• BMB Reports
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• v.35 no.4
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• pp.358-363
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• 2002

Chemical and photochemical processes during storage and preparation rapidly degrade retinol, the most active form of vitamin A. therefore, the efficacy of incorporation into liposomes in order to modulate the kinetics of retinol degradation was investigated. Retinol was readily incorporated into multilamellar liposomes that were prepared form soybean phosphatidylcholine; the extent of the incorporation was 98.14±0.93% at pH 9.0 at a ratio of 0.01 : 1 (wt:wt) retinol : phospholipid. It was only marginally lower at higher retinol concentrations. The pH of the hydration buffer had a small effect. The incorporation efficiency ranged from 99.25±0.47% at pH 3 to 97.45±1.13% at pH 11. The time course of the retinol degradation in the aqueous solution in liposomes was compared to that of free retinol and free retinol with α-tocopherol under a variety of conditions of pH(3, 7, and 11), temperature(4, 25, 37, and 50℃), and light exposure(dark, visible, and UV). The retinol that was incorporated into the liposomes degraded significantly slower than the free retinol or retinol with α-tocopherol at pH 7 and 11. At pH 3, where the free retinol degrades rapidly, the degradation kinetics were similar in liposomes and the presence of α-tocopherol. At pH 7.0 and 4℃ in the light, for example, free aqueous retinol was completely degraded within 2 days, while only 20% of the retinol in the liposomes were degraded after 8 days. In general, the protective effect of the liposome incorporation was greater at low temperatures, at neutral and high pH, and in the dark. The results suggest that protection is greater in the solid, gel phase than in the fluid liquid crystalline phase lipids. These results indicate that the incorporation into liposomes can extend the shelf-life of retinol under a variety of conditions of temperature, pH, and ambient light conditions.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.352-356
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• 2001

A simple and rapid determination of total retinol from various pharmaceuticals containing retinol derivatives was described. Retinol derivatives were hydrolyzed with alcoholic KOH to alcoholic retinol, which was determined by HPLC. Pretreatments and HPLC conditions depend on the kind of retinols and preparation forms. The total amount of alcoholic retinol could be determined with this method from many pharmaceutical preparation of retinol derivatives. Treating time of KOH, acidic reagents and HPLC conditions were investigated.

• Proceedings of the Korean Nutrition Society Conference
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• 1995.05c
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• pp.21-21
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• 1995

Absorption of fat-soluble vi tamin, retinol occurs mainly in the proximal part of small intestine. But its intestinal transport mechanism isn't yet clear. The aim of the present study was to investigate on the mechanism of absorption of retinol by determining a concentration-dependent kinetic of retinol absorption in rats. The study was carried out by applying in vivo technique in which vitamin solution was infused to intestinal lumen and at the same time thoracic duct and choledochus duct were canulated to collect samples. The investigations showed that retinol is absorbed in the small intestine by a saturable, carrier-mediated transport system, i.e. wi thout signi ficant differences between the proximal and distal halves of the small intestine. The transport of retinol taken up by the enterocytes occured via different mechanisms: while the main vitamin A transport via the thoracic duct was saturated by limiting transport factors such as retinol-CRBP-II-complex formation and retinol esterification with increasing substrate concentrations, the transport of retinol metabolite product via the portal vein was proportional to the substrate concentration.ration.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.60-72
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• 2003

To investigate the effect of cholesterol in liposome on the stability of incorporated retinol, the physico-chemical experiments for various amounts of cholesterol-containing liposomes were performed. Liposome with retinol containing cholesterol was prepared as multilamella vesicles(MLVs) by dehydration/rehydration method. The incorporation efficiency of retinol into liposome was maximized as 99.31 % at 50:50 (phosphatidylcholine/cholesterol) at pH 9. The stability of incorporated retinol at low storage temperature was enhanced with increasing cholesterol content than at high storage temperature. For example, incorporated retinol in liposome at glycine buffer(pH 9} was degraded slowly during storage at 4. The degradation of retinol in liposomes was slower at pH 9 than at pH 7. These results supported that cholesterol in liposome increased largely the stability of incorporated retinol.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.116-122
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• 1998

