tong hop

n cng ngh 1

GVHD: Ths. Nguyn Th Lan

M U Trong lnh vc sc khe hin nay, ngi ta ni n nhiu tc hi ca cht oxy ho, phn ng xy ho v nhn mnh s cn thit s dng cht chng oxy ho bo v v duy tr sc khe. Trong c th con ngi gc t do (cht oxy ha) lun lun c sinh ra v cng c vai tr tch cc i vi c th (c th ni ta khng th sng c nu trong c th hon ton thiu vng gc t do). Oxy m ta ht th hng ngy l cht cn thit nhng chnh n cng tr thnh gc t do (khi gi l oxy n bi). Hin tng thc bo hoc hin tng h hp trong t bo hoc c ch gii c gan u l cc hot ng lm sinh ra gc t do. Ngi ta chng minh, khi c s tng qu nhiu gc t do s gy ra tnh trng vim nhim cc c quan, cc bnh l nh tim mch, bnh thn kinh, c thu tinh th... chng li s bi tng cc gc t do sinh ra qu nhiu m h thng cht xy ho ni sinh khng sc cn bng v hiu ho, cc nh khoa hc t vn dng cc cht chng xy ha ngoi sinh (tc l t bn ngoi a vo c th) vi mc ch phng bnh, nng cao sc khe, chng lo ha. Cc cht chng xy ha ngoi sinh nh beta-caroten, cht khong selen, cc hp cht flavonoid, polyphenol... Cc cht xy ha ngoi sinh c t cc ngun thin nhin l thc phm nh rau ci, tri cy ti v mt s loi dc tho. Hoa bp gim ang l i tng c th gii v nc ta quan tm v chng c nhng tc dng rt ln trong thc phm cng nh trong y hc. Nc chit t i hoa bp gim c cha rt nhiu hp cht tan c nhiu tc dng khc nhau nh: pectin polysacharit lm chm s pht trin ca khi u sarcoma 180 cy ghp trn chut, HIB-3 c trong polysaccharid c kh nng c ch s pht trin ca t bo ung thTrong c hp cht anthocyanin hin ang l cht mu c s dng rng ri trong thc phm, dc phm... V chng c kh nng khng oxy ha, chng vim, lm bn thnh mch, chng ung th Trn c s ti chn ti: Kho st cc yu t nh hng n kh nng khng oxy ha ca hp cht tan trong i hoa bp gim. kin em nng cao thm kin thc. V khng c lm thc nghim nn khng trnh khi nhng sai st mong thy, c ng gp thm

SVTH: Nguyn Th Thu Tho

Trang 1

n cng ngh 1


PHN I: TNG QUAN TI LIU 1.1. S lc v cht chng oxy ha C th ngi v ng vt c hai h thng bo v, l h thng min dch v h thng cc cht chng oxy ha sinh hc. Cc cht chng oxy ha sinh hc c vai tr tiu dit cc cht ha hc c hi trong c th c tn l gc t do. Nhng gc t do ny l th phm ca nhiu bnh. Tuy nhin c th li c v kh v hot cc gc t do, l cc cht chng oxy ha. 1.1.1. Gc t do (free radical) v c ch hot ng ca chng Gc t do l nhng nguyn t hay nhm nguyn t m lp ngoi cng ca n cha nhng in t l cp. V gc t do cha nhng in t l cp cho nn chng lun tm cch cp ly in t ca nguyn t hay phn t khc. Nguyn t hay phn t khc mt in t li tr thnh gc t do v chng li i cp in t ca nguyn t hay phn t khc na. C nh vy theo dy chuyn, mt s ln gc t do c hnh thnh v c mt khp ni trong c th. Khi mt t bo b mt i mt in t, chuyn ha ca t bo b ri lon, t bo lnh tr thnh t bo bnh [11]. 1.1.3. Tc hi ca gc t do Theo tin s Bruce Ames ca i hc Berkley, California th mi t bo n l ca c th mi ngy phi chu khong 10.000 c tn cng. Rt nhiu cuc tn cng trong s ny nhm vo cc DNA, vic ny a n mt trong nhng hu qu l lm gia tng tc bin i ca gen, t dn n s bin i t bo v gy nguy c ung th. Bnh c thy tinh th cn gi l cm mt (cataracts) l do protein thy tinh th b gc t do bn ph lm bin tnh, b c li. Da b kh, chai sn khi v gi hay khi b tia t ngoi tc ng l do gc t do ph hy nhng si collagen trong da. Lipid l cht nhy cm nht vi s tn cng ca gc t do, c bit cc acid bo khng no nhiu ni i (t chuyn mn gi l PUFA : poly unsatured fatty acid). Cc PUFA khi b gc t do tn cng th hnh thnh cc peroxide (qu trnh peroxide ha), chng u c mng t bo, cn tr s hnh thnh v hot ng ca cc enzyme bn trong t bo. H min dch cng rt nhy cm vi gc t do. T bo min dch hot ng ch yu da vo s thng tin gia cc t bo, c bit theo con ng cc receptor gn vi mng t bo. Mng t bo li rt giu PUFA, nu mng t bo b peroxide ha th mngSVTH: Nguyn Th Thu Tho Trang 2

n cng ngh 1


b tn hi, cc tn hiu t bo khng chuyn cho nhau c, chc nng t bo b hng (gim hoc mt kh nng biu th receptor mng t bo). Tm li, gc t do c th gy nhng tn hi sau: ung th, bnh tim mch, t qy, c thy tinh th, suy gim min dch, lo ha [11]. 1.1.2. S hnh thnh ca gc t do Gc t do hnh thnh t hai ngun, l ngun ni sinh v ngun ngoi sinh. ngun ni sinh, gc t do hnh thnh: - T chui chuyn in t trong ty th (cc phn ng phosphoryl oxy ha ca mitochondria): superoxide anion (O2), hydrogen peroxide (H2O2), gc hydroxyl (OH). - T hot ng h hp ca leucocyte, gc t do hnh thnh git vi khun. - T qu trnh t cht ca t bo (apoptosis): bng in vitro, ngi ta thy cht oxy ha ni sinh AXO c th ngn tr apoptosis. ngun ngoi sinh, gc t do hnh thnh t kh ozone, bc x t ngoi, khi

thuc l, dng thuc phin,cc thc phm nhn to, mi trng nhim, mt cn bng dinh dng hoc thm ch c nhng chn thng tm l (stress), tui gi...[11]. 1.1.4. Cht chng oxi ha (antioxidant) Cht chng oxy ha l mt phn t c kh nng lm chm hay ngn nga s oxy ha nhng phn t khc. Oxy ha l phn ng gia mt phn t vi oxy, hoc bt c khi no mt phn t mt mt in t trong phn ng ha hc. Nhng phn ng oxy ha c th sn sinh cc gc t do v khi ng nhng phn ng lin hon gy tn hi t bo. Cc cht chng oxy ha ngn chn cc phn ng lin hon ny bng cch tch cc gc t do v c ch nhng phn ng oxy ha khc. 1.2. Phn loi cht chng oxy ha Cht chng oxy ha c phn thnh cc nhm: nhm ha tan trong nc nh: Glutathione, Vitamin C (ascobic acid), anthocyanin; nhm tan trong nc v du nh: Lipoic Acid (ALA); nhm ha tan trong lipid nh: Vitamin E (tocopherol), Coenzyme Q10 (Ubiquinone). Ngoi ra cn c cc cht khc nh: Dehydroepiandrosterone (DHEA), Melatonin Ni chung nhm ha tan trong nc phn ng vi cc cht oxy ha trong t bo cht, huyt tng, trong khi nhm ha tan trong lipid th bo v mng t bo khng b peroxide ha. Cc cht chng oxy ha c th c tng hp trong c th hay nhn t thc phm [12]. 1.3. Gii thiu tng qut v cy hoa bp gimSVTH: Nguyn Th Thu Tho Trang 3 Hnh 1.1: Cy hoa bp gim [17]

n cng ngh 1


Tn khoa hoc: Hibiscus sabdariffa L. Tn khac: Cy gim, hng i, ay Nht. Ho: Bng (Malvaceae) 1.3.1. c im hnh thi Bp gim l mt cy thng, nhiu nhnh, mc thnh bi, cao 1-2m c th cao n 3,5m. Thn mu lc hoc ta, phn cnh gc. Cnh nhn hoc hi c lng. L mc so le nhau, di khong 7,5 12,5cm, mu xanh vi nhng gn l mu hi , khng c lng, cung l di, la di gc nguyn, la phia trn x thy khong 3 -7 thuy ging hinh chn vit, quanh mep l co rng ca. Hoa mc ring l nch l, gm 5 l i ln cac la ai day, nhon u, mong nc mau o tia v ai phu (tiu ai) gm 8 12 l bc mng xung quanh cung hoa, co lng nho, n xoe ra va gp xung bao bc hon ton qu. Hoa c th ln n 12,5cm, mu vng nht hay mu ht d chnh gia c mu nu , chuyn thnh mu hng khi ho vo cui ngy. Qua nang c hinh trng, nhon u, co lng min, c nhiu hat mau en [13][14].

Hnh 1.2. Cy hoa bp gim [14].

