Powdered Red Clover Extract
» Powdered Red Clover Extract is prepared from Red Clover by extraction with hydroalcoholic mixtures or other suitable solvents. The ratio of plant material to extract is between 3:1 and 25:1. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of isoflavones, calculated on the dried basis as the sum of daidzein, genistein, formononetin, and biochanin A. It may contain suitable added substances.
Packaging and storage— Preserve in tight, light-resistant containers, in a cool place.
Labeling— The label states the Latin binomial and, following the official name, the part of the plant from which the article was prepared. The label also indicates the content of isoflavones, the extracting solvent or solvent mixture used for preparation, and the ratio of the starting crude plant material to Powdered Extract. It meets the requirements for labeling under Botanical Extracts 565.
A: Thin-Layer Chromatographic Identification Test 201
Standard solution, Developing solvent system, Spray reagent A, Spray reagent B, and Procedure— Proceed as directed for Thin-Layer Chromatographic Identification Test 201 under Red Clover.
Test solution— Shake a quantity of Powdered Extract, equivalent to 25 mg of the labeled amount of isoflavones, in 20 mL of methanol. Allow to stand for 15 minutes before use.
B: The chromatogram of the Test solution exhibits peaks for daidzein, genistein, formononetin, and biochanin A at retention times that correspond to those in the chromatogram of Standard solution 1, as obtained in the test for Content of isoflavones. Calculate the ratio of 5,7-dihydroxyisoflavones to 7-hydroxyisoflavones by the formula:
(B + G)/(D + F)
in which B, G, D, and F are the percentages of biochanin A, genistein, daidzein, and formononetin, respectively, as obtained in the test for Content of isoflavones: the ratio is between 0.1 and 10.0.
Microbial enumeration 2021 It meets the requirements of the tests for absence of Salmonella species and Escherichia coli. The total aerobic microbial count does not exceed 104 cfu per g, the total combined molds and yeasts count does not exceed 1000 cfu per g, and the enterobacterial count is not more than 1000 cfu per g.
Loss on drying 731: Dry 1 g at 105 for 2 hours. It loses not more than 5.0%.
Heavy metals, Method II 231: not more than 10 µg per g.
Content of isoflavones—
Solvent, Solution A, Solution B, Standard solution 1, Standard solution 2, and Chromatographic system— Proceed as directed under Red Clover.
Test solution— Transfer an accurately weighed quantity of Powdered Extract, equivalent to about 30 mg of the labeled content of isoflavones, to a 250-mL volumetric flask. Add 15 mL of dehydrated alcohol, sonicate until dissolved, dilute with Solvent to volume, and mix. Transfer 50.0 mL of this solution to a round-bottom flask, and evaporate to dryness under vacuum. Add 15 mL of 2 N hydrochloric acid, and heat in a water bath for 30 minutes. Quantitatively transfer the resulting solution with the aid of about 15 mL of alcohol to a 50-mL volumetric flask, and dilute with Solvent to volume. Centrifuge, or pass through a filter having a 0.45-µm or finer porosity.
Procedure— Proceed as directed under Red Clover. Separately calculate the percentage of each relevant isoflavone component in the portion of Powdered Extract taken by the formula:
25F(C/W)(rU / rS)
in which W is the weight, in g, of Powdered Extract taken to prepare the Test solution; and the other terms are as defined therein. Calculate the percentage of isoflavones in the Powdered Extract taken by adding the individual quantities calculated.
Other requirements— It meets the requirements for Packaging and Storage, Residual Solvents, and Pesticide Residues under Botanical Extracts 565.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Maged H. Sharaf, Ph.D.
Senior Scientist
(DSB05) Dietary Supplements - Botanicals
Reference Standards Lili Wang, Technical Services Scientist
2021 Radhakrishna S Tirumalai, Ph.D.
Senior Scientist
(MSA05) Microbiology and Sterility Assurance
USP32–NF27 Page 984
Pharmacopeial Forum: Volume No. 30(2) Page 552
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.