Packaging and storage— Preserve in well-closed containers, protected from light and moisture.

Labeling— The label states the Latin binomial and, following the official name, the part of the plant source from which the article was derived.

USP Reference standards 11—
USP Powdered Milk Thistle Extract RS.
USP Silybin RS.
USP Silydianin RS.

Botanic characteristics— The powder is characterized by fragments of colorless cells, up to approximately 75 µm in length and 8 µm in width, from the palisade layer of the epidermis of the fruit wall, with their adherent pigment layer (they assume a red color in chloral hydrate preparations), and by gray pieces, viewed from above, with the slitlike lumen produced by the pronounced wall thickening or the nodes on the cell wall formed by the thickened ridges; fragments of the pigment layer viewed from above, with red coloration diffusing out of them in chloral hydrate preparations, pigment cells alternating with colorless parenchymal cells; conspicuously stippled colorless cells through which pigment cells are visible when viewed from above; cigar-shaped or monoclinic calcium oxalate prisms, lying free or in groups of cells; numerous fragments of the lemon yellow palisade cells of the seed coat, up to roughly 150 µm in length, having a very narrow lumen and conspicuously stippled when viewed from above; pale yellowish fragments from the net cell layer together with portions of the embryo consisting of thin-walled cells with small glands and lipophilic substances.

Heavy metals 231: 20 µg per g.

Other requirements— It meets the requirements in the tests for Identification, Foreign organic matter, Total ash, Pesticide residues, Loss on drying, Microbial enumeration, and Content of silymarin under Milk Thistle.

Topic/Question	Contact	Expert Committee
Monograph	Maged H. Sharaf, Ph.D. Senior Scientist 1-301-816-8318	(DSB05) Dietary Supplements - Botanicals
Reference Standards	Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org

USP32–NF27 Page 1055

POWDERED MILK THISTLE

Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.