C40H56

C40H56 is the molecular formula associated with carotenoids, a family of natural hydrocarbons that function as pigments in plants, algae, and some fungi. It denotes a tetraterpene skeleton with 40 carbon atoms and 56 hydrogen atoms, giving a degree of unsaturation of 13, which reflects the extensive array of conjugated double bonds and ring structures found in many members of the class.

Within this formula, many distinct carotenoids exist. The best-known examples are beta-carotene and lycopene. Beta-carotene features two cyclic end groups (beta-ionone rings) at the ends of a long conjugated polyene chain, while lycopene is an acyclic molecule with a similarly long conjugated system. Both share the same molecular formula but differ in arrangement of atoms, influencing color, reactivity, and biological activity.

Carotenoids with the C40H56 formula are typically nonpolar and lipophilic, making them soluble in fats and organic solvents but insoluble in water. They produce vivid orange to red colors and are widely used as natural colorants in foods and cosmetics. They also function as antioxidants, quenching singlet oxygen and scavenging free radicals.

Biologically, some C40H56 carotenoids are provitamin A compounds. Beta-carotene, for example, can be enzymatically cleaved in the body to form retinal, a precursor of vitamin A. The efficiency of conversion is dose- and context-dependent, commonly summarized as about 12 µg of dietary beta-carotene yielding 1 µg of retinol activity equivalent. Storage and processing conditions can affect carotenoid stability, as exposure to light, heat, and oxygen promotes degradation.