title: In vitro antibacterial activity and in vivo therapeutic effect of Sesbania grandiflora in bacterial infected silkworms.
abstract: BACKGROUND
  Antibiotic resistance is a serious problem worldwide. Searching for new potential agents is, therefore, essential. The bark of Sesbania grandiflora (L.) Pers. (Fabaceae) has been used in folk medicine against various diseases.
  
  
  OBJECTIVE
  To investigate the antibacterial activity of S. grandiflora bark and explore the therapeutic effect of the highest potent fraction.
  
  
  METHODS
  Bacteria and healthy silkworms were exposed to three fractionated extracts (3.1-400 mg/mL) of S. grandiflora bark from hexane (HXF), chloroform (CFF), and ethyl acetate (EAF). The sets of bacteria were incubated at 37 °C while silkworms were kept at 27 °C for 24 h. To evaluate the therapeutic effect, silkworms infected with bacteria were exposed to the extracts (0.5-60 mg/mL) and incubated at 27 °C for 52 h. Qualitative analysis of the most potent extract was done using HPLC.
  
  
  RESULTS
  EAF showed the highest activity with MIC against methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE) of 1.6 and 0.4 mg/mL, respectively, and against Gram-negative Escherichia coli and Pseudomonas aeruginosa of 6.2 and 3.1 mg/mL, respectively. It is nontoxic to silkworms with LC50>400 mg/mL and has high therapeutic effect on infected silkworms with EC50of 1.9 mg/mL. EAF consists of at least five major compounds, one of them is gallic acid. The activity of EAF is higher than the sum of individual activities of separated compounds.
  
  
  CONCLUSIONS
  These results suggest that EAF is a promising antibacterial extract, suitable for further investigation in rodents infected with drug resistant bacteria.
authors.affiliation: a Department of Pharmaceutical Sciences, Faculty of Pharmacy , Chiang Mai University , Chiang Mai , Thailand.
authors.forename: Pimporn
authors.initials: P
authors.lastname: Anantaworasakul
authors.affiliation: b Institute of Medical Mycobiology , Teikyo University , Tokyo , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hamamoto
authors.affiliation: b Institute of Medical Mycobiology , Teikyo University , Tokyo , Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Sekimizu
authors.affiliation: a Department of Pharmaceutical Sciences, Faculty of Pharmacy , Chiang Mai University , Chiang Mai , Thailand.
authors.forename: Siriporn
authors.initials: S
authors.lastname: Okonogi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D012831:Bombyx / Q000187:drug effects* / Q000382:microbiology*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000502:physiology; D008826:Microbial Sensitivity Tests / Q000379:methods; D024301:Plant Bark; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology; D049931:Sesbania
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts
keywords: Antibacterial extract; drug-resistant organisms; killing rate; silkworm infection