Plant Cell Rep (2004) 23:419–425 DOI 10.1007/s00299-004-0862-3 PHYSIOLOGY AND BIOCHEMISTRY Susan J. Murch · H. P. Vasantha Rupasinghe · D. Goodenowe · Praveen K Saxena A metabolomic analysis of medicinal diversity in Huang-qin (Scutellaria baicalensis Georgi) genotypes: discovery of novel compounds Received: 8 March 2004 / Revised: 21 July 2004 / Accepted: 24 July 2004 / Published online: 22 September 2004  Springer-Verlag 2004 Abstract In vitro manipulation of plant regeneration in the Chinese medicinal species Scutellaria baicalensis Georgi (Huang-qin) resulted in 26 chemically distinct germplasm lines. Antioxidant potential, growth rate and concentration of baicalin, baicalein, melatonin, and wogo- nin were the selective markers used to identify elite lines. Metabolomic analysis of a subset of the most distinct lines revealed that Huang-qin extracts contained over 2,000 compounds including 781 determined to be of pu- tative medicinal importance as determined by a database search, as well as previously unidentified amino-deriva- tives of baicalin and wogonin. Huang-qin also contained a metabolite with the same net formula as hyperforin, pre- viously thought to be unique to Hypericum perforatum L. Together these results provide new insights into the bio- chemical complexity of an important medicinal species and demonstrate the power of in vitro manipulation in combination with untargeted metabolomic screening for the production of new germplasm. Keywords Scutellaria baicalensis · Baicalein · Wogonin · Melatonin · Metabolomics Introduction Huang-qin (Scutellaria baicalensis Georgi) is a medicinal species used extensively in Japanese Kampo medicines (Watanabe et al. 2002) and Chinese prescriptions. Huang- qin is used for the treatment of cancers, hepatitis, cir- rhosis, jaundice, hepatoma, leukemia, hyperlipemia, ar- teriosclerosis and inflammatory diseases (Chang et al. 2002). More recently, studies have focussed on the me- dicinal efficacy of Huang-qin preparations: whole plant preparations were effective in reducing prostate cancer (Hsieh et al. 2002); alcoholic extracts inhibited liver fiberosis (Nan et al. 2002) and delayed apoptosis in neuronal cells (Suk et al. 2003); and individual isolated compounds reduced the symptoms of Type 1 allergic reactions (Lim 2003). Baicalin, baicalein and wogonin— the most commonly isolated medicinal constituents in Huang-qin—were recently shown to inhibit the prolifer- ation of various human hepatoma cell lines (Chang et al. 2002; Okamura et al. 1999). Whole plant preparations are complex mixtures of many thousands of small metabolites and there is an enormous potential for identifying novel compounds in Huang-qin. In 1997, we discovered sig- nificant quantities of the human neurohormone and anti- oxidant, melatonin, in this species (Murch et al. 1997), results recently confirmed by others (Chen et al. 2003). In a complementary human clinical trial, consumption of Huang-qin-containing products was shown to alter diurnal fluctuations in patients’ plasma melatonin concentrations (Watanabe et al. 2002). Although there is growing evi- dence that Huang-qin contains a range of medicinally active phytochemicals from many different chemical classes, many remain unidentified, their phytochemical biosynthesis unknown and the specific details of their mechanisms of action undetermined. The objective of our research is to develop distinct germplasm lines of Huang-qin with differing phyto- Communicated by G.C. Phillips S. J. Murch ( ) ) Institute for Ethnobotany, National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, 96741, HI, USA e-mail: smurch@ntbg.org Tel.: +1-808-3327324 Fax: +1-808-3329765 H. P. V. Rupasinghe Department of Environmental Sciences, Nova Scotia Agricultural College, Nova Scotia, London, B2N 5E3 D. Goodenowe Phenomenome Discoveries, 204-407 Downey Rd, Saskatoon, SK, Canada, S7N 4L8 P. K. Saxena Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada, N1G 2W1