The genus Cinnamomum

110 U.M. Senanayake and R.O.B. Wijesekera
proanthocyanidins, since they release anthocyanidin when heated in presence of acid. In
condensed tannins, the condensation occurs mostly between C 4 of a flavan unit and C 8
and/or C 6 of another unit. A large variety of condensed tannins exists in the plant kingdom,
and in cinnamon and cassia bark the tannins are the condensates of ()-catechin
and ()-epicatechin (Fig. 3A.3).
Nonaka and Nishioka (1980, 1982), Nonaka et al. (1985) and Morimoto et al.
(1985a,b, 1986a,b) conducted detailed analysis of tannins and related compounds from
the barks of cinnamon, cassia and related species. They have isolated many tannin-related
compounds such as flavone-3-ol glucosides, oligomeric procyanidins (named as
cinnamtannins), several known proanthocyanidins, epicetechin etc. The cinnamtannins
(designated as A 2, A 3 and A 4) are tetrameric, pentameric and hexameric procyanidins
respectively, consisting exclusively of ()-epicatechin units linked linearly through
HO
HO
O
O
(1)
(2)
R′
HO
HO
(1)
(2)
R
OH H
13
HO
O
H
O
OH O
OH
OH
H OH O
OH
H
OH
HO OH
Proanthocyanidin 1
R, R′ = H
Proanthocyanidin 11
R = H R′ = Q
Proanthocyanidin 111
R = Q′ R′ = H
OH
N
H
Q
R
R = H
R = CH3 CH3O 10 11
Norcinnamolaurine
(–)-Cinnamolaurine
O H
OH
CH 3 O
HO
HO
(3) Reticuline
(4) (+)-Corydine
OH
OH
OH
OH
HO
Q′ =
N
CH 3
OH
HO
O
OH
CH 3 O
HO
CH 3 O
CH 3 O
O
H
OH
OH
OH
H OH
Figure 3A.3 Tannins and related compounds from cinnamon bark (see text for explanation).
(3)
12
OH
Q′
(4)
N
OH
CH 3