| China is rich in freshwater fishes and they are abundantly processed into diverse products.However, with the rapid increase of processing, large amounts of by-products are producedevery year. If the by-prducts are not exploited scientifically and rationally, it not only wastesthe resources, but also pollutes the environment. In China, fish brain is considered to benutritious and known to contribute to health and intelligence. Besides, fish brain has beenused in traditional Chinese medicine for the treatment of head diseases. Fish brain is rich inpolyunsaturated fatty acid (PUFA), phospholipids, protein et al. Eicosapentaenoic acid (EPA,C20:5n3) and docosahexaenoic acid (DHA, C22:6n3) which have been proved nutritious aswell as beneficial to physical and intelligent development are abundantly contained in fishbrain. However, brain, with other by-products is discarded or or used as material for feed.Lots of functional substances are not extracted. In the study, the nutritional value of brainfrom silver carp was evaluated and compared with big head carp, grass carp and black carp.The physicochemical properties, volatile compounds and lipid classes of silver carp brainlipids were determined. Furthermore, anti-platelet-activating factor (PAF), antibacterial,antioxidant and anticancer activities of lipids extracted from silver carp brain were studied.The mechanisms of fish brain in contributing to health and intelligence were discussed. Thisstudy was of theoretical significance and of great practical significance in exploiting fishbrain as functional products.Proximate composition, amino acid, essential amino acid score, mineral elements and fattyacid (FA) profiles of brain from silver carp were investigated and compared with big headcarp, grass carp and black carp. The results indicated that brains from the four fish specieswere rich in lipids. The lipids content of silver carp, bighead carp, grass carp and black carpwere20.53g/100g,13.72g/100g,53.75g/100g and73.81g/100g, respectively. No limitingamino acid existed in brains. Na, Ca, and Mg were the predominant minerals in brains of thefour fish species. FA analysis revealed that brains from the four freshwater fish speciescontained abundant PUFA, especially arachidonic acid (ARA, C20:4n6), EPA and DHA.Among the four fish species, silver carp brain had the highest protein content (1.92g/100g),essential amino acid (7.96mg/g), total amino acid (16.64mg/g), ARA (2.54%), EPA (5.42%)and DHA (7.28%) contents, total ω-3PUFA (20.56%) and ω-3/ω-6ratios (2.77). However,ω-6/ω-3ratio in brain of grass carp (7.62) was higher than safe range (4.0).The advantages of fish brain stem from the high content and quality of lipids. Thus, on thebasis of nutritional value evaluation, the physicochemical properties, volatile vompounds,lipid classes, especially phospholipids of silver carp brain lipids were analyzed. The lipidsextracted from brain of silver carp exhibited good physicochemical properties, of which theiodine value (124.26g/100g), peroxide value (2.42meq/kg) and acid value (0.58mg/g) reached to the first-grade criterion of refined fish oil. Forty volatile compounds wereidentified, of which hydrocarbons predominated. The ratios of polar lipid (PL) andphospholipids to total lipids were22.73%and10.95%respectively. Phosphatidylcholine (PC),phosphatidylethanolamine (PE) and phosphatidylserine (PS) accounted for83.9%of thephospholipids. The PUFA level in PL (35.17%) is higher than that in neutral lipid (NL), ofwhich the level of DHA in PL was6.3times of that in NL. The PUFA levels of PC, PE and PSwere33.19%,39.34%and36.27%, respectively. PC, PE and PS were rich in EPA and DHA.The abundant phospholipids and PUFA content may assist to explain the intelligencebeneficial activities as well as pharmacological activities of fish lipids against variousdiseases including cardiovascular diseases, liver disease, cancer and so onThe capabilities of lipids (TL, NL, PL) from silver carp brain in antibacterial, anti-PAFand antioxidant activities were studied. TL, NL and PL from silver carp brain exhibitedantibacterial activity. Because of higher PUFA content in PL, it showed stronger antibacterialactivity than NL. The silver carp brain lipids exhibited strong anti-PAF activity. The IC50value of TL, NL and PL was104.13μg,2.35μg and87.47μg, respectively. Thus, theanti-PAF activity of TL was mainly attributed to NL because NL may contain more PAFantagonists. The scavenging effects for1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assayindicated TL, NL and PL possessed strong antiradical activities. HEK-293cells were used asan oxidative stress model to investigate the protective effects of silver carp brain lipids againstH2O2-induced cytotoxicity and apoptosis. TL, NL and PL showed protective effects onH2O2-induced HEK-293cells, including increasing cell viability, improving injured cellmorphology as well as increasing the activities of superoxide dismutase, Glutathioneperoxidase and catalase which are regarded as the first line of the antioxidant defense systemduring oxidative stress. Therefore, lipids from silver carp brain possessed strong antioxidantactivty, and because of abundant phospholipids and higher level of PUFA contained in PL, PLplayed more important in antioxidant acitivity. Many foods primarily deteriorate because ofmicrobes that give rise to the loss of quality and safety. In addition, numerous bacteria areable to produce PAF. PAF, which is a key in atherosclerosis development, is also an extremelypotent aggregating agent participating in the inflammatory development of plaque and theblockage of blood vessels that finally lead to coronary heart disease. Besides, oxidativedamages are engaged in the development of cardiovascular disease and cancer. The presentstudy may help to explain the protective role of fish lipids against diseases and may beresponsible for the effectiveness of fish brain in benefiting health. Furthermore, the resultsmay shed light on the utilization of silver carp brain lipids as eligible bioactive ones forprevention and treatement of cardiovascular disease.The anticancer activity of silver carp brain lipids (TL, NL, PL) were investigaged. Theproliferations of MCF-7cells，HeLa cells，CACO-2cells and HepG2cells were suppressed by TL from silver carp brain. TL, NL and PL suppressed the proliferations of MCF-7cells andHeLa cells in time-and dose-dependent manner. Exposure MCF-7cells and HeLa cells to TL,NL and PL resulted in loss of adhesion and the cells rounding up, indicating the possibility ofapoptosis occurrence. The results observed from fluorescence microscope showed thatincubated MCF-7cells and HeLa cells with sliver carp brain lipids resulted in nucleifragmentation as indicated in condensed chromatin and bright staining in morphology,indicating apoptosis. Cell cycle progressions were determined by flow cytometry. The resultsindicated that after treatment with TL, NL and PL, MCF-7cells and HeLa cells were arrestedat S stage. The obvious apoptotic peaks were observed after HeLa cells were incubated withlipids for48h. Compared to control, the Sub-G1proportions of TL, NL and PL were increased5.62%,3.06%and9.98%, respectively. Therefore, lipids from silver carp brain inhibited theproliferations of MCF-7cells and Hela cells through promoting apoptosis and blocking Sphase. The detecting of apoptosis proved that the effects of silver carp brain lipids onMCF-7cells and HeLa cells were primarily apoptosis rather than necrosis. The production ofROS was significantly increased in lipids treated MCF-7cells and Hela cells in comparison ofcontrol. For instances, after treated by TL, NL and PL for24h, compared to control, the ROSlevel of MCF-7cells increased23.12%,17.69%and32.76%, respectively. Further analysisindicated that TL, NL and PL could cause the collapse of mitochondrial membrane potential(Ψ) of MCF-7cells and HeLa cells. Thus, the apoptotic effects of silver carp brain lipids onMCF-7cells and HeLa cells were associated with the elevated level of ROS accumulation andthe loss of Ψ. The anticancer role of PL surpassed that of NL which may attributed toabundant phspholipids and higher PUFA level in PL. |
PDF Full Text Request