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While sometimes used interchangeably with "terpenes", terpenoids have additional functional groups, usually containing oxygen.[1] Terpenoids are the largest class of plant secondary metabolites, representing about 60% of known natural products.[2] Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists.[3] Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, the yellow color in sunflowers, and the red color in tomatoes.[4]

Terpenoids Analogue terpenes Number of isoprene units Number of carbon atoms General formula Examples[5]
Hemiterpenoids Isoprene 1 5 C5H8 Dimethylallyl pyrophosphate (DMAPP), isopentenyl pyrophosphate, isoprenol, isovaleramide, isovaleric acid, (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), prenol
Monoterpenoids Monoterpenes 2 10 C10H16 Bornyl acetate, camphor, carvone, citral, citronellal, citronellol, geraniol, eucalyptol, hinokitiol, iridoids, linalool, menthol, thymol
Sesquiterpenoids Sesquiterpenes 3 15 C15H24 Farnesol, geosmin, humulone
Diterpenoids Diterpenes 4 20 C20H32 Abietic acid, ginkgolides, paclitaxel, retinol, salvinorin A, sclareol, steviol
Sesterterpenoids Sesterterpenes 5 25 C25H40 Andrastin A, manoalide
Triterpenoids Triterpenes 6 30 C30H48 Amyrin, betulinic acid, limonoids, oleanolic acid, sterols, squalene, ursolic acid
Tetraterpenoids Tetraterpenes 8 40 C40H64 Carotenoids
Polyterpenoid Polyterpenes >8 >40 (C5H8)n Gutta-percha, natural rubber

Cyclicity[edit | edit source]

Terpenoids can also be classified according to the type and number of cyclic structures they contain: linear, acyclic, monocyclic, bicyclic, tricyclic, tetracyclic, pentacyclic, or macrocyclic.[5] The Salkowski test can be used to identify the presence of terpenoids.[6]

Hemiterpenoids[edit | edit source]

Carotenes[edit | edit source]


Carotene (also carotin, from the Latin carota, "carrot"[7][8]) is used for many related unsaturated hydrocarbon substances having the formula C40Hx, which are synthesized by plants but in general cannot be made by animals (with the exception of some aphids and spider mites which acquired the synthesizing genes from fungi).[9]

Pure carnivores such as ferrets lack β-carotene 15,15'-monooxygenase and cannot convert any carotenoids to retinals at all (resulting in carotenes not being a form of vitamin A for this species); while cats can convert a trace of β-carotene to retinol, although the amount is totally insufficient for meeting their daily retinol needs.[10]

The following foods contain carotenes in appreciable amounts:[11]

Absorption from these foods is enhanced if eaten with fats, as carotenes are fat soluble, and if the food is cooked for a few minutes until the plant cell wall splits and the color is released into any liquid.[11] 12 μg of dietary β-carotene supplies the equivalent of 1 μg of retinol, and 24 µg of α-carotene or β-cryptoxanthin provides the equivalent of 1 µg of retinol.[11][13]

Carotenes include cryptoxanthin, lutein and zeaxanthin.

beta-Carotenes[edit | edit source]

Structure diagram shows beta-carotene. Credit: NEUROtiker.{{free media}}
β-Carotene powder is shown. Credit: 102% Yield.{{free media}}

β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi,[16] plants, and fruits. β-Carotene is biosynthesized from geranylgeranyl pyrophosphate.[17]

In some Mucorales (Mucoralean) fungi, β-Carotene is a precursor to the synthesis of trisporic acid.[16]

β-Carotene, the most common form of carotene in plants when used as a food coloring, has the E number E160a.[18] The structure was deduced by Karrer et al. in 1930.[19] In nature, β-carotene is a precursor (inactive form) to vitamin A via the action of beta-carotene 15,15'-monooxygenase.[17]

Isolation of β-carotene from fruits abundant in carotenoids is commonly done using column chromatography. It can also be extracted from the beta-carotene rich algae, Dunaliella salina.[20] The separation of β-carotene from the mixture of other carotenoids is based on the polarity of a compound. β-Carotene is a non-polar compound, so it is separated with a non-polar solvent such as hexane.[21] Being highly conjugated, it is deeply colored, and as a hydrocarbon lacking functional groups, it is very lipophilic.

