Stability of tryptophan-containing LOs in flaxseed oil and their response towards γ-tocopherol.

Linusorbs (LOs), significantly influence oil quality and sensory properties of flaxseed oil. Trp-containing LOs exhibit distinct oxidative behavior when γ-tocopherol (γ-T) is present. Polar fractions of crude flaxseed oil were stripped via silica absorption, and reintroduced (LO and γ-T) separately into the oil matrix to investigate their interaction during storage. Compared with crude oil, LOs account for 18.49% reduction of p-anisidine value, while LOs with γ-T contributed to most of the endogenous antioxidant effect in crude oil. γ-T was found to suppress oxidation of Trp-containing LO at early stage (Met form), while facilitate oxidation while at their mid-stage (MetO form, Methionine sulfoxide). In vitro oxidation shows that CLD more likely cleaved into peptide fragments, while few products retain intact ring structures. LC-MS/MS analysis and silicon simulation revealed proximity between MetO and Trp residues, facilitating inter- or intra-molecular reactions and ring structure rupture. Remarkably, the presence of γ-T facilitate these phenomena.

The Chemical Composition of Oils and Cakes of Ochna serrulata (Ochnaceae) and Other Underutilized Traditional Oil Trees from Western Zambia.

Currently, the negative effects of unified and intensive agriculture are of growing concern. To mitigate them, the possibilities of using local but nowadays underused crop for food production should be more thoroughly investigated and promoted. The soybean is the major crop cultivated for vegetable oil production in Zambia, while the oil production from local oil-bearing plants is neglected. The chemical composition of oils and cakes of a three traditional oil plant used by descendants of the Lozi people for cooking were investigated. Parinari curatellifolia and Schinziophyton rautanenii oils were chiefly composed of α-eleostearic (28.58-55.96%), linoleic (9.78-40.18%), and oleic acid (15.26-24.07%), whereas Ochna serrulata contained mainly palmitic (35.62-37.31%), oleic (37.31-46.80%), and linoleic acid (10.61-18.66%); the oil yield was high (39-71%). S. rautanenii and O. serrulata oils were rich in γ-tocopherol (3236.18 µg/g, 361.11 µg/g, respectively). The O. serrulata oil also had a very distinctive aroma predominantly composed of p-cymene (52.26%), m-xylene (9.63%), γ-terpinene (9.07%), o-xylene (7.97), and limonene (7.23%). The cakes remaining after oil extraction are a good source of essential minerals, being rich in N, P, S, K, Ca, and Mg. These plants have the potential to be introduced for use in the food, technical, or pharmaceutical industries.

Tocopherols and Tocotrienols-Bioactive Dietary Compounds; What Is Certain, What Is Doubt?

Tocopherols and tocotrienols are natural compounds of plant origin, available in the nature. They are supplied in various amounts in a diet, mainly from vegetable oils, some oilseeds, and nuts. The main forms in the diet are α- and γ-tocopherol, due to the highest content in food products. Nevertheless, α-tocopherol is the main form of vitamin E with the highest tissue concentration. The α- forms of both tocopherols and tocotrienols are considered as the most metabolically active. Currently, research results indicate also a greater antioxidant potential of tocotrienols than tocopherols. Moreover, the biological role of vitamin E metabolites have received increasing interest. The aim of this review is to update the knowledge of tocopherol and tocotrienol bioactivity, with a particular focus on their bioavailability, distribution, and metabolism determinants in humans. Almost one hundred years after the start of research on α-tocopherol, its biological properties are still under investigation. For several decades, researchers' interest in the biological importance of other forms of vitamin E has also been growing. Some of the functions, for instance the antioxidant functions of α- and γ-tocopherols, have been confirmed in humans, while others, such as the relationship with metabolic disorders, are still under investigation. Some studies, which analyzed the biological role and mechanisms of tocopherols and tocotrienols over the past few years described new and even unexpected cellular and molecular properties that will be the subject of future research.

Antioxidant action of vitamin E in vivo as assessed from its reaction products with multiple biological oxidants.