It is well known that all-trans-retinol is not only very unstable in heat, light, air, and water, but also skin-irritant despite a good anti-wrinkle effect. Therefore, it is very difficult to stabilize retinol and make the safe retinol containing cosmetics by using a certain concentration of retinol with real effect. In order to dissolve these problems and apply retinol for skin care cream, firstly retinol is to be encapsulated in the vesicle called Liposphere (pseudo-liposome) which is made by homogenizing under high pressure the mixtures of lecithin, retinol, caprylic/capric triglyceride, and hydroalcoholic solution ; and then this retinol containing Liposphere is to be intercalated in lamellar liquid crystal layer which is prepared by emulsifying in an optimal ratio the mixtures composed of non-ionic emulsifier (cetearyl glucoside, sorbitan stearate & sucrose cocoate etc), cetearyl alcohol, stearic acid, cholesterol, and ceramide. In addition, the stability of the retinol containing oil in water cream by adding the polymeric emulsifier such as acrylate /C10-30 alkyl alkylate crosspolymer is to be ensured even at 55 C. Retinol containing oil in water cream prepared through above procedure could be very stable at 45 C for at least 50 days. The structure identification of lamellar liquid crystal was determined using polarized light microscope and electron microscope Conclusively, we could make the very stable retinol containing oil in water cream by triple procedure, that is, encapsulation of retinol in Liposphere, intercalation of retinol in lamellar liquid crystal layer, and assurance of the high temperature stability of cream even at 55 C.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.604-607
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• 2005

In this study, the effect of ${\beta}$-sitosterol (SS) in the liposome bilayer on the stability of incorporated retinol was evaluated. Retinol was incorporated into liposomes consisting of various ratios of soybean phoaphatidylcholine (PC) to SS, while liposomes were prepared as multilamellar vesicles by the dehydration/rehydration method. Retinol was readily incorporated into liposomes with various SS contents, with incorporation efficiencies higher than 98% for all conditions. The incorporation efficiency of retinol increased slightly as the SS content in liposomes increased. Its average particle size also increased as the SS content increased. Mean particle size at PC to SS ratios of 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 were 12.16, 17.57, 35.00, 40.62, 83.45, and $88.94\;{\mu}m$, respectively. Liposomal retinol degradation in aqueous solution was measured with respect to SS content at various periods of time at four different temperatures of 4, 25, 37, and $50^{\circ}C$, and the stability of the incorporated retinol enhanced as the SS content increased. At $4^{\circ}C$, for example, retinol in the liposomes of 50:50 (PC:SS) remained at 84.42% after storage for 10 days, while in 100:0 (PC/SS) it remained at 42.62%. These results indicate that SS content in liposomes played an important role in the incorporation efficiency of retinol and its stability.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.111-115
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• 1998

We investigated the stability of all-trans-retinol on the liquid crystalline O/W emulsion composed of mainly alkyl polyglycerine, alkyl polyglucose and glycerine, and compared the activity of all-trans-retinol in the various forms of liquid crystal. Under certain conditions, novel liquid crystalline gel was formed around oil droplets, and layers of this liquid crystalline gel were very wide and rigid. (SWLC; Super Wide Liquid Crystal) SWLC was very helpful to stabilize retinol in O/W emulsion. After storage at 45 C for 4 weeks, all-trans-retinol in O/W emulsion composed of SWLC retained above 85% of the activity upon HPLC analysis, whereas those within no liquid crystalline emulsion gave 47% and normal liquid crystalline emulsion composed of fatty alcohols gave 40 60%. Retinol in oil phase is nealy insoluble in pure water, but in cosmetic emulsion systems can be slightly solubilized into water because emulsifiers and polyols in emulsion systems function as solubilizers. In this case, water in outer phase acts as a media for oxygen transporation$.$and thus destabilizes retinol. As a result, retinol in O/W emulsion has a tendency to become unstable. SWLC surrounding oil droplet which contains retinol is wide and rigid, therefore reduces contact between inner phase and outer phase To make SWLC, properties of emulsifiers are very important phase transition temperature should be high, and the structure of surfactants should be bulky, and their ratio should be suitable to make rigid and wide liquid crystalline gel layer in order to reduce contact between retinol in inner phase and water in outer phase.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.58-70
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• 2002

