The following is a collection of tocotrienols abstracts from published scientific research and papers. Integratedhealth.com has designed Complete E, with tocotrienols research in mind.
REFERENCE 1 OF 22
Ngah WZ Jarien Z San MM Marzuki A Top GM Shamaan NA Kadir KA
Effect of tocotrienols on hepatocarcinogenesis induced by 2- acetylaminofluorene in rats.
In: Am J Clin Nutr (1991 Apr) 53(4 Suppl):1076S-1081S
The effects of tocotrienols on hepatocarcinogenesis in rats fed with 2-acetylaminofluorene (AAF) were followed morphologically and histologically for a period of 20 wk. No differences between treated and control rats in the morphology and histology of their livers was observed. Cell damage was extensive in the livers of AAF-treated rats but less extensive in the AAF-tocotrienols-treated rats when compared with normal and tocotrienols-treated rats. 2-Acetylaminofluorene significantly increases the activities of both plasma and liver microsomal gamma-glutamyltranspeptidase (GGT) and liver microsomal UDP-glucuronyltransferase (UDP-GT). Tocotrienols administered together with AAF significantly decrease the activities of plasma GGT after 12 and 20 wk (P less than 0.01, P less than 0.002, respectively) and liver microsomal UDP-GT after 20 wk (P less than 0.02) when compared with the controls and with rats treated only with tocotrienols. Liver microsomal GGT also showed a similar pattern to liver microsomal UDP-GT but the decrease was not significant. These results suggest that tocotrienols administered to AAF-treated rats reduce the severity of hepatocarcinogenesis.
Institutional address: Department of Biochemistry Faculty of Medicine Universiti Kebangsaan Malaysia Kuala Lumpur.
REFERENCE 2 OF 22
Gould MN Haag JD Kennan WS Tanner MA Elson CE
A comparison of tocopherol and tocotrienol for the chemoprevention of chemically induced rat mammary tumors.
In: Am J Clin Nutr (1991 Apr) 53(4 Suppl):1068S-1070S
Two forms of vitamin E, tocopherol and tocotrienol, were tested for chemopreventive activity in two chemically induced rat mammary-tumor models. When mammary tumors were induced by 7,12- dimethylbenz(a)anthracene (DMBA, 50 mg/kg), only the tocotrienol group had a statistically significant increase in tumor latency. There was no effect of either compound on tumor multiplicity. When tumors were induced by N-nitrosomethylurea (NMU, 30 mg/kg), neither analogue of vitamin E modified latency, whereas tocotrienol increased tumor multiplicity. In summary, neither vitamin analog had a major impact on mammary-tumor development after tumor induction with either DMBA or NMU.
Institutional address: Department of Human Oncology University of Wisconsin-Madison 53792.
REFERENCE 3 OF 22
Qureshi AA Qureshi N Hasler-Rapacz JO Weber FE Chaudhary V Crenshaw TD Gapor A Ong AS Chong YH Peterson D et al
Dietary tocotrienols reduce concentrations of plasma cholesterol, apolipoprotein B, thromboxane B2, and platelet factor 4 in pigs with inherited hyperlipidemias.
In: Am J Clin Nutr (1991 Apr) 53(4 Suppl):1042S-1046S
Normolipemic and genetically hypercholesterolemic pigs of defined lipoprotein genotype were fed a standard diet supplemented with 50 micrograms/g tocotrienol-rich fraction (TRF) isolated from palm oil. Hypercholesterolemic pigs fed the TRF supplement showed a 44% decrease in total serum cholesterol, a 60% decrease in low-density- lipoprotein (LDL)-cholesterol, and significant decreases in levels of apolipoprotein B (26%), thromboxane-B2 (41%), and platelet factor 4 (PF4; 29%). The declines in thromboxane B2 and PF4 suggest that TRF has a marked protective effect on the endothelium and platelet aggregation. The effect of the lipid-lowering diet persisted only in the hypercholesterolemic swine after 8 wk feeding of the control diet. These results support observations from previous studies on lowering plasma cholesterol in animals by tocotrienols, which are naturally occurring compounds in grain and palm oils and may have some effect on lowering plasma cholesterol in humans.
Institutional address: Advanced Medical Research Madison WI 53719.
REFERENCE 4 OF 22
Tan DT Khor HT Low WH Ali A Gapor A
Effect of a palm-oil-vitamin E concentrate on the serum and lipoprotein lipids in humans.
