In Vitro Antimicrobial effects of Extracts from Leaves of Medicinal Herbs and Native Brazilian Plants

The objective of this study was to evaluate the antimicrobial effects of crude and lyophilized extracts of leaves from sweet passion fruit (Passiflora alata), araçá (Psidium cattleianum), rosemary (Rosamrinus officinalis) and oregano (Origanum vulgare) on planktonic cells of Staphylococcus aureus and Aspergillus parasiticus. Sweet passion fruit showed no inhibitory effect against the micro-organisms tested. However, crude and lyophilized extracts from Araçá had the highest (P < 0.05) antimicrobial activity against S. aureus, with minimum inhibitory concentrations (MIC) of 0.39 and 0.35 mg/ml, respectively. MIC values against S. aureus for lyophilized extracts from rosemary and crude extracts from oregano were 0.57 and 0.65 mg/ml, respectively. None of the extracts demonstrated effective results against A. parasiticus, although araçá and oregano extracts had the lowest (P < 0.05) MIC values when compared with the other extracts. This preliminary screening study indicated that araçá, rosemary and oregano are interesting alternatives as antimicrobial agents in food substrates, although further studies are needed to develop commercial formulations based on field trials.