Vitamin E acts as essential antioxidant against detrimental oxidation of biological molecules induced by multiple reactive species. To gain more insight into the physiological role of vitamin E, the levels of its oxidation products in humans under normal and pathological conditions were compared. α-Tocopherol quinone (α-TQ) and 5-nitro-γ-tocopherol (5-NgT) were focused. α-TQ is produced by multiple oxidants including oxygen radicals, peroxynitrite, hypochlorite, singlet oxygen, and ozone, while 5-NgT is produced by nitrogen dioxide radical derived from peroxynitrite and the reaction of nitrite and hypochlorite. The reported concentrations of α-TQ and 5-NgT in healthy human plasma are highly variable ranging from 15 to 360 and 4 to 170 nM, respectively. In general, the molar ratio 5-NgT/γ-tocopherol was higher than the ratio α-TQ/α-tocopherol. Both absolute concentrations of α-TQ and 5-NgT and the molar ratios to the parent tocopherols were elevated significantly in the plasma of patients with various diseases compared with healthy subjects except neurological diseases. The molar ratios of the products to the respective parent compounds decreased in the order of 5-NgT/γ-tocopherol > α-TQ/α-tocopherol > hydroxyoctadecadienoate/linoleate > 3-nitrotyrosine/tyrosine > isoprostane/arachidonate. The molar ratios of nitrated products to the respective parent compounds in human plasma are approximately 10-2 for 5-NgT and 10-5 for 3-nitrotyrosine, nitro-oleic acid, and 8-nitroguaine. These data indicate that vitamin E acts as an important physiological antioxidant and that α-TQ and 5-NgT represent biomarker for oxidative stress and nitrative stress respectively.

Synthesis of [18F]F-γ-T-3, a Redox-Silent γ-Tocotrienol (γ-T-3) Vitamin E Analogue for Image-Based In Vivo Studies of Vitamin E Biodistribution and Dynamics.

Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, ß-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E's biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[18F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([18F]F-γ-T-3) was prepared for this purpose. [18F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [18F]fluoride in DMF/K222. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [18F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [18F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [18F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues.

The key role of ovalbumin in lipid bioaccessibility and oxidation product profile during the in vitro digestion of slightly oxidized soybean oil.

The behaviour of slightly oxidized virgin and refined soybean oils during in vitro digestion was studied by 1H nuclear magnetic resonance (1H NMR) and solid phase microextraction-gas chromatography/mass spectrometry. The main objectives were to analyze lipolysis extent and oxidation during digestion, and to assess the impact of two different proportions of ovalbumin on both processes. At the same time γ-tocopherol fate was monitored, when possible, by 1H NMR. The results reveal that the initial oxidation degree of the oils negatively influences the lipolysis extent, reducing the bioaccessibility of the major oil components, which include some essential fatty acids. Although the low ovalbumin proportion tested does not significantly affect lipolysis, this is greatly enhanced when ovalbumin is added at a high level, improving lipid bioaccessibility. It has also been shown that oxidation does not seem to have occurred to a great enough extent during digestion for it to be detected from polyunsaturated acyl group degradation. Moreover, the changes observed in the oxidation product profile of the starting oils after digestion can be considered to be due mainly to the transformation of the initially present hydroperoxides, whose concentration diminishes in the digested samples to give hydroxy-dienes, epoxides and aldehydes. In presence of a high ovalbumin proportion, hydroperoxide reduction to hydroxy-dienes is favoured and lower levels of aldehydes and epoxides are observed. This latter could be due to a diminution in their generation and/or to their reaction with ovalbumin. A high proportion of this protein in the system also increases γ-tocopherol bioaccessibility.

α-Tocopherol, but Not γ-Tocopherol, Attenuates the Expression of Selective Tumor Necrosis Factor-Alpha-Induced Genes in Primary Human Aortic Cell Lines.