In: Am J Clin Nutr (1991 Apr) 53(4 Suppl):1027S-1030S
The effect of a capsulated palm-oil-vitamin E concentrate (palmvitee) on human serum and lipoprotein lipids was assessed. Each palmvitee capsule contains approximately 18, approximately 42, and approximately 240 mg of tocopherols, tocotrienols, and palm olein, respectively. All volunteers took one palmvitee capsule per day for 30 consecutive days. Overnight fasting blood was taken from each volunteer before and after the experiment. Serum lipids and lipoproteins were analyzed by using the enzymatic CHOD-PAP method. Our results showed that palmvitee lowered both serum total cholesterol (TC) and low-density-lipoprotein cholesterol (LDL-C) concentrations in all the volunteers. The magnitude of reduction of serum TC ranged from 5.0% to 35.9% whereas the reduction of LDL-C values ranged from 0.9% to 37.0% when compared with their respective starting values. The effect of palmvitee on triglycerides (TGs) and HDL-C was not consistent. Our results show that the palmvitee has a hypocholesterolemic effect.
Institutional address: Palm Oil Research Institute of Malaysia Bangi Selangor.
REFERENCE 5 OF 22
Hakkarainen RV Tyopponen JT Hassan S Bengtsson SG Jonsson SR Lindberg PO
Biopotency of vitamin E in barley.
In: Br J Nutr (1984 Sep) 52(2):335-49
Investigations were carried out to establish the total biopotency of the natural vitamin E isomers in barley compared with that of DL- alpha-tocopheryl acetate. The chick was used as an experimental animal. Prevention of nutritional encephalomalacia (NE) and chick liver-storage and plasma-storage assays of vitamin E were the methods used in the study. The individual tocopherols and tocotrienols, both in the tissue samples and in the grain and barley oil, were analysed using high-pressure liquid chromatography (HPLC) with fluorescence detection. The diagnosis of NE was based on careful clinical and histopathological observations. It can be concluded from the results that full protection against NE in the chicks was obtained with a supplementation level of 7.5 mg DL-alpha-tocopheryl acetate/kg diet (i.e. a total vitamin E content of 11.20 mg/kg diet) or with a supplement of 8.7 g barley oil/kg diet (i.e. a total vitamin E content of 22.99 mg from barley oil/kg diet). This gave a biopotency factor of 0.49 for barley for prevention of NE of the chicks, as compared to that of DL-alpha-tocopheryl acetate. Using regression analysis a statistically linear relationship could be observed between the total dietary vitamin E level and the response, as measured by the total vitamin E content in the liver and plasma, both in the groups supplemented with DL-alpha-tocopheryl acetate and in the groups supplemented with corresponding amounts of vitamin E in barley oil. The liver and plasma responses to the total vitamin E in the barley-oil diet compared with those of the DL-alpha-tocopheryl acetate reference diet gave identical values for the regression coefficients, i.e. in both liver-storage and plasma-storage assays the value for slopes of dose-response lines was 0.37. This means that the biopotency of the total vitamin E in barley was 37% of that of dietary DL-alpha-tocopheryl acetate. Thus, barley is not as rich a source of vitamin E as could be supposed on the basis of the chemical determination of its total vitamin E content. It was possible to verify this experimentally established biopotency of 0.37 for the total vitamin E in barley by converting the chemically determined amounts of the vitamin E isomers in barley into DL-alpha-tocopheryl acetate equivalents by multiplying them with internationally accepted potency factors for the individual natural isomers (DL-alpha- tocopheryl acetate 1.00, D-alpha-tocopherol 1.49, D-beta-tocopherol 0.60, D-gamma-tocopherol 0.15, D-alpha-tocotrienol 0.37).(ABSTRACT TRUNCATED AT 400 WORDS)
REFERENCE 6 OF 22
Qureshi AA Burger WC Peterson DM Elson CE
The structure of an inhibitor of cholesterol biosynthesis isolated from barley.
In: J Biol Chem (1986 Aug 15) 261(23):10544-50
Purification of the oily, nonpolar fraction of high protein barley (Hordeum vulgare L.) flour by high pressure liquid chromatography yielded 10 major components, two (I, II) of which were potent inhibitors of cholesterogenesis in vivo and in vitro. The addition of purified inhibitor I (2.5-20 ppm) to chick diets significantly decreased hepatic cholesterogenesis and serum total and low density lipoprotein cholesterol and concomitantly increased lipogenic activity. The high resolution mass spectrometric analysis and measurement of different peaks of inhibitor I gave a molecular ion at m/e 424 (C29H44O2) and main peaks at m/e 205, 203, and 165 corresponding to C13H17O2, C13H15O2, and C10H13O2 moieties, respectively. which are characteristic of d-alpha-tocotrienol. This identification was confirmed against synthetic samples. The tocotrienols are widely distributed in the plant kingdom and differ from tocopherols (vitamin E) only in three double bonds in the isoprenoid chain which appear to be essential for the inhibition of cholesterogenesis.
