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1.
Molecules ; 21(1): 99, 2016 Jan 15.
Article in English | MEDLINE | ID: mdl-26784162

ABSTRACT

The wild mushroom Leucopaxillus candidus (Bres.) Singer was studied for the first time to obtain information about its chemical composition, nutritional value and bioactivity. Free sugars, fatty acids, tocopherols, organic and phenolic acids were analysed by chromatographic techniques coupled to different detectors. L. candidus methanolic extract was tested regarding antioxidant potential (reducing power, radical scavenging activity and lipid peroxidation inhibition). L. candidus was shown to be an interesting species in terms of nutritional value, with high content in proteins and carbohydrates, but low fat levels, with the prevalence of polyunsaturated fatty acids. Mannitol was the most abundant free sugar and ß-tocopherol was the main tocopherol isoform. Other compounds detected were oxalic and fumaric acids, p-hydroxybenzoic and cinnamic acids. The methanolic extract revealed antioxidant activity and did not show hepatoxicity in porcine liver primary cells. The present study provides new information about L. candidus.


Subject(s)
Agaricales/chemistry , Antioxidants/chemistry , Mannitol/isolation & purification , Metabolome , beta-Tocopherol/isolation & purification , Animals , Antioxidants/isolation & purification , Antioxidants/pharmacology , Biphenyl Compounds/antagonists & inhibitors , Cell Survival/drug effects , Cinnamates/isolation & purification , Cinnamates/metabolism , Complex Mixtures/chemistry , Fatty Acids, Unsaturated/isolation & purification , Fatty Acids, Unsaturated/metabolism , Fumarates/isolation & purification , Fumarates/metabolism , Hepatocytes/cytology , Hepatocytes/drug effects , Mannitol/metabolism , Nutritive Value , Oxalates/isolation & purification , Oxalates/metabolism , Parabens/isolation & purification , Parabens/metabolism , Picrates/antagonists & inhibitors , Primary Cell Culture , Swine , beta-Tocopherol/chemistry , beta-Tocopherol/metabolism
2.
J Sci Food Agric ; 95(4): 672-8, 2015 Mar 15.
Article in English | MEDLINE | ID: mdl-24841131

ABSTRACT

BACKGROUND: The present study examined the contents of tocopherols and tocotrienols and their distribution in 58 different varieties of whole rice cultivated in Malaysia. The analytical method used was saponification of samples followed by dispersive liquid-liquid microextraction and reverse phase high-performance liquid chromatography. RESULTS: The total vitamin E contents of different varieties of whole rice ranged between 19.36 and 63.29 mg kg⁻¹. Contents of vitamin E isomers varied among rice varieties both within and between grain color groups. Black-pigmented rice showed significantly higher mean contents of α-tocopherol, ß-tocopherol and α-tocotrienol than non-pigmented rice and red-pigmented rice. Red-pigmented rice had significantly lower mean contents of γ-tocotrienol and total vitamin E than non-pigmented rice. The mean contents of δ-tocotrienol and total vitamin E in non-pigmented rice, however, were similar to those in black-pigmented rice. γ-Tocotrienol was the predominant form of vitamin E isomer in all analyzed varieties. The Pearson correlations among vitamin E isomers and total vitamin E content of whole rice were also studied. CONCLUSION: This study provides information on vitamin E content of different rice varieties that would be beneficial for decision making in genetic breeding of bioactive compound-rich rice varieties.


Subject(s)
Crops, Agricultural/chemistry , Oryza/chemistry , Seeds/chemistry , Tocopherols/analysis , Tocotrienols/analysis , Chromatography, High Pressure Liquid , Chromatography, Reverse-Phase , Crops, Agricultural/growth & development , Crops, Agricultural/metabolism , Food Handling , Humans , Hydrolysis , Liquid-Liquid Extraction , Malaysia , Nutritive Value , Oryza/growth & development , Oryza/metabolism , Pigments, Biological/biosynthesis , Reproducibility of Results , Seeds/growth & development , Seeds/metabolism , Species Specificity , Tocopherols/metabolism , Tocotrienols/metabolism , alpha-Tocopherol/analysis , alpha-Tocopherol/metabolism , beta-Tocopherol/analysis , beta-Tocopherol/metabolism
3.
Eukaryot Cell ; 8(11): 1648-57, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19717743

