Citrus limonoids and flavonoids : extraction, antioxidant activity and effects on hamster plasma cholesterol distribution /

Bibliographic Details
Main Author: Yu, Jun, 1973-
Other Authors: Pike, Leonard M. (Thesis advisor), Patil, Bhimanagouda S. (Thesis advisor)
Format: Thesis eBook
Language:English
Published: [College Station, Tex.] : [Texas A&M University], [2005]
Subjects:
Online Access:Link to OAK Trust copy

MARC

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035 |a (OCoLC)ocm77549758 
035 |a (TxCM)http://handle.tamu.edu/1969.1/2772 
040 |a TXA  |c TXA  |d UtOrBLW 
049 |a TXAM 
099 |a 2004  |a Dissertation Y95 
100 1 |a Yu, Jun,  |d 1973- 
245 1 0 |a Citrus limonoids and flavonoids :  |b extraction, antioxidant activity and effects on hamster plasma cholesterol distribution /  |c by Jun Yu. 
264 1 |a [College Station, Tex.] :  |b [Texas A&M University],  |c [2005] 
336 |a text  |b txt  |2 rdacontent 
337 |a computer  |b c  |2 rdamedia 
338 |a online resource  |b cr  |2 rdacarrier 
500 |a "Major Subject: Horticulture" 
500 |a Title from author supplied metadata (automated record created on Nov. , 09:45:50.) 
500 |a Vita. 
500 |a Abstract. 
502 |b Ph. D.  |c Texas A&M University  |d 2004. 
504 |a Includes bibliographical references. 
516 |a Text (Dissertation). 
520 3 |a Four in vitro models were used to measure the antioxidant activity of 11 citrus phytochemicals. The citrus limonoids and bergapten showed very weak antioxidant activity. The flavonoids demonstrated mild, to moderate, to strong antioxidant activity. In addition to some other commonly accepted structural features our data indicated that the hydroxyl group in position 6 of ring A could also increase the antioxidant activity of flavonoids. Compared with the active flavonoids, limonoids are highly oxygenated triterpenoids, with fewer hydroxyl groups to stabilize unpaired electrons (or scavenge free radicals). Bergapten lacks a hydroxyl group. This is the first report on the antioxidant activity of limonoids and neoeriocitrin. A feeding study using Syrian hamsters was followed to determine the effect of citrus limonoids and flavonoids on plasma cholesterol. Hamsters fed with limonin, limonin 17-Beta-D-glucopyranoside and grapefruit pulp significantly inhibited the increase of LDL/HDL-cholesterol (36.6%, 52.9% and 57% respectively) compared with the basal control (65.8%) and the pectin control (70%). Furthermore, hamsters fed with limonin had significantly larger LDL particle size (21.21 nm) compared with the control group (19.96 nm). Further studies demonstrated that LDLs from hamsters fed with limonin and limonin 17-Beta-D-glucopyranoside were less susceptible to oxidation. These data suggest that limonin, limonin 17-Beta-D-glucopyranoside and grapefruit pulp have potential inhibitory effects against atherogenesis. Supercritical CO₂ (SC-CO₂) was attempted to extract limonoids from grapefruit seeds and molasses. Limonin aglycone was successfully extracted with SC-CO₂ directly from grapefruit seeds with the yield of 6.3 mg/g seeds at 48.3 MPa, 50°C and 60 min with CO₂ top feeding; and the limonin glucoside was extracted using SC-CO₂ and ethanol as co-solvent from the defatted seeds with the yield of 0.73 mg/g seeds at 42 MPa, 52°C, 45% ethanol (X[subscript]Eth=0.45) and 40 min with CO₂ top feeding; and limonin glucoside also was extracted using SC-CO₂ and ethanol with the yield of 0.61mg/g grapefruit molasses at 48.3 MPa, 50°C and 10% ethanol (X[subscript]Eth=0.1), 40 min with CO₂ top feeding. CO₂ flow rate was around~5 l/min in experiments. The results demonstrated SC-CO₂ extraction of limonoids from citrus juice industry byproducts has practical significance for future commercial production. 
538 |a Mode of access: World Wide Web. 
538 |a System requirements: World Wide Web access and Adobe Acrobat Reader. 
500 |a Electronic resource. 
650 4 |a Major Horticulture. 
653 |a Cholesterol 
653 |a Limonoids 
653 |a Hamster 
653 |a Flavonoids 
653 |a Antioxidant Activity 
653 |a Supercritical Fluids Extraction 
700 1 |a Pike, Leonard M.,  |e thesis advisor. 
700 1 |a Patil, Bhimanagouda S.,  |e thesis advisor. 
856 4 0 |u http://hdl.handle.net/1969.1/2772  |z Link to OAK Trust copy  |t 0 
948 |a cataloged  |b cmulkey  |c 2007/1/11  |d 11:06:39 am 
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999 |a MARS 
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952 f f |a Texas A&M University  |b College Station  |c Electronic Resources  |d Available Online  |t 0  |e 2004 Dissertation Y95  |g Electronic  |h Other scheme 
998 f f |a 2004 Dissertation Y95  |t 0  |l Available Online