Lycopene

Physical properties

Since there are 11 conjugated double bonds and 2 non-conjugated double bonds in the lycopene molecule, the stability of lycopene is relatively poor, and cis-trans isomerization and oxidative degradation can occur under certain conditions. Lycopene is sensitive to the oxidation reaction, and the lycopene in the solution is substantially lost after 12 hours of exposure to sunlight. Fe3+ and Cu2+ in solution will catalyze the photooxidation of lycopene, while other metal ions such as K+, Mg2+, Ca2+, Zn2+ have little effect on them, so natural lycopene is extracted and applied. Iron and copper containers should be avoided as much as possible. The pH value also affects lycopene. When lycopene is dissolved in ethanol and adjusted to a pH of 1 to 14, the results show that lycopene is unstable to acid and stable to alkali, so lycopene is used as a pigment. It is not suitable for acidic drinks. It can be seen that the factors affecting the stability of lycopene are aerobic, light, metal ion pH, etc., so the extraction, storage, processing and analysis of lycopene should be carried out under the control of environmental factors.
Coloring ability
As a natural red pigment, lycopene is essential to maintain its strongest tinting strength. Lycopene in tomato fruit has two states of existence: most of them are in the form of elongated, needle-like crystals in the color body, showing a bright red color. When the crystal of lycopene is formed, the plastid film disappears, and the pigment crystal is freely dispersed in the protoplasm. When observed under a microscope, a small granular body can be seen, indicating the color of the color body; another small part (about 10%) forms a complex with proteins and is present in cells. Lycopene has different colors and intensities when present in different forms, and exhibits different colors depending on the solvent and medium. For example, lycopene dissolved in petroleum ether is yellow and red in carbon disulfide.
Solubility
Lycopene is a fat-soluble pigment, soluble in other lipids and non-polar solvents, insoluble in water, difficult to dissolve in strong polar solvents such as methanol, ethanol, etc., soluble in aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbons. Such as ethane, benzene, chloroform and other organic solvents. The solubility of lycopene in various solvents increases with increasing temperature, however, the more pure the sample, the more difficult it is to dissolve. Crystallized lycopene dissolves slowly and tends to form a supersaturated state. Although increasing the temperature accelerates its dissolution, crystallization may occur upon cooling, and ultrasonic waves may be used to accelerate its dissolution. Pure lycopene, although insoluble in water, has a higher solubility when it combines with certain substances such as proteins to form a complex.

Antioxidant
Lycopene quenches singlet oxygen or captures peroxidic free radicals by physical and chemical means. Singlet oxygen is a highly active oxygen free radical with cytotoxic effects. It is most sensitive to cell membranes, mitochondria, etc., and can interact with various biological macromolecules in cells, causing damage to the cell membrane system through binding with molecules. Lycopene can accept the energy of different electronic excited states, absorb light energy and transfer the energy of singlet oxygen to lycopene through singlet-single-state energy transfer process to generate ground state oxygen molecules and triplet lycopene molecules. The triplet lycopene is regenerated by a series of optical and vibratory reactions with a solvent, and the energy is dissipated in the process; the quenching ability of carotenoids is closely related to the number of conjugated double bonds contained in the molecule. There are 11 conjugated double bonds in the lycopene molecule. One lycopene molecule can remove thousands of singlet oxygen, and its rate constant for quenching singlet oxygen is 2 times higher than that of β-carotene. In 1990, Paolo et al reported that more than 30 kinds of biological antioxidants such as carotenoids and tocopherols quenched the action of singlet oxygen, and lycopene was the strongest to quench singlet oxygen.
Lycopene can also eliminate oxidative free radicals, such as hydrogen peroxide, nitrite, etc., by chemical reaction with other forms of reactive oxygen species, and oxidative free radicals can cause lipid peroxidation to form various products. It is related to diseases such as human aging, cancer, autoimmune diseases and anemia.
Regulates cell growth and metabolism
Usually, there is a membrane composed of membrane proteins between the cell gaps, which has selective permeability, allows the passage of the second messenger and growth regulators, and transmits cell growth regulation signals through cell gap junction communication (GJIC) to regulate the cells. Normal proliferation and differentiation. Experiments have shown that lycopene inhibits tumor growth by inducing cell-to-cell junctions, enhancing GJIC between normal cells, controlling cell growth, and inducing cell differentiation. Japanese scholars used fluorescent dye tracer technology to study the effect of lycopene on GJIC in rat liver tissue. It was found that feeding 5 mg/kg BW lycopene every day for 5 days can significantly enhance GJIC function; The GJIC function of tumor cells is weak or absent, and the GJIC function is reduced or inhibited after cell transformation. The inhibition or destruction of GJIC function is considered to be an important mechanism of the cancer-promoting stage.
Can regulate cholesterol metabolism
Lycopene is a low cholesterol agent that inhibits macrophage 3-hydroxy-3-methylglutaryl coenzyme A, a rate-limiting enzyme in cholesterol biosynthesis. It was found that the addition of lycopene to the medium in which macrophages were cultured reduced cholesterol synthesis, while lycopene also increased macrophage low density lipoprotein (LDL) receptor activity. The experiment also showed that the human body supplemented with 60 mg of lycopene per day for 3 months can reduce the cytoplasmic LDL cholesterol concentration by 14%.
Health effects
The above biological properties of lycopene determine its various health functions such as anti-oxidation, inhibition of mutation, reduction of nucleic acid damage, reduction of cardiovascular disease and prevention of cancer.
Prevent and inhibit the role of tumors
Lycopene has the effect of preventing and inhibiting tumors, on the one hand because of its anti-oxidation effect; on the other hand, lycopene can block the genetic mutation process of tissue cells under the action of external mutagens, which is tumor-generated. One of the important mechanisms. It has been found that lycopene can affect the S phase of the cancer cell cycle of breast, lung and uterus; lycopene affects cell growth by inhibiting the G1 to S transformation phase of the cell cycle; lycopene can inhibit the oxidation of LDL cholesterol The formation of heterocyclic amines produced in the brown reaction of fried barbecue and fish, thereby effectively inhibiting the production of carcinogens and inducing tumors. Studies have shown that lycopene has certain inhibitory effects on digestive tract cancer, cervical cancer, breast cancer, skin cancer and bladder cancer.