Anti-oxidative Properties of Lycopene Blythe Beavers FSTC 605 Oral Presentation 4/12/16

WHAT is lycopene? Lycopene is a member of the carotenoid family The chemical and biological function of a carotenoid is determined by their characteristic structure It is a naturally occurring compound that gives the characteristic red color to tomatoes, watermelon, guava, grapefruit, and other red produce It is an antioxidant known for its ability to prevent cardiovascular disease (caused by oxidative stress) and possess an inverse relationship with cancer Antioxidants mitigate oxidative damage More than 600 carotenoids have been found in plants and microorganisms and many of these have been found in human blood and tissue Carotenoids prevent the initiating events in atherogensesis by inhibiting LDL (low density lipoprotein) oxidation

Chemical structure of lycopene Sensitivities: will discuss why these are important to remember when we get to thermally processed tomatoes Lycopene is a linear, acyclic isomer of β-carotene It contains 11 conjugated double bonds along the center and 2 unconjugated double bonds at each end Bonds are arranged linearly in the all-trans form Possesses open β-ionone rings to an open chain

Lycopene Bioavailability Lycopene is found in the photosynthetic pigment-protein complex of plants The disruption of lycopene-protein complexes through breaking down cell wall structures, disrupting membranes, and reducing cellular integrity increases the accessibility of lycopene Processed fruits and vegetables tend to be considered less valuable than fresh, however bioavailability of lycopene is improved after processing Heat processing results in a conformational change in the cis-isomeric form which improved bioavailability Sometimes the lycopene pigment is hidden in a plant because the green of the chlorophyll covers it up; after green degradation the red becomes apparent Bioavailability of lycopene is improved after processing due to the denature of the lycopene-protein complex and subsequent release from the cell matrix (harsh treatments like mechanical disruption and steam are sometimes used)

Carotenoid comparison Lycopene and β-carotene possess nearly identical structures, the main difference is the β-ionone ring - This one seemingly small difference results in lycopene possessing significantly stronger antioxidant capabilities

Antioxidant properties Antioxidant properties of lycopene evaluated in two ways: Examining its protective effect against oxidative damage Measuring its capability to scavenge free radicals directly Lycopene is the most effective singlet oxygen quencher Singlet oxygen (not technically a free radical) is a very reactive high-energy and short-lived oxygen species Antioxidants scavenge radicals from the system either by reacting with them or by disrupting free radical chain reactions The polyene chain is the structural feature that determines the chemical reactivity of carotenoids toward free radicals (aka anti- oxidative properties) Carotenoid antioxidant activity highlighted also by ability to trap peroxyl radicals (ROO) Oxidative damage can be to biological molecules like DNA, lipids, and protein in cell culture or animal experiments Antioxidant reactions with free radicals result in stable and harmless products Polyenes are highly unsaturated conjugate compounds. The predominant properties of polyenes are color and antioxidant activity. Polyenes occur as carotenoids. The configuration of this chain determines the reactivity

Singlet oxygen quenching Lycopene’s superior ability to quench singlet oxygen as opposed to other carotenoids is due to the opening of the β-ionone ring The increased number of conjugated double bonds allows lycopene molecules to effectively quench energy from singlet oxygen and scavenge many free radicals - The efficacy of physical quenching greatly exceeds that of chemical quenching and involves the transfer of excitation energy from O2 to the carotenoid, resulting in ground-state oxygen and excited triplet-state carotenoid. The energy is dissipated through rotational and vibrational interactions between the excited carotenoid and the surrounding solvent to yield the ground state carotenoid and thermal energy. In the process of physical quenching the carotenoid remains intact and can undergo further cycles of singlet oxygen quenching, thus acting like a catalyst.

Stability of lycopene Harsh treatments of tomatoes, including cooking or fine grinding, results in higher bioavailability of lycopene Degradation via isomerization and oxidation do occur during processing High temp short duration = beneficial effects on quality retention During tomato processing, an initial los of 15.8% lycopene content from raw to scalding pulp After this, no further degradation occurred Lycopene content was stable for up to 12 months of storage under a variety of temps These results indicate that lycopene is present in a variety of tomato products, is stable under conditions of processing and storage, is bioavailable and acts as an antioxidant providing protection against lipid, protein, and DNA damage

Benefits Natural colorant Antioxidant activity improves after thermal processing This is a perk the industry can really benefit from A study was performed with human subjects which determined that a daily intake of 30 mg of lycopene can be achieved through a variety of processed tomato products. The results show the benefit of long term lycopene consumption in preventing oxidative damage. Lycopene is also highly hydrophobic and easily dissolves in oil Fat in the diet has the potential to improve the absorption of lycopene Mediterranean Diet This diet can be achieved and represent a typical NA diet while keeping in the dietary guidelines.

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