Terpenes

Terpenes are a large family of natural products and are known to be the primary constituents of essential oils. They are biosynthesized via the mevalonate pathway. The basic structure is derived from five-carbon isoprene units1,2) which are linked together in a head-to-tail fashion to form linear chains or rings. They can be classified on the basis of the length of the carbon chains as illustrated below.

Table 1. Classification of Terpenes and Examples

Name Number of Carbons Examples
Hemiterpenes 5 Isoprene
Monoterpenes 10 Menthol, Geraniol: Flavors, Food Additives
Sesquiterpenes 15 Artemisinin: Antimalarial Drug
α-Bisaborol: Flavor, Cosmetic Ingredients
Diterpenes 20 Paclitaxel: Antitumor Agent, Gibberellins: Plant Hormones
Triterpenes 30 Lanosterol: Precursor of Steroid Biosynthesis

Terpenes are widespread in nature existing in marine organisms as well as in plants. Some terpenes show characteristic bioactivity such as antitumor activities, and their modes of action is currently under investigation. Since terpenes are mainly found in plants, they are frequently used as markers in plant metabolome analyses.

■Nomenclature
According to the IUPAC Nomenclature Appendix, 42 parent skeletons are shown.3) Practically, other common names are also used frequently. For further trivial names, please refer to References.2,4)

■Solubility
In general, most of the terpenes are insoluble in water but soluble in ethanol, chloroform and diethyl ether. They can be added to the buffer solution as a dimethyl sulfoxide solution to examine their activity in living organisms. Please take caution that the solution becomes suspended as the concentration level of the dissolved substance increases. It is recommended to define the optimal concentration level and volume of addition in advance. Glycosides of terpenes are more water-soluble than their aglycones.

■Stability
In general, monoterpenes are relatively stable. However, oily sesquiterpenes and diterpenes are less stable bearing more oxygen fuctional groups rendering them unsuitable for storage over longer periods. However, most of the triterpenes are solid and show good stability.

■Detection
Since some terpenes do not have chromophore unit, UV detection by normal-phase HPLC is difficult. As a result, RI (refractive index) detector can be used instead. Normal-phase TLC is also frequently used to visualize terpenes by spraying them with phosphomolybdic acid solution or cerium sulfate solution followed by heating.

■Some Tips
▪ Monoterpenes and some sesquiterpenes form azeotropic mixtures with the traces of water present in the sample, leading to a considerable loss during distillation. It is therefore recommended that these terpenes should be properly dried prior to their use using the following procedure:
(1) dissolution of the sample in an appropriate organic solvent (2) drying it over anhydrous sodium or magnesium sulfate and (3) removal of the solvent in vacuo.
▪ In NMR measurement, using two different solvents separately, deuteriochloroform (CDCl3) and benzene-d6 (C6D6), may change the signal patterns to facilitate interpretation of the spectrum (mainly for proton). In addition, some hidden signals might also appear owing to the variation in the residual water signal positions.
▪ During storage over longer periods, CDCl3 might partially decompose to form phosgene which can damage your precious sample. Therefore care should be taken especially while using CDCl3 with high deuterium ratio (no less than 99.95%D). The sample should not be stored in the NMR tube as a solution after its analysis but recovered from the tube and the solvent should be evaporated completely to prevent its decomposition.

Hemiterpenes

Acyclic Monoterpenes

Monocyclic Monoterpenes

Bicyclic Monoterpenes

Sesquiterpenes

Diterpenes

Triterpenes

Others

Hemiterpenes

M0178 M0178 M0714 M0714 M0726 M0726
M0378 M0378 M0543 M0543 A1090 A1090
A1136 A1136 I0160 I0160 M0182 M0182
T0246 T0246 T1003 T1003
M0178 2-Methyl-3-buten-2-ol
M0714 3-Methyl-2-buten-1-ol
M0726 3-Methyl-3-buten-1-ol
M0378 3-Methyl-3-buten-2-one (stabilized with HQ)
M0543 3-Methylcrotonic Acid
A1090 alpha-Angelicalactone
A1136 Angelic Acid
I0160 Isoprene (stabilized with TBC)
M0182 Isovaleric Acid
T0246 Tiglic Acid
T1003 trans-2-Methyl-2-butenal
Page Top

