Caraway 279
Flavonoids (flavonoid glycosides) are the other important secondary metabolites
of Carum and seed flavonoids occur in the form of 3-0-glycosides in Carum carvi.
Few crystalline compounds were obtained from caraway seed methanolic extract and
are terpenoid constituents, predominating the oil constituent is S(+) carvone (formerly
carvol and d-carvone), results mostly from allylic oxidation of R(+) limonene with
carveol. The monoterpene R(+) limonene ratios vary from 3:2 up to 3:1, depending
on variety of plant and storage conditions. The following compounds were obtained
crystalline from caraway seed methanolic extract (Glidewell, 1991; Kunzemann and
Herrmann, 1977; Ruszkowska, 1998). From the water-soluble portion of the methanolic
extract of caraway fruits, an aromatic compound glucoside and a glucide were isolated
together with 16 known compounds. Their structures were clarified as 2-methoxy-2-
(4¢-hydroxyphenyl) ethanol, junipediol A 2-O-b-d-glucopyranoside and L-fucitol,
respectively (Matsumura, et al., 2002). The important flavonoids isolated are listed
below.
quercetin 3-glucuronide
isoquercitrine = quercetin-3-O-B-glucopyranoside
quercetin-3-0-Caffeylglucoside
kalmpferol-3-glucoside
Isoquercitrine is the predominating constituent (80 mg/kg dry weight) present in
caraway seed while others are found between two and ten times lower than this
quantity. The above-mentioned flavonoids are known to possess antioxidative
properties and activate enzymes detoxifying carcinogenic substances and metabolites
in the cells.
The enantiomeric composition of limonene and carvone caraway seed oils was
determined by chiral gas chromatography. Two different gas chromatography chiral
Table 15.1 The constituents of caraway essential oil
Constituents Contents (% of dry weight)
El Wakeil et al., 1986) Pushman et al. 1992Essential oil 0.99 5.36
Carvone 80.17 50.46
Limonene 9.75 47.66
a pinene 0.10 –
b pinene 0.40 –
Terpinolene 0.20
Myrecene 0.06 0.35
Paracymene 0.06 –
Caryophyllene 0.11 –
Trans-dihydrocarvone 0.59 0.18
Cis-dihydrocarvone 0.11 –
Cuminaldehyde 0.08 –
Cis-perrilyl alcohol 0.14 –
Trans-carvone 0.01 –
Cis-carvone 0.14 –
Dihydrocarveol 0.04 0.56
Cuminyl alcohol 0.02 –
Carrylaceate – 0.16
Unidentified compounds 8.17 Less than 1.00