By Abimbola Farinde and Robert Chapman
It has been reported that throughout most of human history, the existence of natural products have served as the foundation for the development of therapeutic agents used to treat a wide array of diseases and conditions. Plants have been identified as having a significant role in the treatment of human disease, and medicinal plants can be utilized in various forms either as raw materials, extracts, or as traditional preparations to manage or alleviate these conditions.
The value of pharmaceuticals derived from plants is not only their inexpensive nature, but the ability to transform them into being used as drugs or sources of drugs in a matter of time, in some cases. Plant-made pharmaceuticals (PMPs) come from a landmark discovery related to the application of biotechnology to plants to elicit therapeutic proteins that can be used to treat chronic or even fatal illnesses. Proteins from the biomass undergo processes of extraction, refinement, and production as pharmaceuticals. The advent of biotechnology has allowed plants to be biomanufacturers of non-native proteins used for production on an experimental scale or even larger. The growth and interest in plant-derived products can be attributed to the clinical efficacy that has been demonstrated particularly with the production of anti-cancer drugs, such as with the discovery of vincristine/vinblastine (I-II) from Catharamthus roseus. Other compounds that may not yield as great a therapeutic outcome can offer the basis as leads for the development of more effective drugs, such as with the development of atracurium (IV) and other muscle relaxants.
Of recent interest is the application of methods used in biotechnology to drug design and discovery from plants. Researchers are just beginning to understand how various polysaccharide constituents found in Astragalus membranosus and Codonopsis pilosulae roots, which have been used as traditional Chinese medicines for thousands of years, provide benefits to patients with cancer and infections through modulation of the immune system. Antibodies produced against Ebola are an example of success in this area, the importance of which is being discussed in scientific literature and the popular press, during an epidemic outbreak of the virus. ZMapp was the first therapeutically successful example of such an antibody cocktail, which was used to treat two health care providers who contracted the virus during a medical mission to Africa. While such methods and their applications are attractive because they offer rapid and economically feasible solutions to antibody production for Ebola, malaria, and HIV on a large scale, they are not without challenge. Yield optimization, post-transcriptional modification, and product stability are factors to study and consider.
Research into the use of medicinal plants will continue to thrive as more and more drugs are created but this requires interest in the research, studying, and problem-solving how plants can be sources of complex active drugs in order to achieve these therapeutic outcomes.