REFERENCE 7 OF 22
Parker RA Pearce BC Clark RW Gordon DA Wright JJ
Tocotrienols regulate cholesterol production in mammalian cells by post-transcriptional suppression of 3-hydroxy-3-methylglutaryl- coenzyme A reductase.
In: J Biol Chem (1993 May 25) 268(15):11230-8
Tocotrienols are natural farnesylated analogues of tocopherols which decrease hepatic cholesterol production and reduce plasma cholesterol levels in animals. For several cultured cell types, incubation with gamma-tocotrienol inhibited the rate of [14C]acetate but not [3H] mevalonate incorporation into cholesterol in a concentration- and time-dependent manner, with 50% inhibition at approximately 2 microM and maximum approximately 80% inhibition observed within 6 h in HepG2 cells. 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase total activity and protein levels assayed by Western blot were reduced concomitantly with the decrease in cholesterol synthesis. In HepG2 cells, gamma-tocotrienol suppressed reductase despite strong blockade by inhibitors at several steps in the pathway, suggesting that isoprenoid flux is not required for the regulatory effect. HMG- CoA reductase protein synthesis rate was moderately diminished (57% of control), while the degradation rate was increased 2.4-fold versus control (t1/2 declined from 3.73 to 1.59 h) as judged by [35S]methionine pulse-chase/immunoprecipitation analysis of HepG2 cells treated with 10 microM gamma-tocotrienol. Under these conditions, the decrease in reductase protein levels greatly exceeded the minor decrease in mRNA (23 versus 76% of control, respectively), and the low density lipoprotein receptor protein was augmented. In contrast, 25-hydroxycholesterol strongly cosuppressed HMG-CoA reductase protein and mRNA levels and the low density lipoprotein receptor protein. Thus, tocotrienols influence the mevalonate pathway in mammalian cells by post-transcriptional suppression of HMG-CoA reductase, and appear to specifically modulate the intracellular mechanism for controlled degradation of the reductase protein, an activity that mirrors the actions of the putative non-sterol isoprenoid regulators derived from mevalonate.
Institutional address: Department of Metabolic Diseases Bristol-Myers Squibb Pharmaceutical Research Institute Princeton New Jersey 08543.
REFERENCE 8 OF 22
He L, Mo H, Hadisusilo S, Qureshi AA, Elson CE
Isoprenoids suppress the growth of murine B16 melanomas in vitro and in vivo.
Sundry mevalonate-derived constituents (isoprenoids) of fruits, vegetables and cereal grains suppress the growth of tumors. This study estimated the concentrations of structurally diverse isoprenoids required to inhibit the increase in a population of murine B16(F10) melanoma cells during a 48-h incubation by 50% (IC50 value). The IC50 values for d-limonene and perillyl alcohol, the monoterpenes in Phase I trials, were 450 and 250 micromol/L, respectively; related cyclic monoterpenes (perillaldehyde, carvacrol and thymol), an acyclic monoterpene (geraniol) and the end ring analog of beta-carotene (beta-ionone) had IC50 values in the range of 120-150 micromol/L. The IC50 value estimated for farnesol, the side- chain analog of the tocotrienols (50 micromol/L) fell midway between that of alpha-tocotrienol (110 micromol/L) and those estimated for gamma- (20 micromol/L) and delta- (10 micromol/L) tocotrienol. A novel tocotrienol lacking methyl groups on the tocol ring proved to be extremely potent (IC50, 0.9 micromol/L). In the first of two diet studies, experimental diets were fed to weanling C57BL female mice for 10 d prior to and 28 d following the implantation of the aggressively growing and highly metastatic B16(F10) melanoma. The isomolar (116 micromol/kg diet) and the Vitamin E-equivalent (928 micromol/kg diet) substitution of d-gamma-tocotrienol for dl-alpha- tocopherol in the AIN-76A diet produced 36 and 50% retardations, respectively, in tumor growth (P < 0.05). In the second study, melanomas were established before mice were fed experimental diets formulated with 2 mmol/kg d-gamma-tocotrienol, beta-ionone individually and in combination. Each treatment increased (P < 0.03) the duration of host survival. Our finding that the effects of individual isoprenoids were additive suggests the possibility that one component of the anticarcinogenic action of plant-based diets is the tumor growth-suppressive action of the diverse isoprenoid constituents of fruits, vegetables and cereal grains.