Plant carotenoids are the primary dietary source of provitamin A worldwide, with β-carotene as the best-known provitamin A carotenoid. Others include alpha-Carotene (α-carotene) and cryptoxanthin (β-cryptoxanthin). Carotenoid absorption is restricted to the duodenum of the small intestine and dependent on class B scavenger receptor (SR-B1) membrane protein, which is also responsible for the absorption of vitamin E (α-tocopherol).[22] One molecule of β-carotene can be cleaved by the intestinal enzyme β,β-carotene 15,15'-monooxygenase into two molecules of vitamin A.[23]

Factors that determine the provitamin A activity of carotenoids:[24]

  • Species of carotene
  • Molecular linkage
  • Amount in the meal
  • Matrix properties
  • Effectors
  • Nutrient status
  • Genetics
  • Host specificity
  • Interactions between factors

Monoterpenoids[edit | edit source]

Lemon balm[edit | edit source]

Lemon balm flavor comes from geraniol (3–40%), neral (3–35%), geranial (4–85%) (both isomers of citral), (E)-caryophyllene (0–14%), and citronellal (1–44%).[25]

Lemon balm contains eugenol, tannins, and terpenes.[26] It also contains (+)-citronellal, 1-octen-3-ol, 10-α-cadinol, 3-octanol, 3-octanone, α-cubebene, α-humulene, β-bourbonene, caffeic acid, caryophyllene, caryophyllene oxide, catechin, chlorogenic acid, cis-3-hexenol, cis-ocimene, citral A, citral B, copaene, δ-cadinene, eugenyl acetate, γ-cadinene, geranial, geraniol, geranyl acetate, germacrene D, isogeranial, linalool, luteolin-7-glucoside, methylheptenone, neral, nerol, octyl benzoate, oleanolic acid, pomolic acid, ((1R)-hydroxyursolic acid), protocatechuic acid, hamnazin, rosmarinic acid, stachyose, succinic acid, thymol, trans-ocimene and ursolic acid.[27][28] Lemon balm may contain traces of harmine.[29]

Rosmarinic acid appears to be the most important active component, but the interaction of the chemicals in lemon balm and herbs that it is used with, is poorly understood.[30] Lemon balm leaf contains 36.5 ± 0.8 mg rosmarinic acid per gram.[31]

Composition of lemon balm oil[32]
Component minimum % maximum %
Methyl Heptenone 2.2 8.6
Citronellal 1.0 8.4
Linalool 0.5 2.7
Neral 19.6 36.1
Geranial 25.3 47.5
Geranyl acetate 1.2 6.2
Carophyllene 1.9 9.7
Carophyllene oxide 0.5 9.0

Triterpenoids[edit | edit source]

Centella contains pentacyclic triterpenoids, including asiaticoside, brahmoside, asiatic acid, and brahmic acid (madecassic acid), where other constituents include centellose, centelloside, and madecassoside.[33][34][35]

Centella asiatica, commonly known as Gotu Kola, kodavan, Indian pennywort and Asiatic pennywort, is a herbaceous, perennial plant in the flowering plant family Apiaceae.[36] It is native to the wetlands in Asia.[37][38] It is used as a culinary vegetable and as a medicinal herb.[36]

See also[edit | edit source]

References[edit | edit source]

