Originally inherited from the Aztec in Mesoamerica, guava leaves have a long history in Guatemala as a useful, and sometimes lifesaving, tool for battling diarrhea and intestinal discomfort. They are listed alongside 15 other plants in “Plants used in Guatemala for the treatment of gastrointestinal disorders,” published in the Journal of Ethnopharmacology, in 1993.
This paper “reports the in vitro studies [studies done in a petri dish] of the activity of 16 plant extracts against pathogenic enterobacteria (31). The researchers start out with a list of 408 plants; they narrow the list down to 34 plants which are deemed worthy of further study. Of these 34 plants, 16 are chosen for “confirmation” of antibacterial activity against E coli, Salmonella enteritidis, and Shigella flexneri pathogens. Guava leaf (Psydium guajava) turns out to be one of three plants (out of the 16) that inhibits growth of all three kinds of bacteria.
For a majority of these plants, the most effective extraction agent for antibacterial activity is ethanol. Ethanol extract, acetone extract, and n-hexane extracts of each plant are tested and compared for effectiveness. For guava leaf, the acetone extract proved most effective for antibacterial activity.
In Guatemala, guava leaf is used for diarrhea, dysentery, stomach pain, leucorrhea (a condition of unusual vaginal discharge), and a variety skin infections.
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