ABSTRACT

Tocopherols (vitamin E) comprise a class of lipid-soluble antioxidants synthesized only in plants, algae, and some cyanobacteria. The majority of tocopherols in photosynthetic cells is in the alpha form, which has the highest vitamin E activity in humans, whereas the beta, gamma, and delta forms normally account for a small percentage of total tocopherols. The antioxidant activities of these forms of tocopherol differ depending on the experimental system, and their relative activities in vivo are unclear. In a screen for suppressors of the xanthophyll-deficient npq1 lor1 double mutant of Chlamydomonas reinhardtii, we isolated a vte3 mutant lacking alpha-tocopherol but instead accumulating beta-tocopherol. The vte3 mutant contains a mutation in the homolog of a 2-methyl-6-phytyl-1,4-benzoquinone methyltransferase gene found in plants. The vte3 npq1 lor1 triple mutant with beta-tocopherol survived better under photooxidative stress than did the npq1 lor1 mutant, but the vte3 mutant on its own did not have an obvious phenotype. Following transfer from low light to high light, the triple mutant showed a higher efficiency of photosystem II, a higher level of cell viability, and a lower level of lipid peroxide, a marker for oxidative stress, than did the npq1 lor1 mutant. After high-light transfer, the level of the photosystem II reaction center protein, D1, was also higher in the vte3 npq1 lor1 mutant, but the rate of D1 photodamage was not significantly different from that of the npq1 lor1 mutant. Taken together, these results suggest that the replacement of alpha-tocopherol by beta-tocopherol in a xanthophyll-deficient strain of Chlamydomonas reinhardtii contributes to better survival under conditions of photooxidative stress.


Subject(s)
Chlamydomonas reinhardtii/metabolism , Chlamydomonas reinhardtii/radiation effects , Oxidative Stress/radiation effects , Xanthophylls/deficiency , alpha-Tocopherol/metabolism , beta-Tocopherol/metabolism , Algal Proteins/chemistry , Algal Proteins/genetics , Algal Proteins/metabolism , Amino Acid Sequence , Cell Survival/radiation effects , Chlamydomonas reinhardtii/chemistry , Chlamydomonas reinhardtii/genetics , Light , Molecular Sequence Data , Photosystem II Protein Complex/genetics , Photosystem II Protein Complex/metabolism , Sequence Alignment
4.
Andrologia ; 40(5): 282-5, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18811917

ABSTRACT

Dietary vitamin E supplementation plays a key role in animal reproduction by protecting germ cells from oxidative damage. Recently, alpha-tocopherol homologues (namely, beta-, gamma- and delta-tocopherol) have been the object of increasing research because of their peculiar nonantioxidant properties. We found that these tocol-derived compounds are not homogeneously distributed among semen components. Alpha-T was the major vitamin E homologue found in all semen fractions. Half of the total gamma (+beta)-T was found in germ cells, while more than 50% of total delta-T was preferentially accumulated in seminal plasma. The concentration of various tocol-derived compounds depended on their relative amounts in diet and the competition for saturable enzymes implicated in their metabolism. A higher concentration of delta-T in seminal plasma may be related to its more polar nature. However, the biological function of this compound in semen remains to be cleared. To our knowledge, this is the first study aimed at identifying alpha-tocopherol homologues in rabbit semen fractions.


