RESUMO
Daucus carota L. (Family: Apiaceae alt. Umbelliferae), commonly known as 'wild carrot' or 'Queen Anne's-lace,' is an ecologically invasive erect biennial naturalized to Scotland. The ethnobotanical 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. carota seeds by reversed-phase preparative high performance chromatography were luteolin, luteolin 3'-O-beta-D-glucopyranoside and luteolin 4'-O-beta-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, luteolin showed the highest degree of free radical scavenging activity (RC50 = 4.3 x 10(-4) mg/mL) in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Both luteolin and its 4'-O-glucoside demonstrated bactericidal activity against Staphylococcus aureus and Escherichia coli (Minimum Inhibitory Concentration [MIC] = 5.0 x 10(-2) - 1.0 x 10(-1) mg/mL). Luteolin also demonstrated antibactericidal activity against Bacillus cereus and Citrobacter freundii (MIC = 5.0 x 10(-2) mg/mL). Luteolin 3'-O-glucoside showed bactericidal activity against Bacillus cereus and Lactobacillus plantarum (MIC = 2.5 x 10(-1) mg/mL and 5 x 10(-1) mg/ mL, respectively). In the brine shrimp lethality assay, the LD50 value of luteolin was 5.3 x 10(-2) mg/mL, and that of its 3'-O-glucoside and 4'-O-glucoside were > 1.0 mg/mL.