Preparation and characterization of a novel colorimetric indicator film based on gelatin/polyvinyl alcohol incorporating mulberry anthocyanin extracts for monitoring fish freshness.

This work aimed to develop a novel colorimetric indicator film for monitoring of food freshness based on gelatin/polyvinyl alcohol matrix incorporated with anthocyanin extracts from mulberry. The color of anthocyanin extracts solutions obviously changed from bright red to dark green in the pH range of 2.0-11.0. FTIR spectra and isothermal titration calorimetry showed that the anthocyanin extracts were successfully combined with gelatin/polyvinyl alcohol matrix by hydrogen binding and electrostatic interaction, which enhanced the stability of anthocyanin. The scanning electric microscopy showed that the compatibility between polyvinyl alcohol and gelatin were improved owing to the addition of anthocyanin extracts. With the anthocyanin extracts addition from 0 to 45 mg/100 mL mixed solution, the tensile strength decreased from 30.80 to 21.01 MPa and the elongation at break increased from 589.22% to 905.86%. The color response of film in buffer solution of different pH were in accordance with anthocyanin extracts solutions, and its color changes were clearly visible with naked eye. Finally, the film was evaluated by a test on monitoring fish spoilage, which presented visible color changes due to volatile nitrogenous compounds formed over time. These results showed that this developed film could be used as an effective method for the monitoring of food freshness.

Tyrosinase inhibitory effects and antioxidative activities of novel cinnamoyl amides with amino acid ester moiety.

Nine cinnamoyl amides with amino acid ester (CAAE) moiety were synthesized by the conjugation of the corresponding cinnamic acids (cinnamic acid, 4-hydroxy cinnamic acid, ferulic acid and caffeic acid) with amino acid esters, and their inhibitory effects on the activities of mushroom tyrosinase were investigated, using l-3,4-dihydroxyl-phenylalanine (l-DOPA) as the substrate. Among these CAAE amides, ethyl N-[3-(4-hydroxy-3-methoxyphenyl)-1-oxo-2-propen-1-yl]-l-phenylalaninate (b(4)) showed the strongest inhibitory activity; the IC(50) was 0.18 µM. The IC(50) values, inhibition types, inhibition mechanisms and kinetics of all these CAAE amides were evaluated. A structure-activity relationship (SAR) study found that the inhibitory effects were potentiated with the increasing length of hydrocarbon chains at the amino acid esters and also influenced by the substituents at the styrene groups. Furthermore, the hydroxyl radical scavenging and anti-lipid peroxidation activities of four CAAE derivatives were also investigated. Among these compounds, b(3) (ethyl N-[3-(3,4-dihydroxyphenyl)-1-oxo-2-propen-1-yl]-l-phenylalaninate) and b(4) exhibited potential antioxidant activities.

Optimization of alkaline extraction of polysaccharides from Ganoderma lucidum and their effect on immune function in mice.

Response surface methodology was employed to optimize the conditions for alkaline extraction of polysaccharides from Ganoderma lucidum. The results indicated that the optimum conditions were an extraction temperature of 60.1 degrees C, an extraction time of 77.3 min, a sodium hydroxide (NaOH) concentration of 5.1% and a substrate/liquid ratio of 1:21.4. Immunological assays results have shown that the alkaline soluble polysaccharides have no noticeable effects on monocyte phagocytosis and immune organ (spleen, thymus) weight of immunocompromised mice at the tested dosages. However, they could restore delayed type hypersensitivity reaction to dinitrofluorobenzene (DFNB), hemolysis antibody levels at the three doses applied, and improve the natural killer cell activity at the high-dose and medium dose.

Extraction of polysaccharide from Ganoderma lucidum and its immune enhancement activity.

In the present study, in order to maximize the yield of polysaccharides from Ganoderma lucidum, response surface methodology was employed to optimize the ultrasonic/microwave-assisted extraction (UMAE) conditions. The results indicated that the optimal extraction conditions were ultrasonic power of 50W, microwave power of 284W, extraction time of 701s and water/solid ratio of 11.6:1, respectively. Using UMAE, the yield of polysaccharides was 115.56% above that of classical hot water extraction (HWE) and increased by 27.7% as against ultrasound-assisted extraction (UAE), which confirmed the great potential application of UMAE technology in the extraction of polysaccharides. The immunological assays results demonstrated that polysaccharides of G. lucidum extracted by ultrasonic/microwave (UMP) could improve the weight of immune organ of immunocompromised mice, restore delayed-type hypersensitivity (DTH) reaction to DFNB, improve hemolysis antibody level and natural killer cell activity at high-dose. However, UMP had no noticeable effects on phagocytosis of monocyte at the tested dosage range.

Physical performance of migrant schoolchildren with marginal and severe iron deficiency in the suburbs of Beijing.

OBJECTIVES: To investigate relationship between iron deficiency of different degrees and physical performance and habitual activity of migrant schoolchildren at the age of 11-14 years. METHODS: Ninety one randomly selected schoolchildren were divided into three groups according to their iron status. Iron status including hemoglobin (Hb), serum ferritin (SF), serum iron (SI) and sTfR was determined. Physical performance tests included maximum oxygen consumption (VO2max) and maximum work time. Energy expenditure (EE) and daily physical activity were estimated by recording 24-h heart rate (HR). Dietary intake was assessed with frequency questionnaires, and physical activity level was estimated with frequency and physical activity questionnaires. RESULTS: Severe iron deficiency (IDA) impaired the aerobic capacity and habitual physical activity. When fat-free mass (FFM) was considered, VO2max (VO2max/FFM) was significantly lower in the iron-marginal group than in the iron-adequate groups among girls (P = 0.02), but such a deference was not found among boys (P = 0.28). Aerobic activity and EE at leisure were significantly lower in the severe iron deficient group than in the marginal iron deficient and iron adequate groups. Net HR at leisure time was correlated with Hb, log SF, body weight, and FFM (P < 0.05). CONCLUSION: The functional effect of iron deficiency on physical performance and habitual physical activity rely on the degree of current iron deficiency. Severe iron deficiency significantly impairs both aerobic capacity and habitual physical activity. Iron-marginal deficiency impairs VO2max/FFM in girls, rather than in boys.

[Genetic diversity of Camellia sinensis germplasm in Guangdong Province based on morphological parameters and SRAP markers].

By the methods of phenotypic identification and SRAP makers amplification, the genetic diversity of twenty-five local tea cultivars in Guangdong Province and five contrastive cultivars from other regions was assessed and classified, and the phenotypic traits of the cultivars were clustered by Pearson correlation and Farthest neighbor methods. The coefficient of variation of the phenotypic traits was averagely 32.15%. Fine-hair had the highest coefficient of variation (42.41%), while the growth period of bud leaves had the smallest one (18.52%). Based on the cluster analysis of phenotypic traits, the test 30 tea cultivars could be clustered into 4 groups, 17 cultivars in the first group, 10 cultivars in the second group, 2 contrastive cultivars Yunnan-dayezhong and Lingyun-baimaocha in the third group, and 1 contrastive cultivar Hainan-dayezhong in the fourth group. After the amplification with 21 SRAP primers, a total of 127 fragments were detected, among which, 114 fragments were polymorphic, accounting for 88.67% of the total. The amplified fragments and polymorphic fragments per primer combination were averagely 6.05 and 5.43, respectively. At the genetic distance of 0.39 cm, the tea cultivars could be classified into three groups A, B and C, and 83.33% of the cultivars were belonged to group A. At the genetic distance of 0.31 cm, group A could be further classified into three sub-groups I , II and III, 13 cultivars in subgroup I, 2 cultivars in subgroup II, and 10 cultivars in subgroup III. It was not exactly the same between the clustering based on SRAP markers amplification and the performance of phenotypic traits.

Structure-activity relationship of flavonoids active against lard oil oxidation based on quantum chemical analysis.

In this study, the antioxidant activities of 15 flavonoids against lard oil oxidation were determined by using the Rancimat test. Quercetin, dihydromyricetin, luteolin and kaempferol showed the strongest antioxidant activity, with protection factor values (PF) of 11.50, 11.29, 4.24 and 2.49, respectively. The role of conjugated hydroxyl groups of the B and C ring is discussed. By using the following descriptors: DeltaH(f) (the difference in heat of formation between flavonoids and their free radicals resulted after hydrogen atom donation) and H(BC) (the number of conjugated hydroxyl groups of the B and C ring), the result obtained in the antioxidant Rancimat test could be successfully explained.

Antioxidation properties and mechanism of action of dihydromyricetin from Ampelopsis grossedentata.

AIM: To assess the antioxidative properties and the mechanism of action of dihydromyricetin (DMY) from Ampelopsis grossedentata. METHODS: The antioxidative properties of DMY were measured by scavenging 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and inhibiting lipid peroxidation induced by FeSO4-edetic acid in linoleic acid. The mechanism of antioxidative properties of DMY was tested by measuring the chelating activities of DMY for Fe2+ with ultraviolet spectrum (UV) method. RESULTS: The specific absorption of DPPH radical solution at 517 nm was reduced 73.3%-91.5% when DMY was added into the reaction solution in the concentration range from 0.01% to 0.04%. DMY was shown to greatly inhibit the increase of lipid peroxidation (LPO) values in linolei acid system catalyzed by FeSO4-edetic acid. The reaction rates (A532.min-1) of lipid peroxidation were 0.0021-0.0004 in the concentration range from 0.01% to 0.04% and the inhibition activities of DMY was found to be in a concentration-dependent manner. The mechanism of antioxidative properties of DMY was chelating Fe2+ in the Fe(2+)-dependent lipid peroxidation system. CONCLUSION: DMY showed great antioxidative effect and would be a good natural antioxidant.