Carotene is a group of naturally occurring carotenoids with the same molecular formula as that of lycopene. Carotene was first isolated from carrots. Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. Xanthophyll is a class of carotenoids with oxygenated carotenes.

Lycopene is a bright red carotene and carotenoids pigment and phytochemical found in tomatoes and other red fruits and vegetables such as red carrots, red bell peppers, watermelon and pappayas.

Carotenoids are tetraterpenes. They are present in both plants and animals. The isoprene derivatives of carotenoids are highly unsaturated. Due to the presence of many conjugated double bonds, they are red or yellow in colour. For example, the pigments of tomato (lycopene) and carrot (α- and β-carotene) are red, whereas oxygen-containing carotenoids are yellow (xanthophyll).

Rubber is a polyterpene present in the latex of many tropical plants. A molecule of rubber is made of 500–5000 isoprene units joined in a long straight chain.

Triterpenes are mostly the intermediate in the biosynthesis of cholesterol. Two such compounds are squalene and lanosterol. Their structures are as follows:

Diterpenes are found as substituents of resins and balsams. Abeitc and sapietic are the best-known diterpenes. Vitamins A1 and A2 are important monocyclic diterpenes. Phytol: It’s an acyclic diterpenes and is obtained from the hydrolysis of cholorophyll. Given below is its structure:

Important monoterpenes are myrcene (from oil of bay), geraniol (from rose oil), limonene (from lemon oil), and menthol (from peppermint oil). Their structures are given below: Among the sesquiterpenes, farnesol is widely distributed but is present in essential oils in small amounts. Its structure is as follows:

Among the non-saponifiable lipids found in plants are mainly hydrocarbon known as terpenes. The simplest terpenes are called monoterpenes and conform the formula C10H16 (equivalent to two isoprene units), sesquiterpenes with the formula C15H24, diterpenes with C2H32, and triterpenes C30H48.

They are concerned primarily with the metabolism of carbohydrates, proteins, and fats. Example: Cortisone, cortisol, and corticosterone. The structure of cortisol is given below: