Hydrocarbons or their derivatives formed by the condensation of eight isoprene units (that is, four terpenes) and therefore containing 40 carbon atoms; for example, various carotenoids.
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Sesquiterpenoids and diterpenes (including the retinoids), and tetraterpenes (carotenoids such as a and a carotene, lutein, lycopene, zeaxanthin and cryptoxanthin) are of the ingredients of H.
Elmadfa, Biological Relevance of Terpenoids: Overview Focusing On Mono-Di and Tetraterpenes, Ann.
In addition, several types of terpenoids or terpenes ([C.sub.10][H.sub.16]), such as diterpenes ([C.sub.20]), triterpenes ([C.sub.30]), tetraterpenes ([C.sub.40]), hemiterpenes ([C.sub.5]), and sesquiterpenes ([C.sub.15]), have also effective antifungal activity [16].
They are classified as hemiterpenes (C5), monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), sesterpenes (C25), triterpenes (C30), tetraterpenes (C40), and polyterpenes (>C40).
Depending on the number of blocks, they can be classified as monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), triterpenes (C30), tetraterpenes (C40), and polyterpenes [21].
Terpenoids are classified to hemi-terpenes (C5), monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), triterpenes (C30), and tetraterpenes (C40) [25].
This synergy is probably due to the lipophilic properties of terpenoids (mono-, di-, tri-, and tetraterpenes), mainly influencing the permeability of the cell membrane.
They occur as di (C20), tri (C30), and tetraterpenes (C40), as well as hemi (C5) and sesquiterpenes (C15).
All of this marvelous mixture of colors results from the combination of three groups of basic chemical compounds: chlorophyll, which consists of green pigments of porphynidic structure, quite similar to the hemoglobin found in blood, but with a magnesium atom in the middle of the molecule (hemoglobin has an iron atom); the carotenoids, among them the red and orange carotene and the yellow xanthophyll, that are tetraterpenes; and the anthocyanins of red and blue colors, which are complex molecules that include sugars and flavonoid compounds in their composition.
Elmadfa, "Biological relevance of terpenoids: Overview focusing on mono-, di- and tetraterpenes," Annals of Nutrition and Metabolism, vol.
Carotenoids are natural tetraterpenes (C40) which are produced by microorganisms, plants, and marine invertebrates.