effective extracts are considered, e.g. clove extract (95 mg/mL)
which had relatively lower activity than guava (122 mg/mL) and
garlic (133 mg/mL) extracts, and all these extracts showed similar
antimicrobial activity patterns. Such results were different from
data reported in literature. Samy (7) used methanolic extracts of
ginger which did not present antimicrobial effect against S.
aureus and E. coli. However, Indu et al. (5), using a different
method of ginger extract preparation, verified an inhibitory
action against E. coli as well as high antimicrobial activity of
garlic extracts against E. coli and Salmonella.
Ahmad and Aqil (2) concluded that ethanolic extracts of
garlic did not have anti-E. coli or anti-Shigella action. Using
another methodology, Vuddhakul et al. (9) observed that garlic
extracts inhibited the growth of V. parahaemolyticus, E. coli
and S. aureus; however, lemongrass and ginger extracts did not
show any antimicrobial activity. Such behavior of the
antibacterial action was also verified by Adonizio et al. (1), who
used lemongrass extracts and did not observe antibacterial
effects.
Comparisons with pertinent data from literature indicate that,
according to the methodology adopted in studies on
antimicrobial activity, the most diverse results can be obtained.
Plant extracts have shown inhibitory effect on the growth of
the bacteria studied, although of distinct forms. It is therefore
recommended that the nature and the number of the active
antibacterial principles involved in each plant extract be studied
in detail.
ACKNOWLEDGMENTS
This work was supported by Fundação de Amparo a
Pesquisa do Estado de São Paulo (FAPESP, Brazil). The authors
thank Dr. Lin Chau Ming (FCA/Unesp/Botucatu) for providing
the plant specimens and Dr. Maria de Lourdes Ribeiro de Souza
da Cunha (IBB/Unesp/Botucatu) for supplying S. aureus
strains.