Delta 9 desaturase index

metabolic

$$\frac{C18:1[\omega -9]}{C18:0+C18:1[\omega -9]}\text{\hspace{1em}(1)}$$

$$\frac{C16:1[\omega -7]+C18:1[\omega -9]}{C16:0+C18:0+C16:1[\omega -7]+C18:1[\omega -9]}\text{\hspace{1em}(2)}$$

Note

There are different versions of this index calculation. The first version calculates only the conversion from $C18:0$ to $C18:1$, while the second calculates the total conversion of $C16:0$ and $C18:0$.

Abbreviations

• $\Delta 9$-desaturase
• $\Delta 9$-DI

Synonyms

• Delta 9 desaturase

Description

Represents the estimated activity of the delta 9 desaturase enzyme (also known as stearoyl-CoA desaturase) in tissues, calculated using the product/substrate ratio approach. This enzyme catalyzes the introduction of a double bond at the delta-9 position of saturated fatty acids, primarily converting palmitic acid ($C16:0$) and stearic acid ($C18:0$) into their corresponding monounsaturated fatty acids, palmitoleic acid ($C16:1[\omega -7]$) and oleic acid ($C18:1[\omega -9]$).

This is a metabolic indicator used to evaluate the endogenous synthesis of monounsaturated fatty acids from saturated precursors. It is widely used in animal nutrition and meat/egg quality research to discriminate metabolic changes caused by dietary factors, genetics, age, or rearing systems. Like the elongase and thioesterase indices, it serves as a practical and cost-effective surrogate for measuring true desaturase enzyme activity in the laboratory.

References

1. • Vessby et al., 2002
   • Zhang et al., 2007
   • Dal Bosco et al., 2022
2. • Dal Bosco et al., 2022
   • Kralik et al., 2025