NMR Applications for Botanical Mixtures: The Use of HSQC Data to Determine Lignan Content in Sambucus williamsii

Lignans found in the botanical extract of the Traditional Chinese Medicine Sambucus williamsii Hance exhibit protective effects on trabecular bone mass and mechanical strength of cortical bone of ovariectomized rats. A novel approach was adapted using HSQC NMR methods to estimate the total amount of these bioactives in a complex mixture. It was determined that lignans possessing the hydroxy- or oxybenzyl carbon signal were bioactive. These compounds were readily identified and assigned in a defined region of the ¹³C NMR spectrum at 80-90 ppm and calculated as 10-15% of the lignan-rich fraction of S. williamsii. Comparison of the peak heights of the oxybenzyl-substituted carbon resonance signals of the lignans in the botanical extract was made against those of a standard lignan pinoresinol. The application of this simple and reliable NMR method can be used to estimate amounts of related compounds and chemical families in complex mixtures or botanical extracts and offers measurable scientific evidence in quality processes. This is of particular importance for registration requirements of botanical drugs and in complex mixtures of botanical extracts.