Isolation of Antimicrobials from Native Plants of Taif Governorate

Abstract

Plant defensins are subgroup of plant antimicrobial peptides that have high potentials in developing safe natural agricultural and pharmaceutical biocontrol products as alternatives for the current chemical pesticides, insecticides, and antibiotics. In this study, the level of defensin gene expression was evaluated in floral buds of 9 native plants from Saudi Arabia environment using reverse transcription and polymerase chain reaction (RT-PCR). As defensins are highly expressed at the mRNA level in Ochradenus baccatus (Ob), it was used for the isolation of defensin peptides using ion exchange chromatography followed by gel filtration using Sephadex G50. SDS-PAGE of ion exchange purified proteins detected several bands in a range of 2–10 kD. These proteins were separated by gel filtration using Sephadex G50. The resultant peptide of 5 kD showed an antimicrobial activity. The peptide inhibited Gram positive and Gram negative bacteria with IC50 ranged from 10 to 25 μg/mL. It also inhibited 25 to 60% of fungal linear growth at concentrations of 12.5 and 25 μg/mL. The present results demonstrate that, we could separate and purify a 5 kD peptide from Ob. This peptide could be utilized to develop natural antimicrobial products.