# Lycopene: A Natural Arsenal in the War against Oxidative Stress and Cardiovascular Diseases
## 2 Discovery, Chemical Structure, Properties, Biosynthesis and Physiological Role of Lycopene  
Lycopene is a carotenoid with a molecular formula (C40H56) that gives the _Solanum Lycopesicum_ L. fruits their red color [40]. Chemically, the lycopene molecule has 11 conjugated double bonds, and its structures can have over 70 Z-isomers [41; 42]. According to estimations, all-E-lycopene contains 80 percent to 97 percent lycopene in tomato fruit. However, Z-isoforms account for more than half of the lycopene present in human blood and tissues [43; 44] (Figure 2). [PERSON] identified lycopene in 1876 and named it as'soanorubin'; later on, it was named lycopene and it was purified [45]. Tomato is a major source of natural lycopene; however, it is found in many plants at variable concentrations [46; 47]. The extended conjugated double bond system of these compounds is a significant property of the carotenoids and is responsible for their attractive colors [48; 49]. Lycopene produces the light-absorbing chromophore, and the extended conjugated double bond system of these compounds is a significant property of the carotenoids that is responsible for their attractive colors. In order for a molecule to have visible color, it must have at least seven conjugated double bonds. The maximum absorption wavelength increases as the number of conjugated double bonds increases [50; 51]. Lycopene is not a precursor molecule for vitamin A because it lacks the terminal b-ionic ring found in vitamin A's core structure. Lycopene is the most effective singlet oxygen quencher among the carotenoids, with the number of conjugated double bonds and, to a lesser degree, the presence of cyclic or acyclic end groups dictating its quenching abil  
Figure 1: Lycopene as a nutraceutical compound has applications against multiple diseased conditions. Figure 2: Common isomers of lycopene. (**A**) all-E-lycopene isomer, (**B**) Z-lycopene isomer. ity [52]. Furthermore, its biological properties, such as oxidative sensitivity, are impacted by its chain structure, which includes a large conjugated polyene system [53; 54]. Lycopene is found in nature as an all trans form with seven double bonds that can be isomerized to mono-cis or poly-cis when exposed to high temperatures, light, oxygen, acids, catalysts, and metal ions. Lycopene is a lipophilic molecule with hydrophobic properties due to its acyclic structure and 11 linear conjugated double bonds, making it more soluble in organic solvents, such as chloroform, benzene, hexane, methylene chloride, acetone, and petroleum ether [55]. Lycopene is a vivid red pigment that is water insoluble [56]. Lycopene is present in the chloroplasts of fresh fruit, a plant cell organelle that is rarely eaten [57]. [57]. Thermal food processing, particularly in the presence of cooking oils, causes lycopene to micelle and enhance its intestinal absorption rate by a factor of ten [58]. The complicated process of lycopene manufacturing begins when chlorophyll degrades to produce white-colored leucoplast, which produces particular red-colored pigmented organelles called chromoplast. The biosynthetic process begins with the conversion of acetyl-Co-A to isopentenyl diphosphate (IPP) via the mevalonate route [59]. IPP (SC) interacts with DMAPP (5C) to form geranyl diphosphate (GPP), a ten-carbon molecule [60]. The next step entails adding two IPP molecules one at a time, resulting in the synthesis of geranylegenyl diphosphate (GGPP), a 20-carbon complex. Two molecules of GGPP are joined head-to-head in a condensation process to generate phytoene, a 40-carbon chemical that is then converted to lycopene via a mechanism mediated by phytoene desaturase [61; 62] (Figure 3). The brilliant crimson hue of lycopene crystals in the shape of small globules hang throughout the fruit [63]. Lycopene is located in the thylakoid membranes as a protein lycopene complex at the cellular level, owing to its lipophilic nature. Despite the fact that lycopene is not an essential ingredient, it has been discovered to provide a variety of health advantages.