Hinokitiol

Source: Wikipedia, the free encyclopedia.
Hinokitiol[1]
Skeletal formula of hinokitiol
Ball-and-stick model of the hinokitiol molecule
Names
Preferred IUPAC name
2-Hydroxy-6-(propan-2-yl)cyclohepta-2,4,6-trien-1-one
Other names
β-Thujaplicin; 4-Isopropyltropolone
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
100.007.165 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C10H12O2/c1-7(2)8-4-3-5-9(11)10(12)6-8/h3-7H,1-2H3,(H,11,12) checkY
    Key: FUWUEFKEXZQKKA-UHFFFAOYSA-N checkY
  • O=C1/C=C(\C=C/C=C1/O)C(C)C
Properties
C10H12O2
Molar mass 164.204 g·mol−1
Appearance Colorless to pale yellow crystals
Melting point 50 to 52 °C (122 to 126 °F; 323 to 325 K)
Boiling point 140 °C (284 °F; 413 K) at 10 mmHg
1.2 g/L (0 °C)
Solubility in ethanol 20 g/L[2]
Solubility in dimethyl sulfoxide 30 g/L[2]
Solubility in dimethylformamide 12.5 g/L[2]
Hazards
Flash point 140 °C (284 °F; 413 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Hinokitiol (β-thujaplicin) is a natural

monoterpenoid found in the wood of trees in the family Cupressaceae. It is a tropolone derivative and one of the thujaplicins.[3] Hinokitiol is used in oral and skin care products,[4][5] and is a food additive used in Japan.[6]

History

Hinokitiol was discovered by a Japanese chemist

East Asian countries, particularly to Japan and Taiwan.[11] Hinokitiol has also been found in other trees of the Cupressaceae family, including Thuja plicata Donn ex D. Don which is common in the Pacific Northwest
.

Woods that are rich in hinokitiol were used by people of ancient

insects, wood-rotting fungi, and molds for a long time of about 840 years. Additionally, there are some old famous Buddhist temples and Shinto shrines using trees, later known to contain hinokitiol.[12] Beginning in the 2000s, the biological properties of hinokitiol have become of research interest, focusing on its biological properties.[10] And the resistance of cypress trees to wood decay was the leading reason prompting to study their chemical content and to find the substances responsible for those properties.[13]

Natural occurrence

Hinokitiol has been found in the heartwood of the conifer trees of the

Its concentration in the trees are 0.1-0.2% in

Thujopsis dolabrata var. hondai (0.4 mg of hinokitiol per 1 g of dry sawdust), and 0.02% in Chamaecyparis obtusa (0.2 mg of hinokitiol per 1 g of dry sawdust).[7][18]

There are three naturally found thujaplicins: α-thujaplicin, β-thujaplicin (hinokitiol) and γ-thujaplicin. Hinokitiol is the most common isomer and it appears to be the only isomer that exerts all biological activities attributed to thujaplicins.[19][20]

Chemical synthesis

There are different pathways to synthesize thujaplicins. Hinokitiol, as other thujaplicins, can be synthesized by

ultrasonication.[25]

(1) Synthesis of hinokitiol from troponeirontricarbonyl complex:

(2) Synthesis of hinokitiol by electro-reductive alkylation of substituted cycloheptatrienes:

(3) Synthesis of hinokitiol through ring expansion of 2-isopropylcyclohexanone:

(4) Synthesis of hinokitiol through oxyallyl cation [4+3] cyclization (Noyori's synthesis):

Chemistry

Hinokitiol is a tropolone derivative containing an unsaturated seven-membered carbon ring. It is a monoterpenoidcyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2 and an isopropyl group at position 4.[26][27][28] It is a enol and a cyclic ketone. It derives from a hydride of a cyclohepta-1,3,5-triene. Thujaplicins are soluble in organic solvents and aqueous buffers.[2] Hinokitiol provides acetone on vigorous oxidation and gives the saturated monocyclic diol upon catalytic hydrogenation.[7] It is stable to alkali and acids, forming salts or remaining unchanged, but does not convert to catechol derivatives. Hinokitiol, as other thujaplicins and tropolones, reversibly binds metal ions. It forms complex salts with metal ions.

Ionophore

Hinokitiol, as other tropolones, reversibly binds metal ions (i.e. Zn2+, Fe2+, Cu2+, Co2+, Mn2+, Ag2+) and form complex salts. It is considered as a broad-spectrum metallophore, and an efficient iron-chelating agent.[17] The iron complex with hinokitiol with the formula (C10H11O2)3Fe is called hinokitin. Hinoki oil is rich in hinokitin which has an appearance of dark red crystals.[7] The complexes made of iron and tropolones display high thermodynamic stability and has shown to have a stronger binding constant than the transferrin-iron complex.[29] It is believed that metal-binding activity may be the principal mechanism of action underlying the most part of its biological activities, especially binding iron, zinc, and copper ions.[20] By binding different metal ions and serving as an ionophore, it accelerates the intracellular uptake of those ions and increases their intracellular levels, thus influencing on different biological activities. It is shown that a synergistic effect in some biological activities and settings may occur when ionophores are combined with the ions they bind.[30] As an ionophore, its molecule has an hydrophilic center and a hydrophobic part. The hydrophobic part interacts with biological membranes. The hydrophilic center binds metal ions and form ionophore-ion complexes.

