This high purity monounsaturated fatty acid is ideal as a standard and for biological systems. Being an odd numbered longchain fatty acid that is unusual in most biological systems it is often useful as an internal standard and for comparison against other fatty acids.1 cis-10-Nonadecenoic acid, as well as other monounsaturated fatty acids, demonstrates human p53 DNA binding domain inhibition.2 This fatty acid has a cis double bond at an even carbon (carbon 10) and therefore cannot be enzymatically degraded via the usual beta-oxidation pathway. Instead, a reductase-isomerase or an epimerase pathway must be employed in the metabolism of this fatty acid.3