Methylated eicosapentaenoic acid and tetradecylthioacetic acid: effects on fatty acid metabolism

Stable analogs of 13‑hydroxy-9,10-trans-epoxy-(11E)-octadecenoate (13,9-HEL), an oxidized derivative of linoleic acid implicated in the epidermal skin barrier

Hydroxy-epoxy- and trihydroxy derivatives of linoleic acid are proposed to play an essential function in formation of the mammalian skin permeability barrier, which could account for the essential nature of its precursor, linoleic acid. Recent literature suggests that a specific oxidized enone derivative of LA esterified in ceramides facilitates binding to proteins, potentially serving a structural role in formation of the epidermal skin barrier. However, it is still to be established if other linoleic acid derivatives are also required for skin barrier formation, and whether the essential role is performed exclusively by an esterified, structural lipid or as an unesterified, labile signaling lipid, or by some combination of these derivatives. Progress in this domain is limited by lack of availability of hydroxy‑epoxy-and trihydroxy- and octadecenoate derivatives of linoleic acid and related compounds, and challenges in maintaining them in the unesterified lipid pool. Here we describe methods for the total synthesis of hydroxy‑epoxy-octadecenoate derivatives of linoleic acid (HEL¹), and stable analogs that are designed to be resistant to inactivation by: (a) acylation/esterification (thus trapping these lipids in the free acid pool), (b) dehydrogenation, and (c) analogs combining both modifications. We further provide a total synthesis of corresponding hydroxy‑epoxy- derivatives of sebaleic acid (a regioisomer of linoleic acid present in skin), and of small molecule scaffolds containing the allylic and non-allylic epoxide 7-carbon substructures shared by both families of hydroxy‑epoxy-and trihydroxy- octadecenoates. Finally, we demonstrate that 2,2-dimethyl analogs of hydroxy‑epoxy-and trihydroxy- octadecenoates are resistant to esterification with an in vitro assay and thus provide a novel template for stabilizing labile, bioactive lipids as free acids by preventing acylation/esterification.

Thermogenic effect of meltdown RTD energy drink in young healthy women: a double blind, cross-over design study

Background

The purpose of this study was to examine the acute metabolic effects of a high-energy drink in healthy, physically-active women.

Methods

Ten women (20.4 ± 0.70 y; 166.9 ± 7.2 cm; 67.0 ± 7.0 kg; 29.6 ± 6.5% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. Subjects reported to the laboratory in a 3-hr post-absorptive state and were provided either 140 ml of the high-energy drink (SUP; commercially marketed as Meltdown RTD™) or placebo (P). Subjects consumed two 70 ml doses of SUP or P, separated by 30 min and rested in a semi-recumbent position for 3 hours. Resting oxygen consumption (VO₂) and heart rate (HR) were determined every 5 min during the first 30 min and every 10 min during the next 150 min. Blood pressure (BP) was determined every 15 min during the first 30 min and every 30 min thereafter. Area under the curve (AUC) analysis was computed for VO₂, whereas a 3-hour average and hourly averages were calculated for respiratory quotient (RQ), total kcal, HR, BP, and profile of mood states (POMS).

Results

AUC analysis revealed a 10.8% difference (p = 0.03) in VO₂ between SUP and P. No difference in VO₂ was seen between the groups in the first hour, but VO₂ in SUP was significantly greater than P in the second (13.9%, p = 0.01) and third hours (11.9%, p = 0.03). A difference (p = 0.03) in energy expenditure was seen between SUP (1.09 ± 0.10 kcal·min^-1) and P (0.99 ± 0.09 kcal·min^-1) for the 3-hour period. Although no difference in energy expenditure was seen in the first hour, significant differences between SUP and P were observed in the second (1.10 ± 0.11 kcal·min^-1 and 0.99 ± 0.09 kcal·min^-1, respectively; p = 0.02) and third hour (1.08 ± 0.11 kcal·min^-1 and 0.99 ± 0.09 kcal·min^-1, respectively; p = 0.05). Average systolic BP was significantly higher (p = 0.007) for SUP (110.0 ± 3.9 mmHg) compared to P (107.3 ± 4.4 mmHg). No differences were seen in HR, diastolic BP, or POMS at any time point.

Conclusions

Results showed a significant increase in energy expenditure in young, healthy women following an acute ingestion of a high-energy drink.

Thermogenic effect of an acute ingestion of a weight loss supplement

Background

The purpose of this study was to examine the acute effects of a weight loss supplement on resting oxygen uptake (VO₂), respiratory quotient (RQ), caloric expenditure (kcal), heart rate (HR), and blood pressure (BP) in healthy and physically active individuals.

Methods

Ten subjects (5 male, 5 female; 20.2 ± 1.2 y; 172.2 ± 8.9 cm; 71.5 ± 17.2 kg; 17.3 ± 2.6% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory after at least 3-h post-absorptive state and were provided either 3 capsules of the weight loss supplement (SUP), commercially marketed as Meltdown^® or 3 capsules of a placebo (P). Subjects then rested in a semi-recumbent position for three hours. VO₂ and HR were determined every 5 min during the first 30 min and every 10 min during the next 150 min. BP was determined every 15 min during the first 30 min and every 30 min thereafter. The profile of mood states was assessed every 30 min.

