*2.2.1.5 Sesterterpenes C25*

Sesterterpenes consist of 5 units of isoprene (25 carbon backbone). They exist in a wide variety of forms, including linear, monocyclic, bicyclic, tricyclic, tetracyclic, and macrocyclic frameworks [4].

## *2.2.1.6 Triterpenes C30*

The triterpenes are made up of six isoprenes, they have relatively complex cyclic structures.

There are also tetraterpenes which consist of 8 units of isoprene (C40H64); and when the number of isoprene units exceeds 8 units, terpenes are called polyterpenes (C > 40).
