Identities and differences in the metabolism of tocotrienols and tocopherols in HepG2 cells

The metabolism of alpha- and gamma-tocotrienol was investigated in HepG2 cells. Metabolites were identified by HPLC and gas chromatography/mass spectrometry. gamma-Tocotrienol was degraded to gamma-CEHC (carboxyethyl hydroxychroman), gamma-CMBHC (carboxymethylbutyl hydroxychroman), gamma-CMHenHC (carboxymethylhexenyl hydroxychroman), gamma-CDMOenHC (carboxydimethyloctenyl hydroxychroman) and gamma-CDMD(en)(2)HC (carboxydimethyldecadienyl hydroxychroman). alpha-Tocotrienol yielded alpha-CEHC, alpha-CMBHC, alpha-CMHenHC and alpha-CDMOenHC, whereas alpha-CDMD(en)(2)HC could not be detected. These findings demonstrate that the trienols are metabolized essentially like tocopherols, i.e., by omega-oxidation followed by beta-oxidation of the side chain. The failure to detect CMBHC with the original double bond in the side chain reveals that auxiliary enzymes are involved, as in the metabolism of unsaturated fatty acids. CMBHC were the most abundant metabolites obtained from the tocotrienols as well as from alpha-tocopherol. Quantitatively, the tocotrienols were degraded to a larger extent than their counterparts with saturated side chains. The pronounced quantitative differences in the metabolism between individual tocopherols as well as between tocotrienols and tocopherols in vitro suggest a corresponding lack of equivalence in vivo.     

金雀异黄素诱导人乳腺癌细胞凋亡作用机制研究

目的探讨金雀异黄素对体外培养的人乳腺癌MCF7细胞凋亡的影响及作用机制。方法采用MMT法、凋亡细胞的荧光显微镜、电镜观察和流式细胞仪的检测,观察了不同剂量的金雀异黄素诱导细胞凋亡。同时采用免疫组化法检测凋亡相关基因Bax和癌基因erbB2蛋白的表达。结果通过荧光显微镜和电镜技术观察到凋亡的MCF7细胞。流式细胞仪也检测到了金雀异黄素诱导MCF7细胞产生凋亡,并随着金雀异黄素浓度的增加,细胞凋亡率显著增加。蛋白水平检测表明金雀异黄素促进MCF7细胞Bax表达升高,抑制erbB2表达。结论金雀异黄素可诱导MCF7细胞凋亡,并主要是通过调节Bax和erbB2蛋白表达实现的。     

Induction of apoptosis by immature fruits of Prunus salicina Lindl. cv. Soldam in MDA-MB-231 human breast cancer cells

The goal of this study was to evaluate the anticancer effect of Prunus salicina Lindl. cv. Soldam at three maturity stages (immature, midmature and mature stages). Previous studies have shown that this fruit (plums) possesses hematopoiesis effects, prevents osteoporosis and has anti-mutagenic effects. An acetone extract of immature P. salicina Lindl. cv. Soldam fruit contained higher levels of total phenolics and condensed tannins than midmature and mature plums. The results showed that an acetone extract of immature plums possesses cytotoxic effects, which are related to the activity of the total polyphenols in the fruits. Apoptosis in MDA-MB-231 cells mediated by the immature plums was associated with an increase in Bax levels and a reduction in Bcl-2 levels and the cleavage of caspase 3, caspase 7, caspase 9 and poly-(ADP-ribose) polymerase. These results indicate that immature fruit of P . salicina Lindl. cv. Soldam can be regarded as a safe and promising new dietary source for decreasing the risk of developing breast cancer.     

Induction of apoptosis by immature fruits of Prunus salicina Lindl. cv. Soldam in MDA-MB-231 human breast cancer cells

The goal of this study was to evaluate the anticancer effect of Prunus salicina Lindl. cv. Soldam at three maturity stages (immature, midmature and mature stages). Previous studies have shown that this fruit (plums) possesses hematopoiesis effects, prevents osteoporosis and has anti-mutagenic effects. An acetone extract of immature P. salicina Lindl. cv. Soldam fruit contained higher levels of total phenolics and condensed tannins than midmature and mature plums. The results showed that an acetone extract of immature plums possesses cytotoxic effects, which are related to the activity of the total polyphenols in the fruits. Apoptosis in MDA-MB-231 cells mediated by the immature plums was associated with an increase in Bax levels and a reduction in Bcl-2 levels and the cleavage of caspase 3, caspase 7, caspase 9 and poly-(ADP-ribose) polymerase. These results indicate that immature fruit of P. salicina Lindl. cv. Soldam can be regarded as a safe and promising new dietary source for decreasing the risk of developing breast cancer.     

