ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P91. Antimicrobial Activity of Amino Acid and Dipeptide Based
Amphiphiles
N. Kayal a , S. Roy b
a
Department of Biotechnology, Vellore Institute of Technology, University (VITU, 1/1 thakurpukur road, kol-
63, 700063, kolkata, India
e-mail: nilanjan_kayal@hotmail.com
b
Department of Biological Chemistry, Indian Association for the Cultivation of Science, , 1/1 thakurpukur
road, kol-63, 700063, kolkata, India
Cationic surfactants bear anti-bacterial activity. Surfactants are usually organic compounds which are
amphiphilic in nature; they contain both hydrophobic groups (their “tails”) and hydrophilic groups (their
“heads”). Thus they are soluble in both organic solvents and water. Quaternary ammonium compounds are
found to be quite effective against both Gram’s positive and Gram’s negative bacteria, but they are also toxic.
Their toxicity is related primarily to the various biological effects of the quaternary ammonium head and its
metabolism (such as oxidative dealkylation), but it is also believed that the surfactant characteristics of the
molecules, particularly in liver, causes additional alterations in a number of chemical, biological and transport
phenomena. The mechanism of action of cationic surfactants on bacteria is understood to be purely
electrostatic interaction and physical disruption. The cationic site of the agent is able to bind to the anionic
sites of the cell wall surface. With a significant lipophilic component present, it is then able to diffuse through
the cell wall and bind to membrane. As a surfactant it is able to disrupt the membrane and permit the release of
electrolytes and nucleic materials, leading to cell death. Amino acid (Tryptophan) based cationic surfactants
having carbon lengths C14 and C16 were tested with Klebshiella aerogens (Gram -ve) and Bacillus substilis
(Gram +ve) and also give rise to semi-solid materials i.e. Gels, which can in turn have antimicrobial properties
and can have a variety of uses in terms of antibiotics.
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5074, (b) Das, D.; Roy, S.; Das, P. K. Org. Lett. 2004, 6, 4133-4136
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