Triterpenoid saponins are triterpenes which belong to the group of saponin compounds. Triterpenes are a type of terpene containing 30 carbon atoms. Triterpenes are assembled from a five-carbon isoprene unit through the cytosolic mevalonate pathway to make a thirty-carbon compound. Some triterpenes are steroidal in nature. Cholesterol, phytosterols and phytoecdysteroids are triterpenes. The triterpenes are subdivided into some 20 groups, depending on their particular structures. Some triterpenoid compounds are found as saponin glycosides which refers to the attachment of various sugar molecules to the triterpene unit. These sugars can be cleaved off in the gut by bacteria, sometimes allowing the aglycone (triterpene) to be absorbed into the bloodstream or to insert into cell membranes.