The Assessment of Biological Activities Associated with the Major Constituents of the Methanol Extract of ‘Wild Carrot’(Daucus carotaL.) Seeds

Daucus carotaL. (Family: Apiaceae alt.Umbelliferae), commonly known as ‘wild carrot’ or ‘Queen Anne’s-lace,’ is an ecologically invasive erect biennial naturalized to Scotland. The ethno-botanical uses of this species include applications in the treatment of cough, diarrhea, dysentery, cancer, malaria and tumors, and as an antiseptic, abortifacient, aphrodisiac, carminative, stimulant, stomachic and tonic. The major constituents isolated from the methanol extract of D. carotaseeds by reversed-phase preparative high performance chroma-tography were luteolin, luteolin 3′-O-β-D-glucopyranoside and luteolin 4′-O-β-D-glucopyranoside, three flavones. The constituents were assessed for their antibacterial and free radical scavenging activities, as well as toxicity towards brine shrimp. Among these three flavones, lu-teolin showed the highest degree of free radical scavenging activity (RC50 = 4.3 ×10−4 mg/mL) in the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. Both luteolin and its 4′-0-glucoside demonstrated bactericidal activity against Staphylococcus aureusand Escherichia coli(Minimum Inhibitory Concentration [MIC] = 5.0 ×10−2-1.0 ×10−1 mg/mL). Luteolin also demonstrated antibactericidal activity against Bacillus cereusand Citrobacter freundii(MIC = 5.0 ×10−2 mg/mL). Luteolin 3′-0-glucoside showed bactericidal activity against Bacillus cereusand Lactobacillus plantarum(MIC = 2.5 ×10−1 mg/mL and 5 ×10−1 mg/ mL, respectively). In the brine shrimp lethality assay, the LD50 value of luteolin was 5.3 ×10−2 mg/mL, and that of its 3′-0-glucoside and 4′-0-glucoside were > 1.0 mg/mL.