Abstract
Fatty acids containing a cyclopropane ring in their structure (cyclopropane FA) have been found in a wide variety of bacteria, a number of protozoa, and Myriapoda. Little is known about cyclopropane FA in mammal, especially in human tissues. The present study deals with the identification of cyclopropane FA in adipose tissue and serum of humans and rats. Fatty acids extracted from the adipose tissue and serum obtained from obese women during bariatric surgery were methylated and analyzed on GC–MS. We have identified: cyclopropaneoctanoic acid 2-hexyl, cyclopropaneoctanoic acid 2-octyl, cyclopropanenonanoic acid, and 2-[[2-[(2-ethylcyclopropyl)methyl]cyclopropyl]methyl] acid in human adipose tissue. We confirmed the presence of cyclopropaneoctanoic acid 2-hexyl by derivatization of FA extracted from human adipose tissue to picolinyl esters. Cyclopropaneoctanoic acid 2-hexyl was the main cyclopropane FA (approximately 0.4 % of total fatty acids in human adipose tissue, and about 0.2 % of total fatty acids in the serum). In adipose tissue cyclopropaneoctanoic acid 2-hexyl was found mainly in triacylglycerols, whereas in serum in phospholipids and triacylglycerols. The cyclopropaneoctanoic acid 2-hexyl has also been found in serum, and adipose tissue of rats in amounts comparable to humans. The content of cyclopropaneoctanoic acid 2-hexyl decreased in adipose tissue of rats maintained on a restricted diet for 1 month. In conclusion, we demonstrated that cyclopropaneoctanoic acid 2-hexyl is present in human adipose tissue and serum. Adipose tissue cyclopropaneoctanoic acid 2-hexyl is stored mainly in triacylglycerols and the storage of this cyclopropane FA is affected by food restriction.
Highlights
Adipose tissue (AT) constitutes the main depot of energy stored as triacylglycerols (TAG) in the human body
When cyclopropaneoctanoic acid 2-hexyl was expressed as lg per mg of lipids, the amount of this cyclopropane fatty acids (FA) was essentially similar in humans and rats (Fig. 2g, h)
We have shown for the first time that cycloproane FA (Fig. 1) are present in human AT and serum (Table 2)
Summary
Adipose tissue (AT) constitutes the main depot of energy stored as triacylglycerols (TAG) in the human body. In the last two decades, AT has been studied extensively as an endocrine organ, producing and releasing many biologically active proteins and peptides, called adipokines [1]. Free fatty acids (FFA) originating from hydrolysis of TAG are released by AT in the greatest amount [1]. FFA released from AT circulate in the blood complexed with albumin and are collected by organs (mainly skeletal and heart muscle, kidney cortex) as a substrate for energy production. Elevated serum FFA concentrations (a state, which is often present in obese subjects) lead to several abnormalities including insulin resistance, inflammatory responses, and a decrease in NO production [1].
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