Acyclic Monoterpenes

C0369 C0369 C1466 C1466 C2254 C2254
C1454 C1454 D1277 D1277 D1212 D1212
D1442 D1442 D3382 D3382 C0370 C0370
C1211 C1211 C1708 C1708 C0915 C0915
D1592 D1592 G0027 G0027 G0028 G0028
G0218 G0218 G0241 G0241 G0236 G0236
L0048 L0048 L0049 L0049 M0235 M0235
N0077 N0077 N0463 N0463 T1298 T1298
C0369 (+)-Citronellal
C1466 (-)-beta-Citronellol
C2254 (-)-beta-Citronellol
C1454 (-)-Citronellal
D1277 2,6-Dimethyl-2,4,6-octatriene
D1212 2,6-Dimethyloctane
D1442 3,7-Dimethyl-1-octanol
D3382 3,7-Dimethyl-1-octen-3-ol
C0370 beta-Citronellol
C1211 Citral Dimethyl Acetal
C1708 Citronellic Acid
C0915 Citronellyl Acetate
D1592 Dihydrolinalool
G0027 Geraniol
G0028 Geranyl Acetate
G0218 Geranyl Formate [for Perfumery]
G0241 Geranyl Nitrile (cis- and trans- mixture)
G0236 Geranylacetone (contains Nerylacetone)
L0048 Linalool
L0049 Linalyl Acetate
M0235 Myrcene (stabilized with BHT)
N0077 Nerol
N0463 Neryl Acetate
T1298 Tetrahydrolavandulol
Page Top

Monocyclic Monoterpenes

L0047 L0047 L0105 L0105 M0826 M0826
M1221 M1221 N0626 N0626 M0407 M0407
T2581 T2581 L0046 L0046 M0321 M0321
T1993 T1993 M0051 M0051 L0132 L0132
M0545 M0545 M0513 M0513 M0573 M0573
M0571 M0571 A1107 A1107 M0834 M0834
M0990 M0990 P0866 P0866 M0319 M0319
M1044 M1044 I0726 I0726 M1066 M1066
C0703 C0703 C0704 C0704 T2605 T2605
D2112 D2112 I0744 I0744 M2023 M2023
I0076 I0076 M0317 M0317 T0022 T0022
T0984 T0984 I0077 I0077 C0026 C0026
I0284 I0284 I0168 I0168 M0318 M0318
H0142 H0142 M0320 M0320 L0143 L0143
C0798 C0798 E0796 E0796 C0799 C0799
C0513 C0513 P1783 P1783 T2344 T2344
T0817 T0817 T0023 T0023 M0410 M0410
I0285 I0285 M1129 M1129 S0444 S0444
L0047 (+)-Limonene
L0105 (+)-Limonene
M0826 (+)-Menthol
M1221 (+)-Menthyl Chloroformate
N0626 (+)-Neomenthol
M0407 (+)-Pulegone
T2581 (+)-Terpinen-4-ol
L0046 (+/-)-Limonene
M0321 (+/-)-Menthol
T1993 (+/-)-Terpinen-4-ol
M0051 (-)-alpha-Phellandrene
L0132 (-)-Limonene
M0545 (-)-Menthol
M0513 (-)-Menthone
M0573 (-)-Menthoxyacetic Acid
M0571 (-)-Menthoxyacetyl Chloride
A1107 (-)-Menthyl Acetate
M0834 (-)-Menthyl Chloride
M0990 (-)-Menthyl Chloroformate
P0866 (-)-Perillaldehyde
M0319 (-)-Terpinen-4-ol
M1044 (1R,2S,5R)-(-)-Menthyl (S)-p-Toluenesulfinate
I0726 (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl (R)-2-Hydroxypropionate
M1066 (1S,2R,5S)-(+)-Menthyl (R)-p-Toluenesulfinate
C0703 (R)-(-)-Carvone
C0704 (S)-(+)-Carvone
T2605 2,2,6-Trimethyl-6-vinyltetrahydropyran-3-ol (mixture of isomers)
D2112 2,2-Dimethyl-3-(2-methyl-1-propenyl)cyclopropane Carboxylic Acid Ethyl Ester
I0744 2-Isopropenyl-5-methyl-5-vinyltetrahydrofuran (mixture of isomers)
M2023 8-Mercaptomenthone
I0076 alpha-Ionone
M0317 alpha-Terpinene
T0022 alpha-Terpineol
T0984 alpha-Terpineol
I0077 beta-Ionone
C0026 Carvacrol
I0284 cis-1-Isopropyl-4-methylcyclohexane
I0168 Cuminaldehyde
M0318 gamma-Terpinene
H0142 Hinokitiol
M0320 Isopulegol
L0143 Linalool Oxide
C0798 m-Cymene
E0796 N-Ethyl-p-menthane-3-carboxamide
C0799 o-Cymene
C0513 p-Cymene
P1783 Piperitone
T2344 Terpin Monohydrate
T0817 Terpinolene
T0023 Terpinyl Acetate
M0410 Thymol
I0285 trans-1-Isopropyl-4-methylcyclohexane
M1129 trans-p-Menthane-3,8-diol
S0444 trans-Sobrerol
Page Top

