Isolation of antibacterial components from infusion of Caesalpinia paraguariensis bark. A bio-guided phytochemical study

The antimicrobial activities and toxicity of infusion, decoction and tincture of Caesalpinia paraguariensis Burk. bark (CPBEs) were investigated to validate its traditional use as drink additive and to identify microbicidal component(s). The minimum inhibitory concentrations (MIC) of CPBEs against aerobic bacteria (Gram-negative and Gram-positive species) were determined using standardised dilution methods. The LC50 were determined by Brine Shrimp Test. CPBEs showed bacteriostatic and bactericidal activity against tested strains. The highest activity was observed for infusion (MIC:200 μg/mL) against Morganella morganii, Erwinia carotovora, Bacillus spp., Staphylococcus spp. and Enterococcus spp. The bacterial species were susceptible to CPBEs (MIC:200–1993 μg/mL) at lower concentration than sodium benzoate, a known food preservative. Two bioactive components were isolated from liophylised infusion by bio-guided chromatographic procedures; these were identified by spectrometric techniques as ellagic and 3-O-methylellagic acids. This study demonstrated that C. paraguariensis bark infusion it is safe for human consumption and a possible source of food natural preservatives.