Cnicin

Cnicin is a sesquiterpene lactone, esterified with a substituted acrylic acid, and belonging to the germacranolide class of natural products. It is mainly found in Cnicus (Cnicus benedictus L. (Asteraceae)), and is present in spotted knapweed plants, where highest and lowest concentrations are found in the leaves (0.86-3.86% cnicin) and stems respectively.[1][2] Cnicin is used as a bitter tonic and the bitterness value is approximately 1,500.

Cnicin

Names
IUPAC name [(1R,2S,4E,8Z,10S)-8-(hydroxymethyl)-4-methyl-13-methylidene-12-oxo-11 -oxabicyclo[8.3.0]trideca-4,8-dien-2-yl] (3S)-3,4-dihydroxy-2-methylidene-butanoate
Identifiers
CAS Number	24394-09-0^Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1257707^N
ChemSpider	4444781^Y
ECHA InfoCard	100.042.004
PubChem CID	5281435
UNII	C998MWY30L^Y
CompTox Dashboard (EPA)	DTXSID90878518
InChI InChI=1S/C20H26O7/c1-11-5-4-6-14(9-21)8-17-18(13(3)20(25)27-17)16(7-11)26-19(24)12(2)15(23)10-22/h5,8,15-18,21-23H,2-4,6-7,9-10H2,1H3/b11-5+,14-8-/t15-,16-,17+,18+/m0/s1^Y Key: ZTDFZLVUIVPZDU-QGNHJMHWSA-N^Y InChI=1/C20H26O7/c1-11-5-4-6-14(9-21)8-17-18(13(3)20(25)27-17)16(7-11)26-19(24)12(2)15(23)10-22/h5,8,15-18,21-23H,2-4,6-7,9-10H2,1H3/b11-5+,14-8-/t15-,16-,17+,18+/m0/s1 Key: ZTDFZLVUIVPZDU-QGNHJMHWBP
SMILES O=C/1O[C@@H]2/C=C(/CC/C=C(/C[C@H](OC(=O)\C(=C)[C@@H](O)CO)[C@H]2C\1=C)C)CO
Properties
Chemical formula	C20H26O7
Molar mass	378.421 g·mol^−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

References

1. Olson, B. E.; Kelsey, R. G. (1997). "Effect of Centaurea maculosa on sheep rumen microbial activity and mass in vitro". J. Chem. Ecol. 23 (4): 1131–1144. doi:10.1023/B:JOEC.0000006391.88098.12.
2. Providing Supplement, with or without PEG, to reduce the effects of cnicin and enhance grazing of spotted knapweed by sheep and cattle, Masters Thesis, M Cheeseman, Montana State University