  1. Chemistry, International Union of Pure and Applied. IUPAC Compendium of Chemical Terminology. IUPAC. doi:10.1351/goldbook.T06279. 
  2. Firn, Richard (2010). Nature's Chemicals. Oxford: Biology. 
  3. Ashour, Mohamed; Wink, Michael; Gershenzon, Jonathan (2010). "Biochemistry of Terpenoids: Monoterpenes, Sesquiterpenes and Diterpenes". Biochemistry of Plant Secondary Metabolism. pp. 258–303. doi:10.1002/9781444320503.ch5. ISBN 9781444320503. 
  4. Specter, Michael (September 28, 2009). "A Life of Its Own". The New Yorker.
  5. 5.0 5.1 Ludwiczuk, A.; Skalicka-Woźniak, K.; Georgiev, M.I. (2017). "Terpenoids". Pharmacognosy: 233–266. doi:10.1016/B978-0-12-802104-0.00011-1. ISBN 9780128021040. 
  6. "Phytochemical Screening and Antioxidant Activities of Some Selected Medicinal Plants Used for Malaria Therapy in Southwestern Nigeria". Tropical Journal of Pharmaceutical Research 7 (3): 1019–1024. 2008. doi:10.4314/tjpr.v7i3.14686. 
  7. Mosby’s Medical, Nursing and Allied Health Dictionary, Fourth Edition, MosbypoopBook 1994, p. 273
  8. carotene. 
  9. Boran Altincicek; Jennifer L. Kovacs; Nicole M. Gerardo (2011). "Horizontally transferred fungal carotenoid genes in the two-spotted spider mite Tetranychus urticae". Biology Letters 8 (2): 253–257. doi:10.1098/rsbl.2011.0704. PMID 21920958. PMC 3297373. // 
  10. Green AS, Tang G, Lango J, Klasing KC, Fascetti AJ (2011). "Domestic cats convert ((2) H(8))-β-carotene to ((2) H(4))-retinol following a single oral dose". Journal of Animal Physiology and Animal Nutrition 96 (4): 681–92. doi:10.1111/j.1439-0396.2011.01196.x. PMID 21797934. 
  11. 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 11.12 11.13 11.14 "Carotenoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University. 1 August 2016. Retrieved 19 August 2019.
  12. "Determination of carotenoids and their esters in fruits of Lycium barbarum Linnaeus by HPLC-DAD-APCI-MS". J Pharm Biomed Anal 47 (4–5): 812–8. 2008. doi:10.1016/j.jpba.2008.04.001. PMID 18486400. 
  13. 13.0 13.1 13.2 13.3 "Vitamin A: Fact Sheet for Health Professionals". Office of Dietary Supplements, US National Institutes of Health. 9 July 2019. Retrieved 19 August 2019.
  14. Schweiggert, Ralf M.; Kopec, Rachel E.; Villalobos-Gutierrez, Maria G.; Högel, Josef; Quesada, Silvia; Esquivel, Patricia; Schwartz, Steven J.; Carle, Reinhold (2013-08-12). "Carotenoids are more bioavailable from papaya than from tomato and carrot in humans: a randomised cross-over study". British Journal of Nutrition 111 (3): 490–498. doi:10.1017/s0007114513002596. ISSN 0007-1145. PMID 23931131. PMC 4091614. // 
  15. Adewusi, Steve R A; Bradbury, J Howard (1993). "Carotenoids in cassava: Comparison of open-column and HPLC methods of analysis". Journal of the Science of Food and Agriculture 62 (4): 375. doi:10.1002/jsfa.2740620411. 
  16. 16.0 16.1 Lee, Soo Chan; Ristaino, Jean B.; Heitman, Joseph (13 December 2012). "Parallels in Intercellular Communication in Oomycete and Fungal Pathogens of Plants and Humans". PLOS Pathogens 8 (12): e1003028. doi:10.1371/journal.ppat.1003028. PMID 23271965. PMC 3521652. // 
  17. 17.0 17.1 Van Arnum, Susan D. (1998), "Vitamin A", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, pp. 99–107, doi:10.1002/0471238961.2209200101181421.a01, ISBN 978-0-471-23896-6
  18. Milne, George W. A. (2005). Gardner's commercially important chemicals: synonyms, trade names, and properties. New York: Wiley-Interscience. ISBN 978-0-471-73518-2. 
