Quantitative Determination of β-Arbutin and Seven Flavonoids from Turnera diffusa (Damiana) Extracts and Dietary Supplements Claiming to Contain Damiana by Using HPLC-UV Method
Turnera diffusa Willd (Turneraceae), common name damiana, is an aromatic shrub with small yellow flowers. The leaves and sometimes the stems of damiana have medicinal uses. Evaluation of herbal dietary supplements marketed on the internet for recreational use shows that 10% of the most common products were claiming to contain damiana in the product ingredients [1,2]. An HPLC/UV method permitting the simultaneous determination of 8 compounds isolated from T. diffusa has been developed. A separation was achieved within 45 minutes by using the C-18 material column. The mobile phase was comprised of acetonitrile/methanol (90:10, v/v) containing 0.1% acetic acid and 50 mM ammonium acetate (pH = 4.2) at a flow rate of 1 mL/min and the column temperature was maintained at 30°C. The method was validated for linearity, repeatability, limits of detection (LOD) and limits of quantification (LOQ). The developed method was applied for the quantitative determination of eight compounds [β-Arbutin (1), apigenin 7-O-β-D-glucoside (2), tricin 7-O-β-D-glucoside (3), turneradiffusin (4), diffusavone (5), turneradin (6), apigenin 7-O-β-D-(5-O-β-coumaroyl)-glucoside (7) and echinaticin (8)] for two different species of Turnera and dietary supplements. The eight compounds in two different species of Turnera and dietary supplements were further confirmed by LC-ESI/MS. Acknowledgements: This research is funded in part by “Science Based Authentication of Dietary Supplements” Funded by the Food and Drug Administration grant number 2 U01 FD 002071-07. The authors would like to thank Annette Ford, University of Mississippi for extraction of samples. References:  Wiggins IL, (1980), Flora of Baja California, Stanford University Press, p.817.  Dermely CE, et al. (2005) The Ann. of Pharmacotherapy, 39: 1634–1639.