RESUMO
In this study, subcritical n-butane was adopted to extract oil from flaxseed. The extraction conditions i.e. extraction temperature, extraction time, and liquid-solid ratio were investigated and optimized by response surface methodology. The flaxseed oil obtained by subcritical n-butane were characterized and compared with those prepared by n-hexane and cold pressing. Results indicated that the optimal combination of parameters was 53.93â, 56.82 min, and 19.98:1 mL/g. Subcritical n-butane had higher yield (28.75%) than n-hexane and cold pressing. GC analysis indicated that subcritical n-butane extraction had no obvious influence on the fatty acid composition. Nevertheless, the oil obtained by subcritical n-butane with higher contents of phytosterols (2.93 mg/g) and carotenoids (46.56 mg/kg), and presented a higher oxidation stability (9.27 h). Thus, it was suggested that subcritical n-butane extraction is a promising alternative to extract high quality flaxseed oil.
Assuntos
Butanos , Linho/química , Qualidade dos Alimentos , Óleo de Semente do Linho/isolamento & purificação , Extração Líquido-Líquido/métodos , Carotenoides/análise , Ácidos Graxos/análise , Hexanos , Óleo de Semente do Linho/química , Oxirredução , Fitosteróis/análise , TemperaturaRESUMO
Kenaf seed oil was extracted with 3 different solvents, i.e. hexane, ethanol and aqueous enzymatic medium with or without ultrasonic assistance. The synergistic effects of ultrasound and extraction solvent on the content of bioactive compound in kenaf seed oil was investigated. Results show that ultrasound-assisted extraction with hexane obtained the highest yield (84.71%), while yield with aqueous enzymatic medium was the lowest (51.12%). Two endothermic peaks exhibited on the melting curve of kenaf seed oil at the temperature range - 37 to - 25 °C and - 12 to - 2 °C, respectively. Linoleic, oleic and palmitic acid are the major fatty acids, accounting for above 96% of the total fatty acids. The content of vitamin E, phosphatide, total phenols and sterol are 92.38-105.01 mg/100 g oil, 0.38-22.28 g/kg, 0.51-71.02 mg GAE/100 g and 161.79-533.12 mg/100 g, respectively. The solvent employed has significant effect (p < 0.05) on the thermal property, fatty acid composition and bioactive constituents of the extracted kenaf seed oil. The oil extracted with ethanol contained more nervonic acid and bioactive components such as ß-carotene, phosphatide, total phenols and sterols. The introduction of ultrasound reduced the extraction time remarkably. The results demonstrate that extraction with ethanol combined with ultrasound is an effective method to extract kenaf seed oil, as more reasonable fatty acid composition and higher content of bioactive components can be achieved.
RESUMO
The effects of thermal oxidation at 65 °C for 24 days on oxidation indices, fatty acid positional distribution, thermal properties, vitamin E composition and sterol composition of kenaf seed oil are investigated. The results showed that total oxidation value (TOTOX) of the oil increased from initial 8.83 to 130.74 at the end of 24 days storage. Linoleic acid at sn-1, 3 positon of kenaf seed oil was less stable than the one at sn-2 positon. Oxidative degradation changed the melting profile of kenaf seed oil, the value of endothermic enthalpy reduced from 58.17 to 20.25 J/g after 24 days of storage. Moreover, the content of vitamin E and total sterol decreased by 84.26% and 38.47%, respectively. Tocotrienols were more stable than tocopherols during the accelerated storage. Correlation analysis indicated vitamin E content was significantly related to p-anisidine value, while sterol content was significantly related to peroxide value. PRACTICAL APPLICATION: Kenaf seed oil is rich in polyunsaturated fatty acids and bioactive compounds. Heating process and long-term storage cause oil oxidation and bioactive compounds degradation. The oxidation process of kenaf seed oil is simulated with accelerated storage. The study evaluates fatty acid composition and distribution, vitamin E and sterol content, melting thermal characteristics of kenaf seed oil at different oxidation levels. The research shows the stability of fatty acid is related with its type and position in backbone of triacylglycerol molecule. There are good correlation among oxidation level, vitamin E and sterol content, and melting enthalpy value of kenaf seed oil.
Assuntos
Ácidos Graxos/química , Hibiscus/química , Óleos de Plantas/química , Armazenamento de Alimentos , Temperatura Alta , Ácido Linoleico/análise , Oxirredução , Sementes/química , Tocoferóis/análise , Tocotrienóis/análise , Triglicerídeos/análise , Vitamina E/análiseRESUMO
Fungal infection is inevitable in the cultivation and storage process of soybean. Gamma irradiation is an effective method to control fungal growth and inactivate mycotoxins. The effects of gamma irradiation and fungal damage on the number of fungi, aflatoxin B1 content, proximate composition of soybeans, and quality of soybean oil (acid value, peroxide value, iodine value, fatty acid profile, tocopherols content, and oxidation stability) were investigated in this work. Growth of fungi caused some changes in proximate composition of soybean and qualities of soybean oil. However, the changes depended on the damage extent of soybeans. No significant change was found for the soybeans incubated for 30 days (moderately fungi-damaged). Gamma irradiation could completely eliminate the fungi and greatly reduce the content of aflatoxin B1 in soybeans at 10â¯kGy. For soybeans incubated for 30 days, there were no significant changes in the quality attributes, tocopherols content and oxidation stability of oil when the gamma irradiation dose was less than 20â¯kGy. Gamma irradiation is a promising method to improve the safety and economy of moderately fungi-damaged soybean used for feedstuff.
