ABSTRACT
Although much study has been done assessing activity of antioxidants at ambient and accelerated storage temperatures, the results cannot correctly depict their performance under frying conditions. Due to the stringent conditions imposed, most conventional antioxidative compounds failed under frying conditions, suggesting the need for a continuous modification to improve their effectiveness. Although syntheses and performance evaluation of over a hundred (semi)synthetic antioxidants have been reported in literature, only a small fraction have been specifically designed and/or evaluated under frying conditions. Here, the performance under frying conditions of major natural and synthetic antioxidants is reviewed. The recent trend in the designing of antioxidants for frying applications is also reviewed with the view of stimulating further study in this direction.
Subject(s)
Antioxidants/chemistry , Cooking/methods , Nutritive Value , Plant Extracts/chemistry , Plant Oils/chemistry , Carotenoids/chemistry , Hot Temperature , Lignans/chemistry , Phenylpropionates/chemistry , Phospholipids/chemistry , Phytosterols/chemistry , Polyphenols/chemistry , Squalene/chemistry , alpha-Tocopherol/chemistry , beta-Tocopherol/chemistryABSTRACT
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/metabolismABSTRACT
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/metabolismABSTRACT
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.