Results

Area under the curve analysis revealed a significant 28.9% difference in VO₂ between SUP and P for the three hour study period. In addition, a significant difference in energy expenditure was also seen between SUP (1.28 ± 0.33 kcal·min^-1) and P (1.00 ± 0.32 kcal·min^-1). A trend (p = 0.06) towards a greater utilization of stored fat as an energy source was also demonstrated (0.78 ± 0.23 kcal·min^-1 and 0.50 ± 0.38 kcal·min^-1 in P and SUP, respectively). Significant elevations in HR were seen during hours two and three of the study, and significantly higher average systolic BP was observed between SUP (118.0 ± 7.3 mmHg) and P (111.4 ± 8.2 mmHg). No significant differences were seen in diastolic blood pressure at any time point. Significant increases in tension and confusion were seen in SUP.

Conclusion

Results indicate a significant increase in energy expenditure in young, healthy individuals following an acute ingestion of a weight loss supplement. In addition, ingestion of this supplement appears modify mood and elevate HR and systolic BP following ingestion.

Sulfur-substituted and alpha-methylated fatty acids as peroxisome proliferator-activated receptor activators

FA with varying chain lengths and an alpha-methyl group and/or a sulfur in the beta-position were tested as peroxisome proliferator-activated receptor (PPAR)alpha, -delta(beta), and -gamma ligands by transient transfection in COS-1 cells using chimeric receptor expression plasmids, containing cDNAs encoding the ligand-binding domain of PPARalpha, -delta, and -gamma. For PPARalpha, an increasing activation was found with increasing chain length of the sulfur-substituted FA up to C14-S acetic acid (tetradecylthioacetic acid = TTA). The derivatives were poor, and nonsignificant, activators of PPARdelta. For PPARgamma, activation increased with increasing chain length up to C16-S acetic acid. A methyl group was introduced in the alpha-position of palmitic acid, TTA, EPA, DHA, cis9,trans11 CLA, and trans10,cis12 CLA. An increased activation of PPARalpha was obtained for the alpha-methyl derivatives compared with the unmethylated FA. This increase also resulted in increased expression of the two PPARalpha target genes acyl-CoA oxidase and liver FA-binding protein for alpha-methyl TTA, alpha-methyl EPA, and alpha-methyl DHA. Decreased or altered metabolism of these derivatives in the cells cannot be excluded. In conclusion, saturated FA with sulfur in the beta-position and increasing carbon chain length from C9-S acetic acid to C14-S acetic acid have increasing effects as activators of PPARalpha and -gamma in transfection assays. Furthermore, alpha-methyl FA derivatives of a saturated natural FA (palmitic acid), a sulfur-substituted FA (TTA), and PUFA (EPA, DHA, c9,t11 CLA, and t10,c12 CLA) are stronger PPARalpha activators than the unmethylated compounds.

Effects of structural changes of fatty acids on lipid accumulation in adipocytes and primary hepatocytes

Conjugated linoleic acids (CLAs), tetradecylthioacetic acid (TTA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are all shown to differently affect lipid homeostasis. Additionally, previous studies have shown that introducing a methyl group in the molecule potentiates the hypolipidemic effect of EPA. The objective of this study was to determine how cis9,trans11 CLA, trans10,cis12 CLA, TTA, EPA and DHA affect lipid accumulation in 3T3-L1 adipocytes and in cultured primary rat hepatocytes, and to what extent changes in cis/trans configuration or introducing a methyl group in the molecules influence their way of affecting lipid accumulation in these cells. Our results show that trans10,cis12 CLA is highly specific in preventing lipid accumulation in adipocytes, and that small structural changes in the molecule (changing to trans/trans or introducing an alpha-methyl group) totally abolish this effect and up-regulate the expression levels of adipogenic marker genes towards control levels. Furthermore, all the fatty acids increased hepatic lipid accumulation, whereas the lipid content was normalized after adding an alpha-methyl group into the molecules. Taken together, our data demonstrate that the various fatty acids are highly specialized molecules, and that small structural changes markedly alter their way of affecting lipid accumulation in adipocytes and hepatocytes.

The biochemistry of hypo- and hyperlipidemic fatty acid derivatives: metabolism and metabolic effects

A selection of amphipatic hyper- and hypolipidemic fatty acid derivatives (fibrates, thia- and branched chain fatty acids) are reviewed. They are probably all ligands for the peroxisome proliferation activation receptor (PPARalpha) which has a low selectivity for its ligands. These compounds give hyper- or hypolipidemic responses depending on their ability to inhibit or stimulate mitochondrial fatty acid oxidation in the liver. The hypolipidemic response is explained by the following metabolic effects: Lipoprotein lipase is induced in liver where it is normally not expressed. Apolipoprotein CIII is downregulated. These two effects in liver lead to a facilitated (re)uptake of chylomicrons and VLDL, thus creating a direct transport of fatty acids from the gut to the liver. Fatty acid metabolizing enzymes in the liver (CPT-I and II, peroxisomal and mitochondrial beta-oxidation enzymes, enzymes of ketogenesis, and omega-oxidation enzymes) are induced and create an increased capacity for fatty acid oxidation. The increased oxidation of fatty acids "drains" fatty acids from the body, reduces VLDL formation, and ultimately explains the antiadiposity and improved insulin sensitivity observed after administration of peroxisome proliferators.