單萜 monoterpenes
『ㄊㄧㄝ/ tiē』占星油樂園
精油化學中最廣泛代表的烴類是萜烯。各種萜烯的基本單元是稱為異戊二烯的五碳分子;然而，異戊二烯在自然界中不會作為游離分子出現。相反，多個異戊二烯單元通過化學鍵合連接在一起以形成由10/15/20等碳組成的分子。這類分子可以從其科學名稱中識別，其通常使用後綴-ene。
Geranyl pyrophosphate is the precursor to monoterpenes (and hence monoterpenoids). Biosynthesis is mediated by terpene synthase.
當兩個異戊二烯單元之間形成化學鍵時，產生稱為單萜的10碳分子。單萜形狀可以是環狀，直鍊和支鏈變種。單萜的常見物理特徵是低分子量，意味著它們與其他類型的分子相比它們小而輕，顏色清晰，自由流動（不粘稠），高揮發性和強烈的香氣。您將在下面看到，幾乎每種精油中都含有不同量的單萜！
主要作用：
️My YL MEMBER ONLY
加入Gloria YL會員可繼續閱讀更多秘笈…
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings. Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are called monoterpenoids. Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries.
Monoterpenes are derived biosynthetically from units of isopentenyl pyrophosphate, which is formed from acetyl-CoA via the intermediacy of mevalonic acid in the HMG-CoA reductase pathway. An alternative, unrelated biosynthesis pathway of IPP is known in some bacterial groups and the plastids of plants, the so-called MEP-(2-methyl-D-erythritol-4-phosphate) pathway, which is initiated from C5 sugars. In both pathways, IPP is isomerized to DMAPP by the enzyme isopentenyl pyrophosphate isomerase.
Elimination of the pyrophosphate group from geranyl pyrophosphate leads to the formation of acyclic monoterpenes such as ocimene and the myrcenes. Hydrolysis of the phosphate groups leads to the prototypical acyclic monoterpenoid geraniol. Additional rearrangements and oxidations provide compounds such as citral, citronellal, citronellol, linalool, and many others. Many monoterpenes found in marine organisms are halogenated, such as halomon.