ABSTRACT
BACKGROUND: Agiotensin Ⅰ -converting enzyme (ACE) inhibitory peptides which are separated from red tilapia skin collagen should be researched further.OBJECTIVE: To obtain a peptide of high ACE inhibitory activity through enzymic hydrolysates of red tilapia skin collagen.DESIGN: Enzymic hydrolysates were done with orthogonal experimental method; decompression peptide was separated with ultrafiltration, gel chromatography and hypertensive liquid chromatography.SETTING: Laboratory of Aquatic Products, Chinese Marine University.MATERIALS: The red tilapia weighing (500+50)g was donated by Branch Factory of Jimo Redian Factory. ACE was isolated from hog lung.METHODS: The experiment was carried out in the Laboratory of Aquatic Products, Chinese Marine University from May Bergman.①The collagen from red tilapia skin was extracted using the method described by Grossman and Bergman.The collagen extraction was hydrolyzed with compound enzymes in the order of bromelain and Alcalase 2.4 L.The red tilapia collagen hydrolysates (RTCH) were subsequently boiled to inactivate the enzyme. The resultant RTCH was fractionated through three different UF membrane bioreactor system having a range of molecular weight cut-offs (MWCO) of Mr 6 000, 4 000 and 1 000. Three portions were obtained: RTCH-I (M, 6000-4000), RTCH- Ⅱ (Mr 4000-1000)and RTCH-Ⅲ(Mr＜1000).②The ACE inhibitory 50%of ACE activity was defined as the IC50 value.③RTCH-Ⅲ(1.5 Ml) with the highest activity among RTCHs was loaded onto a Sephadex G-25 column (1.6×100 cm), and the absorbance of theeluent was monitored at 220 nm. Four samples of primary hydrolysates, RTCH- Ⅰ, RTCH- Ⅱ and RTCHⅢ were separated to collect active fractions which were pooled and lyophilized, immediately. The lyophilized fraction was separated with HPLC ODS-C18 analysis column to obtain component of high activity. Meanwhile, the same method was used to measure ACE inhibitory rate.④Each sample was hydrolyzed with 6 mol/L hydrochloric acid containing 1g/L thioglycolic acid at 110 ℃ for 24 hours in vacuum. The amino acid compositions of the resultant hydrolysates were determined on an amino acid auto analyzer, and molecular weight was measured with HPLC technique.MAIN OUTCOME MEASURES：①ACE inhibitory activity of fractionated RTCHS;②Purification of ACE inhibitory peptide;③Amino acid analysis of ACE inhibitory peptides.RESULTS:①ACE inhibitory activityof fractionated RTCHs:IC50values of RTCH-Ⅰ,RTCH-Ⅱand RTCH-Ⅲ were 3.30,2.23 and 0.31 g/L,and inhibitory of RTCH-Ⅲ was the highest.②Purification of ACE inhibitory peptide: The IC50 value of the four peak were 3.5, 2.12, 1.56 and 0.65 g/L, respectively. Results in Figures 2, 3, 4 and 5 showed that the high active fractions were: 6K4, 4K2, 1K2 and ACF2, and the inhibitory ratio were 11.1%, 89.9%, 65.0% and 49.7%, respectively.Among of these fractions,the 4K2 exhibited the highest inhibitory rate.③Amino acid analysis of ACE inhibitory peptides: Separated peptide products had more aromatic and hydrophobic amino acids.CONCLUSTON: Enzymic hydrolysates of red tilapia skin collagen have high ACE inhibitory peptide which is separated with ultrafiltration, gel chromatography and hypertensive liquid chromatography.
ABSTRACT
Objective The adsorption effects of four sorts of dietary fibres from seaweeds on exogenous NO~-_(2) were studied in vitro and in vivo.Methods By simulating the environment of stomach and small intestine in vitro,and feeding rat in vivo.At the same time,the adsorption effect of wheat bran was studied comparatively.Results The results showed that:(1) the adsorption effect of dietary fibres on NO~-_(2) were related with the pH and the species of dietary fibres.Under the simulated stomach environment,the adsorption capacity of Laminaria japonica was the strongest with 1.19 mg?g~(-1),the next was Eucheuma with 0.94 mg?g~(-1),and Sargassum was the weakest with 0.60 mg?g~(-1).The adsorption ratio of Laminaria japonica and Eucheuma was significantly higher than that of wheat bran(P
ABSTRACT
Objective Adsorption effect of dietary fibers from seaweeds on extrinsic estrogens was studied.Methods The methods included the tests in vivo and in vitro which simulated environments of stomach and small intestine of rat. Results The adsorption effect of four kinds of dietary fibers on estradiol in simulated environments of small intestine was better than that in simulated environments of stomach. The effect of Laminaria japonica was the best. And the rate of adsorption on estradiol was 108 g?g~ -1.It is 1.5,1.8, 3.1, and 3.0 times that of Sargassum,wheat blan,Gracilaria and Eucheuma,respectively. The rates of adsorption on estradiol of four kinds of dietary fibers from Gracilaria, Eucheuma, Sargassum and laminaria japonica was 11.1%,13.6%,27.5% and 38.7%, respectively. Adsorption rate of Sargassum and laminaria japonica was 1.9 and 1.3 times than that of wheat bran, respectiveiy which was 20.4%. While for Gracilaria and Eucheuma, adsorption rate was lower than that of wheat bran. Conclusion The dietary fibers from four seaweeds showed adsorption effect on extrinsic estrogens. The dietary fibers from brown seaweeds (Sargassum and laminaria japonica) had more adsorption effect than that of red seaweeds (Gracilaria and Eucheuma).
ABSTRACT
Objective:The nutritional value and edible safety were evaluated for fastfood Eucheuma. Methods:The nutritional composition and the contents of heavy metal element and microbiology index were tested, and the test of acute toxicity and mutation were performed to evaluate the nutritional value and edible safety. Results:The main components of fastfood Eucheuma were dietary fibre and mineral components, and the contents of protein and fat were very low. The gross content of dietary fibre was 88.6%. The contents of Zn and Ca were the highest among the mineral components.The index of heavy metal elements and microbes(cfu) were lower than that of the national standard. It was non-toxic and non-mutagenic. Conclusion:The fastfood Eucheuma is a functional food, and also a safe food of new resource.