Assuntos
Aflatoxina B1/análise , Aflatoxina B1/efeitos da radiação , Irradiação de Alimentos/métodos , Glycine max/química , Glycine max/efeitos da radiação , Óleo de Soja/química , Óleo de Soja/efeitos da radiação , Ácidos Graxos/análise , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Fungos/isolamento & purificação , Fungos/efeitos da radiação , Raios gama/uso terapêutico , Humanos , Oxirredução , Tocoferóis/análiseRESUMO
Supercritical carbon dioxide extraction (SC-CO2) technology was used to extract oil from Eucommia ulmoides seed. The optimum conditions and significant parameters in SC-CO2 were obtained using response surface methodology (RSM). The qualities of the extracted oil were evaluated by physicochemical properties, fatty acid composition, vitamin E composition. It was found that the optimum extraction parameters were at pressure of 37 MPa, temperature of 40°C, extraction time of 125 min and CO2 flow rate of 2.6 SL/min. Pressure, temperature and time were identified as significant parameter effecting on extraction yield. The importance of evaluated parameters decreased in the order of pressure > extraction time > temperature > CO2 flow rate. GC analysis indicated that E. ulmoides seed oil contained about 61% of linolenic acid and its fatty acid composition was similar with that of flaxseed oil and perilla oil. The content and composition of vitamin E was determined using HPLC. The E. ulmoides seed oil was rich in vitamin E (190.72 mg/100 g), the predominant vitamin E isomers were γ- tocopherol and δ- tocopherol, which accounted for 70.87% and 24.81% of the total vitamin E, respectively. The high yield and good physicochemical properties of extracted oil support the notion that SC-CO2 technology is an effective technique for extracting oil from E. ulmoides seed.
Assuntos
Cromatografia com Fluido Supercrítico/métodos , Eucommiaceae/química , Qualidade dos Alimentos , Óleos de Plantas/química , Óleos de Plantas/isolamento & purificação , Sementes/química , Dióxido de Carbono , Fenômenos Químicos , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/análise , Pressão , Temperatura , Fatores de Tempo , Vitamina E/análise , Ácido alfa-Linolênico/análiseRESUMO
Eucommia ulmoides seed oil is the main byproduct of E. ulmoides cultivation. To better understand its functions, E. ulmoides seed oil is characterized comprehensively in this work. The composition of E. ulmoides seed, physicochemical properties, thermal properties, fatty acid composition, triacylglycerol (TAG) composition and Vitamin E composition of E. ulmoides seed oil were determined. The results show that the E. ulmoides seed contained about 34.63% oil. The excellent physicochemical properties of E. ulmoides seed oil ensured it has a potential to be developed as an edible oil. The main fatty acids in E. ulmoides seed oil were linolenic acid (61.36%), oleic acid (17.02%), and linoleic acid (12.04%). HPLC-ELSD method determined that LnLnLn (37.99%), LnLnO (22.62%), LnLnL (14.5%), and LnLnP (8.78%) were the oil's major TAG components. The oil exhibited a unique thermal curve which contained 2 melting peaks at -38.45 and -22.22 °C, respectively. The total content of vitamin E in E. ulmoides seed oil was 190.96 mg/100g, which exist mainly in γ-tocopherol and δ-tocopherol isomer. Overall, the results indicated that E. ulmoides seed oil is a promising oil in food, pharmaceutics, cosmetics and other nonfood industries.
Assuntos
Eucommiaceae/química , Óleos de Plantas/química , Ácido alfa-Linolênico/química , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/química , Ácido Linoleico/análise , Ácido Oleico/análise , Sementes/química , Tocoferóis/análise , Triglicerídeos/análise , Vitamina E/análise , gama-Tocoferol/análiseRESUMO
AMP-activated protein kinase (AMPK) serves as an energy sensor and is considered a promising drug target for treatment of type II diabetes and obesity. A previous report has shown that mammalian AMPK alpha1 catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in alpha subunits, we screened a chemical library with inactive human alpha1(394) (alpha1, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK alpha1(394), alpha1(335), alpha2(398), and even heterotrimer alpha1beta1gamma1. Based on PT1-docked AMPK alpha1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys-156 residues near the autoinhibitory domain and directly relieve autoinhibition. Further studies using L6 myotubes showed that the phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase, were dose-dependently and time-dependently increased by PT1 with-out an increase in cellular AMP:ATP ratio. Moreover, in HeLa cells deficient in LKB1, PT1 enhanced AMPK phosphorylation, which can be inhibited by the calcium/calmodulin-dependent protein kinase kinases inhibitor STO-609 and AMPK inhibitor compound C. PT1 also lowered hepatic lipid content in a dose-dependent manner through AMPK activation in HepG2 cells, and this effect was diminished by compound C. Taken together, these data indicate that this small-molecule activator may directly activate AMPK via antagonizing the autoinhibition in vitro and in cells. This compound highlights the effort to discover novel AMPK activators and can be a useful tool for elucidating the mechanism responsible for conformational change and autoinhibitory regulation of AMPK.