Department of Nutritional Sciences, University of Wisconsin, Madison 53706, USA.
J Nutr 1997 May;127(5):668-74
REFERENCE 9 OF 22
Guthrie N, Gapor A, Chambers AF, Carroll KK
Inhibition of proliferation of estrogen receptor-negative MDA-MB-435 and -positive MCF-7 human breast cancer cells by palm oil tocotrienols and tamoxifen, alone and in combination.
Tocotrienols are a form of vitamin E, having an unsaturated isoprenoid side-chain rather than the saturated side-chain of tocopherols. The tocotrienol-rich fraction (TRF) from palm oil contains alpha-tocopherol and a mixture of alpha-, gamma- and delta- tocotrienols. Earlier studies have shown that tocotrienols display anticancer activity. We previously reported that TRF, alpha-, gamma- and delta-tocotrienols inhibited proliferation of estrogen receptor- negative MDA-MB-435 human breast cancer cells with 50% inhibitory concentrations (IC50) of 180, 90, 30 and 90 microg/mL, respectively, whereas alpha-tocopherol had no effect at concentrations up to 500 microg/mL. Further experiments with estrogen receptor-positive MCF-7 cells showed that tocotrienols also inhibited their proliferation, as measured by [3H] thymidine incorporation. The IC50s for TRF, alpha- tocopherol, alpha-, gamma- and delta-tocotrienols were 4, 125, 6, 2 and 2 microg/mL, respectively. Tamoxifen, a widely used synthetic antiestrogen inhibits the growth of MCF-7 cells with an IC50 of 0.04 microg/mL. We tested 1:1 combinations of TRF, alpha-tocopherol and the individual tocotrienols with tamoxifen in both cell lines. In the MDA-MB-435 cells, all of the combinations were found to be synergistic. In the MCF-7 cells, only 1:1 combinations of gamma- or delta-tocotrienol with tamoxifen showed a synergistic inhibitory effect on the proliferative rate and growth of the cells. The inhibition by tocotrienols was not overcome by addition of excess estradiol to the medium. These results suggest that tocotrienols are effective inhibitors of both estrogen receptor-negative and -positive cells and that combinations with tamoxifen should be considered as a possible improvement in breast cancer therapy.
Department of Biochemistry, The University of Western Ontario, London, Canada.
REFERENCE 10 OF 22
Interactions among antioxidants in health and disease: vitamin E and its redox cycle.
In: Proc Soc Exp Biol Med (1992 Jun) 200(2):271-6
Probably most diseases at some point during their course involve free radical reactions in tissue injury. In some cases, free radical reactions may be involved in multiple sites and at different stages of a chronic disease. So, both acute and degenerative diseases are thought to involve free radical reactions in tissue injury. An overview will be given of the evidence for the occurrence of free radicals and the importance of antioxidant interventions, with particular reference to the lipophilic antioxidant vitamin E (tocopherols and tocotrienols).
Institutional address: Department of Molecular and Cell Biology University of California Berkeley 94720.
REFERENCE 11 OF 22
Hayes KC Pronczuk A Liang JS
Differences in the plasma transport and tissue concentrations of tocopherols and tocotrienols: observations in humans and hamsters.
In: Proc Soc Exp Biol Med (1993 Mar) 202(3):353-9
Certain aspects of tocopherol and tocotrienol absorption, plasma transport, and tissue distribution were examined in humans and hamsters. Plasma transport differed in that tocopherols were found primarily in low density lipoprotein and high density lipoprotein in association with plasma surface components, whereas tocotrienols disappeared from plasma with chylomicron clearance. In keeping with transport by triglyceride-rich lipoproteins, tocotrienols were deposited in conjunction with triglycerides in the adipose tissue of hamsters. In hamsters, tocopherols were the only tocol readily detected in all tissues, except adipose during tocotrienol supplementation. In fasting humans, the plasma tocotrienol concentration was not significantly increased after tocotrienol supplementation, whereas the platelet concentration of delta- tocotrienol doubled. Furthermore, tocotrienol intake did not appear to modulate the plasma cholesterol concentration in normolipemic hamsters. Thus, the transport, tissue concentration, and relative biologic function of tocopherol and tocotrienol appear somewhat disparate and possibly unrelated.
