The genus Cinnamomum

170 Nguyen Kim Dao
acids, coumarin, benzaldehyde, O-methoxy benzaldehyde and methyl-O-coumaraldehyde.
In the natural oil the auto-oxidation of cinnamic aldehyde to cinnamic acid is prevented
by the presence of cinnamyl acetate, which acts as a very efficient preservative.
In 1972 Ter Heide examined the chemical composition of a crude essential oil from
China using GC, TLC, NMR, MS and IR, in addition to using authentic reference
compounds and GC retention indices. He identified benzaldehyde, salicylaldehyde,
2-methoxy cinnamaldehyde, 2-hydroxy acetophenone, methyl benzoate, phenyl ethyl
acetate, 3-phenyl propyl acetate, trans-cinnamyl acetate, trans-2-methoxy-cinnamyl
acetate, phenyl ethyl alcohol, trans-cinnamyl alcohol, coumarin, phenol, O-cresol,
guaicol, 2-vinyl phenol, chavicol, 4-ethyl guaneol and eugenol. The following acids
were also identified: hexanoic, heptanoic, octanoic, benzoic, cinnamic, methoxy cinnamic,
dihydro cinnamic and 2-methoxy dihydroxy cinnamic acids.
In 1977 Senanayake compared the chemical composition of lab-distilled leaf and
bark oils with that of a commercial oil. The results of the study indicated a cinnamaldehyde
content of 69.6%, 87.0% and 77.2% in leaf, bark and commercial
oils, respectively. The coumarin content of the oil was found to be very high
(8.06%, 0.28%, 15.3% respectively in leaf, bark and commercial oils (Tables 6.5
and 6.6).
Lawrence (2001) recently summarised a series of studies on Chinese cassia oil. Zhu
et al. (1993) analysed the cassia leaf oil from China and recorded the compounds listed
in Table 6.5.
Vernin et al. (1990) carried out a detailed compositional analysis of cassia bark oil
(Table 6.6). In 1994 Vernin et al. analysed cassia bark powder using head space GC/MS
and recorded the substances given in Tables 6.7 and 6.8.
Further reports on the chemical composition of cassia oil were published by
Jayatilaka et al. (1995), Ehlers et al. (1995) Miller et al. (1995) and Kwon et al.
(1996). Kwon et al. (1996) isolated salicylaldehyde from bark extract and reported
that this compound inhibited farnesyl protein transferase activity. In 1998 Li et al.
made a detailed comparison of leaf and bark oils from Chinese cassia grown
in Yunnan province using GC/MS (Table 6.9). Li and Yuan (1999) reported 36 compounds
in their analysis of a cassia oil sample from China by GC and GC/MS
(Table 6.10). Gong et al. (2001) developed a complex interactive optimisation procedure
to resolve co-eluting peaks in a GC/MS analysis of cassia bark grown in four
different geographical regions of China.
Kondou et al. (1999) analysed the commercial cassia barks (different grades such as
Xijang and Donxing bark from China and Yen Bai and Mien Nam barks from Vietnam)
in order to bring out the salient differences among them based on the contents of
coumarin, cinnamaldehyde, cinnamic acid, cinnamyl alcohol, cinnamic acetate and
eugenol (Table 6.11).
In addition to the components present in the essential oil, a number of diterpenes
named cinncassioles have been isolated from cassia bark. They include cinncassiols A,
B and C 1, and their glucosides, cinncassiols C 2 and C 3, cinncassiols D 1, D 2 and D 3, and
their glucosides, cinncassiol E, cinnzeylanol, cinnzeylanin, anhydrocinnzeylanol and
anhydrocinnzeylanin (Yagi et al., 1980; Nohara et al., 1980a,b,c, 1981, 1982, 1985;
Kashiwada et al., 1981). The following compounds were also isolated from the stem
bark of cassia: