Antioxidative peptides derived from enzyme hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection.

This study focused on the preparation method of antioxidant peptides by enzymatic hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection. Phosphoric acid showed the highest ability of hydrolysis among the four other acids tested (hydrochloric acid, sulfuric acid and/or citric acid). The highest degree of hydrolysis (DH) was 9.5% using 4 mol/L phosphoric acid with a ratio of 1:6 under a microwave intensity of 510 W for 240 s. Neutral proteinase gave higher DH among the four protease tested (Acid protease, neutral protease, Alcalase and papain), with an optimum condition of: (1) ratio of enzyme and substrate, 4760 U/g; (2) concentration of substrate, 4%; (3) reaction temperature, 55 °C and (4) pH 7.0. At 4 h, DH increased significantly (P < 0.01) under nitrogen protection compared with normal microwave assisted acid pre-treatment hydrolysis conditions. The antioxidant ability of the hydrolysate increased and reached its maximum value at 3 h; however DH decreased dramatically after 3 h. Microwave assisted acid pre-treatment and nitrogen protection could be a quick preparatory method for hydrolyzing bone collagen.

[Levels of environmental endocrine disruptors in umbilical cord blood and maternal blood of low-birth-weight infants].

OBJECTIVE: To monitor the biological levels of environmental endocrine disruptors (EDs, phthalates and surfactants) in the umbilical cord blood and maternal blood of low-birth-weight infants. METHODS: All 30 umbilical cord blood samples and 21 maternal blood samples were collected from low-birth-weight infants. The concentration of four kinds of phthalates (di-2-ethylhexyl phthalate, DEHP; mono-2-ethylhexyl phthalate, MEHP; di-ethyl phthalate, DEP; di-n-butyl phthalate, DBP) and two kinds of surfactants (4-nonylphenol, 4-NP; octylphenol, OP) in these blood samples were measured by using reversed-phase high performance liquid chromatography. RESULTS: The mean birth weight and birth length of low-birth-weight infants were (2158.48 +/- 125.06) g and (45.36 +/- 2.52) cm, respectively. The concentrations of DEP, MEHP, DBP, DEHP, 4-NP and OP were 18.90, 11.87, 7.67, 8.84, 1.51 and 2. 86 mg/L in maternal blood, and the detective rates were 86.7%, 63.3%, 60.0%, 63.3%, 56.7% and 66.7%, respectively. In umbilical cord blood, the concentrations of those EDs were 11.92, 9.94, 5.71, 5.20, 1.12 and 1.19 mg/L; the detective rates were 86.7%, 63.3%, 60.0%, 63.3%, 56.7% and 66.7%. No matter in maternal blood or in umbilical cord blood, the contents and detective rates of phthalates were higher than the surfactants. The concentration of MEHP was higher than its primer, DEHP. The contents of the target EDs in umbilical cord blood were less than those in the matched maternal blood. The percentages were 47.82% -84.05%. CONCLUSION: People could be exposed to EDs from embryo period. And this should be paid attention by the related departments.