Of the antioxidant vitamin E isoforms, α-tocopherol (αT) and γ-tocopherol (γT) are the most abundant in the human diet, and αT is consumed from both natural and synthetic sources. αT and γT may differentially impact inflammation and influence cardiovascular outcomes, in part by modulating gene expression. The goal of this study was to compare the effects of natural αT, synthetic αT, and γT on gene expression in two human cell lines. Human aortic smooth muscle cells (HASMC) and endothelial cells (HAEC) were either: (1) treated with 25 µM tocopherols alone, or (2) pretreated with tocopherols prior to a pro-inflammatory cytokine (tumor necrosis factor-alpha, TNF-α) stimulation. The expression of atherosclerosis-related genes was measured using RT2 Profiler PCR arrays. Tocopherol treatments alone did not significantly modulate the expression of genes in unstimulated HASMC or HAEC. TNF-α stimulation significantly upregulated genes involved with apoptosis and stress response in both cell lines. Pretreating cells with tocopherols did not normalize the gene expression changes induced by TNF-α. However, αT pretreatments, but not γT pretreatments, attenuated TNF expression in both HASMC and HAEC. These findings suggest that under stimulated conditions, αT modestly modulates the expression of selective genes and that αT may be more anti-inflammatory than γT.

A thorough insight into the complex effect of gamma-tocopherol on the oxidation process of soybean oil by means of 1H Nuclear Magnetic Resonance. Comparison with alpha-tocopherol.

The effect of γ-tocopherol in proportions between 0.02 and 2% by weight on the accelerated storage process of refined soybean oil is studied by 1H NMR, and compared with that of α-tocopherol. Whereas the lowest γ-tocopherol enrichment level does not affect oil evolution, at higher concentrations both γ- and α-tocopherols initially accelerate acyl groups degradation and hydroperoxides generation, more as higher is the tocopherol concentration, this effect being less marked for γ-tocopherol. However, after this initial stage, the rates of acyl groups degradation and hydroperoxides formation decrease with tocopherol concentration. Furthermore, in the case of γ-tocopherol, the higher the enrichment degree, the later hydroperoxides decomposition occurs, so that, unlike α-tocopherol, γ-tocopherol delays the generation of most secondary oxidation products (aldehydes, (E,E)-keto-dienes, epoxy-keto-enes, (E)-epoxystearates and alcohols) with the exception of some epoxides. Similarly to α-tocopherol, γ-tocopherol modifies the oil oxidation pathway at the highest addition level, promoting the formation of compounds with (Z,E)-isomerism, although less noticeably than α-tocopherol.

Methionine sulfone-containing orbitides, good indicators to evaluate oxidation process of flaxseed oil.

This study aimed to explore the possibility of using methionine sulfone (Msn)-containing orbitides as indicators to evaluate the oxidation process of flaxseed oils. Results showed that after 4 days' heating, oxidation values slightly increased (p > .05) with significant decrease in methionine (Met)-containing peptides (p < .05) instead of γ-tocopherol (p > .05). However, as oxidation time continues increasing, oxidation values significantly increased (p < .05) with significant reduction of γ-tocopherol (p < .05). It demonstrated that Met-containing peptides were more readily oxidized compared with γ-tocopherol and showed certain antioxidant activity. Besides, high logarithmic correlations were found between oxidation values and Msn-containing orbitides (0.94-1.00), such as between total carbonyl compounds and orbitide [1-8-NαC],[1-MetO2]-CLE (64.95 lnx - 52.14, R2 = 0.99, Dingya23 oil). Therefore, in comparison with common oxidation indices, Msn-containing orbitides may be better indicators for evaluating the oxidation process of flaxseed oil with superior separation efficiency, specific information and high stability.

Hemin- and myoglobin-catalyzed reaction of 1-palmitoyl-2-linoleoyl-3-sn-phosphatidylcholine 13-hydroperoxide with γ-tocopherol in micelles and liposomes.

