In vitro anti-amoebic and anti-giardial activity of some medicinal plants of the family Myrtaceae

According to WHO, diarrhea is the passage of 3 or more loose or liquid stools per day. It is usually a symptom of gastrointestinal infection, which can be caused by a variety of microorganism, parasites or viruses. Severe diarrhea leads to fluid loss, and may be life-threatening. Among the causative agents of diarrhea are parasitic protozoan Entamoeba histolytica and Giardia intestinalis. These parasites became recently multidrug resistant, so the finding of new synthetic or natural drugs is of great necessity. We tested the aqueous crude extracts of some medicinal plants belonging to the family Myrtaceae that are used popularly for the treatment of diarrhea [1] such as the Syzygium aromaticum (L.) Merr. & Perry, Eucalyptus camaldulensis Dehnh and the Myrtus communis L. The extracts showed an important degree of inhibition effect against Entamoeba histolytica and Giardia intestinalis. The extracts were not toxic to hep 2 and vero cells at the IC₅₀ concentrations. Results were compared also with metronidazole as shown in the table.

IC50
Entamoeba histolytica	Giardia intestinalis	Plant name
300µg/ml	60µg/ml	Myrtus communis
150µg/ml	150µg/ml	Eucalyptus camaldulensis
30µg/ml	60µg/ml	Syzygium aromaticum
0.7µg/ml	0.7µg/ml	Metronidazole

References: 1. Duke, J.A. (2003) CRC Handbook of Medicinal, Boca Raton-Florida.