Institutional address: Foster Biomedical Research Laboratory Brandeis University Waltham Massachusetts 02254.
REFERENCE 12 OF 22
Choudhury N, Truswell AS, McNeil Y
Comparison of plasma lipids and vitamin E in young and middle-aged subjects on potato crisps fried in palmolein and highly oleic sunflower oil.
We previously found no difference in healthy young adults’ plasma cholesterols between palmolein and olive oil as the major dietary lipid, although the former is high in palmitic acid (16:0) but the latter in oleic acid (18:1 cis). In the experiment reported here we compared the effects of palmolein against another monounsaturated oil, highly oleic sunflower oil (HOSO), on plasma cholesterol in both young and middle-aged healthy adults. The test oils were provided as frying oil of potato crisps (150 g/day in men; 100 g/day in women) against low-fat background diets in free-living motivated volunteers. The design was a randomised double-blind 4-week/3-week crossover trial. Compliance was monitored with continuous dietary diaries and by measuring (fasting) plasma lipid fatty-acid pattern. Plasma lipids and vitamin-E compounds were measured at the start and twice at the end of each test period. In combined young plus older subjects (n = 42) mean plasma total and low-density-lipoprotein cholesterol (LDL-c) values were both 7% (significantly) lower on HOSO than on palmolein, but because high-density-lipoprotein cholesterol (HDL-c) was also 5% lower, the LDL-c/HDL-c ratio was only 3% lower on HOSO than on palmolein. The difference between the present results with HOSO and previous results with olive oil both compared against palmolein suggest that olive oil is associated with higher plasma cholesterols than other monounsaturated oils. In both the young and older subgroup, LDL-c was lower on HOSO but because HDL-c moved down too in the young subgroup, the LDL-c/HDL-c ratio was lower on HOSO only in the older subjects. Palmolein has an unusual pattern of E vitamins, with a high content of tocotrienols, notably the gamma-isomer. Unlike alpha-tocopherol however, there was no sign of these tocotrienols in subjects’ plasmas.
Department of Biochemistry, University of Sydney, New South Wales, Australia.
Ann Nutr Metab 1997;41(3):137-48
REFERENCE 13 OF 22
Wang Q, Theriault A, Gapor A, Adeli K
Effects of tocotrienol on the intracellular translocation and degradation of apolipoprotein B: possible involvement of a proteasome independent pathway.
Gamma-Tocotrienol (gamma-T3), a HMG CoA reductase inhibitor, was previously shown to stimulate the intracellular degradation of apolipoprotein B (apoB) in HepG2 cells. The aim of this study was to explore the effects of gamma-T3 on the proteasome dependent co- translational degradation and the proteasome independent post- translational degradation of apoB. Previous studies have shown that apoB translocation across the endoplasmic reticulum (ER) membrane governs the co-translational degradative pathway of apoB. Therefore, we first examined the effects of gamma-T3 on this pathway using a specific translocation assay derived from HepG2 cells. Our results indicated that gamma-T3 reduced the efficiency of apoB translocation across the ER membrane, suggesting that co-translational degradation may be partially involved. Evidence of an ER associated post- translational degradation was also provided upon pre-treating digitonin-permeabilized HepG2 cells with a proteasome inhibitor, lactacystin. When chased for 2h, ER degradation of apoB was observed and was further enhanced in the presence of gamma-T3 versus untreated control, in spite of proteasome inhibition. Combined with the ability of ALLN, a proteasome and cysteine protease inhibitor, to block the post-translational degradation of apoB, the data suggest that gamma- T3 diverted more apoB to a cytosolic proteasomal dependent and possibly an ER-associated proteasomal independent degradation pathways.
Division of Medical Technology, University of Hawaii at Manoa, Honolulu 96822, USA.
Biochem Biophys Res Commun 1998 May 29;246(3):640-3
REFERENCE 14 OF 22
Hosomi A, Arita M, Sato Y, Kiyose C, Ueda T, Igarashi O, Arai H, Inoue K
Affinity for alpha-tocopherol transfer protein as a determinant of the biological activities of vitamin E analogs.