Induction of apoptosis in HT-29 colon cancer cells by phloretin

Phloretin, which is present in apples and pears, has been found to inhibit the growth of several cancer cells and induce apoptosis of B16 melanoma and HL60 human leukemia cells. The present study examined whether and how phloretin induces apoptosis of HT-29 human colon cancer cells. Phloretin (0-100 micromol/L) substantially decreased viable cell number and induced apoptosis of HT-29 cells in a dose-dependent manner. Western blot analysis of total cell lysates revealed that phloretin increased the protein levels of Bax but had no effect on Bcl-2. In addition, phloretin induced cleavage of caspase-8, -9, -7, and -3 and poly(ADP-ribose) polymerase. Furthermore, phloretin increased the levels of cytochrome c and Smac/Diablo in the cytosol. The present results indicate that phloretin inhibits HT-29 cell growth by inducing apoptosis, which may be mediated through changes in mitochondrial membrane permeability and activation of the caspase pathways.     

Vitamin E: tocopherols and tocotrienols as potential radiation countermeasures

Despite the potential devastating health consequences of intense total-body irradiation, and the decades of research, there still remains a dearth of safe and effective radiation countermeasures for emergency, radiological/nuclear contingencies that have been fully approved and sanctioned for use by the US FDA. Vitamin E is a well-known antioxidant, effective in scavenging free radicals generated by radiation exposure. Vitamin E analogs, collectively known as tocols, have been subject to active investigation for a long time as radioprotectors in patients undergoing radiotherapy and in the context of possible radiation accidents or terrorism scenarios. Eight major isoforms comprise the tocol group: four tocopherols and four tocotrienols. A number of these agents and their derivatives are being investigated actively as radiation countermeasures using animal models, and several appear promising. Although the tocols are well recognized as potent antioxidants and are generally thought to mediate radioprotection through ‘free radical quenching’, recent studies have suggested several alternative mechanisms: most notably, an ‘indirect effect’ of tocols in eliciting specific species of radioprotective growth factors/cytokines such as granulocyte colony-stimulating factor (G-CSF). The radioprotective efficacy of at least two tocols has been abrogated using a neutralizing antibody of G-CSF. Based on encouraging results of radioprotective efficacy, laboratory testing of γ-tocotrienol has moved from a small rodent model to a large nonhuman primate model for preclinical evaluation. In this brief review we identify and discuss selected tocols and their derivatives currently under development as radiation countermeasures, and attempt to describe in some detail their in vivo efficacy.     

Induction of apoptosis by the aqueous extract of Rubus coreanum in HT-29 human colon cancer cells

OBJECTIVES: The incompletely ripened fruit of Rubus coreanum (IRFRC) has been used in traditional herbal medicine to manage various diseases. To explore the possibility that IRFRC has chemopreventive effects, we examined whether or not extracts of IRFRC inhibits HT-29 cell growth and explored the mechanism for this effect. METHODS: We cultured HT-29 cells in the presence of the aqueous or ethanol extract of IRFRC. DNA synthesis was estimated by 5-bromo-2'-deoxyuridine incorporation. We measured apoptosis using a DNA fragmentation assay and Annexin V staining. We used western blot analyses to determine the cleavage of caspases and poly (adenosine diphosphate-ribose) polymerase. RESULTS: Aqueous extract of IRFRC substantially inhibited viable HT-29 cell number in a dose-dependent manner, whereas ethanol extract had only a minimal effect. Aqueous extract inhibited DNA synthesis and induced apoptosis of HT-29 cells in a dose-dependent manner. Aqueous extract induced cleavage of caspase-3, -7, and -9 and induced the activity of caspase-3 and cleavage of poly (adenosine diphosphate-ribose) polymerase. CONCLUSIONS: We have shown that aqueous extract of IRFRC inhibits cell proliferation and stimulates apoptosis in HT-29 cells, and that this may be mediated by its ability to activate the caspase-3 pathway. It remains to be determined whether the aqueous extract of IRFRC has chemopreventive activities in animal models.     

