Phytochemical screening and evaluation of the anti-diarrheal activity of Syzygium emirnense (Baker) Labat and G.E. Schatz (MYRTACEAE)

Syzygium emirnense (Myrtaceae), a plant endemic to Madagascar, is used in traditional medicine to treat diarrhea. Phytochemical screening of its leaves revealed the presence of tannins, polyphenols, steroids and irridoids, as well as the absence of alkaloids, flavonoids and saponins. The use of three different extraction methods, including reflux decoction, first boiling decoction and halving decoction, yielded extracts RFM114a, RFM114b and RFM114c respectively. The anti-diarrheal properties of these extracts were assessed by an antibiogram test (1mg/ml) against the bacterial strains responsible for diarrhea (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella enterica, Clostridium perfringens, Proteus mirabilis and Listeria monocytogenes). No antibacterial effect was observed. On the other hand, an in vivo intestinal transit test was carried out on mice previously induced with diarrhea by castor oil, by measuring the displacement of the colored meal. All three extracts inhibited diarrhea at all doses tested (100mg/kg and 300mg/kg) compared with the untreated control (p < 0.05). At 300mg/kg, the RFM114a extract was the most active. These results suggest that Syzygium emirnense leaf decoction is effective against secretory and motor diarrhea, but not against bacterial diarrhea.