A very long chain fatty acid (24:1n-9) enriched in nervous tissue and particularly abundant in sphingolipids, such as sphingomyelin; poorly produced in demyelinating disorders, including multiple sclerosis and adrenoleukodystrophy; binds and inhibits DNA polymerase β (Ki = 4.0 uM) and HIV-1 reverse transcriptase (Ki = 1.2 uM).