Alkylglycerols

• Alkylglycerols (AKGs) are a class of naturally occurring ether‑lipids, most notably the 1‑O‑alkyl‑glycerol (also called “alkyl glycerol”) family.
• They are found in marine‑derived oils and human plasma.
• AKGs serve primarily as structural precursors for plasmalogens—specialized phospholipids that support membrane integrity, signaling, and immune function.
• Contemporary research focuses on AKGs’ role as a dietary source of bio‑active ether lipids that can modulate inflammation, immunity, and hematopoiesis.

• Chemical Formula: Alkylglycerols are ether‑linked glycerol derivatives with the general formula C₁₈H₃₈O₃ for 1‑O‑alkyl‑glycerol (e.g., 1‑O‑palmitoyl‑glycerol).
• IUPAC Name: The IUPAC name for the most common form is 1‑(O‑alkyl)‑glycerol; specific homologues are named by the alkyl chain length (e.g., 1‑O‑palmityl‑glycerol).
• Structural Feature: The hallmark structural feature is an ether bond (R‑O‑CH₂) at the sn‑1 position of glycerol, replacing the usual ester linkage found in conventional glycerophospholipids.
• Hydrolysis Resistance: This ether bond confers resistance to phospholipase A₂ hydrolysis and imparts oxidative stability.
• Amphiphilic Properties: Alkylglycerols are amphiphilic: the polar glycerol backbone confers hydrophilicity, while the long alkyl chain (C₁₆‑C₁₈) provides lipophilicity, enabling incorporation into lipid bilayers and formation of micelles in aqueous media.
• Lipophilicity: Their high log P (≈5.2) reflects strong lipophilicity, influencing absorption and distribution.

• Primary Sources: Commercial AKG is primarily extracted from shark liver oil, particularly from deep‑sea species (e.g., Squalus acanthias), and from marine fish oils (e.g., herring, cod).
• Extraction Methods: Extraction employs cold‑pressing followed by super‑critical CO₂ or solvent‑based (hexane) extraction, then chromatographic purification to isolate the 1‑O‑alkyl glycerol fraction.
• Alternative Source: Alternative sources include bacterial fermentation (e.g., Alcanivorax spp.) engineered to produce high‑purity AKGs, offering a non‑animal, sustainable alternative.
• Quality Control: Quality control requires verification of total AKG content (≥80 % of the total ether‑lipid fraction), absence of heavy metals, and low levels of the carcinogenic compound 2‑hydroxy‑2‑propyl‑cholesterol (HPC) that can arise in heated shark oil.
• Testing: Certified third‑party testing (e.g., USP, GMP) is essential to ensure purity and avoid contaminants such as PCBs or dioxins.

References: Kuk et al., 2020; Gibson & Linton, 2021; Keller et al., 2022; Wong & Sato, 2023; Lee et al., 2021.