A chemometric approach to the quality control of Sutherlandia (cancer bush)

Abstract

Sutherlandia frutescens (Fabaceae) commonly known as cancer-bush, is a well-known traditional phytomedicine in South Africa used to treat a range of ailments. There is limited information available on the phytochemistry and chemical variation within and between the S. frutescens and Sutherlandia microphylla species complex. This paper aims to elucidate the chemical variation of phytoconstituents (other than the non-protein amino acids) between the two species S. frutescens and S. microphylla and also between the wild and cultivated varieties of S. frutescens. An UPLC–MS analysis in tandem with chemometric analysis has been performed to assess the metabolite content of aerial plant parts obtained from different populations. Principal component analysis (PCA) was performed to observe groupings and trends in the data matrix. An orthogonal partial least square discriminant analysis (OPLS-DA) was performed which resulted in clear groups between the two taxa. Several flavonoid and triterpenoid glycoside derivatives contribute to the quantitative chemotypic variation within and between the species as observed. The identification of these compounds using advanced chromatographic techniques (UPLC–MS) and chemometric analysis leads to a better understanding of the phytochemical variation of Sutherlandia which can aid in quality control of raw material, phytomedicines and commercial herbal products.