Induction of apoptosis signaling by glycoprotein of Capsosiphon fulvescens in human gastric cancer (AGS) cells

Capsosiphon fulvescens is a well-known green sea algae that has been touted in recent years as a potential anticancer drug. In this study, C. fulvescens glycoprotein (Cf-GP) showed proapoptotic signaling in AGS cells. An MTS assay indicated that Cf-GP inhibited the proliferation of AGS cell lines in a dose-dependent manner. Cells were treated with Cf-GP and the expression of proteins associated with apoptosis was examined by Western blotting. Based on the Western blot, expression of Cf-GP-activated caspase-cascade and PARP, which is a substrate of caspase-3 and -8, and proteins of the Bcl-2 family was observed. Cf-GP treatment stimulated the release of cytochrome C and apoptotic protease activating factor-1 from mitochondria to the cytosol. Cf-GP inhibited the growth of AGS cells through induction of sub-G1 phase arrest. We confirmed that sub-G1-phase arrest was associated with a decrease in the expression of cyclin D, cyclin E, Cdk2, Cdk4, and Cdk6, and an increase in the protein levels of p21 and p27. As a result, the increased sub-G1 ratio appears to be inhibited by cell proliferation. Therefore, we can confirm apoptosis in the AGS cells. Our results suggest that Cf-GP could be a potential source of biofunctional material that shows anticancer effects in human gastrointestinal cancer.     

萝藦果壳多糖诱导人肺癌A549细胞凋亡的研究

目的 探究萝藦果壳多糖（MJP-1’）诱导人肺癌A549细胞凋亡的作用。方法 采用CCK8法检测萝藦果壳多糖对A549细胞活力的影响;采用比色法检测A549细胞内乳酸脱氢酶的释放量变化情况;通过TUNEL实验探究萝藦果壳多糖对A549细胞凋亡的影响;通过JC - 1荧光探针探究萝藦果壳多糖对A549细胞线粒体膜电位的影响;通过蛋白质分子印迹法探究萝藦果壳多糖作用后A549细胞凋亡相关蛋白表达的变化。结果 CCK8法显示萝藦果壳多糖抑制A549细胞的增殖,并呈剂量依赖趋势（125 μg/ml组:t = 3.092,P = 0.015;250 μg/ml组:t = 3.929,P = 0.004;500 μg/ml组:t = 5.626,P＜0.001;1 000 μg/ml组:t = 7.512,P＜0.001;2 000 μg/ml组:t = 9.677,P＜0.001;4 000 μg/ml组:t = 12.290,P＜0.001;8 000 μg/ml组:t = 16.000,P＜0.001）;比色法显示A549细胞乳酸脱氢酶释放量增加（2 mg/ml组:t = 8.233,P = 0.001;4 mg/ml组:t = 12.640,P＜0.001;8 mg/ml组:t = 27.530,P＜0.001）;TUNEL实验显示萝藦果壳多糖可促进A549细胞凋亡（2 mg/ml组:t = 7.803,P＜0.001;4 mg/ml组:t = 12.460,P＜0.001;8 mg/ml组:t = 39.340,P＜0.001）;JC - 1探针实验结果显示萝藦果壳多糖导致A549细胞线粒体膜电位降低（2 mg/ml组:t = 24.120,P＜0.001;4 mg/ml组:t = 28.530,P＜0.001;8 mg/ml组:t = 31.600,P＜0.001）;蛋白质分子印迹法结果显示萝藦果壳多糖可以下调Bcl - 2蛋白表达（2 mg/ml组:t = 3.790,P = 0.019;4 mg/ml组:t = 6.598,P = 0.003;8 mg/ml组:t = 12.840,P＜0.001）,并使Bax、cleaved - caspase - 3蛋白表达增加（Bax组:2 mg/ml组:t = 17.280,P＜0.001;4 mg/ml组:t = 36.040,P＜0.001;8 mg/ml组:t = 22.520,P＜0.001;cleaved - caspase - 3组:2 mg/ml组:t = 6.487,P = 0.003;4 mg/ml组:t = 9.326,P＜0.001;8 mg/ml组:t = 22.380,P＜0.001）。结论 本研究发现萝藦果壳多糖可以诱导人肺癌A549细胞凋亡,为进一步开发利用萝藦果壳多糖奠定了基础。     

