide and malondialdehyde concentrations compared with the +fruit treatment, indicating photo-oxidative damage.

Photosynthesis in response to sink-source activity and in relation to end products and activities of metabolic enzymes in peach trees.

Fruits were removed (-fruit) or retained (+fruit) on limbs of 'Yanfengyihao' peach (Prunus persica (L.) Batch) trees. In addition to the -fruit and +fruit treatments, leaves on 1-year-old fruit-bearing shoots of 'Bayuecui' peach trees were covered with bags for varying periods of time. Net photosynthetic rate (P(n)), stomatal conductance and transpiration rate around midday significantly decreased in the -fruit treatment and significantly increased in bagged leaves after removal of the bags compared with values in the +fruit treatment. Leaf temperature (T(l)) was higher in the -fruit treatment than in the +fruit treatment, and P(n) decreased in the -fruit treatment, especially when T(l) exceeded 38 and 36 degrees C in 'Yanfengyihao' and 'Bayuecui', respectively. Fruit removal resulted in a significant accumulation of sorbitol and starch in leaves, but it did not decrease activities of enzymes involved in carbon metabolism in leaves of 'Yanfengyihao'. In contrast, activities of aldose-6-phosphate reductase and ADP-glucose pyrophosphorylase sometimes increased in leaves in the -fruit treatment. In 'Bayuecui', fruit removal significantly decreased maximal fluorescence and photochemical efficiency and increased minimal fluorescence around midday compared with values in the +fruit and bag treatments. The photosynthetic apparatus of peach may be damaged when T(l) exceeds a critical temperature under conditions of decreased sink demand. Decreased stomatal aperture and increased T(l) may regulate photosynthesis by affecting electron transport.