Biological activity of common mullein, a medicinal plant Arzu Ucar Turker a,b , N.D. Camper a, * a Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29634-0377, USA b Department of Biology, Abant Izzet Baysal University, Bolu 14280, Turkey Received 1 June 2001; received in revised form 20 June 2002; accepted 27 June 2002 Abstract Common Mullein (Verbascum thapsus L., Scrophulariaceae) is a medicinal plant that has been used for the treatment of inflammatory diseases, asthma, spasmodic coughs, diarrhea and other pulmonary problems. The objective of this study was to assess the biological activity of Common Mullein extracts and commercial Mullein products using selected bench top bioassays, including antibacterial, antitumor, and two toxicity assays */brine shrimp and radish seed. Extracts were prepared in water, ethanol and methanol. Antibacterial activity (especially the water extract) was observed with Klebsiella pneumonia , Staphylococcus aureus , Staphylococcus epidermidis and Escherichia coli . Agrobacterium tumefaciens- induced tumors in potato disc tissue were inhibited by all extracts. Toxicity to Brine Shrimp and to radish seed germination and growth was observed at higher concentrations of the extracts. # 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Mullein; Bioassays; Antibacterial; Antitumor; Brine shrimp; Radish seed 1. Introduction Common Mullein, also known as Wooly Mullein (Verbascum thapsus L., Scrophulariaceae), is an erect biennial plant, low growing rosette of bluish gray-green color in the first year, while mature second-year flower- ing plants grow to 5  /10 ft in height, including the conspicuous flowering stalk. It is native to Europe and Asia (Semenza et al., 1978) and was probably intro- duced to North America several times as a medicinal herb (Gross and Werner, 1978). Since ancient times, Common Mullein has been used as a medicinal herb. The leaves and flowers are reported to have expectorant and demulcent properties which are used to treat respiratory problems such as bronchitis, dry coughs, whooping cough, tuberculosis, asthma, and hoarseness (Grieve, 1981; Mabey, 1988; Tyler, 1993, 1994). The mucilaginous constituents are primarily responsible for the soothing actions on mucous mem- branes, and saponins may be responsible for the expectorant actions of mullein (Tyler, 1993). The plant is reported to be mildly diuretic and to have a soothing and anti-inflammatory effect on the urinary tract, and to act as a mild sedative. Oil made from the flowers is used to help sooth earache, and can be applied externally for eczema and other types of inflamed skin conditions (Millspaugh, 1974; Grieve, 1981; Tyler, 1993, 1994; Yarnell, 1997). Mullein is astringent and is used to treat hemorrhoids and diarrhea. It has also been used as a domestic remedy for pneumonia, fever, congestion, allergies, migraine, tumor formation, throat ailments, tonsilitis, skin ailments, catarrhs and colic (Millspaugh, 1974; Grieve, 1981; Mabey, 1988). Antiviral activity against influenza in chicken embryos has been reported (Mehrotra et al., 1989). Leaf extracts of V. thapsus have been shown to be active against bovine herpes virus type 1, and showed slight antibacterial and antifungal activity (McCutcheon et al., 1992, 1994, 1995). A methanol extract has been shown to be effective against mosquito larvae (Gross and Werner, 1978). Constituents of V. thapsus include polysaccharides; iridoid glycosides including harpagoside; harpagide and aucubin (especially in the leaf); flavonoids, including 3?- methylquercitin, hesperidin and verbascoside; saponins and volatile oils (Pascual Teresa et al., 1978a,b, 1980; Hattori and Hatanaka, 1958; Khuroo et al., 1988; Mehrotra et al., 1989; Warashina et al., 1991, 1992). * Corresponding author. Tel.:  /1-864-656-5743; fax:  /1-864-656- 0274 E-mail address: dcamper@clemson.edu (N.D. Camper). Journal of Ethnopharmacology 82 (2002) 117  /125 www.elsevier.com/locate/jethpharm 0378-8741/02/$ - see front matter # 2002 Elsevier Science Ireland Ltd. All rights reserved. PII:S0378-8741(02)00186-1