The Application Of Classic And Modern Pharmacognosy In Monographing African Traditional Medicines

• By: VILJOEN, Alvaro (Tshwane University of Technology, South Africa)
• Co-author(s): Prof Alvaro Viljoen (Tshwane University of Technology, Pretoria, South Africa)
  Dr Maxleene Sandasi (Tshwane University of Technology, Pretoria, South Africa)
  
• Abstract:

  The application of classic and modern pharmacognosy in monographing African traditional medicines
  
  Prof. Alvaro M. Viljoen1,2, Dr Maxleene Sandasi1,2
  
  1Department of Pharmaceutical Sciences, Faculty of Science, Tshwane University of Technology, Pretoria 0001, South Africa, 2SAMRC Herbal Drugs Research Unit, Faculty of Science, Tshwane University of Technology, Pretoria 0001, South Africa
  
  Background: Southern Africa harbours a unique flora comprising of over 22 000 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 characterizing plant material and requires a dedicated approach to develop analytical methods for the profiling of complex herbal extracts.
  
  Purpose: Funding from the National Research Foundation (DSI-NRF 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.
  
  Method: 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 gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography coupled to mass spectrometry (LC-MS) respectively, high performance thin layer chromatography (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.
  
  Results: Comprehensive chemical profiles were developed for selected indigenous medicinal plants and documented in comprehensive monographs; as well as the identification and isolation of biomarker compounds, which are important in the quality control of herbal products. Chemometric modelling using large sample sizes enabled the recording of chemotypic variation in wild harvested medicinal plant species, which is also an important quality parameter to monitor in herbal products.
  
  Conclusion: 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 product development.
  
  Topic area: New medicines