Anticancer and Antiviral Effect of Some Triterpenes Isolated from the Natural Sources

The diverse, widespread, and exceedingly numerous family of natural products constructed from five carbon building-units and so comprising compounds with $C_{5}$, $C_{10}$, $C_{15}$, $C_{20}$, ${\cdots}$, $C_{40}$ skeletons (together with a few higher members) are synoymously termed terpenes or terpenoids. Among the terpene classes, the triterpenes ($C_{30}$ skeletones) form the largest group and are widely distributed in the plant kingdom, either in the free state or as esters or glycosides, although a few important members found in the animal kingdom such as squalene and a number of tetracyclic component including lanosterol. (omitted)