159
10
with one ring (monocyclic, olefins). Among the monocyclic monoterpenes are limonene
(odour constituent of citrus), α-terpinene (in cardamom and marjoram) and phellandrene
(in eucalyptus, resin of the balsam fir tree, Abies balsamea, known as Canada balsam).
Limonene is also an important precursor for the formation of pulegone. The enzyme
pulegone reductase then forms menthone from pulegone. Menthol is the oxidized form
of menthone (Ahkami et al. 2015). Menthofuran is a side product from pulegone, mainly
produced under high light intensities but unwanted in the production of menthol. The
main producer of menthol and its derivatives is mint (Mentha spp.), making this plant an
Linalyl cation α-Terpinyl cation
GPP
Linalool Myrcene β-Ocimene
Limonene
α-Terpinene
Pulegone
Menthone
Menthol
Menthofuran
Geraniol
1,8-Cineole
(-)-α-Thujone
Iridoids, e.g. Loganic acid
Indol alkaloids
Sabinene
bicyclic
monocyclic
acyclic
Geranyl cation
OH
OH
P
O
O
OH
O
O
P
OH
HO
OH
OH
O
P
P
O
O
O
+
+
+
O
O
O
OH
OH
OH
O
HO
OH
O
OH
OH
HO
HO
O
. Fig. 10.3 Schematic overview of the biosynthetic pathways and representative members of various
monoterpene subfamilies. Abbreviations: GPP geranyl pyrophosphate
10.2 · Monoterpenes (From MEP Pathway, C10, e.g. Menthol, Camphor and Thujone)
10
with one ring (monocyclic, olefins). Among the monocyclic monoterpenes are limonene
(odour constituent of citrus), α-terpinene (in cardamom and marjoram) and phellandrene
(in eucalyptus, resin of the balsam fir tree, Abies balsamea, known as Canada balsam).
Limonene is also an important precursor for the formation of pulegone. The enzyme
pulegone reductase then forms menthone from pulegone. Menthol is the oxidized form
of menthone (Ahkami et al. 2015). Menthofuran is a side product from pulegone, mainly
produced under high light intensities but unwanted in the production of menthol. The
main producer of menthol and its derivatives is mint (Mentha spp.), making this plant an
Linalyl cation α-Terpinyl cation
GPP
Linalool Myrcene β-Ocimene
Limonene
α-Terpinene
Pulegone
Menthone
Menthol
Menthofuran
Geraniol
1,8-Cineole
(-)-α-Thujone
Iridoids, e.g. Loganic acid
Indol alkaloids
Sabinene
bicyclic
monocyclic
acyclic
Geranyl cation
OH
OH
P
O
O
OH
O
O
P
OH
HO
OH
OH
O
P
P
O
O
O
+
+
+
O
O
O
OH
OH
OH
O
HO
OH
O
OH
OH
HO
HO
O
. Fig. 10.3 Schematic overview of the biosynthetic pathways and representative members of various
monoterpene subfamilies. Abbreviations: GPP geranyl pyrophosphate
10.2 · Monoterpenes (From MEP Pathway, C10, e.g. Menthol, Camphor and Thujone)