| ORIGINAL ARTICLE |
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| Year : 2019 | Volume
: 9
| Issue : 10 | Page : 434-442 |
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Bioguided isolation of antimicrobial polyphenols from Cuspidaria convoluta leaves and their synergistic effect with antibiotics
Carola A Torres1, Mario A Sturla2, Ana M Romero3, María A Judis3
1 Department of Basic and Applied Sciences, Microbiology Laboratory, Universidad Nacional del Chaco Austral, Comandante Fernández 755, Presidencia Roque Sáenz Peña, Chaco; Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
2 Department of Basic and Applied Sciences, Laboratory of Organic Chemistry, Universidad Nacional del Chaco Austral, Argentina
3 Department of Basic and Applied Sciences, Food Industry Laboratory, Universidad Nacional del Chaco Austral, Argentina
Correspondence Address:
Carola A Torres
Comandante Fernández 755, Presidencia Roque Sáenz Peña, Chaco
Argentina
 Source of Support: This work is financially supported by Secretaría de Ciencia y Técnica
UNCAUS and by Consejo Nacional de Investigaciones Científicas y Técnicas
(CONICET), Argentina, Conflict of Interest: None  | 3 |
DOI: 10.4103/2221-1691.269525
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Objective: To identify and isolate phenolic compounds from Cuspidaria convoluta, and to evaluate their antibacterial activity and synergistic effect with antibiotics.
Methods: The crude extract was prepared by maceration with methanol (5%). The dry extract was suspended in water and fractionated successively. The most active extract was selected by its antibacterial activity and its total phenol content was determined by spectrophotometry and by HPLC-MS/MS. Bioactive fractions of the most active extract were separated by column chromatography and evaluated by bioautography. Isolated compounds were identified. Minimum inhibitory concentration (MIC) of these compounds was determined by microdilution broth method, and synergism with antibiotics (ampicillin, gentamicin and oxacillin) was tested by checkerboard and time-kill assays.
Results: Coumaric acid, catechin/epicatechin, and luteolin were purified and identified from the extract. There was an increase in the antibacterial activity of antibiotics when they were combined with these compounds. The combination of luteolin and ampicillin had the most potent antibacterial activities. The MICs of oxacillin for each of methicillin-resistant Staphylococcus aureus strains were reduced between 4 and 8-fold when these strains were coincubated with sub-MIC (≤ ½ MIC) levels of these compounds, demonstrating that the combination had synergistic effect for all cases.
Conclusions: Cuspidaria convoluta contains important pharmacologically active substances that can be used to improve antibiotic efficacy.
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