Journal of Pharmaceutical and Biomedical Analysis 53 (2010) 723–728 Contents lists available at ScienceDirect Journal of Pharmaceutical and Biomedical Analysis journal homepage: www.elsevier.com/locate/jpba Short communication Secondary metabolite mapping identifies Scutellaria inhibitors of human lung cancer cells Jiayu Gao a , Huiying Zhao b , Peter J. Hylands b , Olivia Corcoran a,∗ a Medicines Research Group, School of Health and Bioscience, University of East London, Stratford, London E15 4LZ, UK b Department of Pharmacy, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK article info Article history: Received 11 February 2010 Received in revised form 1 April 2010 Accepted 3 April 2010 Available online 20 April 2010 Keywords: Scutellaria Metabolomics Human lung cancer cells Baicalein Baicalin Wogonin abstract Scutellaria baicalensis root is widely used in China as an adjuvant to orthodox chemotherapy of lung cancer. However, functional biomarkers of this plant for anti-lung cancer activity have not yet been reported. We therefore determined the growth inhibition activity by MTT assay of eight solvent extracts of S. baicalensis in the human lung cancer cell line SK-MES-1. This activity was then mapped onto the secondary metabolite profile of crude extracts by principal components analysis (PCA) of proton NMR and HPLC-UV data. NMR- and HPLC-PCA maps revealed highest inhibitory activity for the non-aqueous extracts. The first two components of both maps discriminated extract activity mainly based on the differential content of three compounds, which were then tested individually. The IC 50 values for baicalin (IC 50 : 64 ± 5 M), baicalein (IC 50 : 80 ± 6 M) and wogonin (IC 50 : 39 ± 10 M) were comparable to that of the antineoplastic cisplatin (IC 50 : 79 ± 16 M). A partial least squares regression (PLS)-NMR model highly correlated with the corresponding PLS-HPLC model for prediction of inhibition. Secondary metabolite mapping of lung cancer growth inhibitors in crude extracts may be an important first step to qualify Chinese herbal prescriptions required for meaningful clinical trials of such integrated therapies. © 2010 Elsevier B.V. All rights reserved. 1. Introduction In China, a hot water infusion of Scutellaria baicalensis Georgi root (Chinese skullcap) is used as an oral adjuvant in conventional chemotherapy of lung cancer [1]. However, the clinical evidence- base for this traditional herbal use, either alone or as part of a Chinese patent medicine Huang Qin, is sparse [1]. Clearly a con- founding variable in evaluating such integrated therapy is the herbal quality, a point rarely addressed in clinical reports. In con- trast to Chinese practitioners using oral infusions as an adjuvant to lung cancer chemotherapy, UK medical herbalists use S. baicalen- sis tincture to treat inflammation [2]. There is a similar lack of scientific evidence for this clinical practice although some of us recently reported wide variability in quality amongst commercial products of identical claimed formulation [3]. An ongoing prob- lem concerning herbal products remains the validation of agreed functional biomarkers within the complex natural product and their clinical formulations. These are defined here as chemical con- stituents shown to have in vitro activity relevant to therapeutic use. Commonly, functional biomarkers for a plant product are agreed by government expert panels on the basis of published chemi- cal analysis of major constituents [1,4,5]. However, this is often ∗ Corresponding author. Tel.: +44 208 223 4034; fax: +44 208 223 4965. E-mail address: o.corcoran@uel.ac.uk (O. Corcoran). confounded by species differences in chemical constituents and conflicting results from published in vitro pharmacological assays for formulations that are not relevant to clinical use. Concerning S. baicalensis root, the flavonoids, baicalein, baicalin and wogonin (Fig. 1), have been reported as functional biomark- ers of anti-cancer activity against a wide range of in vitro cancer cell lines except lung cancer. Selective induction of apoptosis and cell cycle arrest in cancer cells compared to normal cells are but two of a myriad of mechanisms that constitute rational anti-cancer drug targets [6]. Baicalein is an inhibitor of one important regula- tor of human cancer development, platelet-type 12-lipoxygenase (12-LOX) and has already been shown to initiate apoptosis in prostate cancer cell lines DU-145 and PC-3 in a dose-dependent manner. Mechanistic evidence included decreased phosphoryla- tion of Akt, loss of survivin and subsequent activation of caspase-3 and caspase-7 in both lines, decreased Bcl-2 and Bcl-X L expression only in DU-145, and a shift in Bcl-2/Bax levels favouring apoptosis in PC-3 cells. Baicalein (25 M) has been shown to induce expression of cyclin D1 and D3 proteins causing G 0 /G 1 stage arrest in DU-145 and PC-3 cells [7]. Wogonin has also been reported to induce G 1 stage arrest for human U-937 leukaemia cells via stimulating the expression of phosphorylated protein kinase C (PKC), upregulat- ing p21 protein and decreasing the cyclin D-CDK 4 complex and p-Rb [8]. However, in vitro activity of either Scutellaria extracts or the biomarkers in animal or human lung cancer cell lines has not yet been reported. Therefore we employed a multivariate data 0731-7085/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jpba.2010.04.019