Verbascum spp. (flower)

Botanical Voucher Specimen

Verbascum thapsus Source: MOBOT, Tropicos.org	Verbascum densiflorum Source: MOBOT, Tropicos.org	Verbascum phlomoides Source: MOBOT, Tropicos.org

Organoleptic Characteristics

Odor peculiar, agreeable; taste mucilaginous, not agreeable. [Dried,] nearly odorless; taste mucilaginous and slightly bitter. Source: United States Dispensatory (1918)

Macroscopic Characteristics

[Verbascum thapsus] is easily recognized by its tall, straight stem, its large felty or flannellike leaves, and its long, dense spike of yellow flowers. During the first year it produces only a rosette of downy leaves followed from June to August of the second year by the long flowering stalk. The densly hairy, erect stem sometimes reaches a height of 7 feet. The thick, felty leaves are from 4 to 6 inches in length and, with the exception of the basal ones, are stemless. Source: American Medicinal Plants of Commercial Importance (1930) Corolla light-yellow, the outer surface grayish with a fine, soft, woolly indumentum, the inner surface sparsely hairy and finely veined; tube of the corolla only 1 or 2 mm. in length and almost equally broad, the limb from 14 to 30 mm. in breadth, between wheel-shaped and saucer-shaped, obscurely two-lipped, the unequal lobes rounded-obovate. Stamens five, borne on the base of the corolla, shorter than the corolla, two of them longer than the other tliree, the filaments thick and fleshy, more or less pilose, especially the three shorter ones, usually orange colored. Stamen-hairs cylindrical, unicellular, non-branching, surface minutely reticulate, apex rounded, frequently enlarged. Pollen grains smooth, triangular and more or less rounded, from 0.025 to 0.03 mm. in diameter. The flowers impart a yellow color to boiling water, and a rather permanent green color with dilute sulphuric acid, the latter color becoming brown upon the addition of alkalies. Obovate with narrowed base, or varying to oblong or oblong-lanceolate, without a true petiole, obtuse or tending toward acuteness at the summit, from 1 to 6 dm. in length and from 3 to 15 cm. in breadth; very thick, rather tough, light yellowish-gray or greenish-gray, densely long-tomentose, with numerous, multicellular, branching, non-glandular hairs. Source: United States Dispensatory (1918) Source: PlantaPhile Source: PlantaPhile

High Performance Thin Layer Chromatographic Identification

Mullein (flower) HPTLC ID - NP and PEG reagent, UV 366 nm Mullein (flower) (Verbascum thapsus L., V. densiflorum Bertol. syn. V. thapsiforme Schrad, V. phlomoides L.) Lane Assignments Lanes, from left to right (Track, Volume, Sample): 2 µL Mullein flower 1 4 µL Mullein flower 1 8 µL Mullein flower 1 1 µL Mullein flower 1 (Ph. Eur extr.) 3 µL Mullein flower 1 (Ph. Eur extr.) 6 µL Mullein flower 1 (Ph. Eur extr.) 2 µL Caffeic acid 2 µL Rutin 2 µL Hyperoside 2 µL Mullein flower 2 4 µL Mullein flower 2 8 µL Mullein flower 2 2 µL Mullein flower 3 4 µL Mullein flower 3 8 µL Mullein flower 3  Reference Sample(s) Reference: Dissolve 3.5 mg of rutin in 5 mL of methanol; Dissolve 2 mg of caffeic acid in 5 mL of methanol; Optional: 4 mg of hyperoside in 5 mL of methanol.  Stationary Phase Stationary phase, i.e. Silica gel 60, F254  Mobile Phase Ethyl acetate, formic acid, water, ethyl methyl ketone 50:10:10:30 (v/v/v/v)  Sample Preparation Method Sample: Mix 1 g of powdered sample with 10 mL of methanol and sonicate at 60°C for 10 minutes, then centrifuge or filter the solutions and use the supernatants / filtrates as test solutions. Derivatization reagent: 1.) NP reagent, Preparation: 1 g of NP reagent in 200 mL ethyl acetate; 2.) PEG reagent, Preparation: 10g of polyethylene glycol 400 in 200 mL of dichloromethane, Use: Heat plate for 3 min at 100°C, then dip (time 0, speed 5) in NP reagent, dry and dip (time 0, speed 5) in PEG reagent.  Detection Method Saturated chamber; developing distance 70 mm from lower edge; relative humidity 33%  Other Notes Images presented in this entry are examples and are not intended to be used as basis for setting specifications for quality control purposes. System suitability test: Rutin: orange fluorescent zone at Rf ~ 0.38; Caffeic acid: blue fluorescent zone at Rf ~ 0.89. Identification: Compare result with reference images in Image Comparison Viewer. The fingerprint of the test solution is similar to that of the corresponding botanical reference sample. Additional weak zones may be present. The chromatogram of the test solution shows an intense bluish zone at Rf ~ 0.40 just above the position of reference substance rutin. There is another bluish zone at Rf ~ 0.60 slightly higher than the position of reference substance hyperoside. Just below the position of reference substance caffeic acid there is an intense bluish zone at Rf ~ 0.82 and just above caffeic acid there is a yellow zone at Rf ~ 0.90. Source: HPTLC Association