The application of classic and modern pharmacognosy in monographing African traditional medicines – a botanical travelogue

Southern Africa harbours a unique flora comprising of over 24 000 species of flowering plants. Woven within this tapestry of botanical diversity is the traditional use of indigenous plants as ethnomedicines. Developing official monographs, establishing a national repository of botanical standards, and producing validated analytical methods is a fundamentally important prerequisite to encourage research and commercialisation of Africa’s medicinal flora. Furthermore, the availability of reference standards, analytical methods and comprehensive monographs would be highly beneficial to the regulator, consumer and nascent industries. The unfortunate underrepresentation of pharmacognosy in the curricula of many pharmacy schools has left a void of expertise, which has hampered the development of a comprehensive herbal Pharmacopoeia. A further challenge involves the inherent complexity of medicinal plants, exacerbated by extensive chemotypic variation. Chemical fingerprinting is a crucial component in characterising plant material and requires a dedicated approach to develop analytical methods for the profiling of complex herbal extracts. Funding from the National Research Foundation (NRF/DST SARChI Initiative) and the South African Medical Research Council has catalysed initiatives at the Tshwane University of Technology to develop herbal monographs that aid in the identification and quality control of important South African herbal medicines. Selected examples will be presented to illustrate the daunting workflow, which includes extensive sampling, the development of analytical methods to profile volatile and non-volatile compounds using GC-MS and LC-MS, HPTLC, vibrational spectroscopy, as well as the use of preparative chromatography to isolate biomarkers. The powerful tandem application of analytical chemistry and chemometric modelling will be highlighted. Developing comprehensive species monographs requires a multidisciplinary collaborative effort which will inevitably contribute to the safety, efficacy and quality of African Traditional Medicines and commercial herbal formulations.