Incensole
Names
IUPAC name
(1R,2R,5E,9Z)-1,5,9-trimethyl-12-propan-2-yl-15-oxabicyclo[10.2.1]pentadeca-5,9-dien-2-ol
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C20H34O2/c1-15(2)20-12-11-17(4)8-6-7-16(3)9-10-18(21)19(5,22-20)13-14-20/h7,11,15,18,21H,6,8-10,12-14H2,1-5H3/b16-7+,17-11-/t18-,19-,20?/m1/s1
    Key: SSBZLMMXFQMHDP-AWBFOCMTSA-N
  • CC1=CCCC(=CCC2(CCC(O2)(C(CC1)O)C)C(C)C)C
Properties
C20H34O2
Molar mass 306.490 g·mol−1
Density 1.0±0.1 g/cm3
Boiling point 408.9±45.0 °C at 760 mmHg
Vapor pressure 0.0±2.2 mmHg at 25°C
1.493
Hazards
Flash point 160.7±23.0 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Incensole is a C20 diterpene alcohol and biomarker for some plants of the Boswellia genus. It, along with its acetate ester Incensole Acetate, is an abundant component of frankincense, the resin collected from Boswellia trees[1]. Incensole is used archaeologically to assist in identifying trade routes and distinguishing the identity of frankincense from other resins which may have been used together in incense and other salves. Incensole has also been deemed to be an active component in medicinal frankincense[1].

Background edit

Incensole was first isolated in 1966 at the Institute of Organic Chemistry at the University of Rome by S. Corsano and R. Nicoletti while investigating the neutral components of Boswellia carteri resin[2], though it is believed that the sample was likely actually from an "Eritrea" type B. papyrifera specimen[3]. In 2005 Incensole was used as a biomarker for frankincense (or olibanum) in order to determine the composition of Ancient Egyptian mummification balms and unguents[4], speaking to its role in studying the history religion.

Frankincense roots its historical significance in its global medicinal use and it's religious and ceremonial use as a component of incense. It's been used for thousands of years in religious ceremonies of all kinds and is notably one of the three gifts the magi presented to the baby Jesus in the Bible.

Chemistry edit

Oily in appearance, incensole has a low volatility. It can be synthetically prepared from Cembrene[5], a terpenoid, and Cembrenol (Serratol), its biologic precursor[5]. Diterpenes and terpenoids are classes of biomarkers which are synthesized in plants and have been found in insects[6], possibly because of accumulation of terpenoids within their diets[7]. Terpenoids have gained special interest due to their potential as anti-inflammatories, anti-carcinogens, and antiparasitics[6].

 
Incensole with its proposed biosynthetic precursors Serratol and GGPP

Biosynthetic Pathway edit

It has been proposed that Incensole is produced in Boswellia plants via Serratol from Geranylgeranyl Pyrophosphate (GGPP)[3], a C20 precursor for many metabolic branches such as the Chlorophyll, Carotenoid, and Gibberellin biosynthetic pathways[8]. To begin, GGPP loses its pyrophosphate group enabling it to be 1,14-cyclized to form Cembrene after the loss of a proton. Cembrene is then hydrolyzed to form Serratol which in turn undergoes epoxidation and intramolecular cyclization to form Incensole[3]. Though this makes sense chemically, and has been used synthetically to make Incensole[5], the incongruent abundances of Incensole, Serratol, Incensole Acetate, and Iso-serratol in the Boswellia species which are known to produce Incensole indicates that this pathway is somewhat improbable to occur[3].

Biological Sources edit

 
Frankincense resin seeping out of B. sacra trunk

Incensole is mainly found in the resin of Boswellia trees which grow in a region across Northern Africa from Ethiopia to Nigeria[9]. Boswellia trees prefer to grow in arid, stony regions[9], and cuts to the body of the trees seep frankincense resin which hardens and darkens when exposed to the air[10]. Incensole is a biomarker of frankincense from certain Boswellia species; these species are B. papyrifera, B. occulta, B. carteri, B. sacra[11][12][13][4], and possibly B. serrata though there are conflicting results as to whether it really produces incensole[3]. It should be noted that B. carteri and B. sacra have been determined to actually be the same species, except that B. carteri is native to Africa while B. sacra is native to South Arabia.[3]

It has also been proposed that Incensole and Incensole Acetate can be derived from other sources such as these[3]:

But no isolation or structural identification tests were run to identify Incensole in these specimen than gas chromatography and mass spectrometry. Thus incensole/incensole acetate has not been conclusively identified in any of these species[3].

Derivatization and Characterization edit

 
Deconvoluted mass spectrum of Incensole from Incensole and Serratol total ion count peak. RT of 24.02 min. (Baeten et al. 2014)

Incensole was originally isolated in 1966 by S. Corsano and R. Nicoletti using several ether extractions and vacuum separations, and then characterized using UV-Vis, IR, and H-NMR spectroscopy. They found Incensole to have no UV-Vis absorption above 210 mμ[2]. The distinguishing IR and H-NMR peaks of Incensole are reported in the tables below[2], and the observed mass spectrogram of Incensole from a study done in 2014 on frankincense in incense pots is pictured to the right[14].