1.3.2. c im sinh thi Bp gim thch nghi chu yu vung nhit i va a nhit i, nhit trung binh khoang 23 240C, a nng, rt chu hn, chu t kh cn v bc mu, khng chiu ung, thi gian sinh trng ngn (6 thng) [14]. 1.3.3. Phn b Bp gim c ngun gc t Ty Phi, sau lan sang n (40 loai), Malaysia, Philippin va Indonesia, Thi Lan... Bup gim c nhp vao Vit Nam cach y khoang 10 nm, n nay c khong 23 loi, trng ch yu cc tnh min Trung v c trng th nghim ph t trng i trc cho kt qu tt Ba V (HSVTH: Nguyn Th Thu Tho Trang 4

n cng ngh 1


Ty), Lng Sn (Ho Bnh), Tam o (Vnh Phc), Bc Giang, Thi Nguyn... Mt s tnh sau ny nh B Ra, Vng Tu, ng Nai... ly ging t c, trng i tr xut khu [13][14]. 1.3.4. Thnh phn ha hc ca hoa bp gim: Bup gim cha: [14] - Anthocyan 1,5%: bao gm chu yu la delphinidin-3-sambubiosid va cyanidin-3-sambubiosid. Ngoai ra, con co cyanidin -3-glucosid, delphinidin-3glucosid, delphinidin va mt it sc t khac. - Acid hu c: acid hibiscic 23%. - Qu cha chu yu la acid citric 12 - 17%, acid malic, acid tartric. - L v i hoa cha nhiu acid tan trong nc v protein nh: acid citric, acid malic, acid tartric, acid hibiscus. Chng cng cha gossypetin v clorid hibiscin l nhng cht c tnh khng sinh. - Hoa cha hibiscitrin, hibiscetin, gossypitrin v sabdaritrin l loi flavonol glucosid c mu vng. - Qu kh cha canxi oxalat, gossypetin, anthocyanin v vitamin C. - Ht cha 7,6% nc, 22,3% du, 24% protein, 13,5% cht x, 7% cht khong. 1.3.5. Mt s cng dng ca hoa bp gim Bp gim c rt nhiu cng dng c trong y hc, thc phm v mt s lnh vc khc. Di y l mt s cng dng ca hoa bp gim [14][15]: - i qu (cc sn phm chnh ca cy) c th c ch bin thnh nhiu loi thc phm nh: tr nhng, ru vang, xir, mai, mt. - Du p t ht bp gim c tc dng khng sinh trn mt s chng vi khun nh Escherichia coli, Salmonella typhi, Bacillus subtilis, Coryne bacterium pyogenes, Staphylococcus aureus... v c tc dng khng nm trn mt vi loi nm: aspergillus, trychophyton, cryptococcus... - Hp cht anthocyanin v quercelin trong dch chit i hoa c kh nng khng khun, khng nm. c bit khi chng tc dng ln chc nng gan, mt th c th iu ho hm lng cholesterol trong mu, chuyn ho cht bo gip hn ch nguy c x va ng mch tai bin mch mu. - Mt chit on polysaccharit n hoa bp gim tan trong nc c tnh cht nh pectin polysacharit lm chm s pht trin ca khi u sarcoma 180 cy ghp trn chut.SVTH: Nguyn Th Thu Tho Trang 5

n cng ngh 1


- Nghin cu dc l cho thy i hoa bp gim c tc dng chng co tht c trn, lm th gin c trn t cung, lm h huyt p v c tnh khng sinh, tr ho, vim hng. Kinh nghim dn gian l nhai ngm i hoa bp gim tr vim hng, ho. - C cy c rt nhiu polysaccharid trong cht nhy. Nm 1992, Muller v Frranz tch polysaccharid tan trong nc ra ba loi HIB, HIB-3 c kh nng c ch ung bu. - Nc p t l i ti ca Bp gim c tc dng b dng v phng nga bnh ung th. ( c sn phm nc ung gii kht vi nhn hiu ng k l HibC ca Malaysia). - Trn th gii v c Vit Nam chit mu t l, i bp gim lm mu thc phm thay th cho cc loi ho cht khc. Ngoi ra cc b phn khc ca cy cng c s dng trit trong i sng hng ngy: + L, hoa , i qu s dng n sng, nu canh chua, kho c, gim st, h nhit. + Ht dng p du n v chn nui gia sc (thnh phn du tng ng du chit xut t ht hng dng) sn phm ph sau khi p du dng lm phn bn cho cy trng (nng sut ht t 700-800kg/ha). + V cy dai tng ng nh ay, c th dng dt bao ti, bn dy thng. + Thn cy lm bt giy cht t (thu ng 500-600kg/ha). 1.4. Gii thiu tng qut v mt s hp cht tan c kh nng khng oxy ha trong dch chit t i hoa bp gim Trong dch chit t i hoa bp gim c cha rt nhiu hp cht tan l cc anthocyanin, antraquinon, cumarin, acid uronic, saponin v cc cht anthycyanosid, ng kh, acid hu c, steroid, tinh du, ancaloid, cc vitamin. Nh vy trong i hoa bt gim c rt nhiu cht c gi tr trong lnh vc thc phm cng nh y hc. Di y l mt s hp cht c kh nng khng oxy ha: 1.4.1. Vitamin C (acid ascorbic) Axit ascorbic (cn c gi l vitamin C) c tm thy nhiu nht trong tri cy v l cht dinh dng rt cn thit cho s sng ca sinh vt. lnh vc ha sinh, n l cht chng oxi ha, tham gia vo cc qu trnh tng hp enzim, tng sc khng, phcSVTH: Nguyn Th Thu Tho Trang 6

n cng ngh 1


hi sc khe, c bit ngn nga bnh scurvy ngi. Axit ascorbic cn c dng lm cht bo qun thc phm v lm hng v cho mt s loi nc ung. 1.4.1.1. Cu to vitamin C Cng thc phn t: C6H8O6 Cng thc cu to:

Dng kh

Dng oxy ha

Hnh 1.3: Cng thc dng kh v dng oxy ha ca vitamin C [20] Tn theo IUPAC: 2-oxo-L-threo-hexono-1,4- lactone-2,3-enediol Tn thng thng: axit ascorbic, vitamin C. 1.4.1.2. Tnh cht [20] - Khi lng phn t: 176,13 g/mol, c dng bt mu trng n vng nht (khan), nng chy 190192 C - Kh nng ha tan trong nc cao. - D trong cng thc khng c nhm COOH nhng vitamin C vn c tnh axit. N c tnh cht ha hc tng t cc axit thng thng, c kh nng b oxi ha v b phn hy thnh CO2 v nc. 1.4.1.3. Lch s nghin cu v vitamin C - Vo th k 16, trong cuc pht kin a l ca cc nc chu u, nhng nh thm him lun thy thy th ca h phi cht v cn bnh k l vi triu chng mt mi, au khp, chy mu nu, l bnh Scurvy (hay Scorbut). - Mi n nm 1774, James Lind, bc s hng hi qu tc Anh, pht hin n tri cy s phng trnh c bnh scurvy. ng cho rng nhng ngi thy th i bin ch tip xc nhng mn n kh, mn, t n tri cy dn n cn bnh trn. Kinh nghim ca Lind cu sng rt nhiu thy th trong nhng chuyn hnh trnh bng ng bin sau ny. - Ngi nghin cu k v vitamin C l Albert Szent-Gyorgyi (1893-1986) gcSVTH: Nguyn Th Thu Tho Trang 7

n cng ngh 1


Hungary v ng c trao gii Nobel y hc nm 1937 v cng lao trn. Cng vo nm ny, gii Nobel ha hc c trao cho Walter Norman Haworth, ngi Anh tng hp thnh cng vitamin C. Tuy nhin, quy trnh tng hp vitamin C li c tn l Tadeus Reichstein, ngi cng tng hp thnh cng vitamin C cng lc vi Haworth (2 ngi tm ra cch tng hp hon ton c lp). Hin nay, vitamin C khng cn l vi mi ngi. T tri cy cho n nc ung, t vin thuc cho n ko ngm, u c s hin din ca n [20]. 1.4.1.4. Vai tr ca vitamin C i vi sc khe con ngi [21] Chng oxy ha km hm s lo ho ca t bo: nh phn ng chng oxy ho m vitamin C ngn chn nh hng xu ca cc gc t do, hn na n c phn ng ti sinh m vitamin E - cng l mt cht chng oxy ho - khng c. Kch thch s bo v cc m: chc nng c trng ring ca viamin C l vai tr quan trng trong qu trnh hnh thnh collagen, mt protein quan trng i vi s to thnh v bo v cc m nh da, sn, mch mu, xng v rng. Kch thch nhanh s lin so: do vai tr trong vic bo v cc m m vitamin C cng ng vai tr trong qu trnh lin so. Ngn nga ung th: kt hp vi vitamin E to thnh nhn t quan trng lm chm qu trnh pht bnh ca mt s bnh ung th (vm ming, d dy) Tng cng kh nng chng nhim khun: kch thch tng hp nn interferon cht ngn chn s xm nhp ca vi khun v virut trong t bo. Dn sch c th: vitamin C lm gim cc cht thi c hi i vi c th nh thuc tr su, kim loi nng, CO, SO2, v c nhng cht c do c th to ra. Chng li chng thiu mu: vitamin C kch thch s hp th st bi rut non. St chnh l nhn t to mu cho mu v lm tng nhanh s to thnh hng cu, cho php lm gim nguy c thiu mu [21]. Bng c ch c ch yu t hoi t bu, vitamine C gii hn s sn xut ra cc cytokine tin vim nh interleukin -1(IL-1), IL6 v IL8 v c c c tnh khng vim [22]. 1.4.2. Vitamin E 1.4.2.1. Cu to vitamin E


Trang 8

n cng ngh 1


Vitamine E thuc loi vitamin tan trong du. L cht gm mt nhn chromanol v mt dy phytyl no cha 16 carbon. S lng carbon v v tr nhm methyl (CH3) trn nhn chromatol cho ta nhng dng tocopherol khc nhau [23].

