Polyphenols, flavonoids and antimicrobial properties of methanolic extract of fennel (Foeniculum vulgare Miller)

To address the ever increasing resistance of pathogens and need of safer preservatives for food products, herbs are being explored for antimicrobial properties. Methanolic extract of Fennel (Foeniculum vulgare Miller) was analyzed for the presence of polyphenolic compounds, flavonoids and antibacterial potential. The extract, rich in flavonoids (9.325 ± 1.25 mg QE/g dry seeds) was subjected to HPLC analysis for identification and quantification of phenolics. Gallic acid (277.131μg), caffeic acid (166.062μg), ellagic acid (99.476μg), quercetin (781.986μg) and kaempferol (92.856μg)/g dry seeds were identified. Antibacterial activities ofmethanolic extract of dried fennel seeds were determined against pathogenic bacteria Bacillus pumilus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by determining cell damage, growth inhibition zone and minimum inhibitory concentration. Fennel extract caused cell damage and effectively inhibited the growth of Bacillus pumilus and Staphylococcus aureus. Minimum inhibitory concentration of fennel, determined by agar well diffusion method, was 8.33mg/ml for B. pumilus and S.aureus. The results suggest that methanolic extract of fennel containing polyphenols including gallic acid, caffeic acid, ellagic acid, quarcetin and kaempferol has efficient antimicrobial activity against pathogenic gram positive bacteria understudy.