Novel hydroxycarotenoids with improved antioxidative properties produced by gene combination in Escherichia coli

Abstract

We have used combinatorial biosynthesis to synthesize novel lipophilic carotenoids that are powerful cellular antioxidants. By co-expressing three different carotenoid desaturases in combination with a carotenoid hydratase, a cyclase, and a hydroxylase on compatible plasmids in Escherichia coli, we synthesized four novel carotenoids not previously detected in biological material or chemically synthesized. Their identification was based on their relative retention times on HPLC, spectroscopic properties, molecular weights, number of hydroxy groups, and 1H-NMR spectra. The carotenoids were designated as 1-HO-3', 4'-didehydrolycopene, 3, 1'-(HO)2-gamma-carotene, 1,1'-(HO)2-3, 4, 3', 4'-tetradehydrolycopene, and 1, 1'-(HO)2-3, 4-didehydrolycopene. These novel acyclic derivatives differ from structurally related compounds by extension of the conjugated polyene chain as well as additional hydroxy groups at position C-1'. We determined their antioxidative activity in a liposome-membrane model system, which showed that their ability to protect against photooxidation and radical-mediated peroxidation reactions was linked to the length of the conjugated double-bond system and the presence of a single hydroxy group. The protection of membrane degradation was superior to the related 1-HO and 1, 1'-(HO)2 lycopene derivatives, making them interesting pharmaceutical candidates.

A novel carotenoid 1,2-hydratase (CruF) from two species of the non-photosynthetic bacterium Deinococcus

“…The antioxidant capacity of carotenoids is thought to be linked to the length of their conjugated double bond system and the presence of functional groups (Albrecht et al, 2000).…”

“…The presence of the hydroxyl group may enhance its scavenging activity by hydrogen abstraction reactions with ROS. Hydroxylycopene has been reported to have greater antioxidant properties than lycopene because of the presence of a hydroxyl group at position C-19 (Albrecht et al, 2000). Therefore, carotenoid 1,2-hydratase (DR0091), responsible for the hydration at C-19,29 in deinoxanthin biosynthesis, is important for the antioxidant activity of deinoxanthin.…”

Functional Expression and Extension of Staphylococcal Staphyloxanthin Biosynthetic Pathway in Escherichia coli

“…The carotenoids found in bacteria and yeast have antioxidative functions and play roles in light harvesting, energy transfer, and the regulation of membrane fluidity (11)(12)(13). The protective functions of carotenoids against oxidative stress, singlet oxygen, and peroxy radicals promote the survival of pathogenic microbes during host immune responses (14,15).…”

Diversifying Carotenoid Biosynthetic Pathways by Directed Evolution

“…2) (4,5,13,69,105,118,192,199,211). Where gene assembly alone successfully yielded a new pathway branch or extension, the recruited enzyme(s) usually catalyzed transformations later in the pathway.…”

“…The polyene chromophores of carotenoids, which absorb light in the 400 to 550-nm range, provide the basis for their characteristic yellowto-red colors and their ability to quench singlet oxygen (5,74,79,95,103,137,218,230). Carotenoids act as antioxidants in vivo (170,183,210), and many beneficial effects of carotenoids on human health have been reported, ranging from cancer prevention and tumor suppression to upregulation of immune function, reduction of the risk of coronary heart disease or age-related degeneration, and cataract prevention (19,21,42,47,83,108).…”