Hnh 1.4: Cu to vitamin E [23]

Hnh 1.5: Cc dng tn ti ca vitamin E trong t nhin [20] Vitamin E t nhin tn ti di 8 dng khc nhau, trong c 4 tocopherol v 4 tocotrienol. Tt c u c vng chromanol, vi nhm hydroxyl c th cung cp nguyn t hir kh cc gc t do v nhm R (phn cn li ca phn t) s nc cho php thm nhp vo cc mng sinh hc. Cc tocopherol v tocotrienol u c dng alpha, beta, gamma v delta, c xc nh theo s lng v v tr ca cc nhm metyl trn vng chromanol. Mi dng c hot ng sinh hc khc nhau [24]. C 2 loi vitamin E: c ngun gc t nhin v tng hp. - Vitamin E c ngun gc thin nhin: c chit xut t du thc vt nh u tng, bp, mm la mch, cc loi ht c du nh ht hng dng. Vitamin E thin nhin l mt ng phn duy nht ca d-alpha tocopherol. - Mc d c tc dng tt nht trong cc loi tocopherol, nhng do chit xut t cc thc phm thin nhin nn khng kinh t, v vy ngi ta sn xut ra loi vitamin E tng hp c cng thc l dl - alpha tocopherol, gm 8 ng phn nhng ch c 1 ng phn ging vitamin E thin nhin l d - alpha tocopherol (ch chim 12,5%), v vy tcSVTH: Nguyn Th Thu Tho Trang 9

n cng ngh 1


dng ca vitamin E tng hp thp hn so vi loi c ngun gc thin nhin. V vy mun t c hiu qu mong mun th khi s dng vitamin E tng hp, phi ung tng liu ln gp 1,4 ln so vi loi thin nhin [24]. 1.4.2.2. Tnh cht sinh hc ca vitamin E a. Tc dng chng oxy ha Chc nng ca vitamin E l bo v c th chng nhng tc dng c hi ca nhng gc t do. Nh dy lipide di (16 carbon), vitamine E gn ni mng lipide, v chnh nh chc v gn gc phenol m n c l cht c tnh chng oxy ha. Mng t bo c cu to bi acid bo c nhiu ni i nn rt d b oxy ha. S oxy ha ca acid bo mng t bo cho ra hng lot phn ng m kt qu cho ra gc lipoperoxyd (ROO) rt linh hot s lm ri lon chc nng sinh hc ca mng. Vitamin E c kh nng ngn chn phn ng ca cc gc t do bng cch nhng 1 hydro (H) ca gc phenol cho gc lipoperoxyl (ROO) bin gc t do ny thnh hydroperoxyd khng gy phn ng (ROOH). Phn ng nh sau: ROO + Tocopherol-OH ROOH + Tocopherol-O Trong qu trnh phn ng, tocopherol (Tocophrol-OH) b chuyn ha thnh gc tocopheryl (Tocopherol-O), bn nn chm dt nhng phn ng gc. Gc tocopheryl b kh oxy tr li tocopherol bi cht kh oxy ha tan trong nc, hin hin trong cytosol ca nhng t bo. Ngoi chc nng ngn chn s to thnh nhng gc t do ni t bo, vitamin E cn bo v nhng cht to nn t bo nh protein v acid nucleic. Vitamin E lm gim s peroxy ha ca lipid trong b nhn ca tc, lm lp da u bt hin tng kch thch, ngha l lm gim s kh x ca tc [25]. b. Tc dng chng vim Vitamin E c ch s peroxyd ha cc lipid bng cch by cc gc t do s to thnh prostaglandines, l cht trung gian sinh l ca s vim. Nhiu nghin cu dc hc chng t hot tnh ca vitamin E trn s chng vim. Vitamin E lm gim bnh ban v bnh ph. Bi vy khi b nng rt da, c th dng vitamin E cha [25]. c. Tc dng nng h min dch Vitamin E c tc dng trong nng h min dch ca c th lm tng chc nng ca cc i thc bo. Bn cnh chng cng lm tng kh nng sinh khng th ca cSVTH: Nguyn Th Thu Tho Trang 10

n cng ngh 1


th v lm gim prostaglandin, mt cht ging nh hormone c lin quan n chc nng min dch. d. Tc dng chng tia t ngoi Vitamin E l hng ro bo v chng nhng tia bc x c hi bi v vitamin E c kh nng hp th nhng bc sng ca tia UV v n c d tr di lp mng t bo nn ngn cn c nhng tia UV trc khi nhng t bo phi t mnh chng li. Nhng tn hi do UV gy ra cho genome ca da c dch ra bng nhng s sai lch trong khi phn chia ADN. Nu chng khng c sa cha th nhng s bt bnh thng ADN s mang n nhng ri lon trong nhng hot ng ca t bo, em theo s thoi ha t bo. nh hng trc tip ca s tn cng ca tia UV trn ADN l n lm mt s st nhp ca Thymidine. c nhng nghin cu chng minh rng vitamin E lm cho thymidine st nhp tr li AND [25]. e. Tc dng chng lo ha Tia UVB lm gia tng sc t lm da sm en, tia UVA lm da b lo ha, b nhn nheo. S tc ng ca tia t ngoi trong nh nng mt tri hay stress trong cng vic, hay nhim mi trng chung quy l to ra gc t do m cc nh khoa hc gi l th phm ca qu trnh lo ha. Cht ny sinh ra nhiu ti mc m h thng bo v t nhin ca c th khng c kh nng chng . V h qu l cc gc t do ny ph hy cu trc collagen, elastin- l thnh phn chnh trong cu trc da lm cho cu trc ny tr nn lng lo, gim i s n hi vn c ca ln da khi cn tr, ln da tr nn kh, mt nc v th rp. Vitamin E s bo v cu trc mng t bo, bo v cu trc collagen, elastin ca da khi s ph hy ca gc t do, nh qu trnh lo ha da b chm li, s xut hin cc np nhn da v th cng b c chiu hng gim [26]. f. Tc dng cha bnh Tc nhn bo v no: gim bnh Alzheimer No cha mt s lng ln cc acid bo khng bo ha. Khi cc acid bo trong mt t bo no b ph hy, s c mt chui phn ng dy chuyn khin cho hng lot acid bo trong t bo no b ph hy theo. Vitamin E l cht ha tan trong m nn n n nhng ni c m v nh mt cht che ch cho cc t bo khi b ph hy. Ta bit vitamin gi m cho mng t bo mm do nn s gip ch cho nhng t bo no thu nhn cht dinh dng d dng cng nh thi cc cht cn b. Nu mng tSVTH: Nguyn Th Thu Tho Trang 11

n cng ngh 1


bo cng, s thm thu s kh khn, cc cht thi s tch t bn trong t bo no khin t bo hot ng km i v cui cng s b thoi ha, dn n bnh Alzheimer. Do dng vitamin E s lm gim nhng bnh thoi ha do cc gc t do gy ra [25]. Tc nhn bo v mt : gim bnh cm mt V vitamin E i qua ng gic mc, ni mt, nn c n s gip gim nguy c b cm mt v gc t do sinh ra do mi trng nhim v tia cc tm ph hng protein ca tinh th mt nn gy ra cm. g. Cc tc dng khc ca vitamin E Vitamin E l mt trong nhng cht nm trong nhm vitamin v cng tun theo chc nng ca nhm vitamin l tham gia vo cc phn ng ca c th vi vai tr xc tc, gip c th chuyn ha (trong nhng trng hp c th, nu thiu c th gy ra nhng bt thng cho c th). Nh vy, tuy vitamin E khng phi l mt cht tham gia trc tip vo qu trnh chuyn ha ca c th nhng li c tnh cht gp phn rt quan trng trong qu trnh ny, gip cho c th khe mnh, chng li s sn xut d tha gc t do, chng li qu trnh cht t bo, km hm qu trnh lo ha, gip da tc mn mng...., ngoi ra cn c nhiu tc dng khc gip nng cao cht lng sng ca con ngi. Vitamin E cng lm gim nh cc triu chng chut rt, au cc bp c hoc au bng khi hnh kinh cc em gi tui v thnh nin. Qua nghin cu thc nghim, cc nh khoa hc nhn thy vitamin E c th c ch qu trnh oxy ha DNA nn c ch hot ng ca chui t bo ung th v, lm gim c 95% s gia tng t bo ung th v ngi s dng alpha tocopherol, ngha l vitamin E c th gy c c tnh chn lc n cc t bo ung th v [25]. Cc nghin cu khc cho thy nhng ph n c b sung vitamin E th t l b ung th bung trng thp hn 67% so vi nhm khng c s dng. Ngoi ra, vitamin E cn gp phn ci thin tnh dc, gip non (trng) v tinh trng pht trin tt hn, nng cao kt qu iu tr v sinh [25]. 1.4.3. - carotene -carotene l tin cht ca vitamin A. Khi b tha vitamin A s b o thi, cn carotene c d tr trong gan n lc cn thit. -carotene tham gia v nh hng n mt s qu trnh sinh l trong c th nh tng cng h min dch, ngn nga mt s ung th ng tiu ho Tinh th -caroten c mu vng v dung dch c muSVTH: Nguyn Th Thu Tho Trang 12