  19. Karrer P, Helfenstein A, Wehrli H (1930). "Pflanzenfarbstoffe XXV. Über die Konstitution des Lycopins und Carotins". Helvetica Chimica Acta 13 (5): 1084–1099. doi:10.1002/hlca.19300130532. 
  20. Extraction Process for Beta-Carotene. 
  21. Mercadante AZ, Steck A, Pfander H (January 1999). "Carotenoids from guava (Psidium guajava l.): isolation and structure elucidation". Journal of Agricultural and Food Chemistry 47 (1): 145–51. doi:10.1021/jf980405r. PMID 10563863. 
  22. van Bennekum A, Werder M, Thuahnai ST, Han CH, Duong P, Williams DL, Wettstein P, Schulthess G, Phillips MC, Hauser H (March 2005). "Class B scavenger receptor-mediated intestinal absorption of dietary beta-carotene and cholesterol". Biochemistry 44 (11): 4517–25. doi:10.1021/bi0484320. PMID 15766282. 
  23. "Conversion of β‐Carotene to Retinal Pigment". Conversion of β-carotene to retinal pigment. Vitamins & Hormones. 75. 2007. pp. 117–30. doi:10.1016/S0083-6729(06)75005-1. ISBN 978-0-12-709875-3. 
  24. "Factors influencing the conversion of carotenoids to retinol: bioavailability to bioconversion to bioefficacy". International Journal for Vitamin and Nutrition Research 72 (1): 40–5. January 2002. doi:10.1024/0300-9831.72.1.40. PMID 11887751. 
  25. Setzer, William (2009). "Essential Oils and Anxiolytic Aromatherapy". Natural Product Communications 4 (9): 1309. doi:10.1177/1934578X0900400928. PMID 19831048. 
  26. Ehrlich, Steven D. (January 2, 2015). "Lemon balm". University of Maryland Medical Center. Retrieved June 23, 2017.
  27. "Feature extracts – Melissa officinalis". Nature Inspired Research Products. 2012. Retrieved December 24, 2013.
  28. Taylor, Leslie (March 4, 2016). "Lemon Balm (Melissa officinalis)". Leslie Taylor. Retrieved June 23, 2017.
  29. Harrington, Natalie (2012). "Harmala Alkaloids as Bee Signaling Chemicals". Journal of Student Research 1 (1): 23–32. doi:10.47611/jsr.v1i1.30. 
  30. Shakeri, Abolfazl; Sahebkar, Amirhossein; Javadi, Behjat (2016). "Melissa officinalis L. – A review of its traditional uses, phytochemistry and pharmacology". Journal of Ethnopharmacology 188: 204–228. doi:10.1016/j.jep.2016.05.010. ISSN 1872-7573. PMID 27167460. 
  31. Shekarchi, Maryam; Hajimehdipoor, Homa; Saeidnia, Soodabeh; Gohari, Ahmad Reza; Hamedani, Morteza Pirali (2012). "Comparative Study of Rosmarinic Acid Content in Some Plants of Labiatae Family". Pharmacognosy Magazine 8 (29): 37–41. doi:10.4103/0973-1296.93316. PMID 22438661. 
  32. Axtell, B.L.; Fairman, R.M. (1992). "Melissa officinalis". Minor Oil Crops. Rome: Food and Agriculture Organization of the United Nations. ISBN 978-92-5-103128-5. 
  33. Singh, Bhagirath; Rastogi, R.P. (May 1969). "A reinvestigation of the triterpenes of Centella asiatica". Phytochemistry 8 (5): 917–921. doi:10.1016/S0031-9422(00)85884-7. 
  34. Singh, Bhagirath; Rastogi, R.P. (August 1968). "Chemical examination of Centella asiatica linn—III". Phytochemistry 7 (8): 1385–1393. doi:10.1016/S0031-9422(00)85642-3. 
  35. Murray, edited by Joseph E. Pizzorno Jr., Michael T. (2012). Textbook of natural medicine (4th ed.). Edinburgh: Churchill Livingstone. p. 650. ISBN 9781437723335. 
  36. 36.0 36.1 "Centella asiatica (Asiatic pennywort)". Invasive Species Compendium, CABI. 22 November 2017. Retrieved 2 January 2018.
  37. United States Department of Agriculture. "Plant Profile for Centella asiatica". Retrieved 15 July 2012.
  38. Floridata. "Centella asiatica". Retrieved 15 July 2012.

Further reading[edit | edit source]

External links[edit | edit source]