Antimicrobial activity of long-chain, water-soluble, dendritic tricarboxylato amphiphiles.
OBJECTIVE
To measure the antimicrobial activities of three series of homologous, dendritic tricarboxylato (three-headed) amphiphiles against a battery of bacteria and fungi.


METHODS
Three series of homologous dendritic amphiphiles were synthesized containing C13 to C22 fatty chains. Susceptibility of Escherichia coli, Klebsiella pneumoniae, Lactobacillus plantarum, Micrococcus luteus, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Mycobacterium smegmatis, Saccharomyces cerevisiae, Candida albicans, Cryptococcus neoformans and Aspergillus niger to the amphiphiles was measured by broth microdilution and reported as the MIC.


RESULTS
Several amphiphiles from each homologous series, designed and constructed to overcome the low solubility of saturated long-chain fatty acids, had antimicrobial activity against MRSA (MIC = 36 mg/L), C. albicans (MIC = 4.4 mg/L), S. cerevisiae (MIC = 1.1 mg/L) and M. smegmatis (MIC = 8.9 mg/L). These amphiphiles had considerably better antimicrobial activities than the corresponding saturated fatty acids. Alkyl chain length influenced the values of MIC; longer chains (C18-C22) were generally more antimicrobial, but there was no uniform pattern among the microorganisms tested.


CONCLUSIONS
As the antimicrobial activity of the amphiphiles increased with increasing chain length, it is anticipated that maximum activity was not reached with these series. Thus, the identification of the optimal chain length would provide a target compound for development of low-cost, topical microbicides and anti-infectives. Further, these series of dendritic amphiphiles with the very long chains can be used as new water-soluble probes for elucidation of membrane structure and for identification of novel targets for antimicrobial design.
Williams
André A
AA
Department of Chemistry MC 0212, Virginia Tech, Blacksburg, VA 24061, USA.
Sugandhi
Eko W
EW
Macri
Richard V
RV
Falkinham
Joseph O
JO
Gandour
Richard D
RD
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D005227:Fatty Acids / Q000138:chemical synthesis / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D012995:Solubility; D013329:Structure-Activity Relationship
D000890:Anti-Infective Agents; D005227:Fatty Acids