Why plant

Why plant antimicrobials?

Microbes (the collective term for bacteria, fungi, parasites, and viruses) cause infectious diseases. Since their discovery during the 20^th century, synthetic antimicrobial agents such as penicillin, streptomycin, and more than 150 others have substantially reduced the threat posed by infectious diseases. Over the years, antimicrobials have saved the lives and eased the suffering of millions of people¹.

Today infectious disease mortality rates are actually increasing in developed countries, such as the United States. It is estimated that infectious disease is the underlying cause of death in 8% of the deaths occurring in the US. This is alarming given that it was once believed that we would eliminate infectious disease by the end of the millennium. The increases are attributed to increases in respiratory tract infections and HIV/AIDS².

Last years we have development of microbes resistant to cheap and effective "first-line" drugs. The bacterial infections that contribute most to human disease are also those in which emerging and microbial resistance is most evident: diarrhoeal diseases, respiratory tract infections, meningitis, sexually transmitted infections, and hospital-acquired infections. The emergence and spread of antimicrobial resistance are complex problems driven by numerous interconnected factors, many of which are linked to the misuse of antimicrobials and thus amenable to change³.

In recent years, there has been growing interest in therapeutic use of natural products, especially those derived from plants. This interest in drugs of plant origin is due to several reasons, namely, conventional medicine can be inefficient (e.g. side effects and ineffective therapy). Abusive and/or incorrect use of synthetic drugs results in side effects and other problems. A large percentage of the world’s population does not have access to conventional pharmacological treatment, and folk medicine and ecological awareness suggest that “natural” products are harmless⁴.

Various biochemical processes lead to the synthesis of several secondary plant metabolites that function as chemical defenses in the plant. Most are secondary metabolites, of which at least 12,000 have been isolated, a number estimated to be less than 10% of the total. Some, such as terpenoids, give plants their odors; others (quinones and tannins) are responsible for plant pigment. Many compounds are responsible for plant flavor, and some of the same herbs and spices used by humans to season food yield useful medicinal compounds⁵.

References:

1. WHO Media centre, Geneva, Fact sheet N°268, January 2002.

2. Maurice, M. et al. New Antimicrobials of Plant Origin; Reprinted from: Perspectives on new crops and new uses, J. Janick (ed.), ASHS Press, Alexandria, VA. 1999, 457-462.

3. Russell, A. D. Biocide use and antibiotic resistance: The relevance of laboratory findings to clinical and environmental situations, The Lancet Infect. Dis. 3, 2003, 794-803.

4. Adewole, L. et. al. Natural antimycobacterial metabolites:current status, Phytochem. 65, 2004, 1017 –1032.

5. Cowan, M. M. Plant products as antimicrobial agents, Clin. Microbiol. Rev. 12, 1999, 564-582.