n cng ngh 1


vng cam. Tt c tin vitamin u khng tan trong trong nc nhng tan trong du v dung mi hu c. -carotene c nhiu trong gc, c rt, da , c ci , du ty, b ng 1.4.3.1. Cu to - carotene 1.4.3.2. Tnh cht sinh hc ca -carotene a. Tc dng chng oxy ha, chng lo ha da Tia UV trong nh nng mt tri to ra rt nhiu gc t do gy tn hi cc t bo da. Cc vitamin v cc dng cht c kh nng chng oxy ha thng tp trung rt nhiu da nh beta-carotene, vitamin E v C. Chng tp trung nhanh chng n nhng ni c nhiu gc tHnh 1.6: Cng thcha cc gc t do [28]. do trn da trung cu to -caroten [27] b. Tc dng ci thin chc nng h min dch -carotene tc ng ln t bo bch cu n nhn (monocyte) mt loi t bo min dch gip tm kim v ph hy cc t bo ung th v cc vi khun gy bnh. Trn b mt cc monocyte c mt loi protein c bit l MHC II gip cho cc monocyte c th nhn din v phn bit cc t bo ung th vi cc t bo bnh thng. MCH II c xem nh mt loi rada chng ung th. Khi MCH II pht hin ra mt t bo ung th, monocyte lp tc gi tn hiu n cc t bo min dch khc, chng s di chuyn n v ph hy t bo bt thng. Tuy nhin, nu monocyte khng c cc MHC II trn b mt, cc t bo ung th s nghim nhin di chuyn m khng b nhn din, v ri chng tip tc sao chp, sinh sn nhn i ngy mt nhiu hn. Ngoi ra, -carotene trong cc ch phm thuc c kh nng lm tng hot ng ca cc t bo tiu dit t nhin (NK). l nhng t bo min dch rt mnh, chng tn cng tiu dit khng ch cc t bo ung th m cn cc t bo b nhim virus [28]. c. Tc dng i vi ung th -carotene cn gip gim thp nguy c nhiu loi ung th khc, nh ung th v, ung th vng chu, tuyn tin lit, ung th thc qun, ung th phi[28] d. Tc dng i vi cholesterol Cholesterol l mt cht thit yu cho cuc sng, n l nn tng cu trc ca nhiu hormone steroid trong c th. C th cng s dng cholesterol sn xut vitamin D. Tuy nhin nng cholesterol trong mu tng cao s l mt vn khng tt cho sc khe, nh to ra qu nhiu gc t do gy tn thng t bo, nht l dng cholesterol t


Trang 13

n cng ngh 1


trng thp LDL (Low Density Lipoprotein Cholesterol) ng vai tr trung tm trong nhiu bnh l tim mch. Cc t bo bch cu trong mu nhn din c nhng LDL oxy ha c hi cho c th, chng tn cng v tiu hy LDL cng tng t nh tn cng cc vi khun xm nhp. Cc bch cu b y LDL-cholesterol b bt gi v mc kt trn thnh cc ng mch, ni y bt u s lng ng cholesterol. Do vy, mt trong nhng bc quan trng trong vic ngn nga cc bnh l tim mch l phng chng s oxy ha LDL thng qua kh chng oxy ha ca -carotene [28]. e. Tc dng tr bnh qung g Qung g l mt triu chng kh ph bin ca tnh trng thiu vitamin A, biu hin bi s khng thch nghi nhanh chng ca mt i vi s thay i nh sng. Qung g c th dn n nhiu bnh mt nguy him, thm ch c th m hon ton. Trong s c c tng nhn p v vim vng mc sc t. V -carotene c th c chuyn thnh vitamin A trong c th, nn n cng c nhng tc dng hu ch tng t nh vitamin A mc d chm hn [28]. 1.4.4. Anthocyanin 1.4.4.1. Cu trc ca anthocyanin Anthocyanin l nhng glucozit do gc ng glucose, glactose... kt hp vi gc aglucon c mu (anthocyanidin). Aglucon ca chng c cu trc c bn c m t trong hnh 1.7. Cc gc ng c th c gn vo v tr 3,5,7; thng c gn vo v tr 3 v 5 cn v tr 7 rt t. Phn t anthocyanin gn ng vo v tr 3 gi l monoglycozit, v tr 5 v 7 gi l diglycozit.R1 OH 7 5 A OH O+ B3

OH R2

3

OH

Hnh 1.7: Cu trc c bn ca aglucon ca anthocyanin Cc aglucon ca anthocyanin khc nhau chnh l do cc nhm gn vo v tr R1 v R2, thng l H, OH hoc OCH3 [3]. Khung cacbon ca anthocyanin gm hai vng benzen A, B v vng pyran C trong vng A kt vi vng C to thnh chroman. Tt c anthocyanin u c cha trong vng pyran oxy ho tr t do. Tuy nhin ngi ta cha bit c chc chn nguyn tSVTH: Nguyn Th Thu Tho Trang 14

n cng ngh 1


no: oxy hay carbon mang in tch dng t do. Do anthocyanin thng c biu din di dng cng thc trung tnh [8].

OA C

B

Cl OA C

B

OHCng thc thng

OHCng thc trung tnh

Nh in tch dng t do ny m cc anthocyanin trong dung dch acid tc dng nh nhng cation v to mui c vi cc acid. Cn trong dung dch kim th cc anthocyanin li tc dng nh anion v to mui c vi base [8]. 1.4.4.2. Tnh cht ca anthocyanin a. Tnh cht vt l: * Tnh tan: Anthocyanin ha tan tt trong dung mi phn cc nh nc v t tan hoc khng tan trong cc dung mi khng phn cc nh ether, benzen, aceton, cloroform... v c bit chng rt bn trong mi trng axit mnh. Trong thin nhin, anthocyanin tn ti dng monome hoc polyme. Khi kt hp vi ng th anthocyanin d ho tan hn [9]. * Mu sc: Mu sc ca anthocyanin lun lun thay i ph thuc vo nhit , pH, s lng OH nhm OH trong vng benzen v nhiu yu t khc... Cc anthocyanin c th b ph hy v mt mu khi bO nhit trong thi gian di, gia c bit cc cht mu HOdng b ph hy hn cht mu vng. d O Mu sc ca anthocyanin ph thucC mnh vo pH mi trng: Thng thng rt A khi pH > 7 cc anthocyanin cho mu xanh, khi pH < 7 cc anthocyanin cho mu . O-Glucose - pH = 1, cc anthocyanin O-Glucose thng dng mui oxonium mu cam n . + - pH = 4,5 5, chng chuyn(dng trungmu: base carbinol hay base chalcone. Cyanidin v khng tnh) - pH = 7 8, li v dng base quinoidal anhydro mu xanh._ OH lng tnh nn chng c kh nng to mui bn O Cc anthocyanin c tnh vng OH trong mi trng acid v base. Mui vi acid th c mu , cn mui vi base th c Oc mu tm H OHB

mu xanh [9]. O HOA C

B

HOA

OC

B

O-GlucoseSVTH: Nguyn Th Thu Tho Cyanidin (dng cation) c mu trong mi trng acid

O-GlucoseTrang 15 Cyanidin (dng anion) c mu xanh trong mi trng kim

O-Glucose

O-Glucose

n cng ngh 1


C

Khi tng s lng nhm OH trong vng benzen th mu cng xanh m. Mc metyl ha cc nhm OH trong vng benzen cng cao th mu cng . Nu nhm OH v tr th 3 kt hp vi cc gc ng th mu sc cng s thay i theo s lng cc gc ng c nh vo nhiu hay t. Cc anthocyanin cng c th to phc vi cc ion kim loi cho cc mu khc nhau nh: mui kali kt hp vi anthocyanin cho ra mu mu, mui canxi kt hp vi anthocyanin cho ra mu xanh ve[9]. * Kh nng hp th ca anthocyanin hp th th hin bn cht ca mi loi anthocyanin do cc anthocyanin khc nhau th kh nng hp th cng khc nhau. hp th ca anthocyanin ph thuc vo cu to, pH mi trng, nng anthocyanin... Thng thng pH thuc vng acid mnh s c hp th ln hn, nng anthocyanin cng cao th hp th cng mnh. Trong vng nh sng nhn thy c, cc anthocyanin c hp th cc i ti bc sng 510 540 nm. hp th l yu t lin quan n mu sc anthocyanin, n phn nh mu sc ca cc anthocyanin v t l vi nng ca chng.


Trang 16

n cng ngh 1


Ngoi ra cc anthocyanin cn c kh nng hp th tia t ngoi do h thng ni i lin hp to ra bi hai vng benzen A, B v vng pyran C. hp th nm trong di 220 280 nm [1][5][6]. b. Tnh cht ha hc Anthocyanin c cu thnh bi vng benzen, cc nhm hydroxyt, phenolic, nhm metyl,...nn n mang c tnh ca cc nhm . Ngoi ra chng cn c nhng tnh cht do v tr v s lng ca cc nhm OH, h ni i lin hp v cc nhm th, ... Di y xt mt s tnh cht c bn: Phn ng ca nhm OH: * Th hin nh acid: Anthocyanin tham gia phn ng trung ha vi NaOH [6].

OH OH HOA B

ONa ONa NaO+ 5NaOHA B

OC

OC

OH OH

ONa ONa

+ 5H2O

* Phn ng ester ha: Do c nhm OH, cc anthocyanin c th tham gia phn ng ester ha theo c ch:

OH+ X-R

O-R o h m

* Phn ng to lin kt hydro:


Trang 17

n cng ngh 1


Khi khng c tr ngi v cu trc khng gian, lin kt hydro c hnh thnh gia cc nhm OH t do trong cng phn t hoc gia cc phn t vi nhau v ng vai tr quan trng trong s n nh cu trc phn t.

OH

...

OH

...

