The frequency of food-borne diseases and growing resistance of bacteria to antibiotics have stimulated the search for plants with antibiotic activity. There is a history of use of such plants to extend shelf life of food products. Assays to evaluate plants for their ability to damage bacteria have been developed for the ability to damage bacterial cell walls.
Cholera is a diarrhea-causing disease spread by water or food that has been contaminated by feces which contain cholera bacteria. This study involves testing 27 different plants for the ability to damage cell walls of cholera bacteria (Vibrio cholera). Damaging cell walls reduces the ability of the bacteria to survive, and damaged cells are unable to maintain normal internal pH.
Plant extracts were prepared in water, ethanol, and methanol* to find a suitable medium for treatment. Twenty-seven plants were examined for a total of 81 extracts, and extensive studies were done of plant viability using the extracts.
Results show that, in general, methanolic extracts worked best. Water extracts were weakest, with ethanolic extracts being intermediate. Overall, the methanolic extracts worked best in the following plants (in descending order): Basil (Ocimum basilicum), nopal cactus (Opuntia ficus-indica var. Villanueva), sweet acacia (Acacia farnesiana), and white sagebrush** (Artemisia ludoviciana).
Testing of the above plants for the ability to damage cholera cell walls was positive. Treatment with these plants made it difficult for cells to maintain normal internal pH. pH values dropped with treatment, making the cells more acid than normal.
Basil and nopal cactus are edible plants which showed the best antimicrobial activity of all. Basil is a culinary herb, flavoring for soups and sauces. The leaves can be included in salads. Nopal plants play a conservation role in soil. The fresh green stems are used as vegetables. The stems and nopal fruit can be used to make jams and as medicine***.
White sagebrush and sweet acacia showed weak antimicrobial activity. It is a medicine used for stomach problems, coughs, colds, and headaches. Sweet acacia is a medicinal plant used for headaches and indigestion, as well. The fruit is used for dysentery.
“These four plant extracts could be studied as future alternative medicines to control V. cholera contamination in foods and the diseases associated with the microorganism.”
CONCLUSION: Of 27 edible and medicinal plants tested, basil was the best at destroying cholera cells by damaging the cell walls. This was followed by nopal cactus, sweet acacia, and white sagebrush. Methanol extracts were more active than ethanol or water extracts.
NOTES: *Methanol is a toxic alcohol that should not be consumed.
**White sagebrush is not the same plant as white sage (Salvia apiana).
***Nopal cactus is an alternative medicine treatment for diabetes.
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Rainbow Grocery sells the following products: Basil, nopal cactus, sweet acacia, and white sagebrush.
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