High Throughput Antibacterial Screening of Plant Extracts by Resazurin Redox with Special Reference to Medicinal Plants of Western Ghats

A new high throughput antibacterial method employing the dye resazurin as an indicator of bacterial growth was developed to evaluate drug susceptibility by combined measurements of microtitre-plates, colorimetric and haemocytometric assays. The bacterial strains E. coli, B. subtilis, P. aeruginosa and S. aureus (multi-drug resistant strain) were used to evaluate the preliminary screening of plant extracts, minimum inhibition concentration (MIC) and minimum bacterial concentration (MBC) with streptomycin and tetracycline as reference antibiotics. The antibacterial activity of selected medicinal plant extracts were carried out against all the four bacteria by the same method and the values compared the value with reference antibiotics. The present study resulted in a rapid, reliable, simple and inexpensive method suitable for testing the susceptibility of bacterial strains to screen the medicinal plant extracts; its employment in evaluating new antibacterial molecules from the plant source is also suggested.