OH

* Phn ng vi kim loi: Do nh hng ca nhn benzen nn H linh ng trong nhm OH, v th n tham gia phn ng vi kim loi:

OH R OHMe2+

O R O

Me

Cc anthocyanin cc loi cy khc nhau c th kt hp vi nhiu loi ion kim loi cho mu sc khc nhau, chng hn anh o s chuyn sang mu tm khi c mt thic hoc nhm nhng nhm li khng nh hng n mu ca nho , cc anthocyanin ca nho th ch thay i ng k khi c mt Fe, Sn hoc Cu. Phn ng ca vng benzen: Do nh hng ca nhm OH n vng benzen m cc anthocyanin u tham gia phn ng th (vi nc brom). Phn ng xy ra ti v tr 6, 8 theo phng trnh [7]:

OH Br HO OA C B

OH

OH +O2

+ Br2

Br O-Glucose

O-Glucose

polyphenoloxydase

OH

Phn ng oxy ha :

HOA

DiO dng ca emzyme polyphenoloxydase, anthocyanin d b oxy ha. HO tc

B

C

A


O-Glucose

Trang 18

O-Glucose

O

n cng ngh 1


c. Tc dng sinh hc ca anthocyanin Anthocyanin trong thc vt l mt trong nhng hp cht t nhin c hot tnh sinh hc cao, lin quan n tnh min dch, tnh chng chu i vi tc ng ngoi cnh, ngha l chng c lin quan n hu ht qu trnh hot ng sng ca thc vt v nhiu hot ng c th con ngi. Tc dng i vi enzyme Mt trong nhng tnh cht quan trng ca cc anthocyanin l kh nng tng tc vi protein. iu ny xy ra l do phn ng gia nhm oxyphenolic (-OH) v oxycacbonyl ca nhm pectic hnh thnh lin kt hydro [4].

HN CO . . . H_O R

Enzyme xc tc phn ng oxy ha cc anthocyanin to thnh hp cht c mu. Cc anthocyanin khi dng oxy ha (quinon) c th tc dng vi nhm -SH, -NH2 ca protein, aminoacid, amin. Phc gia quinon v acid amin thng c mu , phc gia quinon v polypeptid hoc protein th c mu nu. Do anthocyanin c th b mt mu khi c mt ca aminoacid [9]. Tc dng flavonoid ni chung v anthocyanin ni ring ln cc enzyme l c s sinh ha cho vic s dng cc cht flavonoid thin nhin vo lnh vc sinh hc, y hc, phc v sc khe v i sng con ngi. Tc dng chng vim S nhim trng, d ng chn thng,... c nguyn nhn ni sinh hay ngoi sinh, s ri lon qu trnh trao i cht ca t bo gy ra bi tc dng ha hc (c t) hoc sinh vt (nhim trng)... u c th dn n phn ng trong m hoc c quan, i khi lan trn sang ton b c th. Cc anthocyanin cn c tc dng khng mt s loi vi khun tc dng gp phn vo tc dng chng vim.SVTH: Nguyn Th Thu Tho Trang 19

n cng ngh 1


Tc dng lm bn thnh mch Mt s anthocyanin c tc dng lm tng sc bn v tnh n hi ca thnh mch, ch yu l do kh nng iu ha, lm gim sc thm ca mao mch, ngn cn khng cho protein ca mu thm dch qua m khc, c tc dng d phng v mao mch gy xut huyt, ph thn. Anthocyanin khng nhng c tc ng n tnh chng chu ca mch mu cn tc ng n nhng biu hin lm sng nh rt ngn thi gian b st, gim bt thi gian ri lon hot ng ca h tim mch [6]. Tc dng chng tia t ngoi Cc tia phng x tc ng ln c th con ngi s gy kch thch lm t bin gen do thay i ADN gy cc bnh nguy him nh ung th... cc anthocyanin s hp th tia t ngoi c bc sng 220 280 nm v chuyn v trng thi kch thch, t c th ph hy hoc chuyn v trng thi v hi. Chnh v th anthocyanin gip c th t bo v v chng li nhng bc x in t gy bnh. Tc dng i vi ung th Nhng nghin cu gn y cho thy cc dch tit giu anthocyanin c kh nng ngn chn s phn chia v ca t bo ung th. mt liu lng thch hp chng km hm phn ng dy chuyn gy ra bi gc t do nn c tc dng tr bnh, nhng nu vt qu chng s lm tng cng s nhy cm ca t bo sinh vt i vi bc x [6]. 1.4.4.3. Mt s ng dng ca anthocyanin trong cng nghip thc phm cng nh trong y hc c nhiu nghin cu cho thy nhng cht mu tng hp c nhiu tc dng ph gy hi cho c th ngi s dng. Do vy xu hng th gii hin nay l quan tm n vic s dng cc ngun cht mu t nhin. Cht mu t nhin c u im ni bt l ngoi vic to mu cho sn phm, n khng gy ra nhng tc dng ph c hi, m cn c tc dng dc l. Hin c nm cht mu t nhin c s dng l anthocyanin (), annatto (mu vng ), beetroot (c ci ng), turmeric (c ngh) v carmine (c ci ngh). Trong cht c bit nhiu nht l anthocyanin. Anthocyanin c xem l phm mu c th thay th cho cc cht mu tng hp ang b cm s dng v n c nhng u im: khng gy bin chng c hi cho ngi v gia sc, c mu ti sng, c bit vng mu , tan trong nc nn rt d phi trn trong cc sn phm thc phm...[16]. Trong sn phm thc phm cng vi cht mu t nhin khc nh carotenoid,SVTH: Nguyn Th Thu Tho Trang 20

n cng ngh 1


chlorophyll, anthocyanin gip sn phm phc hi li mu t nhin ban u, to ra mu sc hp dn cho mi sn phm. Hn na vi c tnh chng oxy ha, anthocyanin cn c dng lm bn cht bo, dng trong cc sn phm tht, gi, ch Trong lnh vc y hc, qua qu trnh nghin cu, cc nh khoa hc pht hin anthocyanin c nhiu tc dng cha bnh rt tuyt vi. - Cht mu anthocyanin trong Billberies c s dng rng ri nh mt phng thuc cha bnh ri lon tun hon mu, chng lo ho, chng tia t ngoi v l cht chng d ng, vim lot, khng nhiu loi vi khun kh tiu dit, tng cng chc nng chng c ca gan, ngn nga nhim m gan v hoi t m gan, iu ho lng cholesterol trong mu, trnh nguy c tc nghn, x va ng mch, phc hi trng lc tim, iu ho nhp tim v huyt p, iu ho chuyn ho canxi,[6]. - Anthocyanin a cc cht chng oxy ha nh flavonoid vo c th bo v t bo, gip ngn nga cc nguy c nh x va ng mch, tai bin mch mu, lo ha tn thng do bc x, thoi ha gan... Cc dn xut anthocyanin to c phn ng vi cc ion kim loi m chnh cc ion kim loi ny l xc tc cho nhiu phn ng oxy ha. Cc dn xut anthocyanin c tc dng ti to t bo vng mc v gip tng th lc vo ban m. V vy anthocyanin c dng ch yu phng nhng bin c ca x va ng mch, iu tr cc trng hp suy yu tnh mch, nhng trng hp xut huyt nh chy mu cam, ho ra mu, t cung xut huyt...[16]. 1.5. Kh nng khng oxy ha ca cc hp cht tan chit t i hoa bp gim Hin nay ngi ta tm thy c hng trm cht khc nhau c kh nng c ch qu trnh oxy ha ca du m. 1.5.1. C ch ca qu trnh peroxide cc lipid C ch ca qu trnh peroxide cc lipid u thng qua c ch to ra gc t do. C ch gm 3 giai on: - Giai on khi mo. - Giai on pht trin mch. - Giai on kt thc ( tt mch). 1.5.1.1. Giai on khi mo u tin phn ng c khi mo bng mt vi phn t lipid (RH) b oxy ha to thnh gc t do: RH R + H (1.1)Trang 21


n cng ngh 1


Trong : R : gc ca acid bo no hoc khng no t do hoc gc ca acid bo trong phn t glyceryl. H : nguyn t H C so vi ni i, hoc nguyn t H ca nhm metylen bt k trong acid bo no. to thnh gc t do phn ng cn cung cp nng lng t 70 100kcal/mol. Tuy nhin khi c oxy ha tan th tng tc gia RH ban u v oxy s xy ra mt cch mnh m hn. V l s to thnh gc theo phn ng lng phn di y i hi nng lng ch l 47kcal/mol. Trong iu kin c oxy, s tin trin tip theo ca qu trnh t oxi ha c xc nh bi tc tch t hydroperoxide l cc sn phm trung gian ca phn ng:RH + O2 R + HO2

(1.2)

Trng hp nng RH cao th c th xy ra phn ng tam phn: Nng lng cho phn ng ny nh hn phn ng lng phn.RH + O2 + HR1 R + R1 + H2O2 (1.3)

Gc t do ny cng c th pht sinh khi c kim loi giao chuyn v c mt ca oxy:Me2+ + O2 + H+ Me3+ + HO2 (1.4)

Gc ny s phn ng vi cc gc cha no hoc acid bo ca mng v cho ra gc R khi mo mt dy chuyn oxy ha lipid


Trang 22

n cng ngh 1 HO2 + RH R + O2 RO2 + RH ROOH RO2 ROOH + R H2O2 + R H2O2 + R (1.6 )


(1.5)

(1.7) (1.8)

Cho n nay th c ch thc s ca s khi mo, phn ng mch th nht ca du m v hydrocacbua khc cho n nay vn mc gi thit. Nhng c ch to thnh cc gc t do trong phn ng trong trng thi kh cng nh khi oxy ha cc hydrocacbua 1.5.1.2. Giai on pht trin mch Khi c mt oxy gc R s tng tc vi phn t oxy to thnh cc gc RO2. Gc ny c th tc dng vi mt acid bo cha no nh acid linoleic, acid ny cho hydroperoxide (ROOH) v dy chuyn li tip tc vi cc gc R mi theo c ch ging (1.6), (1.7). Trong khi Me2+ s ph hy lipid cho ra cc gc t do theo cc hng khc nhau: Me2+ + ROOH RO + OH- + Me3+ (1.9)

