The genus Cinnamomum

Pharmacology and Toxicology of Cinnamon and Cassia 265
herbal preparation Saiko-keishi-to (SK), which contains cinnamon, clearly inhibited the
calcium binding state change near the cell membrane during bursting activity, which
is characteristic of seizure discharge (Sugaya et al., 1985).
Immunological effects
Several Ayurveda preparations and aquous herbal extracts exert immunomodulatory
activity. It is hypothesised that many multidrug preparations produce their therapeutic
action through the modulation of immune systems. The immune system is a highly
sophisticated defence mechanism against external biological invaders through the interconnected
network between the brain, endocrine and immune system. It also serves to
regulate the internal environment by eliminating aberrant cells or misplaced tissues
within the body. The immune system is composed of two major branches, the humoral
immune system, primarily the domain of the B-lymphocytes, and the cell mediated
immune system, the domain of the T-lymphocytes. The humoral immune system
produces the antibodies that react specifically with the antigens (the invaders), and the
cell-mediated immune system mobilises phagocytic leukocytes for the ingestion and
subsequent destruction of invading organisms. The exposure of antigens to the cells of
the immune system will elicit an immune response, often associated with clonal proliferation,
an expression process by which a few antigen responsible cells can generate a
large number of immune competent cells specifically to cope with the foreign invaders.
Complement is a powerful effector system involved in the body’s immunological
defence. They are a group of self-reacting proteins in blood serum and body fluids that
play an important role as a mediator of immune and allergic reactions. Complement
represents the humoral arm of natural host defence mechanisms. Complement activation
forms a major part of natural defence, with a range of mediators possessing
immuno-inflammatory potency. However, complement activation may also damage
host tissue as in autoimmune diseases, immunodeficiency diseases, etc.
In vitro inhibitory activity against complement formation has been documented for
cinnamon cortex and cinnamon oil (Norhara et al., 1980; Toshihiro et al., 1981; Yoshiki
et al., 1981). These workers have studied the extract of cinnamon bark and reported
anticomplementery activity. An aqueous extract of the herb showed an inhibitory effect on
the complement activity in the heterophile antibody (antibodies that react with multivalent
antigens) reaction (Wang, 1983). Tang and Eisenbrand’s (1992) study ascribes
immunosuppressive action to the extract. They have found that oral administration of the
extract prevented an increase in protein levels in the urine of rats with nephritis. Nephritis
is an autoimmune disease caused by activation of the complement system. Several
diterpenoids have been isolated and characterised from the stem and root bark extracts of
cinnamon and allied species. Cinncassiol C 1 and its glycosides, cinncassiol C 2, C 3, and
cinncassiol D 1 and its glycoside were identified as the active constituents responsible for
the anticomplementery activity. Koh et al. (1999) isolated two cinnamaldehyde derivatives,
2-Hydroxy cinnamaldehyde (HCA) and 2-Benzoxycinnamaldehyde (BCA), from the stem
bark of cinnamon and studied their immunomodulatory effects. These compounds
suppressed lymphoproliferation when treated with Con A stimulated mouse splenocytes
cultures in a dose dependent manner. Both the compounds at micromolar dose inhibited
Con A stimulated proliferation by 60–69%. Decreased levels of antibody production following
HCA or BCA treatment were observed. The inhibitory effect of cinnamaldehyde
on lymphoproliferation was specific to the early phase of cell activation. It was suggested