Assuntos
Ativadores de Enzimas/farmacologia , Complexos Multienzimáticos/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Quinases Proteína-Quinases Ativadas por AMP , Proteínas Quinases Ativadas por AMP , Acetil-CoA Carboxilase/antagonistas & inibidores , Acetil-CoA Carboxilase/metabolismo , Monofosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Benzimidazóis/química , Benzimidazóis/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/enzimologia , Metabolismo Energético/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Ativadores de Enzimas/química , Células HeLa , Humanos , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , Mioblastos/enzimologia , Naftalimidas/química , Naftalimidas/farmacologia , Obesidade/tratamento farmacológico , Obesidade/enzimologia , Fosforilação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Quaternária de Proteína/efeitos dos fármacos , Pirazóis/química , Pirazóis/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Fatores de TempoRESUMO
The peroxisome proliferator-activated receptor gamma (PPARgamma) is an important therapeutic drug target for several conditions, including diabetes, inflammation, dyslipidemia, hypertension, and cancer. It is shown that an antagonist or partial agonist of PPARgamma has attractive potential applications in the discovery of novel antidiabetic agents that may retain efficacious insulin-sensitizing properties and minimize potential side effects. In this work, the dipeptide H-Trp-Glu-OH (G3335) was discovered to be a novel PPARgamma antagonist. Biacore 3000 results based on the surface plasmon resonance (SPR) technique showed that G3335 exhibits a highly specific binding affinity against PPARgamma (K(D) = 8.34 microM) and is able to block rosiglitazone, a potent PPARgamma agonist, in the stimulation of the interaction between the PPARgamma ligand-binding domain (LBD) and RXRalpha-LBD. Yeast two-hybrid assays demonstrated that G3335 exhibits strong antagonistic activity (IC50 = 8.67 microM) in perturbing rosiglitazone in the promotion of the PPARgamma-LBD-CBP interaction. Moreover, in transactivation assays, G3335 was further confirmed as an antagonist of PPARgamma in that G3335 could competitively bind to PPARgamma against 0.1 microM rosiglitazone to repress reporter-gene expression with an IC50 value of 31.9 muM. In addition, homology modeling and molecular-docking analyses were performed to investigate the binding mode of PPARgamma-LBD with G3335 at the atomic level. The results suggested that residues Cys285, Arg288, Ser289, and His449 in PPARgamma play vital roles in PPARgamma-LBD-G3335 binding. The significance of Cys285 for PPARgamma-LBD-G3335 interaction was further demonstrated by PPARgamma point mutation (PPARgamma-LBD-Cys285Ala). It is hoped our current work will provide a powerful approach for the discovery of PPARgamma antagonists, and that G3335 might be developed as a possible lead compound in diabetes research.
Assuntos
Dipeptídeos/farmacologia , PPAR gama/antagonistas & inibidores , Animais , Bioensaio , Células COS , Chlorocebus aethiops , Simulação por Computador , Cristalografia por Raios X , Dipeptídeos/química , Modelos Moleculares , Estrutura Molecular , PPAR gama/agonistas , Rosiglitazona , Sensibilidade e Especificidade , Relação Estrutura-Atividade , Ressonância de Plasmônio de Superfície/métodos , Tiazolidinedionas/antagonistas & inibidores , Tiazolidinedionas/farmacologia , Fatores de Tempo , Técnicas do Sistema de Duplo-HíbridoRESUMO
A plant expression vector pBACG containing the DNA sequence coding for Amaranthus caudatus agglutinin (ACA) and a modified Glanthus nivalis agglutinin (GNA) gene was constructed. Leaf explants of Nicotiana tobacum cv. SRI were transformed with A. tumefaciens LBA4404 harbouring the above expression vector. Results from PCR and Southern blotting analysis showed that both the ACA and GNA gene were inserted into the genome of transformed tobacco plants. Western blottingting analysis of soluble protein isolated from transgenic plants showed that ACA and GNA were synthesized. The results from insect bioassay with peach aphids ( Myzus persicae) revealed that the transgenic plants of pBACG had acquired high resistance against peach aphids. The average aphid-inhibition rate reached up to 83.9% and 85.3% for transgenic plants (T0) and their selfed progenies (T1) respectively,indicating that the functions of these two genes were inheritable.