Khi cc gc t do R hoc RO2 c to ra trong h do qu trnh khi mo th mch bt u bin i oxy ha. Kt qu ca cc qu trnh ny l nhng sn phm trung gian u tin c hnh thnh nh hydroperoxide (ROOH) v cc gc t do mi RO, Rcc gc ny trong iu kin c oxy th chng s tc dng vi oxy to ra gc peroxide (RO2). Cc phn t ROOH ny rt d b phn hy v l nguyn nhn ch yu gy ra s pht sinh mch nhnh ca mch oxy ha:ROOH 2ROOH RO + OH

(1.10)

RO2 + H2O + RO (1.11)

T c th nhn thy rng gc RO2 l gc ch yu dn u trong mch oxy ha [2]. Cng vi vic to ra cc gc t do, qu trnh cn to ra cc sn phm th cp nh ru, cetol, andehydel nhng sn phm c v lm sai lch chc nng bnh thng ca t bo.SVTH: Nguyn Th Thu Tho Trang 23

n cng ngh 1


RO + RH

ROH + R (1.12)

1.5.1.3. Giai on kt thc y l giai on lm mt cc gc t do, xy ra ch yu do kt qu tng tc ca cc gc theo c ch lng phn, ch xy ra khi hai gc tng tc vi nhau to ra sn phm phn t: R R + R + RO2 sn phm phn t sn phm phn t sn phm phn t (1.13) (1.14) (1.15)

RO2 + RO2

Nng lng trong phn ng ny khng ng k khong t 1- 2kcal/mol nn vn tc phn ng rt ln. Tc oxy ha t l thun vi nng c cht oxy ha v t l nghch vi cn bc hai ca tc khi mo. Nng cc cht t do cng tng th tc khi mo cng tng theo [2]. 1.5.2. Cc yu t nh hng n vn tc oxy ha [10] 1.5.2.1. Cc yu t kch thch - nh hng ca cc acid bo t do: acid bo t do c tc dng xc tc qu trnh oxy ha, lm tng nhanh s phn gii hydroperoxide thnh cc gc. - nh hng ca oxy: vn tc t oxy ha ph thuc vo lng oxy trong mi trng. V s pht sinh chui phn ng ch yu ph thuc vo RH + O2. - nh hng ca nhit : nhit c nh hng ln n phn ng ha hc. Tng nhit lm tng lng peroxide to thnh. nhit 40 450C v cao hn, s phn gii hydroxide s tng. - nh hng ca trng thi lipid: b mt tip xc ca cht bo vi khng kh cng ln th vn tc oxy ha cng cao. Vn tc oxy ha cn ph thuc vo chiu dy ca lp lipid. Khi lp dy th oxi kh xm nhp, gim nhit n khi cht bo chuyn sang trng thi rn th vn tc oxy ha cng gim. - nh hng ca kim loi chuyn tip: cc ion cng nh cc hp cht ca kim loi chuyn tip c tc dng xc tc s oxy ha lipid. Thc nghim cho thy rng khi c mt st trong du vi lng 0,2 -10 mg/kg st s lm gim bn ca du i vi oxy ha 20 -50%. Vi Cu ch cn 0,05 -0,2mg/kg s lm gim bn ca du i vi oxy ha 20 -50%. Ion kim loi chuyn tip c cc electron c thn v thc cht l cc gc.SVTH: Nguyn Th Thu Tho Trang 24

n cng ngh 1 Mn+ + RO Mn+ + RO2 M(n+1) + RO2

GVHD: Ths. Nguyn Th Lan M(n+1)+

+ RO

-

(1.16) (1.17) (1.18)

M(n+1)+ + RO2M(n+1)+ + R+ + O2

Nhng tnh cht gc ca chng th hin yu do chng tn ti trong dung dch vi nng ln. Tuy nhin chng c th chuyn hoc ly electron t mt ht bo ha ha tr no to thnh gc t do hot ng hoc gc ion. - nh hng ca nng lng mt tri v tia ion: nng lng nh sng c bit l tia cc tm v tia ngn ca quang ph nhn thy c tc dng xc tc qu trnh oxy haInH2 RO2 RH (1.19) ROOH + InH

lipid. C l nng lng nh sang s quang phn hydroperoxide thnh cc gc t do.

- nh hng ca nc: nc lm tng tnh n nh ca cht bo i vi s oxy ha 950C. 1.5.2.2. nh hng ca yu t km hm Vn tc phn ng RO2 + RH c th c gim bng cch hng cc phn ng ca gc peroxide theo chiu khc bng cch a vo trong lipid cht chng oxy ho InH2 ngha l cht c kh nng phn ng d dng vi gc RO2 hn.

Kt qu l thay gc peroxide RO2 bng gc ca cht chng oxy ha In l gc yu khng th tng tc vi phn t lipid. Cc gc In s b v hot do s t hp:RO2 + InH2 In

(1.20) (1.21) (1.22)Trang 25

In + In

In-In

SVTH: RO2 + In Thu Tho ROOIn Nguyn Th

n cng ngh 1


iu kin tha mn c bng cch a vo nhng cht chng oxy ha c bn cht phenol hoc amin. Mt cch khc gim nng RO2 l gim vn tc phn ng pht sinh ra chng. 1.5.3. C ch km hm qu trnh oxy ha ca cht mu anthocyanin [7] Tc ca qu trnh oxy ha c xc nh do s thay i nng ca gc RO2. Nng ny c xc nh bng t s tc to to thnh v tan r ca cc gc t do trong h phn ng. Do vy mun gim cng ca qu trnh oxy ha tc l gim tc phn ng (1.6). Bng cch ngi ta thm vo du m cc cht chng oxy ha (IH). Gc t do RO2 d dng phn ng vi cc cht ny hn phn t ca c cht RH. RO2 + IH ROOH + I (1.23)

Kt qu phn ng l gc peroxide bin i thnh cht chng oxy ha I, gc ny c i lc yu nn khng th tin hnh mch oxy ha c, tc l khng th tc dng tng h vi cc phn t ca c cht RH. Nhiu nh khoa hc a ra cc lp lun khc nhau v c ch km hm oxy ha du m ca hp cht phenol, nhng bn cht c ch c mi ngi tha nhn l chng rt d b oxy ha v lc bt u oxy ha th nguyn t hydro c tch ra v gc phenoxyl (I) c to thnh. Gc ny khng c hot tnh nn khng th c kh nng tip tc qu trnh mch oxy ha c. RO2 + IH I + I RO2 + I ROOH + I (1.24) I RO2I (1.25) (1.26)

Cc cht phenol c c im l nng lng lin kt ca nguyn t hydro trong thnh phn nhm hydroxyl nh hn so vi nng lng lin kt ca nguyn t hydro trong cc nhm metylen ca mch hydrocacbua ca cc glycerin du m. Chnh do tnh cht trn m cc cht phenol c hiu lc chng oxy ha i vi qu trnh oxy ha hydrocacbua.


Trang 26

n cng ngh 1


Anthocyanin khng ch l cht mang mu sc, m chng cn hot ng nh mt cht chng oxy ha. Kh nng chng oxy ha ca anthocyanin mnh hay yu l do cu to ca chng. Kh nng khng oxy ha ca anthocyanin l do: - To phc bn vng vi cc kim loi (Fe2+, Cu2+) do lm mt kh nng phn ng oxy ha cht bo. - C kh nng nhn cc gc t do:R + Ar-OH RH + ArO

(1.27)

RO2 + Ar-OH

RO2H + ArO (1.28)

Trong : R, RO2: gc t do hot ng, km bn vng. ArO : gc t do km hot ng, bn vng. Cc gc t do c sinh ra nh R, RO, RO2t bn vng v c kh nng phn ng rt ln l nguyn nhn gy ra qu trnh peroxide ha cc hp cht hu c, lm tn thng ti mng t bo, tc ng n hot ng bnh thng ca t bo. Nh vy s lng tng ln cc gc t do hot ng trong t bo lm cho cc phn t sinh hc b bin i, nhng protein bt thng xut hin trong c th lin quan ti s lo ha sm, cc chng vim, ung th. Kh nng chng oxy ha ca anthocyanin th hin khi a chng vo c th s sinh ra cc gc t do bn vng trong qu trnh bnh l. Gc ArO c gi l tc nhn thu dn v hy dit cc gc t do c hi bo v c th. Tnh cht chng oxy ha ca cc hp cht tan c trong dch chit ca i hoa bp gim gip c th bo v v phng chng li mt s bnh. N ng vai tr quan trng trong bo v gan, vim gan cp tnh, x gan, c bit dng lm cht bo trong cng ngh thc phm.

PHN II: I TNG V PHNG PHP NGHIN CU Trong dch chit t i hoa bp gim c nhiu hp cht tan c kh nng khng oxy ha nh vitamin C, vitamin E, -caroten... Nhng chng ch c hm lng rt t, cn hm lng anthocyanin li nhiu nn ti ch nghin cu cc yu t nh hng n kh nng khng oxy ha ca hp cht anthocyanin.


