Citral Explained

Citral is an acyclic monoterpene aldehyde. Being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named geranial (trans-citral; α-citral[1]) or citral A. The Z-isomer is named neral (cis-citral; β-citral) or citral B. These stereoisomers occur as a mixture, often not in equal proportions; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.[2]

Occurrence

Citral is present in the volatile oils of several plants, including lemon myrtle (90–98%), Litsea citrata (90%), Litsea cubeba (70–85%), lemongrass (65–85%), lemon tea-tree (70–80%), Ocimum gratissimum (66.5%), Lindera citriodora (about 65%), Calypranthes parriculata (about 62%), petitgrain (36%), lemon verbena (30–35%), lemon ironbark (26%), lemon balm (11%), lime (6–9%), lemon (2–5%), and orange.[3] [4] [5] Further, in the lipid fraction (essential oil) of Australian ginger (51–71%). Of the many sources of citral, the Australian myrtaceous tree, lemon myrtle, Backhousia citriodora F. Muell. (of the family Myrtaceae), is considered superior.[6]

Uses

Citral has a strong lemon (citrus) scent and is used as an aroma compound in perfumery. It is used to fortify lemon oil. (Nerol, another perfumery compound, has a less intense but sweeter lemon note.) The aldehydes citronellal and citral are considered key components responsible for the lemon note, with citral preferred.[6]

It also has pheromonal effects in acari and insects.[7] [8]

Citral is used in the synthesis of vitamin A, lycopene, ionone and methylionone, and to mask the smell of smoke.

The herb Cymbopogon citratus has shown promising insecticidal and antifungal activity against storage pests.[9]

Food additive

Citral is commonly used as a food additive ingredient.[10]

It has been tested (2016) in vitro against the food-borne pathogen Cronobacter sakazakii.[11]

Medical exploration

In a report (1997), citral is mentioned as cytotoxic to P(388) mouse leukaemia cells.[9] It has strong antimicrobial qualities.[12]

Adverse effects

A number of studies have shown allergic reactions to Citral.[13] The International Fragrance Association gives a no-observed-adverse-effect level of 1400 micrograms.[14] Citral has been extensively tested, with no known genotoxicity or carcinogenic effect.[15]

See also

External links

Notes and References

  1. Waghulde . S. . Parmar . P. . Mule . J. . Pashte . D. . Patil . B. . Modhale . N. . Gorde . N. . Kharche . A. . Kale . M. . 2020 . Lead Finding from Plant Cymbopogon Citratus with Immunomodulator Potentials through in Silico Methods . Chemistry Proceedings . en . 3 . 1 . 77 . 10.3390/ecsoc-24-08302 . 2673-4583 . free .
  2. Book: Zachariah . T. J. . Parthasarathy . V. A. . Chempakam . B. . Chemistry of spices . 76 . 2008 . CABI . 1120264204 . 9781845934057 . Wallingford.
  3. Book: Fenaroli . G. . Furia . T.E. . Bellanca . N. . Handbook of Flavor Ingredients . 0-87819-532-7.
  4. Book: Lawless . J. . The Illustrated Encyclopedia of Essential Oils . 2 November 1995 . Element . 1-85230-661-0.
  5. Web site: The Aromatic Plant Project . 1 June 2008 . 24 November 2019 . https://web.archive.org/web/20191124031814/http://www.aromaticplantproject.com/articles_archive/lemon_citrus_scented_oils.html . dead .
  6. Southwell . Ian . Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral . Foods . 9 July 2021 . 10 . 7 . 1596 . 10.3390/foods10071596 . 34359465 . 8305781 . free .
  7. Kuwahara . Yasumasa . Suzuki . Hiroshi . Matsumoto . Katsuhiko . Wada . Yoshitake . Pheromone Study on Acarid Mites. XI. Function of Mite Body as Geometrical Isomerization and Reduction of Citral (the Alarm Pheromone) . Applied Entomology and Zoology . 1983 . 18 . 1 . 30–39 . 10.1303/aez.18.30 . free .
  8. Robacker, D.C. . Hendry, L.B. . 1977 . Neral and geranial: components of the sex pheromone of the parasitic wasp, Itoplectis conquisitor . Journal of Chemical Ecology . 3 . 563–577 . 10.1007/BF00989077 . 5. 11568355 .
  9. Dubey . N. K. . Takeya . Koichi . Itokawa . Hideji . Citral: A cytotoxic principle isolated from the essential oil of Cymbopogon citratus against P388 leukaemia cells . Current Science . 1997 . 73 . 1 . 22–24 . 24098141 .
  10. Liao . Pei-Chun . Yang . Tsung-Shi . Chou . Ju-Ching . Chen . Jie . Lee . Shu-Ching . Kuo . Yueh-Hsiung . Ho . Chen-Lung . Chao . Louis Kuo-Ping . Anti-inflammatory activity of neral and geranial isolated from fruits of Litsea cubeba Lour . Journal of Functional Foods . 1 December 2015 . 19 . 248–258 . 10.1016/j.jff.2015.09.034 . free .
  11. Shi . Chao . Song . Kaikuo . Zhang . Xiaorong . Sun . Yi . Sui . Yue . Chen . Yifei . Jia . Zhenyu . Sun . Huihui . Sun . Zheng . Xia . Xiaodong . Antimicrobial Activity and Possible Mechanism of Action of Citral against Cronobacter sakazakii . PLOS ONE . 14 July 2016 . 11 . 7 . e0159006 . 10.1371/journal.pone.0159006 . 27415761 . 4945043 . 2016PLoSO..1159006S . free .
  12. Onawunmi . Grace O. . Evaluation of the antimicrobial activity of citral . Letters in Applied Microbiology . September 1989 . 9 . 3 . 105–108 . 10.1111/j.1472-765X.1989.tb00301.x . 84751250 .
  13. 31566752 . 2020 . Hagvall . L. . Bruze . M. . Engfeldt . M. . Isaksson . M. . Lindberg . M. . Ryberg . K. . Stenberg . B. . Svedman . C. . Karlberg . A. T. . Bråred Christensson . J. . Contact allergy to citral and its constituents geranial and neral, coupled with reactions to the prehapten and prohapten geraniol . Contact Dermatitis . 82 . 1 . 31–38 . 10.1111/cod.13404 .
  14. Web site: International Fragrance Association. IRFA Standards, 47th Amendment: Citral.
  15. Book: Dorthe N. . Andersen . Rikke D. . Holmberg . Jette R. . Larsen . Inge . Søborg . Karl-Heinz . Cohr . Survey and health assessment of chemical substances in massage oils . Danish Toxicology Centre . Survey of Chemical Substances in Consumer Products, No. 78 . 2006 .

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