Alpha-Tocopherol transfer protein (alphaTTP), a product of the gene which causes familial isolated vitamin E deficiency, plays an important role in determining the plasma vitamin E level. We examined the structural characteristics of vitamin E analogs required for recognition by alphaTTP. Ligand specificity was assessed by evaluating the competition of non-labeled vitamin E analogs and alpha- [3H]tocopherol for transfer between membranes in vitro. Relative affinities (RRR-alpha-tocopherol = 100%) calculated from the degree of competition were as follows: beta-tocopherol, 38%; gamma-tocopherol, 9%; delta-tocopherol, 2%; alpha-tocopherol acetate, 2%; alpha-tocopherol quinone, 2%; SRR-alpha-tocopherol, 11%; alpha- tocotrienol, 12%; trolox, 9%. Interestingly, there was a linear relationship between the relative affinity and the known biological activity obtained from the rat resorption-gestation assay. From these observations, we conclude that the affinity of vitamin E analogs for alphaTTP is one of the critical determinants of their biological activity.
Department of Health Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Japan.
FEBS Lett 1997 Jun 2;409(1):105-8
REFERENCE 15 OF 22
Thiele JJ Traber MG Podda M Tsang K Cross CE Packer L
Ozone depletes tocopherols and tocotrienols topically applied to murine skin.
In: FEBS Lett (1997 Jan 20) 401(2-3):167-70
To evaluate ozone damage to hairless mouse skin, two parameters of oxidative damage, vitamin E depletion and malondialdehyde (MDA) production, were measured in vitamin E-enriched and in control skin from mice exposed to ozone (10 ppm). A 5% vitamin E solution (tocotrienol-rich fraction, TRF) in polyethylene glycol (PEG) was applied to 2 sites on the back of hairless mice, PEG to 2 sites. After 2 h, the sites were washed, one of each pair of sites covered and the mice exposed ozone for 2 h. Ozone exposure (compared with covered sites) increased epidermal MDA in PEG-treated sites, while vitamin E was unchanged. In contrast, ozone exposure significantly depleted vitamin E in TRF-treated sites, while significant MDA accumulation was prevented. This is the first demonstration that ozone exposure causes damage to cutaneous lipids, an effect which can be attenuated by vitamin E application.
Institutional address: Department of Molecular and Cell Biology University of California Berkeley 94720-3200 USA.
REFERENCE 16 OF 22
Weber C, Podda M, Rallis M, Thiele JJ, Traber MG, Packer L
Efficacy of topically applied tocopherols and tocotrienols in protection of murine skin from oxidative damage induced by UV- irradiation.
To assess the efficacy of various forms of vitamin E in protection of skin from UV-light-induced oxidative stress, vitamin E (tocotrienol- rich fraction of palm oil, TRF) was applied to mouse skin and the contents of antioxidants before and after exposure to UV-light were measured. Four polypropylene plastic rings (1 cm2) were glued onto the animals’ backs, and 20 microliters 5% TRF in polyethylene glycol- 400 (PEG) was applied to the skin circumscribed by two rings and 20 microliters PEG to the other two rings. After 2 h, the skin was washed and half of the sites were exposed to UV-irradiation (2.8 mW/cm2 for 29 mi: 3 MED). TRF treatment (n = 19 mice) increased mouse skin alpha-tocopherol 28 +/- 16-fold, alpha-tocotrienol 80 +/- 50- fold, gamma-tocopherol 130 +/- 108-fold, and gamma-tocotrienol 51 +/- 36-fold. A significantly higher percentage of alpha-tocopherol was present in the skin as compared with that in the applied TRF. After UV-irradiation, all vitamin E forms decreased significantly (p < .01), while a larger proportion of the vitamin E remained in PEG- treated (approximately 80%) compared with TRF-treated (approximately 40%) skin. Nonetheless, vitamin E concentrations in irradiated TRF- treated skin were significantly higher than in the nonirradiated PEG- treated (control) skin (p < .01). Thus, UV-irradiation of skin destroys its antioxidants: however, prior application of TRF to mouse skin results in preservation of vitamin E.
Department of Molecular and Cell Biology, University of California-Berkeley 94720-3200, USA.
Free Radic Biol Med 1997;22(5):761-9
REFERENCE 17 OF 22
Kramer JK, Blais L, Fouchard RC, Melnyk RA, Kallury KM
A rapid method for the determination of vitamin E forms in tissues and diet by high-performance liquid chromatography using a normal- phase diol column.
