The genus Cinnamomum

Pharmacology and Toxicology of Cinnamon and Cassia 271
therapeutic use of cinnamon or its constituents, a clinical trial must be conducted.
Nevertheless, the results of this study are very significant because a resistant variety of
organism isolated from HIV patients was used for the investigation.
Another significant antibacterial activity exhibited by cinnamon is against Helicobacter
pylori, a human pathogen producing cytokines which cause peptic ulcers. Chronic infection
can lead to stomach cancer. A ethanol and methylene chloride extract of powdered
cinnamon was studied by Tabak et al. (1996). The methylene chloride extract
completely inhibited the growth at a concentration of 50 g/ml in solid medium and
by 15 g/ml in liquid medium. It inhibited the urease activity also. Smith-Palmer
et al. (1998) studied the effect of essential oils against five food borne pathogens and
obtained very significant results. They found that Gram positive bacteria was more
sensitive than Gram negative. A concentration of 0.075% cinnamon oil was found to be
bacteriostatic against Campylobacter jejuni (causes food poison in infants and bacterial
gastroenteritis, and usually grows in chicken, milk products); Salmonella enteritidis
(causes salmonellosis associated with chicken, meat, milk and egg products); Escherichia
coli (several pathogenic strains, produces toxins, which causes diarrhea, gastroenteritis,
enterocolitis, etc.); Staphylococcus aureus (causes food poisoning, intestinal inflammation,
gastroenteritis); Listeria monocytogens (a pathogenic organism, which causes meningitis,
encephalitis, septicemia, endocolitis, abscesses in animals and man). Another observation
in this study was the temperature effect. The bactericidal and bacteriostatic
concentration at 35 °C was less than 0.05% and 0.01%, respectively, whereas when the
temperature was reduced to 4 °C an increase in concentration was required for both
activities, i.e. 0.5% and more than 1% for bacterisotatic and bactericidal activity.
Mikamo et al. (1998) carried out an in vivo study using rat models and an in vitro study
in intrauterine infections of E. coli. In the in vitro experiments the minimum inhibitory
concentration was more than 100 g/ml. In the in vivo experiments, extract was administered
(125 mg/kg) to rats 16 hours after inoculating them with 8.1 10 6 colony
forming units, three times a day p.o. for seven days. Cinnamon extracts significantly
reduced the viable E. coli counts in rat utrine infections.
Lee and Ahn (1998) investigated the effect of cinnamon bark derived materials
against human intestinal bacteria using an impregnated paper disc method. They
compared the effect of cinnamaldehyde, trans-cinnamic acid, cinnamyl alcohol and
eugenol with that of tetracycline and chloramphenecol as standards. The growth
percentage varied with each bacterial strain. With 1 and 0.5 mg/disk, cinnamaldehyde
has shown a potent inhibitory action against Clostridium perfringens (a food infecting
bacteria usually growing in cooked, cooled and reheated foods; it causes gasgangrene,
toxic shock, etc.) and Bacteroides fragilis, major inhabitants of the human intestinal tract
(causative agents of several pathogenic conditions like interabdominal infections, gastrointestinal
abscesses and ulcers). At 1 and 0.5 mg/disk, the growth of Bifidobacterium
bifidum (pathogenicity doubtful) was inhibited and no inhibition was obtained against
B. longum and Lactobacillus acidophilus (useful intestinal bacteria). Cinnamaldehyde was
found to be the most potent inhibitor, and little inhibitory activity was obtained for
trans-cinnamic acid, cinnamyl alcohol and eugenol. Tetracycline and chloramphenicol
inhibited growth of all test bacteria at a low dose of 0.01 mg/disk. The result of
this study indicates the high potential of cinnamom for the development of specific
antibacterial agents for pathogenic bacteria. Sasidharan et al. (1998) also studied the
effect of cinnamon extract on human pathogenic bacteria and reported the significant
antibacterial effects.