Investigation of antibacterial & antioxidant activity for methanolic extract from different edible plant species in Palestine

Abstract

Medicinal plants are finding their way into pharmaceutical derivatives, cosmetics and food supplements. The present study was undertaken to investigate the leave extracts of eleven plant species; Malva sherardiana, Plumbago europaea, Ephedra alata, Arum Palestinum , Centaurea dumulosa , Eruca Sativa, Teucrium polium, Bupleurum subovatum , Geranium robertianum , Ononis speciosa and Plumbago auriculata for their potential activity against human bacterial pathogens and antioxidant efficiency. The crude extract of the plant leaves and selected antibiotic was evaluated against five different bacterial pathogens : Staphylococcus aureus , (gram positive), Escherichia coli , Proteus mirabilis , Klebsiella sp ., and Pseudomonas aeroginosa (gram negative) using agar well diffusion method. The Gram – positive bacteria S. aureus showed the higher susceptibility of inhibition with most plant extracts mainly Plumbago europaea methanol extract with zone of 12 mm, Centaurea dumulosa extract with 10 mm inhibition zone and Ononis speciosa with 6 mm inhibition zone. whereas Gram – negative bacteria; E. coli and P . aeruginosa showed some degree of susceptibility only for extracts of Centaurea dumulosa, and Klebsiella sp . Showed a little degree of inhibition with 2 mm zone for extracts of Bupleurum subovatum . In DPPH ( free radical scavenging assay ) for antioxidant evaluation for each plant extract ; Eruca Sativa had the lowest IC 50 value which was 11.74 μg/mL the closest value to Trolox IC 50 , Ephedra alata & Teucrium polium had also relatively potent antioxidant activity with 15.85 & 15.13 μg/mL IC 50 value respectively. On the other hand Plumbago auriculata was considered as the weakest plant on free radical scavenging assay with 83.56 μg/mL for IC 50 value. Other investigated medicinal plants showed relatively moderate free radical scavenging activity. This study support the use of these herbal plants traditionally to cure some infectious diseases, mainly caused by Gram – positive bacterium and also as antioxidant agents.