The secondary process of lipid peroxidation proceeds by the free radical reaction to produce some toxic aldehydes. Since γ-tocopherol (γ-TH), one of the major forms of vitamin E in some vegetable oils, acts as a free radical scavenger, γ-TH may suppress the formation of such aldehydes. This study reports the effect and reaction products of γ-TH on the hemin- or myoglobin-catalyzed decomposition of 1-palmitoyl-2-linoleoyl-3-sn-phosphatidylcholine 13-hydroperoxide (PLPC-OOH) in micelles and liposomes. γ-TH and PLPC-OOH in micelles were reacted in the presence of hemin, and the reaction products were characterized as 1-palmitoyl-2-[(8a-dioxy-γ-tocopherone)-12,13-epoxyoctadecenoyl]-3-sn-phosphatidylcholines (γT-OO-epoxyPLPC), 1-palmitoyl-2-[(γ-tocopheroxy)-12,13-epoxyoctadecenoyl]-3-sn-phosphatidylcholines (γT-epoxyPLPC), and the adducts of γ-TH dimer with PLPC-OOH derived epoxyperoxyl and epoxyalkyl radicals (γTD-OO-epoxyPLPC and γTD-epoxyPLPC). The hemin- and myoglobin-catalyzed decomposition of PLPC-OOH in micelles produced hexanal and 4-hydroxy-2-nonenal as the major aldehydic products. γ-TH suppressed the formation of these aldehydes as the same level as α-TH did, and γ-tocopherylquinone, tocored, γ-TH dimers, and the addition products (γT-OO-epoxyPLPC, γT-epoxyPLPC, γTD-OO-epoxyPLPC, and γTD-epoxyPLPC) were formed during the reaction. In liposomes, hexanal was detected as the major aldehyde and its suppression by γ-TH was less effective than that by α-TH. The results indicate that γ-TH may suppress the formation of aldehydes by trapping the epoxyperoxyl and epoxyalkyl radicals derived from PLPC-OOH although its ability is weak in liposomal systems.

Identification and evaluation of antioxidants in Japanese parsley.

Two cultivars of Japanese parsley were harvested in different seasons; their antioxidant capacities were evaluated by oxygen radical absorbance capacity (ORAC) methods, and the contents of hydrophilic and lipophilic antioxidants were compared. Japanese parsley possessed potent antioxidant capacities both in hydrophilic and lipophilic extracts when evaluated by ORAC methods. LC/MS/MS analyses revealed that chlorogenic acid and four kinds of quercetin glycosides were major antioxidants in the hydrophilic extract. Lutein was the main contributor to the antioxidant capacity of the lipophilic extract. Antioxidant capacities of the hydrophilic extracts of both cultivars tended to be higher in winter because of the increase in the contents of chlorogenic acid and quercetin glycosides. An obvious trend in the lipophilic antioxidant capacities or lutein contents was not observed irrespective of the cultivar.

Roles of MPBQ-MT in Promoting α/γ-Tocopherol Production and Photosynthesis under High Light in Lettuce.

2-methyl-6-phytyl-1, 4-benzoquinol methyltransferase (MPBQ-MT) is a vital enzyme catalyzing a key methylation step in both α/γ-tocopherol and plastoquinone biosynthetic pathway. In this study, the gene encoding MPBQ-MT was isolated from lettuce (Lactuca sativa) by rapid amplification of cDNA ends (RACE), named LsMT. Overexpression of LsMT in lettuce brought about a significant increase of α- and γ-tocopherol contents with a reduction of phylloquinone (vitamin K1) content, suggesting a competition for a common substrate phytyl diphosphate (PDP) between the two biosynthetic pathways. Besides, overexpression of LsMT significantly increased plastoquinone (PQ) level. The increase of tocopherol and plastoquinone levels by LsMT overexpression conduced to the improvement of plants' tolerance and photosynthesis under high light stress, by directing excessive light energy toward photosynthetic production rather than toward generation of more photooxidative damage. These findings suggest that the role and function of MPBQ-MT can be further explored for enhancing vitamin E value, strengthening photosynthesis and phototolerance under high light in plants.

α-Tocopherol Stereoisomers in Human Plasma Are Affected by the Level and Form of the Vitamin E Supplement Used.

