Authentication of Schisandra chinensis and Schisandra sphenanthera in Chinese patent medicines

Authentication of species is crucial for ensuring the safety and efficacy of herbal medicines. The fruits of Schisandra chinensis and S. sphenanthera have been used for the same traditional Chinese drug, Wuweizi, but are found to be quite different according to their constituents, pharmacological effects, and qualities. These two fruits have been recorded as Schisandrae Chinensis Fructus (Wuweizi) and Schisandrae Sphenantherae Fructus (Nan-wuweizi), respectively, by Chinese Pharmacopoeia, 2000 edition. However, Nan-wuweizi is often found to be taken as Wuweizi in some Chinese patent drugs intentionally or by mistake because of its lower price and similar characteristics to Wuweizi. In this study, the selection and validation of special chemical markers for the identification of Schisandra species were established by HPLC-DAD-MS profiling analysis. Simple TLC and HPLC methods were proposed for the accurate determination of Nan-wuweizi from Wuweizi in Chinese patent medicines, using schisandrin and anwulignan as the identifying markers for Wuweizi and Nan-wuweizi, respectively. Through the establishment of a statistical model, adulterated or misused ratios of Nan-wuweizi in Wuweizi (w/w), as well as in Fenghan Kesou pills, can be determined. The limit of detection of Nan-wuweizi in a mixture (w/w) using both TLC and HPLC methods is 5% (mixed crude drugs of 50mg and 5g in a 1000g prescribed amount). The constructed statistical model relating the HPLC peak area ratio (anwulignan/schisandrin) and adulteration ratio is suitable for mixed crude drugs and Fenghan Kesou pills, and the two fitting equations have a good correlation (r=0.9979). Furthermore, 36 commercial Chinese patent medicines containing Wuweizi or Nan-wuweizi according to their labels were checked by these methods, and Nan-wuweizi was detected in Renshen Wuweizi Granules and Fenghan Kesou Pills. The ratios of Nan-wuweizi in these mixtures (w/w) were 100:0 for both, which does not comply with the statutory prescription. This study provided a simple and reliable method to prevent the adulteration or misuse of Nan-wuweizi in crude drugs and patent medicines of Wuweizi.