Induction of apoptosis by Antrodia camphorata in human premyelocytic leukemia HL-60 cells

Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine, and it has been shown to exhibit antioxidant effects. In this study, the ability of A. camphorata to induce apoptosis was studied in cultured human premyelocytic leukemia HL-60 cells. Treatment of the HL-60 cells with a variety of concentrations of the fermented culture broth of A. camphorata (25-150 microg/ml) resulted in dose- and time-dependent sequences of events marked by apoptosis, as shown by loss of cell viability, chromatin condensation, and internucleosomal DNA fragmentation. Furthermore, apoptosis in the HL-60 cells was accompanied by the release of cytochrome c, activation of caspase-3, and specific proteolytic cleavage of poly (ADP-ribose) polymerase (PARP). This increase in A. camphorata-induced apoptosis was also associated with a reduction in the levels of Bcl-2, a potent cell-death inhibitor, and an increase in those of the Bax protein, which heterodimerizes with and thereby inhibits Bcl-2. The data suggest that A. camphorata exerts antiproliferative action and growth inhibition on HL-60 cells through apoptosis induction and that it may have anticancer properties valuable for application in drug products.     

Long-chain carboxychromanols are the major metabolites of tocopherols and tocotrienols in A549 lung epithelial cells but not HepG2 cells

Human lung type II cell derived A549 epithelial cancer cells and HepG2 hepatocytes constitutively express cytochrome P4504F2, a P450 we previously identified as a tocopherol-omega-hydroxylase. To determine if A549 cells would metabolize tocochromanols via the omega-hydroxylase pathway, we compared the metabolism of tocopherols (alpha-, gamma-, delta-TOH) and tocotrienols (alpha-, gamma-, delta-T3) in these 2 cell lines. Cultures were incubated with alpha-, gamma-, or delta-TOH, or the analogous T3s, and synthesis of their metabolites quantitated by GC-MS. A549 cells metabolized all tocochromanols 2-3 times more extensively than HepG2 cells (P < 0.001) except alpha-TOH, a difference not related to cell uptake of substrate but rather was reflective of greater microsomal TOH-omega-hydroxylase enzyme activity. Notably, 9'-carboxychromanols were the major metabolites of all gamma- and delta-TOHs and T3s in A549 cultures, whereas 3'- and 5'-carboxychromanols predominated in HepG2 cultures. Accumulation of 9'-carboxychromanols in A549 cultures was due to their inefficient conversion to 7'-carboxychromanols relative to HepG2 cells. Sesamin inhibited tocochromanol metabolism in both cells types, and neither cell type exhibited evidence of alternative (sesamin-insensitive) pathways of metabolism. TOH-omega-hydroxylase activity was undetectable in rat primary lung type II cells, suggesting that expression of activity was associated with transformation of normal type II cells to cancer cells. Long-chain carboxychromanol metabolites of gamma-TOH and other forms of vitamin E can be biosynthesized in A549 cultures for assessment of their biological activity, including their potential inhibition of synthesis of inflammatory mediators.     

不同的游离脂肪酸对人乳腺癌细胞凋亡和侵袭的影响

目的探讨不同游离脂肪酸(FFAs)对MDA-MB-231人乳腺癌细胞凋亡和迁移的影响.方法用50、200、500 umol/L三种不同浓度的油酸(0A)和棕榈酸(PA)分别刺激MDA-MB-231细胞,采用实时定量PCR分析细胞中PTEN的mRNA含量,蛋白免疫印迹法检测PTEN和Bcl-2的蛋白表达,原位末端标记法(TUNEL)观察细胞的凋亡情况,小室迁移实验测定细胞的迁移能力.结果OA使MDA-MB-231细胞中PTEN的mRNA和蛋白表达水平降低,Bcl-2蛋白表达升高(P均＜0.05);PA则使PTEN的mRNA和蛋白表达水平上升,Bcl-2蛋白表达下降(P均＜0.05).显微镜下观察到PA刺激后的MDA-MB-231细胞凋亡增加.迁移实验显示OA和PA都能使乳腺癌细胞侵袭能力增强.结论PA可能通过上调PTEN的表达促进MDA-MB-231人乳腺癌细胞凋亡,但同时也增强细胞的侵袭能力.OA也可增强癌细胞侵袭能力.     

