Quorum Sensing Inhibitors as an Alternate …
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cinnamaldehyde analogs also increased the survival of Caenorhabditis elegans nematodes infected with V. anguillarum, V. harveyi and V. vulnificus (Brackman et al. 2008,
2011). The same compound has also enhanced the survival and growth of freshwater
prawn larvae when challenged with pathogenic luminescent V. harveyi (Pande et al.
2013). In the year 2010, Vikram et al. studied the QSI activity of numerous flavonoids
from citrus fruits specifically naringin, quercetin, sinensetin and apigenin. Out of
four flavonoids tested, naringin was identified as potent inhibitor of autoinducermediated cell–cell signalling by inhibiting the Escherichia coli O157:H7 biofilm and
V. harveyi virulence. Also, citrus limonoids from sour orange, specifically isolimonic
acid and ichangin displayed a maximum inhibitory activity against bacterial cell–cell
signalling as measured with the V. harveyi reporter strain model system (Vikram et al.
2011).
Consequently, in the recent years the marine cyanobacteria is also receiving much
attention on their role as source of QSIs. Tumonoic acids isolated from cyanobacteria,
Blennothrix cantharidosmum exhibited anti-QS activity by inhibiting QS dependent
bioluminescence in V. harveyi without affecting the bacterial growth (Clark et al.
2008). Malyngolide and lyngbyoic acid from the cyanobacterium Lyngbya majuscula
inhibited the QS dependent elastase and virulence factors production in P. aeruginosa
(Dobretsov et al. 2010; Kwan et al. 2011). The ability of cinnamaldehyde and its
derivatives to interfere with the AI-2-dependent QS system of Vibrio spp. and its
ability to rescue Artemia shrimp against V. harveyi infection has been documented
in earlier studies as well (Brackman et al. 2009; Musthafa et al. 2011).
In this outlook, Defoirdt et al. (2012) have studied the effect of synthetic
compounds on luminescent QS dependent virulence and biofilm formation of luminescent V. harveyi. In this study, brominated thiophenones TF101 and TF310 effectively inhibited the QS-regulated gene expression system in V. harveyi by changing
the DNA-binding action of the QS master regulator LuxR. Similar to in vitro, in vivo
challenge test with gnotobiotic brine shrimp larvae also has the maximum curative
index of all QS disrupting compounds tested thus far in our brine shrimp model
system against luminescent vibriosis. Another report by Rasch et al. (2004) showed
a noticeable decline in transience of rainbow trout by V. anguillarum cultures in the
presence of furanone C-30 at tested concentration. Based on the second strategy of
inhibition, Bacillus species were amongst the well-known bacteria accounted to open
the lactone ring of AHLs by secreting lactonase enzymes, which inactivate AHLs by
degradation. Earlier reports revealed that AHL-degrading bacterial cultures isolated
from the intestinal tract of healthy shrimp and fish increased the survival of different
aquaculture species, including larvae of turbot (Scophthalmus maximus) and the
freshwater prawn (Nhan et al. 2010).
In recent years, anti-biofilm and anti-QS molecules have listed out a variety of
compounds from diverse sources including natural as well as synthetic compounds
against human pathogens such as Pseudomonas aeruginosa, Proteus mirabilis and
Serratia marcescens as well as aquatic bacterial pathogens including V. harveyi, V.
parahaemolyticus, V. alginolyticus, V. vulnificus and Aeromonas hydrophila. A few of
such compounds, which are known to interfere with the bacterial QS are curcumin
293
cinnamaldehyde analogs also increased the survival of Caenorhabditis elegans nematodes infected with V. anguillarum, V. harveyi and V. vulnificus (Brackman et al. 2008,
2011). The same compound has also enhanced the survival and growth of freshwater
prawn larvae when challenged with pathogenic luminescent V. harveyi (Pande et al.
2013). In the year 2010, Vikram et al. studied the QSI activity of numerous flavonoids
from citrus fruits specifically naringin, quercetin, sinensetin and apigenin. Out of
four flavonoids tested, naringin was identified as potent inhibitor of autoinducermediated cell–cell signalling by inhibiting the Escherichia coli O157:H7 biofilm and
V. harveyi virulence. Also, citrus limonoids from sour orange, specifically isolimonic
acid and ichangin displayed a maximum inhibitory activity against bacterial cell–cell
signalling as measured with the V. harveyi reporter strain model system (Vikram et al.
2011).
Consequently, in the recent years the marine cyanobacteria is also receiving much
attention on their role as source of QSIs. Tumonoic acids isolated from cyanobacteria,
Blennothrix cantharidosmum exhibited anti-QS activity by inhibiting QS dependent
bioluminescence in V. harveyi without affecting the bacterial growth (Clark et al.
2008). Malyngolide and lyngbyoic acid from the cyanobacterium Lyngbya majuscula
inhibited the QS dependent elastase and virulence factors production in P. aeruginosa
(Dobretsov et al. 2010; Kwan et al. 2011). The ability of cinnamaldehyde and its
derivatives to interfere with the AI-2-dependent QS system of Vibrio spp. and its
ability to rescue Artemia shrimp against V. harveyi infection has been documented
in earlier studies as well (Brackman et al. 2009; Musthafa et al. 2011).
In this outlook, Defoirdt et al. (2012) have studied the effect of synthetic
compounds on luminescent QS dependent virulence and biofilm formation of luminescent V. harveyi. In this study, brominated thiophenones TF101 and TF310 effectively inhibited the QS-regulated gene expression system in V. harveyi by changing
the DNA-binding action of the QS master regulator LuxR. Similar to in vitro, in vivo
challenge test with gnotobiotic brine shrimp larvae also has the maximum curative
index of all QS disrupting compounds tested thus far in our brine shrimp model
system against luminescent vibriosis. Another report by Rasch et al. (2004) showed
a noticeable decline in transience of rainbow trout by V. anguillarum cultures in the
presence of furanone C-30 at tested concentration. Based on the second strategy of
inhibition, Bacillus species were amongst the well-known bacteria accounted to open
the lactone ring of AHLs by secreting lactonase enzymes, which inactivate AHLs by
degradation. Earlier reports revealed that AHL-degrading bacterial cultures isolated
from the intestinal tract of healthy shrimp and fish increased the survival of different
aquaculture species, including larvae of turbot (Scophthalmus maximus) and the
freshwater prawn (Nhan et al. 2010).
In recent years, anti-biofilm and anti-QS molecules have listed out a variety of
compounds from diverse sources including natural as well as synthetic compounds
against human pathogens such as Pseudomonas aeruginosa, Proteus mirabilis and
Serratia marcescens as well as aquatic bacterial pathogens including V. harveyi, V.
parahaemolyticus, V. alginolyticus, V. vulnificus and Aeromonas hydrophila. A few of
such compounds, which are known to interfere with the bacterial QS are curcumin