Subject(s)
Semen/metabolism , Seminal Vesicles/metabolism , Spermatozoa/metabolism , Tocopherols/metabolism , alpha-Tocopherol/metabolism , gamma-Tocopherol/metabolism , Animals , Male , Oxidative Stress/physiology , Rabbits , Reproduction/physiology , Semen/chemistry , Seminal Vesicles/chemistry , Seminal Vesicles/ultrastructure , Spermatozoa/chemistry , Spermatozoa/ultrastructure , Tocopherols/analysis , alpha-Tocopherol/analysis , beta-Tocopherol/metabolism , gamma-Tocopherol/analysis
5.
Plant J ; 55(4): 607-18, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18452591

ABSTRACT

SUMMARY: Tocopherols are synthesized and accumulated by all plants and many cyanobacteria. The quenching and scavenging of reactive oxygen species and lipid peroxy radicals by tocopherols can result in the formation of various tocopherol oxidation compounds. A targeted GC/MS profiling method was developed to quantify all tocopherols and pathway intermediates, and 23 potential alpha- and gamma-tocopherol oxidation products. This method was used to study the response of wild-type Arabidopsis (Col) and the tocopherol biosynthetic mutants vte1, vte2 and vte4 during 12 h low- and high-light treatments (LL and HL, 90 and 1500 mumol photon m(-2) sec(-1), respectively) and a subsequent 12 h dark recovery period. All tocopherols and pathway intermediates exhibited HL-dependent increases except 2,3-dimethyl-6-phytyl-1,4-benzoquinone (DMPBQ) in vte1 and beta-tocopherol in Col. Profiling of potential tocopherol oxidation products during HL treatment indicated the presence of only alpha-tocopherolquinol (alpha-TQH(2)) in Col and only gamma-tocopherolquinol (gamma-TQH(2)) in vte4, both of which accumulated to similar levels and with similar kinetics the two genotypes. However, during dark recovery, the level of alpha-TQH(2) in Col decreased several times faster than that of gamma-TQH(2) in vte4, suggesting the presence of biochemical processes with higher specificity for alpha-TQH(2). (14)C-labeled alpha-tocopherolquinone (alpha-TQ) applied to isolated Col chloroplasts was converted to (14)C-alpha-tocopherol, demonstrating the existence of a plastid-based system for recycling oxidized alpha-tocopherol. The accumulation of (14)C-trimethylphytylbenzoquinone (TMPBQ) by isolated vte1 plastids treated with (14)C-labeled alpha-TQ is consistent with the tocopherolquinone-recycling pathway utilizing a yet to be identified plastid-localized dehydratase that converts tocopherolquinone to TMPBQ.


Subject(s)
Arabidopsis/metabolism , Arabidopsis/radiation effects , Tocopherols/metabolism , Gas Chromatography-Mass Spectrometry , Kinetics , Light , Oxidation-Reduction , alpha-Tocopherol/metabolism , beta-Tocopherol/metabolism , gamma-Tocopherol/metabolism
6.
Trends Plant Sci ; 8(1): 6-8, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12523993

ABSTRACT

Vitamin E is thought to be involved in many essential processes in plants, but no functional proof has been reported. To study vitamin E deficiency in plants, a high-throughput biochemical screen for vitamin E quantification in Arabidopsis mutants has been developed, which has led to the identification of VTE1-encoding tocopherol cyclase. Interestingly, the corresponding maize mutation, sxd1, causes plasmodesmata malfunction, suggesting a link between tocopherol cyclase and plasmodesmata function.


Subject(s)
Arabidopsis/metabolism , Tocopherols/metabolism , Vitamin E/biosynthesis , Arabidopsis/enzymology , Arabidopsis/genetics , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , Mutation , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Structures/physiology , Tocopherols/chemistry , Vitamin E/chemistry , Zea mays/genetics , alpha-Tocopherol/chemistry , alpha-Tocopherol/metabolism , beta-Tocopherol/chemistry , beta-Tocopherol/metabolism , gamma-Tocopherol/chemistry , gamma-Tocopherol/metabolism
7.
Eur J Biochem ; 270(1): 84-92, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12492478

ABSTRACT

Tocopherols are essential micronutrients in human and animal nutrition due to their function as lipophilic antioxidants. They are exclusively synthesized by photosynthetic organisms including higher plants. Despite the attributed beneficial health effects and many industrial applications, research on the tocopherol biosynthetic pathway and its regulation in plants is still limited. In the work presented here we performed a detailed biochemical characterization of a gamma-tocopherol methyltransferase (gamma-TMT) from Arabidopsis thaliana and of a gamma-TMT purified from Capsicum annuum fruits, a tissue with high accumulation of tocopherols. The biochemical characteristics of both enzyme preparations were remarkably similar including substrate specificities. Both enzymes converted delta- and gamma- into beta- and alpha-tocopherol, respectively, but beta-tocopherol was not accepted as a substrate, pointing to a specific methylation at the C(5)-position of the tocopherol aromatic head group. A kinetic analysis performed with the Arabidopsis enzyme was consistent with an iso-ordered bi-bi type reaction mechanism. Our results emphasize the role of gamma-TMT in regulating the spectrum of accumulated tocopherols in plants.


