Development and validation of a UHPLC-PDA-MS method for the quantitative analysis of anthraquinones in Bulbine natalensis extracts and dietary supplements

Authors: BAE, JI-YEONG - University Of Mississippi; AVULA, BHARATHI - University Of Mississippi; WANG, YAN-HONG - University Of Mississippi; WANG, MEI - University Of Mississippi; ALI, ZULFIQAR - University Of Mississippi; VILJEON, ALVARO - Tshwane University; KHAN, IKHLAS - University Of Mississippi

Submitted to: Planta Medica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2019
Publication Date: 11/25/2019
Citation: Bae, J., Avula, B., Wang, Y., Wang, M., Ali, Z., Viljeon, A.M., Khan, I.A. 2019. Development and validation of a UHPLC-PDA-MS method for the quantitative analysis of anthraquinones in Bulbine natalensis extracts and dietary supplements. Planta Medica. 86:144-150. https://doi.org/10.1055/a-1037-4051.
DOI: https://doi.org/10.1055/a-1037-4051

Interpretive Summary: • Several Bulbine natalensis dietary supplements claiming to elevate testosterone levels are currently on the market in the United States for the enhancement of sexual behavior and muscle development in men. • To date, no analytical method for quantification and confirmation of anthraquinone-type compounds from B. natalensis reported in the literature. • The developed UHPLC method for the quantitative determination of seven anthraquinone-type compounds from the subterranean parts of B. natalensis and B. frutescens. • The developed method was validated for all parameters tested. • Market products revealed significant product-to-product variations. Five of nine products contained anthraquinone-type compounds with total content ranging from 11.3 to 90.4 mg per daily dose. • LC-mass spectrometry coupled with electrospray ionization (ESI) method was used for the identification of compounds in plant samples and dietary supplements.

Technical Abstract: A validated ultra-high performance liquid chromatography-photodiode array-mass spectrometry (UHPLC-PDA-MS) method was developed for the quantification of seven anthraquinone-type compounds from Bulbine natalensis. The separation was achieved using a reversed phase (C-18) column, photodiode array detection, and a gradient of water/acetonitrile as the mobile phase. The seven compounds could be separated within 15 minutes using the UHPLC method with detection limits of 25 ng/mL with 2 µL injection volume. The analytical method was validated for linearity, repeatability, accuracy, limits of detection (LOD) and limits of quantification (LOQ). The relative standard deviations (RSD) for intra- and inter-day experiments were less than 5% and the recovery efficiency was 98-101%. Nine supplements labeled as containing B. natalensis were examined. Five of nine products contained anthraquinone-type compounds with total content ranging from 11.3 to 90.4 mg per daily dose. Compounds of B. natalensis were not detected in the four of nine supplements. The analytical method is simple, economic, rapid and especially suitable for quality control analysis of B. natalensis. Liquid Chromatography-Mass Spectrometry (LC-MS) coupled with electrospray ionization (ESI) was used for the identification and confirmation of compounds in plant samples and dietary products.