Trang 27

n cng ngh 1


2.1. Quy trnh nghin cu cc yu t nh hng n kh nng khng oxy ha ca hp cht tan anthocyanin

Nguyn liu ti

Ra sch bng nc, ro

Nghin nh

Nguyn liu kh

Chit trong dung mi (etanol/nc = 1:1 c 1% HCl) t = 30 70oC, T =45 75 pht

Lc b kt ta

Bay hi dung mi (500C)

Ly tm ly dch trong dng lm mu phn tch (o mt quang)

Cc yu t nh hng n kh nng khng oxy ha ca hp cht anthocyanin

Nng anthocyanin 2.2. Thuyt minh quy trnh

Thi gian phn ng

Nhit phn ng

Nguyn liu: i hoa bp gim nu ti th tin hnh ra sch bng nc ri

ro, cn i hoa bp gim kh c x l, lm sch. Lm nh: nhm mc ch tng din tch tip xc gia nguyn liu v dung

mi, to iu kin cho qu trnh chit tch c thc hin d dng v hiu qu.SVTH: Nguyn Th Thu Tho Trang 28

n cng ngh 1


Ngm: i vi mu l mu hoa kh trc khi chit tch th phi ngm trong

nc cho cc i hoa trng n thun li cho qu trnh tip theo. Chit: Tin hnh chit mu trong dung mi gm etanol/nc = 1:1 c 1% HCl

trong iu kin t = 30 70oC, T =45 75 pht. Lc: Sau khi chit xong lc b kt ta thu phn dch lng. Bay hi dung mi: Dch chit thu c em un 500C bay hi dung mi. Ly tm: Ly tm ly dch trong dng lm mu phn tch (o mt quang).

Nu dch chit thu c ta khng em ly tm th c th tinh sch bng cch: Cho petroleum ether vo loi tinh du, lp di c cha anthocyanin c chit ly. Tip theo b sung ether acetate nhm loi b cc flavonoid khng phi anthcyanin v loi nc, chit anthocyanin pha di. Cui cng em anthocyanin thu c em kho st cc yu t nh hng n kh nng khng oxy ha ca anthocyanin. 2.3. Kho st cc yu t nh hng n kh nng khng oxy ha ca hp cht tan anthocyanin [7] 2.3.1. Phng php xc nh kh nng khng oxi ha ca anthocyanin Nguyn tc phng php Trong mi trng acid cc cht hydroperoxit s oxy ha Fe2+ thnh Fe3+. Lng Fe3+ to thnh s to phc mu vi ammonium thyocyanate. Mu th c cht chng oxy ha th lng Fe3+ s t hn mu khng c cht chng oxy ha. Hot khng oxy ha c hin th bng phn trm (%) Fe2+ b c ch to thnh Fe3+ mu th so vi mu trng (khng c cht chng oxy ha). C ch ca qu trnh Khi cho Fe2+ vo hn hp c cha cc cht hydroperoxit, th Fe2+ s b oxy ha thnh Fe3+ v phn ng vi NH4SCN to phc c mu mu: Fe2+ - e + H+ Fe3+ + SCNFe3+ Fe(SCN)3 (mu mu)

Cng thc tnh phn trm c ch oxy ha:


Trang 29

n cng ngh 1 A0 A1 A0


Hd =

x 100

%

Trong : Hd: Phn trm c ch oxy ha. A0: Mt quang ca mu trng. A1: Mt quang ca mu th. 2.3.2. Kho st cc yu t nh hng n kh nng khng oxy ha ca hp cht tan anthocyanin 2.3.2.1. Kho st nh hng ca nng cht mu anthocyanin n kh nng khng oxy ha Tc oxy ha ca cht bo chu nh hng ca rt nhiu yu t. kho st nh hng ca nng anthocyanin n kh nng khng oxy ha tin hnh th nghim c nng thay i t 10 70mg/l. a. i vi mu cht chit trong acid - Chun b 8 bnh nh mc 100ml, trong c 7 bnh mu th v mt bnh mu trng. - Cho vo 7 bnh mu th, mi bnh 2ml dung dch anthocyanin chit trong mi trng acid c nng ln lt t 10 -70mg/l, cn bnh th 8 cho vo 2ml nc ct (lm mu trng). - Cho tip vo mi bnh trn 2,3 ml hn hp Tween80 2,5% trong ethanol + 9ml m phosphate. - y kn, lc u, bc giy bc trong t m 370C. - Sau 3h ly ra ngui. - Tip theo chun b hai cp ng nghim chia thnh hai hng, 7 cp u ln lt cho 1ml dung dch mu va ngui c nng ln lt t 10 -70 mg/l, cp th 8 cho 1ml nc ct. - 8 ng nghim hng th nht thm vo mi ng nghim 6ml ( ethanol 75% + dung dch HCl 35% + dung dch FeSO4 0,02M) lm mu th. - 8 ng nghim hng th hai thm vo mi ng nghim 6ml ( ethanol 75% + dung dch HCl 35% + nc ct) lm mu trng. - Sau 5 pht (khi thm FeSO4 ) cho vo mi ng nghim 4ml dung dch NH4SCN 6% SCN- to phc vi Fe3+.SVTH: Nguyn Th Thu Tho Trang 30

n cng ngh 1


- Tin hnh o hp ph bc sng 500 nm. b. i vi mu cht chit trong mi trng trung tnh Lm tng t nh mu chit trong acid. 2.3.2.2. Kho st nh hng ca thi gian n kh nng khng oxy ha ca cht mu anthocyanin Thi gian cng l mt yu t nh hng n s t oxy ha ca cht bo. xc nh yu t ny nh hng nh th no n hot khng oxy ha ca cht mu anthocyanin, tin hnh th nghim cc mc thi gian khc nhau vi hai mu chit trong hai mi trng khc nhau cng nng . a. i vi mu chit trong mi trng acid - Chun b 7 bnh nh mc 100ml. - Cho vo mi bnh 2ml cht mu anthocyanin c nng C = 50mg/l. - Cc bc tin hnh tng t nh mc 2.3.2.1 ch thi thay i thi gian cho tng mu l: Th t Bnh 1 Bnh 2 Bnh 3 Bnh 4 Bnh 5 Bnh 6 Bnh 7 Thi gian (gi) 2 2,5 3 3,5 4 4,5 5

Chun b mu trng song song vi mu th, cch tin hnh tng t nh mu th ch thay anthocyanin bng nc ct. b. i vi mu chit trong mi trng trung tnh Tin hnh th nghim tng t chit mu trong mi trng acid 2.3.2.3. Kho st nh hng ca nhit n kh nng khng oxy ha ca cht mu anthocyanin Nhit cng l mt trong nhng yu t nh hng n s t oxy ha cht bo. kho st nh hng ca yu t ny n hot tnh khng oxy ca cht mu anthocyanin, tin hnh th nghim 5 nhit khc nhau a. i vi cht mu anthocyanin chit trong mi trng acid - Chun b 7 bnh nh mc 100ml. - Cho vo mi bnh 2ml cht mu anthocyanin c nng 50mg/l.SVTH: Nguyn Th Thu Tho Trang 31

n cng ngh 1


- Thi gian phn ng l 3 gi. - Cc bc tin hnh ging nh mc 2.3.2.1 ch thay nhit phn ng cho tng mu ln lt l: 250C, 300C, 350C, 370C, 400C, 450C, 500C. Chun b mu trng song song vi mu th, cch tin hnh tng t nh mu th ch thay anthocyanin bng nc ct. b. i vi mu chit trong mi trng trung tnh Tin hnh th nghim tng t chit mu trong mi trng acid.

Phn III: KT QU V NHN XT Bng 3.1: nh hng ca nng anthocyanin n kh nng khng oxy ha ca mu chit trong mi trng acid [7].

C (mg/l) Kt qu

3 10 0.159 20 0.15 9 0.15 4 3.14 0 0 .159 0 .141 1 1.32 40 0. 159 0. 128 19 .50 50 0.15 9 0.10 1 36.4 8 60 0. 159 0. 70 0. 159 0.

A0

SVTH:A1 Nguyn Th0.157 Thu Tho

HD

1.26

118 134 Trang 32 25 15 .78 .72

n cng ngh 1


Bng 3.2: nh hng ca nng anthocyanin n kh nng khng oxy ha ca mu chit trong mi trng trung tnh [7].

C (mg/l) Kt qu

A0 A1 HD

10 0.159 0.157 1.26

20 0.159 0.153 3.77

30 0.159 0.130 18.24

40 0.159 0.122 23.27

50 0.159 0.090 43.40

60 0.159 0.115 27.67

70 0.159 0.127 20.13


Trang 33

n cng ngh 10.18 0.16 50 45 40 35 30 25 20 15 10 5 0 10 20 30 40 50 A1 60 HD 700.18 0.16

GVHD: Ths. Nguyn Th Lan50 45 40 35 30 25 20 15 10 5 0 10 20 30 40 50 60 70

Mt quang (nm)

Mt quang (nm)

% khng oxy ha

0.12 0.10 0.08 0.06 0.04 0.02 0.00

0.12 0.10 0.08 0.06 0.04 0.02 0.00

Nng (mg/l)A0A0 A1

Nng (mg/l)HD

Hnh 3.1 : th biu din nh hng ca nng anthocyanin n kh nng khng oxy ha ca anthocyanin. a) Trong mi trng acid. b) Trong mi trng trung tnh.

50 45 40 43.40

% khng oxy ha

35 30 25 20 15 10 5 0 10 1.26 1.26 20 3.77 3.14 30 40 50 60 70 Nng (mg/l) 11.32 15.72 18.24 19.50 23.27 36.48 25.78 27.67 20.13

Trong mi trng acid Trong mi trng trung tnh

Hnh 3.2: th so snh nh hng ca nng anthocyanin n kh nng khng oxy ha ca mu chit trong mi trng trung tnh v trong mi trng acid.Nhn xt: Kt qu trn cho thy kh nng khng oxy ha ca anthocyanin cao nht l nng 50 mg/l. Trong mi trng acid kh nng khng oxy ha ca anthocyanin cao nht l 36,48%, cn trong mi trng trung tnh l 40,43%.


