Phytochemical screening, antioxidant and antimicrobial activities of seeds of Foeniculum vulgare (ensilal)

Abstract

Fennel (Foeniculum vulgare Mill) is one of the oldest spice plants which are considered as one of the world’s most important medicinal plants. Phytochemical screening, the total phenolic contents (TPC), total flavonoid contents (TFC), in vitro antioxidant, and antimicrobial activities of extracts of Foeniculum vulgare seeds were investigated. The antioxidant activity was measured using 1, 1 Diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, reducing power and total antioxidant activity. Foeniculum vulgare extracts were also investigated for in vitro antibacterial screening by disc diffusion method against Bacillus megaterium, Entrococcus gallinarium, Escherichia coli and Pseudomona aeruginosa. Methanol extracts contained the highest TPC [(22.93 ± 7.17) mg GAE/g], and TFC [(8.581 ± 1.22) μg CE/mg] and water extract showed the highest DPPH radical scavenging activity (IC₅₀ = 207.94 ± 83.38 μg/mL). The results also showed that the aqueous: methanol (20:80, v/v) extract had strongest reducing ability (0.711 ± 0.102 nm) as compared to other extracts. Methanol extract exhibited the highest total antioxidant capacity (1.63 ± 0.19 mg/mL) as determined by the phosphomolybdenium method. Of the Foeniculum vulgare extracts, the highest inhibition zone was found in aqueous: methanol (20:80, v/v) extracts of the (12.29 ± 1.34 mm) against Bacillus megaterium. The study revealed that antioxidant and antimicrobial activities of the crude extract of Foeniculum vulgare extracted by different solvents indicating a high potential to be used as natural antioxidants in food preservation as well as for preventing oxidative stress mediated human disorders.