Bicyclic Monoterpenes

C1324 C1324 C0015 C0015 C1391 C1391
C0998 C0998 D2715 D2715 B0567 B0567
B1125 B1125 C0047 C0047 C0010 C0010
C0012 C0012 F0163 F0163 C0016 C0016
B1696 B1696 C0009 C0009 C0011 C0011
C0014 C0014 I0275 I0275 C1325 C1325
C0972 C0972 C1393 C1393 C1308 C1308
P0441 P0441 B1012 B1012 C1021 C1021
C1022 C1022 C1251 C1251 F0164 F0164
V0072 V0072 P1099 P1099 C1482 C1482
T1863 T1863 C0013 C0013 H0862 H0862
C1660 C1660 M1341 M1341 M1070 M1070
P0440 P0440 H0863 H0863 C1326 C1326
C1327 C1327 K0028 K0028 C0542 C0542
C0934 C0934 H0830 H0830 P1362 P1362
C1661 C1661 B0525 B0525 B0526 B0526
I0306 I0306 I0638 I0638 I0617 I0617
P1876 P1876 C0017 C0017 T0989 T0989
C1324 (+)-10,2-Camphorsultam
C0015 (+)-10-Camphorsulfonic Acid
C1391 (+)-10-Camphorsulfonimine
C0998 (+)-10-Camphorsulfonyl Chloride
D2715 (+)-3,9-Dibromocamphor
B0567 (+)-3-Bromocamphor
B1125 (+)-3-Bromocamphor-8-sulfonic Acid Ammonium Salt
C0047 (+)-3-Carene
C0010 (+)-Camphor
C0012 (+)-Camphoric Acid
F0163 (+)-Fenchone
C0016 (+/-)-10-Camphorsulfonic Acid
B1696 (+/-)-Borneol
C0009 (+/-)-Camphene (contains ca. 20% Tricyclene)
C0011 (+/-)-Camphor
C0014 (+/-)-Camphorquinone
I0275 (+/-)-Isoborneol
C1325 (-)-10,2-Camphorsultam
C0972 (-)-10-Camphorsulfonic Acid
C1393 (-)-10-Camphorsulfonimine
C1308 (-)-10-Camphorsulfonyl Chloride
P0441 (-)-beta-Pinene
B1012 (-)-Borneol
C1021 (-)-Camphanic Acid
C1022 (-)-Camphanic Chloride
C1251 (-)-Camphor
F0164 (-)-Fenchone
V0072 (-)-Verbenone
P1099 (1R)-(+)-alpha-Pinene
C1482 (1R)-(-)-Camphorquinone
T1863 (1R)-(-)-Thiocamphor
C0013 (1R)-Camphor Oxime
H0862 (1R,2R,5R)-(+)-2-Hydroxy-3-pinanone
C1660 (1S)-(+)-Camphorquinone
M1341 (1S)-(-)-10-Mercaptoborneol
M1070 (1S)-(-)-10-Mercaptoisoborneol
P0440 (1S)-(-)-alpha-Pinene
H0863 (1S,2S,5S)-(-)-2-Hydroxy-3-pinanone
C1326 (2R,8aS)-(+)-(Camphorylsulfonyl)oxaziridine [Asymmetric Oxidizing Reagent]
C1327 (2S,8aR)-(-)-(Camphorylsulfonyl)oxaziridine [Asymmetric Oxidizing Reagent]
K0028 (S)-(+)-Ketopinic Acid
C0542 1,8-Cineole [for Determination of o-Cresol]
C0934 1,8-Cineole
H0830 3-Heptafluorobutyryl-(+)-camphor
P1362 alpha-Pinene Oxide
C1661 anti-(1R)-(+)-Camphorquinone 3-Oxime
B0525 Borneol (contains ca. 20% Isoborneol)
B0526 Bornyl Acetate (contains ca. 20% Isobornyl Acetate)
I0306 Isobornyl Acetate
I0638 Isobornyl Acrylate (stabilized with MEHQ)
I0617 Isobornyl Methacrylate (stabilized with MEHQ)
P1876 Paeoniflorin
C0017 Sodium (+/-)-10-Camphorsulfonate
T0989 Thujone (alpha- and beta- mixture)
Page Top

