356
to keep pathogenic organisms at bay (González and Keshavan 2006; Koh et al.
2013). A variety of phenolic compounds have shown inhibitory activity against
AHL-dependent quorum sensing. Flavonoids have been well studied and have displayed many pharmacological activities apart from presenting their structural divergence (Havsteen 2002; Tang and Zhang 2014). The first identified flavonoid
compound flaven-3-ol catechin was isolated from Combretum albiflorum bark,
which is capable of cutting down the production of virulence factors in Pseudomonas
aeruginosa PAO1 by interfering with Rh1R (Vandeputte et al. 2010; Tang and
Zhang 2014). Now, many other flavonoids inhibit quorum sensing in bacteria
(Vikram et al. 2010; Vandeputte et al. 2011; Mansson et al. 2011; Tang and Zhang
2014). Honey and propolis have been found to be capable of interfering with quorum sensing in Chromobacterium violaceum and Pseudomonas aeruginosa, respectively, which may be because of the presence of high quantity of flavonoids
(Havsteen 2002; Tang and Zhang 2014). Another group of phenolic compounds
called hydrolysable tannins from various plants have shown quorum sensing inhibition against Chromobacterium violaceum and Pseudomonas aeruginosa (Adonizio
et al. 2008; Giménez-Bastida et al. 2012; Tang and Zhang 2014). One more phenolic compound hamamelitannin is capable of blocking quorum sensing in
Staphylococcus spp. (Kiran et al. 2008; Li et al. 2011; Mansson et al. 2011; Tang
and Zhang 2014). Candida albicans, an opportunistic pathogen, has been found to
use farnesol (a common sesquiterpene) as a quorumsensing signal that inhibits the
Pseudomonas quinolone signal (PQS) circuit of Pseudomonas aeruginosa by promoting nonproductive interaction between PqsR and the pqsA promoter (Cugini
et al. 2007; Amaya et al. 2012; Tang and Zhang 2014). Cugini et al. (2007) in their
studies reported that farnesol may probably play a role in interkingdom communications. Apart from farnesol two more sesquiterpene derivatives, drimendiol
obtained from Drimys winteri and sesquiterpene lactones obtained from
Centratherum punctatum, have been identified as AHL-dependent quorumsensing
inhibitors (Jakobsen et al. 2012; Paza et al. 2013; Tang and Zhang 2014).
Cinnamaldehyde was used as a flavoring substance (Brackman et al. 2011; Tang and
Zhang 2014). It has been found that low concentrations of Cinnamaldehyde are
effective in inhibiting QS process in Vibrio harveyi (Niu et al. 2006; Tang and Zhang
2014).
14.4.1.2 Quorum Quenching Compounds from Marine Sources
Most common sources for quorum quenching compounds in marine environment
are bacteria, fungi, algae, bryozoan, corals, and sponges. Marine cyanobacteria have
become one among the best source for obtaining biologically active and structurally
unique natural products. Quorum sensing inhibitors that are AHL-dependent have
been found in various species of marine cyanobacteria. From Blennothrix cantharidosmum, tumonoic acids (E, F, G, and H) are extracted which inhibit the bioluminescence of Vibrio harveyi BB120 without affecting the bacterial growth. Among
these tumonoic acids, tumonoic acid F has been found to be more potent (Clark
et al. 2008; Tang and Zhang 2014). One more cyanobacteria Lyngbya majuscula
produces four distinct compounds including malyngolide (MAL),
G. Seghal Kiran et al.
to keep pathogenic organisms at bay (González and Keshavan 2006; Koh et al.
2013). A variety of phenolic compounds have shown inhibitory activity against
AHL-dependent quorum sensing. Flavonoids have been well studied and have displayed many pharmacological activities apart from presenting their structural divergence (Havsteen 2002; Tang and Zhang 2014). The first identified flavonoid
compound flaven-3-ol catechin was isolated from Combretum albiflorum bark,
which is capable of cutting down the production of virulence factors in Pseudomonas
aeruginosa PAO1 by interfering with Rh1R (Vandeputte et al. 2010; Tang and
Zhang 2014). Now, many other flavonoids inhibit quorum sensing in bacteria
(Vikram et al. 2010; Vandeputte et al. 2011; Mansson et al. 2011; Tang and Zhang
2014). Honey and propolis have been found to be capable of interfering with quorum sensing in Chromobacterium violaceum and Pseudomonas aeruginosa, respectively, which may be because of the presence of high quantity of flavonoids
(Havsteen 2002; Tang and Zhang 2014). Another group of phenolic compounds
called hydrolysable tannins from various plants have shown quorum sensing inhibition against Chromobacterium violaceum and Pseudomonas aeruginosa (Adonizio
et al. 2008; Giménez-Bastida et al. 2012; Tang and Zhang 2014). One more phenolic compound hamamelitannin is capable of blocking quorum sensing in
Staphylococcus spp. (Kiran et al. 2008; Li et al. 2011; Mansson et al. 2011; Tang
and Zhang 2014). Candida albicans, an opportunistic pathogen, has been found to
use farnesol (a common sesquiterpene) as a quorumsensing signal that inhibits the
Pseudomonas quinolone signal (PQS) circuit of Pseudomonas aeruginosa by promoting nonproductive interaction between PqsR and the pqsA promoter (Cugini
et al. 2007; Amaya et al. 2012; Tang and Zhang 2014). Cugini et al. (2007) in their
studies reported that farnesol may probably play a role in interkingdom communications. Apart from farnesol two more sesquiterpene derivatives, drimendiol
obtained from Drimys winteri and sesquiterpene lactones obtained from
Centratherum punctatum, have been identified as AHL-dependent quorumsensing
inhibitors (Jakobsen et al. 2012; Paza et al. 2013; Tang and Zhang 2014).
Cinnamaldehyde was used as a flavoring substance (Brackman et al. 2011; Tang and
Zhang 2014). It has been found that low concentrations of Cinnamaldehyde are
effective in inhibiting QS process in Vibrio harveyi (Niu et al. 2006; Tang and Zhang
2014).
14.4.1.2 Quorum Quenching Compounds from Marine Sources
Most common sources for quorum quenching compounds in marine environment
are bacteria, fungi, algae, bryozoan, corals, and sponges. Marine cyanobacteria have
become one among the best source for obtaining biologically active and structurally
unique natural products. Quorum sensing inhibitors that are AHL-dependent have
been found in various species of marine cyanobacteria. From Blennothrix cantharidosmum, tumonoic acids (E, F, G, and H) are extracted which inhibit the bioluminescence of Vibrio harveyi BB120 without affecting the bacterial growth. Among
these tumonoic acids, tumonoic acid F has been found to be more potent (Clark
et al. 2008; Tang and Zhang 2014). One more cyanobacteria Lyngbya majuscula
produces four distinct compounds including malyngolide (MAL),
G. Seghal Kiran et al.