Trang 34

% khng oxy ha

0.14

0.14

n cng ngh 1


Bng 3.3: nh hng ca thi gian n kh nng khng oxy ha ca mu chit trong mi trng acid [7]. (h) Kt qu

A0 A1 HD

2 0.095 0.082 13.68

2.5 0.113 0.090 20.35

3 0.130 0.101 22.31

3.5 0.135 0.123 8.89

4 0.142 0.132 7.04

4.5 0.158 0.147 6.96

5 0.179 0.173 3.35

Bng 3.4: nh hng ca thi gian n kh nng khng oxy ha ca mu chit trong mi trng trung tnh [7].

(h) Kt qu

A0 A1 HD

2 0.095 0.08 15.79

2.5 0.113 0.085 24.78

3 0.130 0.092 29.23

3.5 0.135 0.112 17.04

4 0.142 0.121 14.79

4.5 0.158 0.142 10.13

5 0.179 0.168 6.15


Trang 35

n cng ngh 10.20 0.18 0.16 hp th (nm) 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 0 2 2.5 3 3.5 4 4.5 5 Thi gi an (gi) A0 A1 HD 5 10 15 20 % khng oxy ha 25

GVHD: Ths. Nguyn Th Lan0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 35 30 % khng oxy ha 25 20 15 10 5 0 2 2.5 3 3.5 4 4.5 5 Thi gian (gi ) A0 A1 HD

Hnh 3.3 : th biu din nh hng ca thi gian n kh nng khng oxy ha ca anthocyanin. a) Trong mi trng acid. b) Trong mi trng trung tnh.

35 30 24.78 25 20 15 10 5 0 2 2.5 3 3.5 4 4.5 5 29.23

% khng oxy ha

22.31 15.79 17.04 14.79

20.35

13.68 8.89 7.04 6.96 3.35 10.13 6.15

hp th (nm)

Thi gian (gi)


Hnh 3.4: th so snh nh hng ca thi gian n kh nng khng oxy ha ca anthocyanin trong mi trng trung tnh v trong mi trng acid.

Nhn xt: Kt qu trn cho thy kh nng khng oxy ha ca anthocyanin cao nht l trong 3 gi. Trong mi trng acid kh nng khng oxy ha ca anthocyanin cao nht l 22,31%, cn trong mi trng trung tnh l 29,23%.


Trang 36

n cng ngh 1


Bng 3.5: nh hng ca nhit n kh nng khng oxy ha ca mu chit trong mi trng acid [7].

T (0C) Kt qu

A0 A1 HD

25 0.108 0.107 0.93

30 0.110 0.106 3.64

35 0.122 0.104 14.75

37 0.128 0.102 20.32

40 0.148 0.125 15.54

45 0.155 0.129 16.77

50 0.161 0.140 13.04

Bng 3.6: nh hng ca nhit n kh nng khng oxy ha ca mu chit trong mi trng trung tnh [7].

T, (0C) Kt qu

A0 A1 HD

25 0.108 0.105 2.78

30 0.110 0.097 11.82

35 0.122 0.094 22.95

37 0.128 0.092 28.130.18 0.16

40 0.148 0.116 21.62

45 0.155 0.123 20.6530 25 20 15 10 5 0

50 0.161 0.135 16.15

0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 25 30 35A0

25 20 15 10 5 0 37A1

% khng oxy ha

hp th (nm)

0.12 0.10 0.08 0.06 0.04 0.02 0.00 25 30 35 37 40 45 50

40 45HD

50

Nhit (oC)A0 A1

Nhit (oC)HD

Hnh 3.5 : th biu din nh hng ca nhit n kh nng khng oxy ha ca anthocyanin. a) Trong mi trng acid. b) Trong mi trng trung tnh.


Trang 37

% khng oxy ha

0.14

hp th (nm)

n cng ngh 1


30 28.13 25 22.95 20.32 20 20.65

21.62

% khng oxy ha

15 11.82 10 14.75 15.54

16.77 13.04

16.15

5

2.78 3.64 30 35 37 40 45 50

0 25

0.93


Nhit 0C

Hnh 3.6: th so snh nh hng ca nhit n kh nng khng oxy ha ca anthocyanin trong mi trng trung tnh v trong mi trng acid. Nhn xt: Kt qu trn cho thy kh nng khng oxy ha ca anthocyanin cao nht l 370C. Trong mi trng acid kh nng khng oxy ha ca anthocyanin cao nht l 20,32%, cn trong mi trng trung tnh l 28,13%. PHN IV: KT LUN V khng c lm thc nghim m ch tng hp ti liu t cc ngun khc nhau nn khng trnh khi nhng sai st. Trong qu trnh tng hp ti liu ti rt ra c mt vi kt lun nh sau: Kh nng khng oxy ha ca mu chit trong mi trng acid l thp hn Ti nng C = 50mg/l th kh nng khng oxy ha ca mu chit l cao Ti thi gian = 3h th kh nng khng oxy ha ca mu chit l cao nht. Ti nhit T = 370C th kh nng khng oxy ha ca mu chit l cao nht. mu chit trong mi trng trung tnh. nht.

Qua thu thp ti liu, ti thy cy bp gim c rt nhiu tc dng ln c trong lnh vc thc phm v trong y hc. Cc hp cht tan c trong dch chit t i hoa bp gimSVTH: Nguyn Th Thu Tho Trang 38

n cng ngh 1


c nhiu tc dng nh khng oxy ha, chng ung th, chng vim nhim, chng lo ha...Trong , c bit c hp cht anthocyanin hin ang s dng rng ri vi vai tr l cht mu trong thc phm va to mu sc p cho sn phm thc phm va an ton cho ngi s dng. Bn cnh , chng cn c cc tc dng tuyt vi trong y hc nh chng ung th, vim nhim...Ti hy vng trong tng lai gn chng ta s tm c cc i tng cho hm lng anthocyanin nhiu hn trong i hoa bp gim, tm c cc iu kin tt nht cho kh nng khng oxy ha ca hp cht ny, ng thi nghin cu kh nng khng oxy ha ca anthocyanin chit t cc i tng khc nhau ng dng cho nhiu lnh vc khc nhau.


Trang 39

n cng ngh 1


PHN V: TI LIU THAM KHO 5.1. Ti liu Ting Vit 1. o Hng Cng (1996), Ha hc cc hp cht hu c, i hc Bch Khoa Nng. 2. B.I.Khomutov, L. N. Lovasev (1977), Nhng khi nim hin i v s t oxy ha du m n, Nxb Khoa hc v K thut H Ni, trang 53- 54. 3. Nguyn Th Lan, Hunh Th Kim Cc, Phm Chu Hunh, Trn Khi Uyn, Xc nh hm lng anthocyanin trong mt s rau qu bng phng php pH vi sai, Tp Ch Khoa Hc v Cng Ngh, i Hc Nng - S 3(7) 2004, trang 4754. 4. Nguyn Th Lan, L Th Lc Quyn, Nghin cu nh hng ca h dung mi n kh nng chit tch cht mu anthocyanin c mu cao t qu Du Hi An, Tp ch khoa hc v cng ngh, i hc Nng, s 2(6), 2004, trang 4144. 5. T Vn Mc, Phn tch l ha, Nxb Khoa Hc v K Thut H Ni. 6. L Thy Ngc (2007), Nghin cu thu nhn cht mu anthocyanin t i hoa bp gim v thm d sn xut cht mu dng bt, n tt nghip, i hc Bch Khoa Nng. 7. Trng Th Nhung (2007), Nghin cu kh nng khng oxy ha ca cht mu anthocyanin chit xut t i hoa bp gim, n tt nghip, i hc Bch Khoa Nng. 8. L Ngc T (1999), Ho hc thc phm, NXB Khoa hc v K thut H Ni. 9. L Ngc T (2002), Ho sinh cng nghip, NXB Khoa hc v K thut H Ni. 10. Trn Th X (2001),Gio trnh ha sinh 2, i hc Bch Khoa Nng. 5.2. Ti liu Internet 11. http://www.hua.edu.vn:85/cnts/index.php. 12.http://vi.wikipedia.org/wiki/Ch%E1%BA%A5t_ch%E1%BB%91ng_oxi_h%. 13. http://www.lamchame.com/forum/archive/index.php/t-157286.html. 14. http://gpmdfamily.gotdns.com/Thuvien/Chuyennganh/Yhoc/Dong-y/Caythuoc/Bup-giam.htm. 15.http://www.thaomoc.com.vn/index.php?option=com_content&view. 16. http://www.vusta.vn/Temps/Home/template2/?nid=394. 17. http:// www.suagcenter.com .SVTH: Nguyn Th Thu Tho Trang 40

n cng ngh 1


18. http://www.dantri.com.vn/suckhoe/2006/7/168521.vip. 19. http://hoahoc.org/archive/index.php/t-9416.html. 20. http://vi.wikipedia.org/wiki/Vitamin_C#T.C3.ADnh_ch.E1.BA.A5t. 21. http://hoahoc.org/archive/index.php/t-9416.html2. 22. http://www.medinet.hochiminhcity.gov.vn/ttyh/bshkhkt/VitamineC.htm 23. http://chemistry.about.com/od/factsstructures/ig/Chemical-Structures--V/Vitamin-E-or-Tocopherol.-0UN.htm. 24. http://vi.wikipedia.org/wiki/Vitamin_E. 25. http://vietsciences.free.fr/timhieu/khoahoc/thucpham/vitamine_e_p.htm. 26. http://suckhoeso.com/detail/vitamin-e-chong-lao-hoa-da-huu-hieu-nhat.html. 27. http://en.wikipedia.org/wiki/File:Beta-carotene-2D-skeletal.svg. 28. http://www.suckhoecongdong.com/thuong-thuc/dinh-duong/vitamin-khoangchat/818-vitamin-a-va-cac-carotenoid.html.


Trang 41

tong hop

Documents