Browsing by Subject "fatty acid"
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Item Cultivar and E-Beam irradiation effects on phytochemical content and antioxidant properties of pecan kernels(2009-05-15) Villarreal Lozoya, Jose EmilioPecan kernels from six cultivars were analyzed for phenolic content and antioxidant properties. In addition, kernels from two cultivars were irradiated with 0, 1.5 and 3.0 kGy using E-Beam irradiation and stored in accelerated conditions (40 ??C and 55% R.H.). Changes in phytochemical profile and antioxidant properties were monitored for 134 days. Cultivars differed greatly in their phytochemical content. Total extractable phenolic content (TP) ranged from 62 to 106 milligrams of chlorogenic acid equivalents per gram of defatted kernel. Antioxidant capacity (AC) measured by the DPPH free radical had a strong correlation with TP. Shells from each cultivar were 6, 4.5 and 18 times greater for TP, AC and condensed tannin content (CT). Gallic and ellagic acids, epicatechin and catechin were identified in hydrolyzed extracts of all cultivars. Prior to hydrolysis, no compounds were positively identified. Fatty acid profile of kernel oil had a strong inverse correlation between oleic and linoleic oil. Kernels from the same cultivar but different location differed in their fatty acid composition but had similar TP. Irradiation of ? Kanza? and ? Desirable? kernels with 1.5 and 3.0 kGy had no detrimental effects on AC and TP by the end of experiments. Phenolic profile was similar for all treatments. Tocopherol content decreased with irradiation treatments, but no further degradation was observed throughout storage. Peroxide values increased slightly after 98 and 134 days of storage for ? Desirable? kernels, with slight differences between controls and irradiated samples. Color of kernels decreased in lightness and yellowness and increased in redness with no differences between irradiated samples and controls. For the first time the effect of pecan cultivar and E-Beam irradiation was assessed in phytochemical and antioxidant attributes of pecan kernels. Additionally, irradiation with E-Beam had no significant detrimental effects in phytochemical composition and only a slight increase in peroxide value, indicating potential as pecan kernel sanitization.Item Glucose oxidation in heart-type fatty acid binding protein null mice(Texas A&M University, 2006-10-30) Adhikari, SeanHeart-type fatty acid binding protein (H-FABP) is a major fatty acid binding factor in skeletal muscles. Genetic lack of H-FABP severely impairs the esterification and oxidation of exogenous fatty acids in soleus muscles isolated from chow-fed mice (CHOW-solei) and high fat diet-fed mice (HFD-solei), and prevents the HFD-induced accumulation of muscle triglycerides. Here, we examined the impact of H-FABP deficiency on the relationship between fatty acid utilization and glucose oxidation. Glucose oxidation was measured in isolated soleus muscles in the presence or absence of 1 mM palmitate (simple protocol) or in the absence of fatty acid after preincubation with 1 mM palmitate (complex protocol). With the simple protocol, the mutation slightly reduced glucose oxidation in CHOW-muscles, but markedly increased it in HFDmuscles; unexpectedly, this pattern was not altered by the addition of palmitate, which reduced glucose oxidation in both CHOW- and HFD-solei irrespective of the mutation. In the complex protocol, the mutation first inhibited the synthesis and accumulation of triglycerides and then their mobilization; with this protocol, the mutation increased glucose oxidation in both CHOW- and HFD-solei. We conclude: (i) H-FABP mediates a non-acute inhibition of muscle glucose oxidation by fatty acids, likely by enabling both the accumulation and mobilidoes not mediate the acute inhibitory effect of extracellular fatty acids on muscle glucose oxidation; (iii) H-FABP affects muscle glucose oxidation in opposing ways, with inhibition prevailing at high muscle triglyceride contents.zation of a critical mass of muscle triglycerides; (ii) H-FABPItem Ligand binding proteins: roles in ligand transfer and activation of nuclear receptors(Texas A&M University, 2004-09-30) Petrescu, Anca DanielaCholesterol and fatty acyl-coenzymeA thioesters are signalling molecules with role in regulation of genes involved in lipid and glucose transport and metabolism. The studies described herein focused on three proteins that bind lipids and have different cellular functions: steroidogenic acute regulatory protein (StAR), hepatocyte nuclear factor-4a (HNF-4a) and acyl-CoA binding protein (ACBP). First, StAR mediates delivery of cholesterol to inner mitochondrial membrane in steroidogenesis by a poorly understood mechanism. In our studies, fluorescent NBD-cholesterol binding assays demonstrate that StAR binds cholesterol at two binding sites with 32 nM Kds and circular dichroism spectra show that cholesterol binding results in changes of StAR secondary structure. Fluorescent sterol exchange assays between donor and acceptor mitochondrial membranes indicate that StAR significantly increased the formation of rapidly transferable cholesterol domains. Second, HNF-4a, a nuclear receptor, had been shown to bind fatty acyl-CoAs as natural ligands with apparent low affinities obtained with radiolabeled ligand binding assays. Our fluorescence spectroscopy studies demonstrate that HNF-4a ligand binding domain (HNF-4aLBD) binds acyl-CoAs at a single binding site with Kds of 1.6-4 nM. Fluorescence resonance energy transfer (FRET) between HNF-4aLBD tryptophan residues and cis-parinaroyl-CoA yielded an intermolecular distance of 42 ? thus pointing to direct molecular interaction. Third, although ACBP has been detected in the nucleus, it is not known whether ACBP may directly and/or functionally interact with a nuclear acyl-CoA binding protein such as HNF-4a to regulate transcription. Our present studies in vitro and in intact cultured cells, including circular dichroism of HNF-4a in the presence of ACBP, coimmunoprecipitation of HNF-4a/ACBP complexes, ACBP and HNF-4a colocalization in nuclei of cells by confocal microscopy demonstrate a physical association of ACBP and HNF-4a. FRET microscopy data indicated an intermolecular distance of 53 ? between ACBP and HNF-4a in rat hepatoma cells. Functional assays (transactivation of an HNF4a-dependent reporter gene) showed significant increase in the presence of ACBP in two different cell lines. Expression of ACBP anti-sense RNA decreased HNF-4a-mediated transactivation, pointing to a role of ACBP in co-regulating HNF-4a-dependent transcription.