IR Peaks of Incensole
Wave Number (cm-1) Peak Identity
3620 -OH
1670 C=C
1375, 1390 CH3-C-CH3
1050 C-O
NMR Peaks of Incensole in CCl4 at 60 Mc[2]
Chemical Shift (ppm) Protons[15] Group Identity
0.90 (d, 6H, J = 6.5 c/s) isopropyl
1.02 (s, 3H) CH3-C-O
1.48, 1.61 (s, 3H) CH3-C=
3.18 (d, 1H, J = 10 c/s) HC-OH
5.06 (2H, broad signal) CH3CH=C(CH3)2

Incensole is most often extracted by chromatographic extractions and hydrodistillations, which produce a frankincense essential oil. Characterization usually occurs by GC/MS although TLC has also been used and NIR spectroscopy[16] is being optimized to provide fast and accurate characterization.[3]

Unfortunately, within some of the earlier literature, frankincense biomarker compositions have been misattributed to different Boswellia species, as was seen in the mistaken attribution of Incensole being first extracted from a B. carteri specimen when it likely came from a B. papyrifera specimen. This likely comes from the use of faulty or absent taxonomic certifications when determining the specimen identities of frankincense purchased from market as opposed to collected straight from the tree.[3]

Incensole in Archaeology edit

Frankincense has been used for thousands of years in religious ceremonies and for medicinal purposes[1]. In fact, by tracing incensole's degraded products, historians have been able to use it to understand the historical use of incense in religion. In one such case, the examination of incensole as a biomarker led to the confirmation of certain porous pots buried in Medieval, Belgian, Christian graves as incense burners. Further study indicated that though frankincense was a main component of funerary incense at the time, other, cheaper local resins were mixed into the incense, possibly to reduce cost[14].

Additionally, frankincense has been used for thousands of years as a medicine. It is listed in texts such as the Papyrus Ebers and the Syriac book of medicine and was prescribed by the practitioners Celsus and Culpepper as a remedy for a variety of ailments from stomach ulcers and gastrointestinal hemorrhages to gout and open wounds[13]. Modern analysis on the medical efficacy of frankincense has elucidated Incensole and Incensole Acetate along with Boswellic Acids as being the main active ingredients in frankincense[1].

Due to its religious and medicinal significance, frankincense and its biomarker components, like Incensole, can be found all over the world in Europe, Asia, the Mediterranean, and the Middle East[1][13][17] as a result of global trade.

Medicinal Properties edit

Previously, the therapeutic properties of frankincense had been attributed to Boswellic acids within the resin, but research from 2019 and 2020 has found Incensole and its acetate ether to be major contributors to frankincense's therapeutic efficacy[1]. This research has found Incensole to act as an anti-inflammatory and neuroprotective compound after murine head-trauma on top of exhibiting anxiolytic, anti-depressive, and sedative effects in mice[1].

It is proposed that Incensole works as an anti-inflammatory through the inhibition of the NF-κB pathway which is responsible for the increased production of proinflammatory proteins. Insensitivity in the NF-κB pathway is correlated to arthritis, asthma, inflammatory bowel disease, ataxia telangiectasia, cancers, and neurodegenerative diseases[1][12][18].

It has also been found that Incensole Acetate activates the TRPV3 channel[1] which, among other things, is responsible for regulating wound healing and the perception of pain and itching[19]. It has been thought that this is another key component of Incensole's role as an anti-inflammatory.

Incensole has also been cited as a potential antibacterial against Bacillus[12].