In an attempt to compare the antioxidation effects of constrain the oxidation and improve the structural stability, retinol and various antioxidants were together encapsulated by liposome. Four water soluble and four oil soluble antioxidants were tested for performance. The influence of tertiary butylhydroquinone(TBHQ), ${\alpha}$-glycosyl rutin(${\alpha}$-G rutin), licorece, pycnogenol as water soluble antioxidants and butylated hydroxytoluene(BHT), ${\alpha}$-lipoic acid, ferulic acid, natural concentrated tooopherol(no-tocopherol) as oil soluble antioxidants on the constraint of oxidation of retinol were investigated. Additional study was conducted to compare the synergic effect of antioxidation for retinol with licorice, pycnogenol, ${\alpha}$-lipoic acid and BHT. All the antioxidant used at the study constrained oxidation of retinol. The effect of antioxidation for retinol increased in order of licorice, pycnogenol, TBHQ, ${\alpha}$-G rutin as water soluble antioxidants and ${\alpha}$-lipoic acid, BHT, no-tocopherol, ferulic acid as oil soluble antioxidants. In conclusion, ${\alpha}$-lipoic acid is more effective retinol antioxidants than BHT. And the combination of ${\alpha}$-lipoic acid and BHT gave best synergic among six combinations.

• Nutrition Research and Practice
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• v.6 no.1
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• pp.45-50
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• 2012

Dietary intakes and plasma concentrations of retinol and carotenoids were estimated in assessing the vitamin A status of Korean adults living in Seoul and the metropolitan area. Three consecutive 24-h food recalls were collected from 106 healthy subjects (33 males and 73 females) aged 20-59 years. Fasting blood samples of the subjects were obtained and plasma retinol and carotenoids were analyzed. The daily vitamin A intakes ($mean{\pm}SD$) were $887.77{\pm}401.35{\mu}g $ retinol equivalents or $531.84{\pm}226.42{\mu}g$ retinol activity equivalents. There were no significant differences in vitamin A intakes among age groups. The retinol intake of subjects was $175.92{\pm}129.87{\mu}g/day$. The retinol intake of the subjects in their 50's was significantly lower than those in their 20's and 30's (P<0.05). Provitamin A carotenoid intakes were $3,828.37{\pm}2,196.29{\mu}g/day$ ${\beta}$-carotene, $472.57{\pm}316.68{\mu}g/day$ ${\alpha}$-carotene, and $412.83{\pm}306.46{\mu}g/day$ ${\beta}$-cryptoxanthin. Approximately 17% of the subjects consumed vitamin A less than the Korean Estimated Average Requirements for vitamin A. The plasma retinol concentration was $1.22{\pm}0.34{\mu}mol/L$. There was no significant difference in plasma retinol concentrations among age groups. However, the concentrations of ${\beta}$-carotene, lycopene, and lutein of subjects in their 50's were significantly higher than those of in their 20's. Only one subject had a plasma retinol concentration < $0.70{\mu}mol/L$ indicating marginal vitamin A status. Plasma retinol concentration in 30% of the subjects was 0.70- < $1.05{\mu}mol/L$, which is interpreted as the concentration possibly responsive to greater intake of vitamin A. In conclusion, dietary intakes and status of vitamin A were generally adequate in Korean adults examined in this study.

• Korean Journal of Human Ecology
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• v.13 no.1
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• pp.75-84
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• 2004

Insufficient dietary intake of vitamin A is one of the major nutritional problems for elderly adults in some parts of Korea. The objective of this study was to determine the vitamin A nutritional status of elderly adults in Asan, Korea by assessing the dietary intake and serum retinol concentration. Five hundred twenty four subjects (218 male and 306 female) over 65 years were recruited from city of Asan. Each subject was interviewed to assess the intake of vitamin A using a 24hr recall method and data were analysed from computer-aided nutrient analysis program. Blood samples after 12hr fasting were collected for serum retinol concentration and reverse phased HPLC with UV detector used. The results showed that subjects did not consume the sufficient amount of energy (82-85% of Korean RDA for male and 77-79% RDA for female) and vitamin A (59% RDA for male and 50% RDA for female). Range for retinol intake was 0 to $4342\;{\mu}g$ a day while that of beta-carotene was 65 to $31595\;{\mu}g$. Serum retinol concentrations were within a normal range for both male ($80\;{\mu}g/dl$) and female ($67\;{\mu}g/dl$) subjects. Many subjects (n=342) consumed less than 50% RDA of vitamin A. However, if retinol intake was high (> $37\;{\mu}g$), even with less than 50% RDA of vitamin A intake, serum retinol concentration was high ($75\;{\mu}g/dl$). Subjects showed normal serum retinol status even with low vitamin A intake. The results suggested that optimal intake ratio of dietary retinol and carotenoid is important to maintain an appropriate serum retinol concentration.