Bioactivity and biotechnological production of punicic acid

Punicic acid (PuA; 18: 3Δ ^{9cis,11trans,13cis} ) is an unusual 18-carbon fatty acid bearing three conjugated double bonds. It has been shown to exhibit a myriad of beneficial bioactivities including anti-cancer, anti-diabetes, anti-obesity, antioxidant, and anti-inflammatory properties. Pomegranate (Punica granatum) seed oil contains approximately 80% PuA and is currently the major natural source of this remarkable fatty acid. While both PuA and pomegranate seed oil have been used as functional ingredients in foods and cosmetics for some time, their value in pharmaceutical/medical and industrial applications are presently under further exploration. Unfortunately, the availability of PuA is severely limited by the low yield and unstable supply of pomegranate seeds. In addition, efforts to produce PuA in transgenic crops have been limited by a relatively low content of PuA in the resulting seed oil. The production of PuA in engineered microorganisms with modern fermentation technology is therefore a promising and emerging method with the potential to resolve this predicament. In this paper, we provide a comprehensive review of this unusual fatty acid, covering topics ranging from its natural sources, biosynthesis, extraction and analysis, bioactivity, health benefits, and industrial applications, to recent efforts and future perspectives on the production of PuA in engineered plants and microorganisms.