Development of Kudzu (Pueraria Montana var. lobata) Reference Materials for the Determination of Isoflavones and Toxic Elements.

Abstract

In collaboration with the Office of Dietary Supplements at the National Institutes of Health, the National Institute of Standards and Technology issued a suite of botanical matrix reference materials (RMs) and Standard Reference Material® (SRM) for determination of isoflavones and toxic elements in kudzu dietary supplement ingredients. RM 8650 Pueraria montana var. lobata (Kudzu) Rhizome, SRM 3268 Pueraria montana var. lobata (Kudzu) Extract, and RM 8652 Kudzu-Containing Solid Oral Dosage Form were issued with values assigned for isoflavones (puerarin, daidzin, and daidzein), toxic elements (arsenic, cadmium, and lead), and selenium. Isoflavone values were assigned using liquid chromatography with UV absorbance or mass spectrometry detection. Element values were assigned using inductively coupled plasma mass spectrometry and results from an interlaboratory comparison exercise. Mass fractions for puerarin were 32.2 ± 3.2 mg/g, 128 ± 13 mg/g, and 68.2 ± 6.9 mg/g in RM 8650, SRM 3268, and RM 8652, respectively. Arsenic increases from 156 ± 14 ng/g to 849 ± 83 ng/g and cadmium decreases from 348 ± 14 ng/g to 82.1 ± 4.9 ng/g from rhizome to extract. The kudzu RM/SRM suite complements previously issued soy-related SRMs with values assigned for isoflavones, which have been studied for their potential health benefits, and expands the analytical resource by providing values for puerarin, an isoflavone not found in soy. The three new kudzurmaterials are for use in the determination of isoflavones, toxic elements, and selenium. For the isoflavones, these new kudzu materials provide higher levels of daidzin and daidzein than existing soy-related SRMs, and they provide a value for an isoflavone not in existing SRMs (puerarin). Toxic elements in RM 8650 and SRM 3268 provide new botanical matrixes for use by dietary supplement manufacturers for the verification of the safety of their raw materials.