Biological properties

Hinokitiol and other thujaplicins have been mainly investigated in in-vitro studies and animal models for their possible biological properties, such as antimicrobial, antifungal, antiviral, antiproliferative, anti-inflammatory, antiplasmodial effects.[10][17][20] However, no evidence exists from clinical studies to support these findings. It has also shown to have insecticidal, pesticidal and antibrowning effects. The vast majority of these properties are thought to be due to the metal ion-binding activity. Hinokitiol appeared to exert all in-vitro activities attributed to thujaplicins.[20]

Hinokitiol has been shown to possess inhibitory effects on Chlamydia trachomatis and may be clinically useful as a topical drug.[31][10]

Safety

The safety of hinokitiol has been tested in rats and no carcinogenic effect to rats was found.[32] In 2006, hinokitiol was categorized under the Domestic substances list (DSL) in Canada as non-persistent, non-bioaccumulative and non-toxic to aquatic organisms.[33]

Uses

Skin and oral care products

Hinokitiol is used in a range of consumer products intended for skin care, such as

shampoos and hair tonics;[4][34][35] for oral care, such as toothpastes, breath sprays.[4][5][36]

In April 2020, Advance Nanotek, an Australian producer of zinc oxide, filed a joint patent application with AstiVita Limited, for an anti-viral composition that included oral care products.[37]

Insect repellent

Hinokitiol is found to have

Dermatophagoides farinae, Tyrophagus putrescentiae) and mosquito larvae (Aedes aegypti, Culex pipiens). Hinokitiol is supplemented in commercial tick and insect repellents.[19]

Food preservative

In experimental studies hinokitiol has been shown to act against

shelf-life extending agent.[41]

Wood preservative

Hinokitiol is one of the chemical compounds isolated from trees, known as

timber treatment.[18]

Research directions

Iron transport

Researchers screening a library of small biomolecules for signs of iron transport found that hinokitiol restored cell functionality. Further work by the team suggested a mechanism by which hinokitiol restores or reduces cell iron.[43]

Cancer research

Different in-vitro studies have investigated the effects of hinokitiol on various tumor cell lines.

See also

References

  1. ^ β-Thujaplicin Archived 2011-07-16 at the Wayback Machine at Sigma-Aldrich
  2. ^ a b c d "Hinokitiol - Product Information" (PDF). www.caymanchem.com. Cayman Chemical.
  3. PMID 19483786
    .
  4. ^ a b c "Hinokitiol | 499-44-5". www.chemicalbook.com.
  5. ^ .
  6. ^ a b "The Japan Food chemical Research Faundation". www.ffcr.or.jp.
  7. ^ .
  8. .
  9. .
  10. ^ a b c d "Hinokitiol". American Chemical Society.
  11. .
  12. .
  13. ^ .
  14. ^ Okabe, T; Saito, K (1994). "Antibacterial and preservative effects of natural Hinokitiol (beta-Thujaplicin) extracted from wood". Acta Agriculturae Zhejiangensis. 6 (4): 257–266.
  15. ^
    PMID 15187442
    .
  16. .
  17. ^ .
  18. ^ .
  19. ^ .
  20. ^ a b c d Falcone, Eric (5 October 2016). "Investigating the Antiproliferative Activity of Synthetic Troponoids". Doctoral Dissertations.
  21. .
  22. .
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  25. .
  26. ^ "2,4,6-Cycloheptatrien-1-one, 2-hydroxy-3-(1-methylethyl)-". pubchem.ncbi.nlm.nih.gov. PubChem.
  27. ^ "Hinokitiol". pubchem.ncbi.nlm.nih.gov. PubChem.
  28. ^ "gamma-Thujaplicin". pubchem.ncbi.nlm.nih.gov. PubChem.
  29. S2CID 43256591
    .
  30. .
  31. .
  32. .
  33. ^ Secretariat, Treasury Board of Canada. "Detailed categorization results of the Domestic Substances List - Open Government Portal". open.canada.ca. Retrieved 2020-06-17.
  34. S2CID 11746050
    .
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  37. ^ "IP Australia: AusPat". Australian Government - IP Australia. Retrieved 2020-05-20.
  38. PMID 10963310
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External links