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concentration of ATP, which is related to the destruction of the microbial membrane
(Helander et al. 1997). The alteration of permeability of cell membrane and the
defects in the transport of molecules and ions result in an imbalance within the
microbial cell. This further results in the coagulation of cytoplasm, the denaturation
of several proteins and the loss of ions and metabolites (Burt and Reinders 2003).
The essential oil of cinnamon bark is about 98% cinnamaldehyde, which has
shown antimicrobial activity against a broad range of microbes. This natural product from spices is also reported to inhibit cell separation in Bacillus cereus.
Cinnamaldehyde decreases the in vitro assembly reaction and bundling of the bacterial cell division protein, FtsZ. Studies show that cinnamaldehyde binds FtsZ, perturbs the cytokinetic Z-ring formation and inhibits its assembly dynamics. This
suggests that cinnamaldehyde, a small molecule of plant origin, is a potential lead
compound that can be developed as an anti-FtsZ agent towards drug design
(Domadia et al. 2007).
11.3 Biofilm Inhibition
Biofilm, which is an assemblage of microbial cells that are irreversibly linked with
a surface and enclosed in an extracellular polymeric substance matrix, develops on
a wide variety of surfaces, including living tissues, medical devices, natural aquatic
systems (Donlan 2002). Biofilms play a significant role in certain infectious diseases and are also associated with a variety of device-related infections. The development of a biofilm may also cause the aggregate cell colony to be more prone to
antibiotic resistance. Quorum sensing or cell-cell communication has been involved
in the formation of biofilm in many bacterial species. Novel and effective biofilm
control strategies have great importance as far as public health is concerned.
Biofilm-based infections cause harm to millions of people annually. The difficulty
of eradicating biofilm bacteria with standard antibiotic treatment is a major concern
in medicine. Propionibacterium acnes, a biofilm-forming microorganism responsible for acne vulgaris, showed susceptibility to plant extracts containing resveratrol,
icariin and salidroside compounds which showed the inhibition of biofilm formation.
The antivirulent property of the plant Melia dubia was studied, and a few compounds
antagonizing the quorum-sensing systems of uropathogenic E. coli were identified
(Ravichandiran et al. 2012). Four compounds isolated from the aerial parts and roots
of Krameria lappacea, Aesculus hippocastanum, Chelidonium majus and Macleaya
cordata containing many alkaloids and flavonoids revealed significant activity
against Staphylococci (Artini et al. 2012), which are a clinically significant bacterial
strain. Two compounds, proanthocyanidin A2-phosphatidylcholine (proAc) isolated
from A. hippocastanum and chelerythrine (CH) purified from Macleaya cordata,
revealed an inhibition of de novo biofilm formation without having bactericidal
activity. These alkaloids downregulate some vital proteins involved in different pathways and inhibit biofilm formation. Sanguinarine and chelerythrine also act on some
elements of bacterial cytoskeleton, which is a potential target for antibacterial therapy. The inhibitors of cytoskeletal proteins may serve as lead compounds for the
development of novel antimicrobial agents.
11 Antimicrobial Agents from Plants
concentration of ATP, which is related to the destruction of the microbial membrane
(Helander et al. 1997). The alteration of permeability of cell membrane and the
defects in the transport of molecules and ions result in an imbalance within the
microbial cell. This further results in the coagulation of cytoplasm, the denaturation
of several proteins and the loss of ions and metabolites (Burt and Reinders 2003).
The essential oil of cinnamon bark is about 98% cinnamaldehyde, which has
shown antimicrobial activity against a broad range of microbes. This natural product from spices is also reported to inhibit cell separation in Bacillus cereus.
Cinnamaldehyde decreases the in vitro assembly reaction and bundling of the bacterial cell division protein, FtsZ. Studies show that cinnamaldehyde binds FtsZ, perturbs the cytokinetic Z-ring formation and inhibits its assembly dynamics. This
suggests that cinnamaldehyde, a small molecule of plant origin, is a potential lead
compound that can be developed as an anti-FtsZ agent towards drug design
(Domadia et al. 2007).
11.3 Biofilm Inhibition
Biofilm, which is an assemblage of microbial cells that are irreversibly linked with
a surface and enclosed in an extracellular polymeric substance matrix, develops on
a wide variety of surfaces, including living tissues, medical devices, natural aquatic
systems (Donlan 2002). Biofilms play a significant role in certain infectious diseases and are also associated with a variety of device-related infections. The development of a biofilm may also cause the aggregate cell colony to be more prone to
antibiotic resistance. Quorum sensing or cell-cell communication has been involved
in the formation of biofilm in many bacterial species. Novel and effective biofilm
control strategies have great importance as far as public health is concerned.
Biofilm-based infections cause harm to millions of people annually. The difficulty
of eradicating biofilm bacteria with standard antibiotic treatment is a major concern
in medicine. Propionibacterium acnes, a biofilm-forming microorganism responsible for acne vulgaris, showed susceptibility to plant extracts containing resveratrol,
icariin and salidroside compounds which showed the inhibition of biofilm formation.
The antivirulent property of the plant Melia dubia was studied, and a few compounds
antagonizing the quorum-sensing systems of uropathogenic E. coli were identified
(Ravichandiran et al. 2012). Four compounds isolated from the aerial parts and roots
of Krameria lappacea, Aesculus hippocastanum, Chelidonium majus and Macleaya
cordata containing many alkaloids and flavonoids revealed significant activity
against Staphylococci (Artini et al. 2012), which are a clinically significant bacterial
strain. Two compounds, proanthocyanidin A2-phosphatidylcholine (proAc) isolated
from A. hippocastanum and chelerythrine (CH) purified from Macleaya cordata,
revealed an inhibition of de novo biofilm formation without having bactericidal
activity. These alkaloids downregulate some vital proteins involved in different pathways and inhibit biofilm formation. Sanguinarine and chelerythrine also act on some
elements of bacterial cytoskeleton, which is a potential target for antibacterial therapy. The inhibitors of cytoskeletal proteins may serve as lead compounds for the
development of novel antimicrobial agents.
11 Antimicrobial Agents from Plants