Application of multivariate statistical analysis for the discovery of compounds with c-Myb-inhibitory activity in extracts of Juglans species

Ellendorff T, Sendker J, Klempnauer KH, Schmidt TJ

Abstract

The identification of bioactive compounds within an extract has always been a capital aim of phytochemical research. Up to now, bioactivity guided fractionation has been the most popular method to achieve this aim, a method characterized by high expenses regarding time and resources. However, the development of fast analytical methods, having taken place during the last decades, finally allows an alternative and reformative approach to the active constituents of an extract. In this project, partial least squares regression (PLS) has been applied to different extracts of Juglans species in order to discover the constituents responsible for their c-Myb inhibitory activity. c-myb, a proto-oncogene and transcription factor, is supposed to be of relevance for the hematopoietic system. The deregulation of c-myb is connected to certain kinds of cancer i.e. leukemia, breast and colon cancer. c-Myb inhibitors are considered interesting as new leads against these diseases1. In the course of the present study, extracts of Juglans sp. have been proven to possess c-Myb inhibitory activity in a cellular assay, based on doxycyclin-induced c-Myb activity coupled with GFP-mediated fluorescence. Samples were taken from different plant materials of diverse Juglans species at variable times in the vegetation period and different extraction methods were applied to obtain a variety of crude extracts. UHPLC-/ESI-qTOF-MS was employed to generate analytical fingerprints of these extracts. IC50 values of the c-Myb inhibition were determined in the assay mentioned above. Using multivariate statistics software (Unscrambler), PLS models were constructed correlating the activity with analytical data. These models allowed localizing compounds in the LC/MS chromatograms which are most likely responsible for the c-Myb inhibitory activity. Targeted isolation of these compounds is in progress. Reference: [1] C. Schomburg, W. Schuehly, F.B. Da Costa, K.-H. Klempnauer, T.J. Schmidt. Eur. J. Med. Chem. 63, 313 - 320 (2013)

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