BACKGROUND: Studies examining vitamin E intake and the percentage of the population meeting dietary guidelines do not distinguish between natural (RRR-α-tocopherol) and synthetic (all-rac-α-tocopherol) intake, even though these different isomeric forms differ in bioactivity. OBJECTIVE: This study aimed to determine the effect of RRR-α-tocopherol vs. all-rac-α-tocopherol intake on the percentage of the population meeting the vitamin E recommendation and on plasma α-tocopherol stereoisomer distribution. METHODS: With the use of data from the Irish National Adult Nutrition Survey (NANS), this study examined the percentage of the Irish population meeting the European Union (EU) RDA for vitamin E of 12 mg/d, correcting for a bioactivity difference in all-rac- vs. RRR-α-tocopherol, where 1 mg of all-rac-α-tocopherol is considered to be equivalent to 1:1.36 (0.74) mg in the EU RDA. In a subcohort of supplement users and nonusers, plasma α- and γ-tocopherol concentrations and α-tocopherol stereoisomer distribution were measured. Receiver operating characteristic (ROC) curve analysis was conducted to determine ability to discriminate supplement user types. RESULTS: Analysis of the NANS showed that 100% of participants still met the recommended intake of 12 mg/d, after all-rac-α-tocopherol intake was corrected for α-tocopherol equivalent bioactivity. In the subcohort analysis, the percentage of plasma RRR-α-tocopherol was significantly lower in high all-rac-α-tocopherol supplement (>11 mg/d) users (82%) compared with nonusers and with high RRR-α-tocopherol supplement (>35 mg/d) users (91% and 93% respectively, P < 0.01). High RRR-α-tocopherol supplement users had a significantly higher plasma α-tocopherol than low all-rac-α-tocopherol supplement (<2.5 mg/d) users (34 vs. 25 µmol/L, P = 0.01). ROC analysis demonstrated an ability to distinguish between RRR- and all-rac-α-tocopherol consumers, which may be useful in investigating the potential effect of RRR- and all-rac-α-tocopherol intake on health. CONCLUSIONS: This study demonstrated that the percentage of the population meeting the vitamin E recommendation was unaffected when all-rac-α-tocopherol intake was corrected for α-tocopherol equivalent bioactivity. all-rac-α-Tocopherol intake led to a decrease in the percentage of plasma RRR-α-tocopherol relative to RRR-α-tocopherol intake.

Concentrations of retinol and tocopherols in the milk of cows supplemented with conjugated linoleic acid.

This study was performed to investigate the hypothesis that supplementation of conjugated linoleic acid (CLA) changes the concentrations of retinol and tocopherols in the milk of cows. To investigate this hypothesis, Holstein cows received daily from 3 weeks ante-partum to 14 weeks post-partum either 172 g of a CLA-free rumen-protected control fat (control group, n = 20) or the same amount of a rumen-protected CLA fat, supplying 4.3 g of cis-9, trans-11 CLA and 3.8 g of trans-10, cis-12 CLA per d (CLA group, n = 20). Milk samples (collected at weeks 1, 3, 5, 8 and 11 of lactation) were analysed for retinol, α- and γ-tocopherol concentrations. Milk of cows supplemented with CLA had higher concentrations of retinol (+34%), α-tocopherol (+44%) and γ-tocopherol (+21%) than milk of control cows (p < 0.05). The daily output of these vitamins via milk was also greater in cows of the CLA group than in cows of the control group (+36, 50 and 24% for retinol, α-tocopherol and γ-tocopherol, respectively, p < 0.05). In agreement with higher concentrations of tocopherols, concentrations of thiobarbituric acid-reactive substances, determined in milk of week 5, were lower in cows of the CLA group than in control cows, indicative of a lower susceptibility of milk lipids to peroxidation. Plasma concentrations of retinol and α-tocopherol, determined at 1 and 5 weeks post-partum, were not different between the two groups of cows. In conclusion, this study shows that supplementing dairy cows with a moderate amount of CLA causes an increase of the concentrations of vitamins A and E in the milk and results in an increased output of those vitamins via milk. These effects might be beneficial with respect to the nutritional value of dairy products and the susceptibility of milk fat to oxidative deterioration.

