Title: Cnicin
CAS Registry Number: 24394-09-0
CAS Name: (3R)-(3aR,4S,6E,10Z,11aR)-3,4-Dihydroxy-2-methylenebutanoic acid 2,3,3a,4,5,8,9,11a-octahydro-10-(hydroxymethyl)-6-methyl-3-methylene-2-oxocyclodeca[b]furan-4-yl ester
Additional Names: (Z,E)-6a,8a,15-trihydroxygermacra-1(10),4,11(13)-trien-12-oic acid 12,6-lactone 8-(3,4-dihydroxy-2-methylenebutyrate); cynisin; centaurin
Molecular Formula: C20H26O7
Molecular Weight: 378.42
Percent Composition: C 63.48%, H 6.93%, O 29.60%
Literature References: Bitter principle of Cnicus benedictus L., Compositae. Isolation and review: Korte, Bechmann, Naturwissenschaften 45, 390 (1958). Structure: Suchy et al., Tetrahedron Letters no. 10, 5 (1969); Ber. 93, 2449 (1960). Revised structure: Samek et al., Tetrahedron Lett. 1969, 2931. Stereochemistry: Tori et al., J. Chem. Soc. B 1971, 1084.
Properties: Crystals, mp 143°. [a]D20 +158° (c = 2.3 in ethanol). uv max: 220 nm (log e 4.34). Slightly sol in water; freely sol in alcohol. Practically insol in ether.
Melting point: mp 143°
Optical Rotation: [a]D20 +158° (c = 2.3 in ethanol)
Absorption maximum: uv max: 220 nm (log e 4.34)
Coal Tar Cobaltic Acetate Cobaltic Fluoride Cobaltic Oxide Monohydrate Cobaltic Potassium Nitrite

CAS number 24394-09-0 YesY
PubChem 5281435
ChemSpider 4444781 YesY
Jmol-3D images Image 1
Molecular formula C20H26O7
Molar mass 378.42 g mol−1
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

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.