Subject(s)
Arabidopsis/enzymology , Capsicum/enzymology , Methyltransferases/metabolism , Plant Proteins/metabolism , Arabidopsis Proteins/metabolism , Fruit/enzymology , Kinetics , Methyltransferases/antagonists & inhibitors , Methyltransferases/isolation & purification , Molecular Weight , Plant Proteins/isolation & purification , Recombinant Proteins/metabolism , S-Adenosylhomocysteine/metabolism , S-Adenosylhomocysteine/pharmacology , Substrate Specificity , alpha-Tocopherol/metabolism , alpha-Tocopherol/pharmacology , beta-Tocopherol/metabolism
8.
Plant Physiol ; 129(1): 321-32, 2002 May.
Article in English | MEDLINE | ID: mdl-12011362

ABSTRACT

Tocopherols, synthesized by photosynthetic organisms, are micronutrients with antioxidant properties that play important roles in animal and human nutrition. Because of these health benefits, there is considerable interest in identifying the genes involved in tocopherol biosynthesis to allow transgenic alteration of both tocopherol levels and composition in agricultural crops. Tocopherols are generated from the condensation of phytyldiphosphate and homogentisic acid (HGA), followed by cyclization and methylation reactions. Homogentisate phytyltransferase (HPT) performs the first committed step in this pathway, the phytylation of HGA. In this study, bioinformatics techniques were used to identify candidate genes, slr1736 and HPT1, that encode HPT from Synechocystis sp. PCC 6803 and Arabidopsis, respectively. These two genes encode putative membrane-bound proteins, and contain amino acid residues highly conserved with other prenyltransferases of the aromatic type. A Synechocystis sp. PCC 6803 slr1736 null mutant obtained by insertional inactivation did not accumulate tocopherols, and was rescued by the Arabidopsis HPT1 ortholog. The membrane fraction of wild-type Synechocystis sp. PCC 6803 was capable of catalyzing the phytylation of HGA, whereas the membrane fraction from the slr1736 null mutant was not. The microsomal membrane fraction of baculovirus-infected insect cells expressing the Synechocystis sp. PCC 6803 slr1736 were also able to perform the phytylation reaction, verifying HPT activity of the protein encoded by this gene. In addition, evidence that antisense expression of HPT1 in Arabidopsis resulted in reduced seed tocopherol levels, whereas seed-specific sense expression resulted in increased seed tocopherol levels, is presented.


Subject(s)
Alkyl and Aryl Transferases/genetics , Arabidopsis Proteins , Arabidopsis/genetics , Bacterial Proteins/genetics , Cyanobacteria/genetics , Tocopherols/metabolism , Alkyl and Aryl Transferases/isolation & purification , Amino Acid Sequence , Antisense Elements (Genetics) , Arabidopsis/enzymology , Baculoviridae/genetics , Catalytic Domain/genetics , Chlorophyll/metabolism , Computational Biology , Cyanobacteria/enzymology , Gene Expression Regulation, Enzymologic , Genetic Complementation Test , Light-Harvesting Protein Complexes , Molecular Sequence Data , Mutation , Photosynthetic Reaction Center Complex Proteins/metabolism , Seeds/enzymology , Seeds/genetics , Sequence Homology, Amino Acid , Tocopherols/chemistry , alpha-Tocopherol/chemistry , alpha-Tocopherol/metabolism , beta-Tocopherol/chemistry , beta-Tocopherol/metabolism , gamma-Tocopherol/chemistry , gamma-Tocopherol/metabolism
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