Exploitation of the ability of γ-tocopherol to facilitate membrane co-localization of Akt and PHLPP1 to develop PHLPP1-targeted Akt inhibitors.

Previously, we reported that Akt inactivation by γ-tocopherol (2) in PTEN-negative prostate cancer cells resulted from its unique ability to facilitate membrane co-localization of Akt and PHLPP1 (PH domain leucine-rich repeat protein phosphatase isoform 1), a Ser473-specific Akt phosphatase, through pleckstrin homology (PH) domain binding. This finding provided a basis for exploiting 2 to develop a novel class of PHLPP1-targeted Akt inhibitors. Here, we used 3 (γ-VE5), a side chain-truncated 2 derivative, as a scaffold for lead optimization. The proof-of-concept of this structural optimization was obtained by 20, which exhibited higher antitumor efficacy than 3 in PTEN-negative cancer cells through PHLPP1-facilitated Akt inactivation. Like 3, 20 preferentially recognized the PH domains of Akt and PHLPP1, as its binding affinities for other PH domains, including those of ILK and PDK1, were an order-of-magnitude lower. Moreover, 20 was orally active in suppressing xenograft tumor growth in nude mice, which underlines the translational potential of this new class of Akt inhibitor in PTEN-deficient cancers.

Sassarandainol: a new neolignan and anti-inflammatory constituents from the stem of Sassafras randaiense.

A new neolignan, (R)-( - )-sassarandainol (1), together with 10 known compounds (2-11), was isolated from the stem of Sassafras randaiense. The structures were determined by spectroscopic techniques. Among these isolates, γ-tocopherol (5), subamolide B (7) and ß-sitosterone (9) exhibited moderate iNOS inhibitory activity on nitrite production induced (%) value of 30.51, 28.68 and 16.96, respectively.

Characteristics, composition and oxidative stability of Lannea microcarpa seed and seed oil.

The proximate composition of seeds and main physicochemical properties and thermal stability of oil extracted from Lannea microcarpa seeds were evaluated. The percentage composition of the seeds was: ash (3.11%), crude oil (64.90%), protein (21.14%), total carbohydrate (10.85%) and moisture (3.24%). Physicochemical properties of the oil were: refractive index, 1.473; melting point, 22.60°C; saponification value, 194.23 mg of KOH/g of oil; iodine value, 61.33 g of I2/100 g of oil; acid value, 1.21 mg of KOH/g of oil; peroxide value, 1.48 meq of O2/kg of oil and oxidative stability index, 43.20 h. Oleic (43.45%), palmitic (34.45%), linoleic (11.20%) and stearic (8.35%) acids were the most dominant fatty acids. Triacylglycerols with equivalent carbon number (ECN) 48 and ECN 46 were dominant (46.96% and 37.31%, respectively). The major triacylglycerol constituents were palmitoyl diolein (POO) (21.23%), followed by dipalmitoyl olein (POP) (16.47%), palmitoyl linoleyl olein (PLO) (12.03%), dipalmitoyl linolein (PLP) (10.85%) and dioleoyl linolein (LOO) (9.30%). The total polyphenol and tocopherol contents were 1.39 mg GAE g-1 DW and 578.56 ppm, respectively. γ-Tocopherol was the major tocopherol (437.23 ppm). These analytical results indicated that the L. microcarpa seed oil could be used as a frying oil and in the cosmetic industry.

Genetic basis of unstable expression of high gamma-tocopherol content in sunflower seeds.

