Effects of Z-Isomerization on the Bioavailability and Functionality of Carotenoids: A Review

Abstract

Carotenoids, the most common fat-soluble plant pigments in nature, are beneficial to human health due to their strong antioxidant activities and abilities to prevent various diseases. Carotenoids have many geometrical isomers forms caused by E/Zisomerization at arbitrary sites within the multiple conjugated double bonds. Several studies have addressed that the bioavailability as well as the antioxidant, anticancer, and antiatherosclerotic activities of carotenoids varies among the isomers. In addition, those variations differ among carotenoids: Z-isomerization resulted in "positive" or "negative" effect for carotenoids bioavailability and functionality, for example, Z-isomers of lycopene are more bioavailable than the all-E-isomer, whereas the opposite is observed for β-carotene. Thus, to efficiently promote the beneficial effects of carotenoids by ingestion, it is important to have a good understanding of the impact of E/Z-isomerization on the corresponding functional changes. The objective of this contribution is to review the effects of carotenoid Z-isomerization on bioavailability and functionality and describe their differences among carotenoids.

Experimental Design and Optimization of Recovering Bioactive Compounds from Chlorella vulgaris through Conventional Extraction

“…More specifically, heat treatment is known for promoting isomerization of the naturally all trans-carotenoids to cis-forms. According to Honda et al [ 45 ], cis-isomerization may have an ambiguous effect on the antioxidant activity of carotenoids and, consequently, the extract’s quality. For example, depending on the assay method applied, cis-conversion of β-carotene was considered responsible for both improvement and deterioration of antioxidant activity [ 46 , 47 ].…”

Nutritional Importance of Carotenoids and Their Effect on Liver Health: A Review

“…The increase in the bioavailability of carotenoids when processing temperatures are above 100 °C (canning and sterilization) has been associated with isomerization, since the cis ( Z ) isomers are more bioavailable [1]. Several investigations have addressed the fact that the Z -isomerization of carotenoids influences not only bioavailability, but also antioxidant, anticancer, and antiatherosclerotic activities [63]. However, these results differ according to the type of carotenoid.…”

“…However, these results differ according to the type of carotenoid. For example, the Z -isomers of lycopene and astaxanthin have a greater bioavailability than the all- E -isomers [64,65], whereas the Z -isomers of β-carotene and lutein have a lower bioavailability than the all- E -isomers [66] It is important to understand the effect of E / Z -isomerization on functional changes, since this depends on its bioavailability and functionality of the carotenoids by ingestion [63]. In addition, mechanical processing, such as chopping and chewing, helps reduce the size of the particles and releases carotenoids from chloroplasts and tissues, increasing their bioavailability [67,68,69].…”

Lycopene in the Prevention of Cardiovascular Diseases

“…In turn, their processed products, such as ketchups, tomato concentrates, juices, are dominated by the forms of cis-lycopene. It is assumed that thanks to the cis form, lycopene is highly bioavailable in the human diet [30,31]. Moreover, some studies confirm that increasing the bioavailability of lycopene as a result of its trans to cis isomerization can be achieved by adding fish oil or olive oil to tomato dishes.…”