Biomedical Engineering Reference
In-Depth Information
6 Quorum-Sensing Inhibitors as Antibiofilm Agent
Quorum sensing (QS) plays a vital role in biofilm formation and virulence factor
production in several bacterial species (De Kievit et al.
2001
). Consequently,
compounds that interfere with QS systems are expected to interfere with biofilm
formation also. Extracts of the south Florida plants,
Conocarpus erectus, Bucida
buceras
, and
Callistemon viminalis,
showed considerable inhibition of
QS-regulated LasA protease, LasB elastase, pyoverdin production, and biofilm
production in
P. aeruginosa
(Adonizio et al.
2008
)
.
Aqueous extracts of edible
plants and fruits such as
Ananas comosus, Musa paradiciaca, Manilkara zapota,
and
Ocimum sanctum
also demonstrated a significant reduction in the biofilm
formation abilities of
P. aeruginosa
strain PAO1 (Musthafa et al.
2010
). Taganna
et al. (
2011
) found that a tannin-rich component of
Terminalia catappa
leaves
(TCF12) was able to inhibit the maturation of biofilms of
P. aeruginosa
to signif-
icant levels. The methanolic extract obtained from
Cuminum cyminum
, a traditional
food ingredient in South Indian dishes, was shown to act as quorum-sensing
inhibitor (QSI). By interfering with the acyl-homoserine lactone activity, it
inhibited biofilm formation in several bacterial pathogens (Issac Abraham
et al.
2012
). The extract of
Capparis spinosa
also showed a high degree of anti-
quorum-sensing activity in a dose-dependent manner without affecting the bacterial
growth of
Serratia marcescens
,
P. aeruginosa
,
E. coli
, and
Proteus mirabilis
.Ata
concentration of 2 mg/mL, an inhibition of
E. coli
biofilm formation by 73 % was
observed. For the pathogens
Serratia marcescens
,
P. aeruginosa,
and
P. mirabilis
,
biofilm biomass was reduced by 79, 75, and 70 %, respectively. Moreover, the
mature biofilm structure was disrupted for all of the studied pathogens (Issac
Abraham et al.
2011
). Similarly, 83 %
P. aeruginosa
biofilm inhibition was
achieved with
Lagerstroemia speciosa
(giant crape myrtle) extract, a concentration
of 10 mg/mL. Application of the extract to
P. aeruginosa
PAO1 biofilms increased
bacterial susceptibility to tobramycin. Significant inhibition of QS-regulated viru-
lence factors: LasA protease, LasB elastase, and pyoverdin production, was also
recorded (Singh et al.
2012
).
Melia dubia
(bead tree) bark extracts reduced
E. coli
biofilm formation by 84 % at a concentration of 30 mg/mL. Bacterial swarming,
regulated by QS, was inhibited by 75 %, resulting in decreased biofilm expansion
(Ravichandiran et al.
2012
).
The biofilm inhibitor ursolic acid (structure 23) was identified from 13,000
samples of compounds purified from whole plants and separated parts such as
fruits, leafs, roots, and stems. Ursolic acid from the tree
Diospyros dendo
added
at the rate of 10
g/mL decreased biofilm formation in
E. coli, V. harveyi
, and
P. aeruginosa
PAO1. Transcriptome analyses showed the induction of chemotaxis
and motility genes in
E. coli
treated with the plant-derived compound, suggesting
that ursolic acid may function as a signal that tells cells to remain motile, hindering
cell adhesion or destabilizing already formed biofilms (Ren et al.
2005
).
Hamamelitannin (structure 24) extracted from the bark of
Hamamelis virginiana
(witch hazel) did not affect the growth of
Staphylococcus
spp., but it did prevent
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