Antibacterial activities of Ligaria cuneifolia and Jodina rhombifolia leaf extracts against phytopathogenic and clinical bacteria

SOBERÓN, J.R.; SGARIGLIA, M.A.; DIP MADERUELO, M.R.; ANDINA, M.L.; SAMPIETRO, D.A.; VATTUONE, M.A.

JOURNAL OF BIOSCIENCE AND BIOENGINEERING

SOC BIOSCIENCE BIOENGINEERING JAPAN

Lugar: Osaka, Japon; Año: 2014 vol. 118 p. 599 - 605

1389-1723

Six plant extracts prepared from Ligaria cuneifolia and Jodina rhombifolia were screened for their potential antimicrobial activities against phytopathogens and clinically standard reference bacterial strains. Bioautography and broth microdilution methods were used to study samples antibacterial activities against 7 bacterial strains. The Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) of samples were attained. An antibacterial activity guided isolation and identification of active compounds was carried out for L. cuneifolia methanolic extract (LCME). Both methanolic and aqueous extracts from L. cuneifolia showed inhibitory activities against phytopatogenic bacteria, with MICs ranging from 2.5 to 156 μg . mL-1 for LCME and 5 mg . mL-1 for the aqueous extract. None of the three J. rhombifolia extracts showed significant antibacterial activities against phytopathogenic strains (MIC > 5 mg . mL-1), except for the aqueous extracts against Pseudomonas syringae (MIC = 312 μg . mL-1). Only LCME showed bactericidal activities against phytopathogenic strains (MBCs = 78 μg . mL-1). The LCME exhibited significant inhibitory activity against reference clinical strains: Escherichia coli (MIC = 156 μg . mL-1) and Staphylococcus aureus (MIC = 78 μg . mL-1, MBC = 312 μg . mL-1). LCME active compounds were identified as flavonol mono and diglycosides, and gallic acid. The antibacterial activity of purified compounds was also evaluated. A synergistic effect against Staphylococcus aureus was found between gallic acid and a quercetin glycoside. Hence, anti-phytopathogenic bacteria potential compounds isolated from L. cuneifolia could be used as an effective source against bacterial diseases in plants.