神经酰胺诱导人结肠癌细胞凋亡的作用

目的 探讨外源性神经酰胺诱导结肠癌HT-29细胞凋亡的作用。方法 采用噻唑兰(MTT)显色法、荧光显微镜、电镜观察以及通过免疫组化方法检测Fas、P53的表达情况。结果 神经酰胺对HT-29细胞的生长有明显抑制作用，并可诱导HT-29细胞产生凋亡，并随着神经酰胺浓度的增加，细胞凋亡率逐渐增加；Fas蛋白的表达随着神经酰胺浓度的增加呈现逐渐升高的趋势，p53蛋白的表达随着神经酰胺浓度的增加呈现降低的趋势。结论 神经酰胺能诱导HT-29细胞产生凋亡。     

Induction of apoptosis and cell cycle arrest in cancer cells by in vivo metabolites of teas

The present study was conducted to determine in vivo possibilities of inducing apoptosis and cell cycle arrest in rat cancer cells by green, oolong, and black teas and also to further identify the mechanisms inhibiting cancer cell proliferation by the sera from tea-treated rats. The tea extracts from these three kinds of tea, the rat sera obtained after oral intubation of the tea extracts, and the tea polyphenolic compounds, (-)-epigallocatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin-3-gallate, and the aflavins, were used in the related tests. The extracts, the sera from the treated rats, and the polyphenolic compounds significantly inhibited the proliferation of a rat hepatoma cell line (AH109A) and murine B16 melanoma cells but not normal rat mesothelial (M) cells. (-)-Epicatechin exhibited synergistic effects with (-)-epigallocatechin-3-gallate, (-)-epicatechin-3-gallate, and theaflavins against AH109A cell proliferation. The fluorescence staining of the nuclei, electrophoresis detection of DNA fragmentation, and analysis of cell cycle indicated that the sera from the tea-treated rats, the tea extracts, and the related tea components resulted in loss of viability, apoptosis, and cell cycle arrest at the G1 phase in AH109A and/or B16 cells, but not in normal M cells. Our results suggest that induction of apoptosis and cell cycle arrest may be important mechanisms of in vivo proliferation inhibition of AH109A and other cancer cells by these teas.     

Effects of retinoic acid isomers on apoptosis and enzymatic antioxidant system in human breast cancer cells

Retinoic acids (RAs) modulate growth, differentiation, and apoptosis in normal, pre-malignant & malignant cells. In the present study, the effects of RA isomers (all-trans RA, 13-cis RA, and 9-cis RA) on the cell signal transduction of human breast cancer cells have been studied. The relationship between RAs and an enzymatic antioxidant system was also determined. Estrogen-receptor (ER) positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells were treated with different doses of each RA isomers, all-trans RA, 13-cis RA, or 9-cis RA. Treatment of RA isomers inhibited cell viability and induced apoptosis of MCF-7 cells as a result of increased caspase activity in cytoplasm and cytochrome C released from mitochondria. All-trans RA was the most effective RA isomer in both cell growth inhibition and induction of apoptosis in MCF-7 cells. However, no significant effect of RA isomers was observed on the cell growth or apoptosis in ER-negative MDA-MB-231 cells. In addition, activities of antioxidant enzymes such as catalase and glutathione peroxidase were decreased effectively after treatment of RA in MCF-7 cells, whereas SOD activity was rarely affected. Thus, the present data suggest that all-trans RA is the most potential inducer of apoptosis and modulator of antioxidant enzymes among RA isomers in MCF-7 human breast cancer cells.     

Bromelain-induced apoptosis in GI-101A breast cancer cells

Bromelain is a proteolytic enzyme extracted from the stems and the immature fruits of pineapple that was found to be antitumorigenic in different in vitro models. Bromelain has been reported to promote apoptosis, particularly in breast cancer cells, with the up-regulation of c-Jun N-terminal kinase and p38 kinase. Our study was designed to determine if bromelain could induce apoptosis in GI-101A breast cancer cells. GI-101A cells were treated with increasing concentrations of bromelain for 24 hours. The effect of bromelain for inducing cell death via activation of the apoptosis mechanism in GI-101A cells was further determined by using caspase-9 and caspase-3 assays along with the M30-Apoptosense assay to measure cytokeratin 18 (CK18) levels in the cytoplasm of the cultured cancer cells. A dose-dependent increase in the activities of caspase-9 and caspase-3 coinciding with elevation of CK18 levels was found in bromelain-treated cells compared with control cells. Furthermore, the apoptosis induction by bromelain was confirmed by DNA fragmentation analysis and 4,6'-diamino-2-phenylindole dihydrochloride fluorescence staining of the nucleus. Our results indicate an increase in apoptosis-related cell death in breast cancer cells with increasing concentrations of bromelain.     

