The genus Cinnamomum

268 K.K. Vijayan and R.V. Ajithan Thampuran
Antimicrobial Activity
Antibacterial activity
The antimicrobial effect of cinnamon is one area of activity that has been extensively
investigated. Reports are available from 1944 onwards. These studies include antibacterial
and antifungal effects. An antiviral effect has also been reported. Kobayashi et al.
(2000) reported the inhibition of HIV-1 by the methanolic extract of cinnamon due
to the inhibition of reverse transcriptase; the IC 50 value being 4.3g/ml. Premanathan
et al. (2000) carried out a survey of Indian medicinal plants for anti-HIV activity
and reported that cassia extract is most effective in inhibiting HIV-1 and HIV-2.
Cinnamon was found to be active against most of the foodborne pathogenic organisms
(see Table 11.1). Many other types of human pathogens have also been found to be
susceptible to the activities of cinnamon and its derived compounds. Scientific evidence
on the preservation potential of spices emerged in the early nineteenth century.
Chamberland first reported the antimicrobial activity of cinnamon oil against spores
and anthrax bacilli (Webb and Tanner, 1944). Later studies indicated the usefulness
of aqueous and alcoholic extracts of ground cinnamon in preserving tomato sauce.
Following a study conducted on different strains of Clostridium botulinum (an anaerobic
spore forming bacteria producing neurotoxins causing fatal food poisoning), Hall and
Maurer (1986) reported that cinnamon was active in inhibiting the growth of three
different strains of C. botulinum at 150–200 ppm level. Ismaiel and Pierson (1990)
observed in their in vitro study that an extract of cinnamon at 150–200 ppm inhibited
the growth and germination of C. botulinum. Spice oils have an advantage over other
antimicrobial agents in that they prevent the germination of C. botulinum. Zhang et al.
(1990) compared the bacteriostatic ability of cinnamon with that of two standard
bacteriostatic substances, nipagin-A and benzoic acid, and found that the same amount
of activity was associated with cinnamon. Iyangar et al. (1994) attributed the bactericidal
activity of the herb to benzylbenzoate, an ester constituent of the oil. A 40%
ethanolic extract of the bark had a good growth inhibitory effect on Enterobacter
aerogenes, a bacterium that causes urinary tract infections. Wendakoon and Sakagudi
(1995) attributed the antibacterial effect to cinnamaldehyde and eugenol. From a study
of the antimicrobial effect of spices Bara and Venetti (1995) reported that cinnamon
bark powder exhibited a bacteriostatic effect. The effect was obtained after 12 hours
at a concentration of 4.1–4.4% w/v of cinnamon powder against Yersinia enterocolitica,
a bacteria causing food borne infections and food poisoning. In an in vitro screening
study of 17 essential oils for antibacterial activity against the growth of Trichomonas
vaginalis, a protozoan parasite on humans that causes infections of the urethra and vagina,
Viollon et al. (1996) found that cinnamon oil had the maximum growth inhibiting
effect with an LD 100 value of 50 mg/ml.
Quale et al. (1996) studied the effect of cinnamon and its constituents against
Candida species and extended a clinical study to patients with candidiasis. They studied
the activity against fluconazole-resistant Candida species isolates from HIV-infected
patients in vitro and found that cinnamon extract completely inhibited growth at a MIC
(minimum inhibitory concentration) value of 0.5–30 mg/ml. trans-cinnamaldehyde
and o-methoxycinnamaldehyde also exhibited activity at a MIC value of 0.03–0.5
mg/ml. A pilot study on five patients with oral candidiasis was made using commercially
available cinnamon preparation. The patients were treated with the formulation
for one week. Three patients exhibited improvement. However, to establish the