BACKGROUND: Tocopherols are natural antioxidants with both in vivo (vitamin E) and in vitro activity. Sunflower seeds contain predominantly alpha-tocopherol (>90% of total tocopherols), with maximum vitamin E effect but lower in vitro antioxidant action than other tocopherol forms such as gamma-tocopherol. Sunflower germplasm with stable high levels of gamma-tocopherol (>85%) has been developed. The trait is controlled by recessive alleles at a single locus Tph2 underlying a gamma-tocopherol methyltransferase (gamma-TMT). Additionally, unstable expression of increased gamma-tocopherol content in the range from 5 to 85% has been reported. The objective of this research was to determine the genetic basis of unstable expression of high gamma-tocopherol content in sunflower seeds. RESULTS: Male sterile plants of nuclear male sterile line nmsT2100, with stable high gamma-tocopherol content, were crossed with plants of line IAST-1, with stable high gamma-tocopherol content but derived from a population that exhibited unstable expression of the trait. F2 seeds showed continuous segregation for gamma-tocopherol content from 1.0 to 99.7%. Gamma-tocopherol content in F2 plants (average of 24 individual F3 seeds) segregated from 59.4 to 99.4%. A genetic linkage map comprising 17 linkage groups (LGs) was constructed from this population using 109 SSR and 20 INDEL marker loci, including INDEL markers for tocopherol biosynthesis genes. QTL analysis revealed a major QTL on LG 8 that corresponded to the gamma-TMT Tph2 locus, which suggested that high gamma-tocopherol lines nmsT2100 and IAST-1 possess different alleles at this locus. Modifying genes were identified at LGs 1, 9, 14 and 16, corresponding in most cases with gamma-TMT duplicated loci. CONCLUSIONS: Unstable expression of high gamma-tocopherol content is produced by the effect of modifying genes on tph2a allele at the gamma-TMT Tph2 gene. This allele is present in line IAST-1 and is different to allele tph2 present in line nmsT2100, which is not affected by modifying genes. No sequence differences at the gamma-TMT gene were found associated to allelic unstability. Our results suggested that modifying genes are mostly epistatically interacting gamma-TMT duplicated loci.

Vitamin E isoforms directly bind PKCα and differentially regulate activation of PKCα.

Vitamin E isoforms have opposing regulatory effects on leucocyte recruitment during inflammation. Furthermore, in vitro, vitamin E isoforms have opposing effects on leucocyte migration across endothelial cells by regulating VCAM (vascular cell-adhesion molecule)-1 activation of endothelial cell PKCα (protein kinase Cα). However, it is not known whether tocopherols directly regulate cofactor-dependent or oxidative activation of PKCα. We report in the present paper that cofactor-dependent activation of recombinant PKCα was increased by γ-tocopherol and was inhibited by α-tocopherol. Oxidative activation of PKCα was inhibited by α-tocopherol at a 10-fold lower concentration than γ-tocopherol. In binding studies, NBD (7-nitrobenz-2-oxa-1,3-diazole)-tagged α-tocopherol directly bound to full-length PKCα or the PKCα-C1a domain, but not PKCζ. NBD-tagged α-tocopherol binding to PKCα or the PKCα-C1a domain was blocked by diacylglycerol, α-tocopherol, γ-tocopherol and retinol, but not by cholesterol or PS (phosphatidylserine). Tocopherols enhanced PKCα-C2 domain binding to PS-containing lipid vesicles. In contrast, the PKCα-C2 domain did not bind to lipid vesicles containing tocopherol without PS. The PKCα-C1b domain did not bind to vesicles containing tocopherol and PS. In summary, α-tocopherol and γ-tocopherol bind the diacylglycerol-binding site on PKCα-C1a and can enhance PKCα-C2 binding to PS-containing vesicles. Thus the tocopherols can function as agonists or antagonists for differential regulation of PKCα.

Antiseptic activity and phenolic constituents of the aerial parts of Vitex negundo var. cannabifolia.

Four phenolics, salviaplebeiaside (1), γ-tocopherol (2), chrysosplenol-D (4), and isovitexin (5), along with α-tocoquinone (3) and ß-sitosterol (6) were isolated from the aerial parts of Vitex negundo var. cannabifolia. The isolation was performed using bio-assay tracking experiments. The structures of compounds 1-5 were established by spectroscopic means. The antibacterial activities of the compounds were assessed against Escherichia coli, Bacillus subtilis, Micrococcus tetragenus and Pseudomonas fluorescens. Chrysosplenol-D (4) exhibited activities against all the four spoilage microorganisms.