This paper describes a simple method for the analysis of tocopherols in tissues by which frozen tissues-70 degrees C were pulverized at dry ice temperatures (-70 degrees C) and immediately extracted with hexane. There was no need to remove the coeluting lipids from tissues by saponification, since at that level of neutral lipids in the sample, there was no reduction in fluorescence response. For the analysis of oil, in which large amounts of neutral lipids were coextracted, a 20% reduction of fluorescence response was observed, but the response was equal for all tocopherol forms, and was appropriately corrected. Saponification was used only when tocopherol esters were present, and only after an initial hexane extraction to remove the free tocopherols in order to avoid their loss by saponification, particularly non alpha-tocopherol and tocotrienols. All the tocopherols and tocotrienols were separated on a normal-phase diol (epoxide) column that gave consistent and reproducible results, without the disadvantages of nonreproducibility with silica columns, or the lack of separation with reversed-phase columns. The tocopherols were quantitated by using a tocopherol form not present in the sample as an internal tocopherol standard, or using an external tocopherol standard if all forms were present, or when the sample was saponified. Piglet heart and liver samples showed the presence of mainly alpha-tocopherol, with minor amounts of beta- and gamma-tocopherol and alpha-tocotrienol, but no delta-tocopherol. Only small amounts of tocopherol esters were present in the liver but not in the heart.
Center for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.
Lipids 1997 Mar;32(3):323-30
REFERENCE 18 OF 22
Traber MG, Rallis M, Podda M, Weber C, Maibach HI, Packer L
Penetration and distribution of alpha-tocopherol, alpha- or gamma- tocotrienols applied individually onto murine skin.
To evaluate skin penetration of various vitamin E homologs, a 5% solution of either alpha-tocopherol, alpha-tocotrienol, or gamma- tocotrienol in polyethylene glycol was topically applied to SKH-1 hairless mice. After 0.5, 1, 2, or 4 h (n = four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5-micron sections–SC1 and SC2), epidermis (next two 10-micron sections–E1 and E2), papillary dermis (next 100 microns, PD), dermis (next 400 microns, D), and subcutaneous fat (next 100 microns, SF). SC1 contained the highest vitamin E concentrations per mu thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers–the lowest layers, PD (40 +/- 15%) and D (36 +/- 15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands–lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA. email@example.com
Lipids 1998 Jan;33(1):87-91
REFERENCE 19 OF 22
Makpol S Shamaan NA Jarien Z Top AG Khalid BA Wan Ngah WZ
Different starting times of alpha-tocopherol and gamma-tocotrienol supplementation and tumor marker enzyme activities in the rat chemically induced with cancer.
In: Gen Pharmacol (1997 Apr) 28(4):589-92
1. alpha-Tocopherol (alpha-T) and gamma-tocotrienol (gamma-T) were supplemented continuously for 8 weeks in the diets of normal rats and rats chemically induced with cancer using diethylnitrosamine (DEN), 2- acetylaminofluorene (AAF) and partial hepatectomy. Hepatocarcinogenesis was followed by determining the plasma gamma- glutamyl-transpeptidase (GGT) and alkaline phosphatase (ALP) activities as well as placental glutathione S-transferase (PGST) and GGT activities histochemically, at 4-week intervals. 2. Male Rattus norvegicus were supplemented alpha-T and gamma-T at two different doses of 30 and 300 mg/kg diet. The supplementation was started at three different times: simultaneously with DEN administration; 4 weeks; and 8 weeks after DEN administration. 3. Elevation of plasma GGT activities and formation of PGST and GGT positive foci were attenuated significantly (P < 0.05) when alpha-T and gamma-T were supplemented simultaneously with cancer induction. Supplementation begun 4 and 8 weeks after cancer induction did not affect plasma enzyme activities and formation of enzyme-positive foci. 4. alpha-T was more effective than gamma-T, and a lower dose of 30 mg/kg was found to be more effective in reducing the severity of hepatocarcinogenesis.
Institutional address: Department of Biochemistry Faculty of Medicine Universiti Kebangsaan Malaysia Kuala Lumpur Malaysia.
REFERENCE 20 OF 22
Kamat JP Sarma HD Devasagayam TP Nesaretnam K Basiron Y
Tocotrienols from palm oil as effective inhibitors of protein oxidation and lipid peroxidation in rat liver microsomes.