Kaempferol induced the apoptosis via cell cycle arrest in human breast cancer MDA-MB-453 cells

The aim of present study was to investigate the effects of kaempferol on cellular proliferation and cell cycle arrest and explore the mechanism for these effects in human breast carcinoma MDA-MB-453 cells. Cells were treated with kaempferol at various concentrations (ranging from 1 to 200 µM) for 24 and 48 hrs. Kaempferol significantly inhibited cancer cell growth in cells exposed to 50 and 10 µM of kaempferol and incubated for 24 and 48 hrs, respectively. Exposure to kaempferol resulted in cell cycle arrest at the G2/M phase. Of the G2/M-phase related proteins, kaempferol down-regulated CDK1 and cyclin A and B in cells exposed to kaempferol. In addition, small DNA fragments at the sub-G0 phase were increased by up to 23.12 and 31.90% at 10 and 50 µM incubated for 24 and 48 hrs, respectively. The kaempferol-induced apoptosis was associated with the up-regulation of p53. In addition, the phosphorylation of p53 at the Ser-15 residue was observed with kaempferol. Kaempferol inhibits cell proliferation by disrupting the cell cycle, which is strongly associated with the induction of arrest at G2/M phase and may induce apoptosis via p53 phosphorylation in human breast carcinoma MDA-MB-453 cells.     

A small-scale sample preparation method with HPLC analysis for determination of tocopherols and tocotrienols in cereals

A small-scale sample preparation method was developed for reliable and economic analysis of tocopherols and tocotrienols in rye and other cereals. The saponification parameters were optimized using two experimental design protocols with statistical analyses. Three critical factors were optimized for hot saponification: time, temperature and amount of potassium hydroxide (KOH). The amount of KOH had the greatest effect. Two direct solvent extraction methods without saponification were tested and found to yield in comparable values than with saponification. Finally, three solvent mixtures for extracting tocopherols and tocotrienols after the optimized saponification step were studied in order to examine the effect of solvent polarity on their recovery. Adding a polar modifier to the solvent, tocopherol and tocotrienol values of rye were significantly increased. The optimized sample preparation method included saponification with 0.5 mL KOH at 100°C for 25 min followed by extraction with n-hexane:ethyl acetate (8:2). The repeatability of the recommended analytical procedure was good and the recoveries of added tocopherols from rye flour samples ranged from 90.3% to 94.3%. The procedure developed was applied to examine the amounts and distribution of tocopherols and tocotrienols in ten rye varieties. The average total tocopherol and tocotrienol content of rye grains was 48.8 μg/g with a 9.3% standard deviation between varieties.     

Distribution of tocopherols in human plasma and red blood cells.

The content of various tocopherols was determined in normal plasma and red blood cells. alpha-Tocopherol concentrations ranged form 6.6 to 15.0 (mean 9.6) mug/ml in plasma and from 0.9 to 1.8 (mean 1.4) mug/ml in red blood cells. gamma-Tocopherol ranged from 0.7 to 2.7 (mean 1.6) mug/ml in plasma and fron 0.1 to 0.4 (mean 0.24) mug/ml in red blood cells. Only a minute amount (smaller than 0.3 mug/ml) of each of alpha-tocotrienol, beta-tocopherol, gamma-tocotrienol and delta-tocopherol was found in plasma but none in red blood cells. No delta-tochotrienol was detected in either plasma or red blood cells. Of the total tocopherols, alpha form accounted 83 per cent in plasma and 87 per cent in red blood cells and gamma from represented 13 per cent in each system. The recovery of added 14-C-alpha-tocopherol averaged 87 per cent and 69 per cent, respectively, for plasma and red blood cells. All alpha-tocopherol in the red blood cells was found to be localized in the membrane fraction.