Evaluation of the antibiofilm and antimicrobial activities of Glycyrrhiza glabra and Viola odorata in poly herbal formulations

Traditional polyherbal formulations are essential part of health system in various populations in the subcontinent region including Pakistan, however scientific evaluation of such claims are not significant. In this investigation, the antibiofilm and antimicrobial activities of Glycyrrhiza glabra and Viola odorata, two important ingredients of a traditional herbal formulation were determined in synergism. Various fractions of plants extract were prepared in the order of polarity. All fractions were tested against Gram negative (Streptococcus pneumoniae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa) and Gram positive (Staphylococcus aureus and Salmonella typhi) bacteria and antimicrobial activity was assessed using agar diffusion method. The MIC (Minimum Inhibitory concentration), was assessed. Finally antibiofilm activities were determined using 96 micro wells plate by calculating percent inhibition. In case of Viola oldorata, the inhibition zone ranged between (6mm to 18 mm +/- 1.24) against the test strains. The highest inhibition was recorded against gram positive bacteria Strep: Pneumoniae (20 mm +/- 0.99) followed by S. aureus (18 mm +/- 1.02) using methanolic extract. A moderate level of inhibition was seen in case of Glycyrrhiza glabra against the microbial strains. It was noticed that Glycyrrhiza Glabra was more active against gram negative bacteria. The methanolic fraction presented highest activity against e coli (18 mm +/- 0.96) followed by K. pneumoniae and P. aureginosa (12 mm +/- 1.22).The MIC ranged between 4-8 mg/mL. During antibiofilm assay, a moderate level of inhibition occurs using the Viola odorata (40% inhibition) and Glycyrrhiza glabra (45% inhibition), that increased by using combination of both plants in 50:50 ratio. It was concluded that the effective properties of indigenous poly herbal formulation are due to synergism causing greater antibiofilm characteristics against the biofilm producer strains as well as other pathogenic microorganisms.