References edit

  1. ^ a b c d e f g h i Moussaieff, Arieh; Mechoulam, Raphael (2009-10). "Boswellia resin: from religious ceremonies to medical uses; a review of in-vitro, in-vivo and clinical trials". Journal of Pharmacy and Pharmacology. 61 (10): 1281–1293. doi:10.1211/jpp.61.10.0003. ISSN 0022-3573. {{cite journal}}: Check date values in: |date= (help)
  2. ^ a b c d Corsano, S.; Nicoletti, R. (1967-01-01). "The structure of incensole". Tetrahedron. 23 (4): 1977–1984. doi:10.1016/S0040-4020(01)82601-6. ISSN 0040-4020.
  3. ^ a b c d e f g h i j Al-Harrasi, Ahmed; Csuk, Rene; Khan, Ajmal; Hussain, Javid (2019-05-01). "Distribution of the anti-inflammatory and anti-depressant compounds: Incensole and incensole acetate in genus Boswellia". Phytochemistry. 161: 28–40. doi:10.1016/j.phytochem.2019.01.007. ISSN 0031-9422.
  4. ^ a b Hamm, Sandrine; Bleton, Jean; Connan, Jacques; Tchapla, Alain (2005-06-01). "A chemical investigation by headspace SPME and GC–MS of volatile and semi-volatile terpenes in various olibanum samples". Phytochemistry. 66 (12): 1499–1514. doi:10.1016/j.phytochem.2005.04.025. ISSN 0031-9422.
  5. ^ a b c Strappaghetti, G.; Proietti, G.; Corsano, S.; Grgurina, I. (1982-03). "Synthesis of incensole". Bioorganic Chemistry. 11 (1): 1–3. doi:10.1016/0045-2068(82)90042-6. {{cite journal}}: Check date values in: |date= (help)
  6. ^ a b Majhi, Sasadhar (2020-10-29). "Diterpenoids: Natural Distribution, Semisynthesis at Room Temperature and Pharmacological Aspects‐A Decade Update". ChemistrySelect. 5 (40): 12450–12464. doi:10.1002/slct.202002836. ISSN 2365-6549.
  7. ^ author., Peters, Kenneth E. (Kenneth Eric), 1950-. The biomarker guide. ISBN 978-1-107-32604-0. OCLC 1030120220. {{cite book}}: |last= has generic name (help)CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  8. ^ Zhou, Fei; Wang, Cheng-Yuan; Gutensohn, Michael; Jiang, Ling; Zhang, Peng; Zhang, Dabing; Dudareva, Natalia; Lu, Shan (2017-06-27). "A recruiting protein of geranylgeranyl diphosphate synthase controls metabolic flux toward chlorophyll biosynthesis in rice". Proceedings of the National Academy of Sciences. 114 (26): 6866–6871. doi:10.1073/pnas.1705689114. ISSN 0027-8424. PMC 5495272. PMID 28607067.{{cite journal}}: CS1 maint: PMC format (link)
  9. ^ a b "African Plant Database". africanplantdatabase.ch. Retrieved 2023-05-01.
  10. ^ R Michael Buch and Joseph A von Fraunhofer. “The Systemic and Brain Health Benefits of Frankincense”. EC Psychology and Psychiatry 9.5 (2020): 50-53.
  11. ^ "Extraction of Frankincense Resins - Bangor University". research.bangor.ac.uk. Retrieved 2023-05-01.
  12. ^ a b c Al-Yasiry, Ali Ridha Mustafa; Kiczorowska, Bożena (2016-01-04). "Frankincense – therapeutic properties". Postępy Higieny i Medycyny Doświadczalnej. 70: 380–391. doi:10.5604/17322693.1200553. ISSN 1732-2693.
  13. ^ a b c Michie, C A; Cooper, E (1991-10). "Frankincense and Myrrh as Remedies in Children". Journal of the Royal Society of Medicine. 84 (10): 602–605. doi:10.1177/014107689108401011. ISSN 0141-0768. PMC 1295557. PMID 1744842. {{cite journal}}: Check date values in: |date= (help)CS1 maint: PMC format (link)
  14. ^ a b Baeten, Jan; Deforce, Koen; Challe, Sophie; Vos, Dirk De; Degryse, Patrick (2014-11-12). "Holy Smoke in Medieval Funerary Rites: Chemical Fingerprints of Frankincense in Southern Belgian Incense Burners". PLOS ONE. 9 (11): e113142. doi:10.1371/journal.pone.0113142. ISSN 1932-6203. PMC 4229304. PMID 25391130.{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link)
  15. ^ "NMR Guidelines for ACS Journals" (PDF). American Chemical Society. December 2013. Retrieved 23 May 2023.{{cite web}}: CS1 maint: url-status (link)
  16. ^ Al-Shidhani, Sulaiman; Rehman, Najeeb Ur; Mabood, Fazal; Al-Broumi, Muhammed; Hussain, Hidayat; Hussain, Javid; Csuk, Rene; Al-Harrasi, Ahmed (2018-05). "Quantification of Incensole in Three Boswellia Species by NIR Spectroscopy Coupled with PLSR and Cross-Validation by HPLC: Quantification of incensole in Boswellia species by NIRS and HPLC". Phytochemical Analysis. 29 (3): 300–307. doi:10.1002/pca.2743. {{cite journal}}: Check date values in: |date= (help)
  17. ^ Gebrehiwot, K.; Muys, B.; Haile, M.; Mitloehner, R. (2003-12). "Introducing Boswellia papyrifera (Del.) Hochst and its non-timber forest product, frankincense". International Forestry Review. 5 (4): 348–353. doi:10.1505/ifor.5.4.348.22661. ISSN 1465-5489. {{cite journal}}: Check date values in: |date= (help)
  18. ^ Moussaieff, Arieh; Shohami, Esther; Kashman, Yoel; Fride, Ester; Schmitz, M. Lienhard; Renner, Florian; Fiebich, Bernd L.; Munoz, Eduardo; Ben-Neriah, Yinon; Mechoulam, Raphael (2007-12-01). "Incensole Acetate, a Novel Anti-Inflammatory Compound Isolated from Boswellia Resin, Inhibits Nuclear Factor-κB Activation". Molecular Pharmacology. 72 (6): 1657–1664. doi:10.1124/mol.107.038810. ISSN 0026-895X. PMID 17895408.
  19. ^ Yang, Pu; Zhu, Michael X. (2014), Nilius, Bernd; Flockerzi, Veit (eds.), "TRPV3", Mammalian Transient Receptor Potential (TRP) Cation Channels: Volume I, Berlin, Heidelberg: Springer, pp. 273–291, doi:10.1007/978-3-642-54215-2_11#abs1, ISBN 978-3-642-54215-2, retrieved 2023-05-01