Abstract The chemical composition of the hydrodistilled oils of the leaves of Psidium guajava L.
(guava leaf) and Psidium cattleianum Sabine (strawberry guava) was determined by GC/MS analysis
to identify their chemotypes. Moreover, in vitro antimicrobial activity of these volatile oils against
selected bacteria, yeast, and mycelia fungi was studied. The yield of the volatile oil hydrodistilled
from the leaves of P. guajava L. and P. cattleianum Sabine was 1.6 and 2.69 g/kg on fresh weight
basis, respectively. Limonene was the major identified hydrocarbon in P. guava leaves’ oil
(54.70%), whereas, 1, 8-cineole was the major identified oxygenated monoterpenoid (32.14%) in
common guava leaves. The foliar oil of P. cattleianum was predominated by the sesquiterpene
hydrocarbon; b-caryophyllene representing 28.83% of the total oil make-up. The antibacterial
activity of guava leaf oil was more pronounced against Bacillus subtilis, Staphylococcus aureus,
Streptococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa than that of strawberry guava
leaves, while P. cattleianum showed a higher activity against ess. The MIC of the volatile oil of the
leaves of P. guajava against S. aureus was 6.75 lg/ml, while that of P. cattleianum exhibited MIC
value of 13.01 lg/ml against Neisseria gonorrhoeae. Results demonstrated that the volatile oil of
both Psidium species showed different chemotypes. Moreover, the volatile oils of guava and strawberry
guava leaves might be good candidates as antimicrobial agents.
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