Sesquiterpenes

B2119 B2119 A1698 A1698 A0792 A0792
C0957 C0957 A2190 A2190 A2118 A2118
A2191 A2191 C0796 C0796 T0608 T0608
F0347 F0347 G0228 G0228 N0454 N0454
C0375 C0375 S0521 S0521
B2119 (+/-)-alpha-Bisabolol
A1698 (S)-(+)-Abscisic Acid
A0792 Abscisic Acid (synthetic)
C0957 alpha-Caryophyllene
A2190 Artemether
A2118 Artemisinin
A2191 Artesunate
C0796 beta-Caryophyllene
B1413 Bisabolene (so called) [for Fragrance]
F0287 Farnesene (mixture of isomers) [for Perfumery]
T0608 Farnesol (mixture of isomers)
F0347 Farnesyl Acetate (mixture of isomers)
G0228 Guaiazulene
N0454 Nerolidol (cis- and trans- mixture)
C0375 Picrotoxin
S0521 Santonin
Page Top

Diterpenes

D1588 D1588 A0001 A0001 D1180 D1180
A0002 A0002 G0221 G0221 G0029 G0029
I0145 I0145 P1632 P1632 P1674 P1674
P0411 P0411 P1675 P1675 R0064 R0064
A0651 A0651 S0594 S0594
D1588 (+)-Dehydroabietylamine [Optical Resolving Agent]
A0001 Abietic Acid
D1180 Dehydroabietylamine
A0002 Ethyl Abietate
G0221 Geranyl-linalool (mixture of isomers)
G0029 Gibberellin A3
I0145 Isophytol
P1632 Paclitaxel
P1674 Phytantriol (mixture of isomers)
P0411 Phytol
P1675 Phytyl Acetate (cis- and trans- mixture)
R0064 Retinoic Acid
A0651 Sodium Abietate
S0594 Stevioside
Page Top

Triterpenes

B2836 B2836 B0803 B0803 G0270 G0270
G0149 G0149 G0150 G0150 C0427 C0427
G0151 G0151 O0317 O0317 H0096 H0096
H0097 H0097 G0217 G0217 U0065 U0065
B2836 Betulinic Acid
B0803 Betulinol
G0270 Dipotassium Glycyrrhizinate Hydrate
G0149 Glycyrrhetic Acid
G0150 Glycyrrhizin
C0427 Lanosterol
G0151 Monoammonium Glycyrrhizinate Hydrate
O0317 Oleanolic Acid Hydrate
H0096 Squalane
H0097 Squalene
G0217 Trisodium Glycyrrhizinate Hydrate
U0065 Ursolic Acid
Page Top

Others

C0560 C0560 S0525 S0525
C0560 beta-Carotene
S0525 Solanesol
Page Top

Literature

1) P. M. Dewick, in Medicinal Natural Products, 3rd ed., John Wiley & Sons Ltd, Chichester, 2009, p. 187.
2) E. Breitmaier, in Terpenes, Wiley-VCH, Weinheim, 2006.
3) P. M. Gills Jr., Pure Appl. Chem. 1999, 71, 587.
4) For Sesquiterpenes: B. M. Fraga, Nat. Prod. Rep. 2008, 25, 1180 [DOI]; For Diterpenes: J. R. Hanson, Nat. Prod. Rep. 2007, 24, 1332 [DOI]; For Triterpenes: J. D. Connolly, R. A. Hill, Nat. Prod. Rep. 2008, 25, 794 [DOI].

Page Top
kdjoad0000003wfa