zeaxanthin and crocin

Saffron (Crocus savitus) is a Middle-Eastern herb with strong antioxidant properties. Its major constituents, safranal, crocin, and crocetin, are also antioxidants and bear structural similarities to other well-known natural antixodant substances, such as zeaxanthin. Given the role of oxidative stress in many diseases, considerable interest has been shown into the potential role of saffron supplementation as a treatment for a range of diseases. In vitro and animal studies have provided evidence that saffron and its constituents may be potent therapies for a range of pathologies, including Alzheimer's disease, age-related macular degeneration (AMD) and cardiac ischemia. Whether these findings translate into clinical efficacy, however, has as of yet been incompletely assessed. This makes assessing the role of saffron supplementation in these diseases difficult. Here, we review the current human clinical evidence supporting saffron supplementation as a treatment for a range of pathologies and the underlying science supporting its use.

Topics: Affect; Animals; Antioxidants; Cardiovascular System; Carotenoids; Clinical Trials as Topic; Cognition; Crocus; Cyclohexenes; Disease Models, Animal; Humans; Oxidative Stress; Phytotherapy; Plant Preparations; Reproduction; Terpenes; Vision, Ocular; Vitamin A; Zeaxanthins

Topics: Carotenoids; Crocus; Dioxygenases; Gardenia; Nicotiana; Zeaxanthins

Crocetin, one of the few colored apocarotenoids known in nature, is present in flowers and fruits and has long been used medicinally and as a colorant. Saffron is the main source of crocetin, although a few other plants produce lower amounts of this apocarotenoid. Notably, Buddleja davidii accumulates crocetin in its flowers. Recently, a carotenoid dioxygenase cleavage enzyme, CCD2, has been characterized as responsible for crocetin production in Crocus species. We searched for CCD2 homologues in B. davidii and identified several CCD enzymes from the CCD1 and CCD4 subfamilies. Unexpectedly, two out of the three CCD4 enzymes, namely BdCCD4.1 and BdCCD4.3, showed 7,8;7',8' activity in vitro and in vivo over zeaxanthin. In silico analyses of these enzymes and CCD2 allowed the determination of key residues for this activity. Both BdCCD4 genes are highly expressed during flower development and transcripts levels parallel the accumulation of crocins in the petals. Phylogenetic analysis showed that BdCCD4.2 grouped with almost all the characterized CCD4 enzymes, while BdCCD4.1 and BdCCD4.3 form a new sub-cluster together with CCD4 enzymes from certain Lamiales species. The present study indicates that convergent evolution led to the acquisition of 7,8;7',8' apocarotenoid cleavage activity in two separate CCD enzyme families.

Topics: Buddleja; Carotenoids; Computer Simulation; Dioxygenases; Escherichia coli; Evolution, Molecular; Flowers; Gene Expression Regulation, Plant; Phylogeny; Plant Proteins; Recombinant Fusion Proteins; Vitamin A; Zeaxanthins