Publications by authors named "Ryouhei Yamashita"

Article Synopsis
  • Bioactive N-acylethanolamines (NAEs), including palmitoylethanolamide and anandamide, have various health benefits, but their breakdown is managed by enzymes like fatty acid amide hydrolase and NAE acid amidase.
  • This study found that acid ceramidase (AC), an enzyme similar in function to NAAA, can also break down NAEs, particularly lauroylethanolamide.
  • Research showed that increasing AC levels in cells decreased NAEs, while reducing AC through siRNA led to higher NAE levels, indicating AC's significant role as a third enzyme responsible for NAE degradation.
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Sphingomyelin (SM) with N-α-hydroxy fatty acyl residues (hSM) has been shown to occur in mammalian skin and digestive epithelia. However, the metabolism and physiological relevance of this characteristic SM species have not been fully elucidated yet. Here, we show methods for mass spectrometric characterization and quantification of hSM.

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Cleanup technology and mass spectrometric determination of sphingosine-1-phosphate (S1P) using a phosphate capture molecule are shown. The protocol is rapid, requires neither thin-layer chromatography nor liquid chromatography, and is applicable to both blood and solid tissue samples. The mass spectrometric method is also applicable to ceramide-1-phosphate.

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N-Acylethanolamines form a class of lipid mediators and include an endocannabinoid arachidonoylethanolamide (anandamide), analgesic and anti-inflammatory palmitoylethanolamide, and appetite-suppressing oleoylethanolamide. In animal tissues, N-acylethanolamines are synthesized from N-acylated ethanolamine phospholipids directly by N-acylphosphatidylethanolamine-hydrolyzing phospholipase D or through multi-step pathways via N-acylethanolamine lysophospholipids. We previously reported that glycerophosphodiesterase (GDE) 4, a member of the GDE family, has lysophospholipase D (lysoPLD) activity hydrolyzing N-acylethanolamine lysophospholipids to N-acylethanolamines.

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Ceramide-1-phosphate (C1P) is a potential signaling molecule that modulates various cellular functions in animals. It has been known that C1P with different N-acyl lengths induce biological responses differently. However, molecular species profiles of the C1P in animal tissues have not been extensively examined yet.

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The structure and biosynthetic route for an unidentified lipid (lipid X) detected by TLC of cabbage (Brassica oleracea) lipids was determined. Lipid X is a phospholipid that is resistant to mild alkali and detectable by MALDI-TOF MS as an adduct with Phos-tag, a phosphate-capture zinc complex. Various α-hydroxy fatty acids (16:0, 22:0, 24:0 and 24:1) were detected by GC-MS of fatty acid methyl esters prepared from lipid X.

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