Screening for antibacterial and antibiofilm activities inAstragalus angulosus.
OBJECTIVE
In a search for finding novel therapeutic agents, extracts from an endemic Lebanese plant,Astragalus angulosus, were evaluated for their potentialin-vitroantibacterial and antibiofilm activities against three Gram-positive bacterial strains;Staphylococcus epidermidis(CIP444),Staphylococcus aureus(ATCC25923), andEnterococcus faecalis(ATCC29212); in addition to two Gram-negative strains,Escherichia coli(ATCC35218) andPseudomonas aeruginosa(ATCC27853).


METHODS
The plant was collected in April of 2013 and divided into several different portions, then its extracts were obtained by maceration using two different solvents. Extract analysis followed directly where microtiter broth dilution method was employed to assess antibacterial activity, while antibiofilm potential was tested using colorimetric method.


RESULTS
Whole plant ethanolic extract showed the highest bacteriostatic effect at a concentration of 12.78 mg/ml and also was the most versatile exerting its effect against 3 different strains. Other extracts also exhibited an effect but at higher concentrations and each against a single strain. Regarding antibiofilm activity, the majority of the extracts were able to eradicate >50% ofS. epidermidispreformed biofilm, where the highest activity was obtained with flower fraction extracted in water, achieving 67.7% biofilm eradication at 0.2 mg/ml.


CONCLUSIONS
This plant possesses a promising potential in regard to eradicating bacteria and their biofilms and it is the first contributing step of establishing a library for the endemic Lebanese plants in this domain.
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon; Centre International de Recherche en Infectiologie-Inserm U1111-Ecole Normale Supérieure de Lyon-CNRS UMR530, Beirut, Lebanon.
Hussein
H
Kanaan
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon.
Majid
M
El-Mestrah
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon; Microbiology Team, EA 1254, UFR Sciences Pharmaceutiques et Biologiques, University of Rennes 1, Université Bretagne.
Alaa
A
Sweidan
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon; PRASE, Platform of Research and Analysis in Environmental Sciences, Doctoral School of Sciences, Lebanese University, Hadat Campus, Beirut, Lebanon.
Falah
F
As-Sadi
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon; PRASE, Platform of Research and Analysis in Environmental Sciences, Doctoral School of Sciences, Lebanese University, Hadat Campus, Beirut, Lebanon.
Ali Al
AA
Bazzal
Department of Life & Earth Sciences, Faculty of Sciences I, Laboratory of Microbiology, Lebanese University, Beirut, Lebanon; PRASE, Platform of Research and Analysis in Environmental Sciences, Doctoral School of Sciences, Lebanese University, Hadat Campus, Beirut, Lebanon.
Ali
A
Chokr
Antibacterial; Astragalus angulosus; antibiofilm; minimal bactericidal concentration; minimal inhibitory concentration; phytochemical screening