IN VITRO VALUATION OF PAEPALANTINE ACTIVITY ISOLATELY AND IN ASSOCIATION WITH ANTIMICROBIALS IN BACTERIA
Name: GERALDO DA SILVA ALVES
Type: MSc dissertation
Publication date: 24/11/2016
Advisor:
Name |
Role |
|---|---|
| RICARDO PINTO SCHUENCK | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| GREICIANE GABURRO PANETO | Internal Examiner * |
| RICARDO PINTO SCHUENCK | Advisor * |
Summary: Bacterial resistance is a global threat to public health. The use of plant-derived
products with antimicrobial activity in association with traditional antibacterial drugs
may be viable alternatives to the production of effective new drugs against
multiresistant microorganisms. Isocoumarin paepalantine (PA) and paepalantine
dimer (PAD) isolated from the capitula of P. bromelioides, have stood out as a
promising substance because of their biological potential. The aim of this study was
to evaluate the in vitro antibacterial activity of PA and PAD alone and in association
with different antimicrobials (vancomycin, oxacillin and meropenem) in multiresistant
strains of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae and
Pseudomonas aeruginosa and to evaluate by scanning electron microscopy possible
morphological changes in strains exposed to inhibitory and subinhibitory
concentrations of paepalantine and dimer alone and in association with antibacterial
agents. In all E. faecium strains, PA and PAD alone presented a minimal inhibitory
concentration (MIC) of 32 μg/mL. The association with vancomycin did not show an
increase in the activity of this drug. For S. aureus, PA and PAD had good inhibitory
potential when tested alone (MIC 16 and 8 μg/mL, respectively). The association
between PA and oxacillin was indifferent in three of the five strains analyzed, while
the association of the PAD with this drug was synergistic in all of them, with a
reduction of up to 256 times in MIC. In Gram-negative microorganisms, K.
pneumoniae and P. aeruginosa, PA and PAD presented weak inhibitory potential
(MIC> 256 μg/mL) and the association with meropenem did not show an increase in
their activity. The present study demonstrated activity of PA and PAD only in Gram-
positive bacteria (E. faecium and S. aureus). The association of these isocoumarin,
especially PAD, with oxacillin presented a relevant synergistic effect, which provides
perspective to additional studies for development of products with association of
these substances. In S. aureus, after SEM analysis, it was verified that the
substances do not act altering the external structure of this microorganism under the
conditions used in this study.
Key-words: Bacterial-resistance; Paepalantine; Synergism.