In: Mol Cell Biochem (1997 May) 170(1-2):131-7
Tocotrienols from palm oil showed significant ability to inhibit oxidative damage induced by ascorbate-Fe2+ and photosensitization, involving different mechanisms, in rat liver microsomes. The tocotrienol-rich fraction from palm oil (TRF), being tried as a more economical and efficient substitute for alpha-tocopherol, showed time- and concentration-dependent inhibition of protein oxidation as well as lipid peroxidation. It was more effective against protein oxidation. The extent of inhibition by TRF varied with different peroxidation products such as conjugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Among the constituents of TRF, gamma-tocotrienol was the most effective followed by its alpha- and delta-isomers. In general, at a low concentration of 5 microM, TRF was able to prevent oxidative damage to significant extent (37% inhibition of protein oxidation and 27-30% of lipid peroxidation at 1 h of incubation). The protective ability of TRF (30.1% at 5 microM with TBARS formation) was significantly higher than that of the dominant form of vitamin E, alpha-tocopherol (16.5% under same conditions). Hence our studies indicate that this fraction from palm oil can be considered as an effective natural antioxidant supplement capable of protecting cellular membranes against oxidative damage.
Institutional address: Radiation Biology and Biochemistry Division Bhabha Atomic Research Centre Bombay India.
REFERENCE 21 OF 22
Kitazawa M, Podda M, Thiele J, Traber MG, Iwasaki K, Sakamoto K, Packer L
Interactions between vitamin E homologues and ascorbate free radicals in murine skin homogenates irradiated with ultraviolet light.
The mechanism of oxidation of ascorbic acid in mouse skin homogenates by UV light was investigated by measuring ascorbate free radical formation using electron spin resonance signal formation. Addition of vitamin E (alpha-tocopherol or alpha-tocotrienol) had no effect, whereas short-chain homologues (2,5,7,8-tetramethyl-6-hydroxychroman- 2-carboxylic acid [Trolox] and 2,2,5,7,8-pentamethyl-6- hydroxychromane [PMC]) accelerated ascorbate oxidation. The similar hydrophilicity of ascorbate, Trolox and PMC increased their interaction, thus rapidly depleting ascorbate. When dihydrolipoic acid was added simultaneously with the vitamin E homologues, the accelerated ascorbate oxidation was prevented. This was due to the regeneration of ascorbate and PMC from their free radicals by a recycling mechanism between ascorbate, vitamin E homologues and dihydrolipoic acid. Potentiation of antioxidant recycling may be protective against UV irradiation-induced damage. The rate of ascorbate oxidation in the presence of vitamin E homologues was enhanced by a photosensitizer (riboflavin) but was not influenced by reactive oxygen radical quenchers, superoxide dismutase or 5,5- dimethyl-1-pyrroline-N-oxide. These experimental results suggest that the UV irradiation-induced ascorbate oxidation in murine skin homogenates is caused by photoactivated reactions rather than reactive oxygen radical reactions.
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
Photochem Photobiol 1997 Feb;65(2):355-65
REFERENCE 22 OF 22
Vandenberg TA, Guthrie NJ, Carroll KK, Ahlgren J
A phase I study of the tocotrienol rich fraction (TRF) of palm oil in metastatic breast cancer (Meeting abstract).
Tocotrienols are a form of vitamin E with an unsaturated side chain, rather than a saturated side-chain of the more common tocopherols. The TRF fraction contains 80% tocotrienols and 20% alpha-tocopherol. Earlier studies have shown that TRF inhibits development of mammary cancer in rats (Nesaretnam, Nutr Res 12:63 1992). Experiments in our laboratory demonstrated that TRF and tocotrienols inhibit proliferation of human breast cancer cells in culture (Guthrie, FASEB J; 9:A988 1995). No significant toxicities of TRF have been noted in animals. Fifteen eligible patients with measurable/evaluable disease refractory to standard hormonal therapy were treated between February 1994 and December 96. Patients were started in cohorts of three at 80 mg of tocotrienols po bid, and if no dose-limiting toxicity (DLT), defined by NCI criteria as grade 2 or more was noted, the next cohort was given double the previous dose. Patients were evaluated every 4-6 weeks. 13 patients are evaluable for toxicity (2 too early). One patient developed transient grade 2 diarrhea, possibly drug related, at 160 mg bid and treatment was held. No other toxicities have been seen up to 600 mg (five capsules, reformulated higher concentration) bid. Serum cholesterol and triglycerides were reduced in some patients. 11 patients were evaluable for response. There were no partial or complete responders. 5 patients had stable disease. We conclude that tocotrienols at 600 mg bid are well tolerated. Studies are planned to determine whether tocotrienol concentrations associated with tumor control preclinically are achievable in vivo.
American Society of Clinical Oncology 1997, University of Western Ontario, London Regional Cancer Centre, London, Canada
Proc Annu Meet Am Soc Clin Oncol 1997;16:A685