Plants have been used to treat many ailments throughout human history. In the present day, most prescription drugs are derived from plant products, a proportion expected to increase further with the discovery of more plants with medicinal properties.
Plant Drug Discovery. Image Credit: ARTFULLY PHOTOGRAPHER/Shutterstock.com
Medicine and plants around the world
Plants provide many resources commonly used in modern society, from food and clothing to building materials and fragrances. Medicinal plants are also of significant value and have been used for over 5000 years, with the earliest records from Mesopotamia recording the use of Commiphora, Cedar, Licorice, and Poppy Juice.
These plants are still used commonly to this day for the cure of diseases, inflammation, or parasitic infections. Indeed, an estimated 50,000 to 80,000 flowering plants are used medicinally worldwide.
To date, it is estimated that 80% of the world's population rely primarily on plant drugs, with 23% of the drugs currently in preparation being derived from plants ready to be sold in a global market estimated to be worth nearly 1 trillion dollars.
Currently, the U.S. Food and Drug Administration (FDA) uses the term ‘botanical drug’ for natural products used for medicinal properties, referring to drugs manufactured with plant substances, including algae, microfungi. Similarly, in Europe, the use of the term herbal medicinal product (HMP) encompasses all drugs that contain one or more kinds of herbal substances in the herbal preparation.
Throughout history, however, the most prevalent use of medicinal plants remains the practice of Traditional Chinese medicine (TCM). Sales of Chinese medication represent 22.7% of the entire drug market and it is expected to grow at the same pace as the recorded high growth at an average of 35% annually over the past 5 years.
The significance of the global botanical medicine market was further discussed in a 2017 review by Kyungseop Ahn. The review discusses the significance of botanical medicine, describing the potential benefits of plant-derived medicine and how countries including Korea are adopting more plant-derived medicine.
However, despite increasing interest, the international consensus remains unconvinced about the popularization of botanical or herbal medicine. Nevertheless, plants are also recognized to play a significant role in the development of other medicinal practices, including traditionally western approaches.
The current state of plant medicines
In the United States alone, of the most common 150 prescription drugs, at least 118 are based on natural sources including plants. Plant-derived cancer drugs alone have saved at least 30,000 lives per year. Other diseases such as leukemia now have a 95% chance to be treated successfully thanks to two drugs derived from a wild plant from Madagascar.
Such promising applications demonstrate the potential for plants to cure a range of harmful diseases. Despite 21,000 medicinal plant species being by the World Health Organization, the number of potentially beneficial species is estimated to be many folds higher. Indeed, less than 1 percent of all tropical plant species have been screened for potential pharmaceutical applications.
Considering the vast chemical biodiversity of the plant world, and the widespread medicinal values of plant-derived natural products, researchers are now focusing on the poorly understood areas of herbs such as genetic background, agricultural traits, and medicinal quality.
New research trajectories in plant medicine
The applications of genomic research in medicinal plants were discussed in more detail in a 2018 review in the journal Open Biochemistry, emphasizing the potential of identifying key metabolic pathways through whole-genome sequencing. The author, Prasanta Chakraborty, discusses how modern molecular methods can be used to identify potentially beneficial traits in plants with unexplored medicinal properties.
Specifically, the review highlights how the identification of enzymes and metabolic end products can provide a rapid and affordable technique for detecting new medicinal species. Such methods will therefore contribute to the acceleration of drug discovery and the development of drug treatments.
Other research prospects also include the use of functional traits in plants. For instance, the development of resistance-modifiers or chemosensitizers may be the solution in combating Plasmodium parasites responsible for transmitting malaria. Chemosensitizer mechanisms were further considered by an Italian team of scientists that used a dozen species of Malagasy plants, who combined existing antimalarial treatments with the species of interest to determine its effectiveness in treating malaria.
This approach of multidrug resistance control is based on mixtures of natural products and classic antimalarial drugs, utilizing the medicinal properties from natural conditions with the synthesized products in existing drugs.
Implications and concerns for the future of herbal medicine
There is a promising future of medicinal plants as there are about half a million plants around the world, and most of them are not investigated for their potential medicinal properties, which could be decisive for treating harmful diseases and conditions.
However, an emerging concern is the accelerated extinction of plant species, which are disappearing faster than we can discover them. Already, about 15,000 medicinal plant species may be threatened with extinction around the world, with experts estimating that we are losing at least one potential major drug every two years.
Such rapid extinction rates are primarily driven by overharvesting, habitat destruction, and a concerning trend of biopiracy. The latter describes the practice of private companies patenting traditional remedies from the wild and selling them at a vast profit. Altogether, the mounting threats to several plant species are threatening the medicinal potential of plants, with an unforeseen and potentially considerable number of repercussions for treating human ailments.
Sources:
- Ahn, K. (2017). The worldwide trend of using botanical drugs and strategies for developing global drugs. BMB Reports, 50(3), 111–116. doi:10.5483/bmbrep.2017.50.3.221
- Benelli, G., Maggi, F., Petrelli, R., Canale, A., Nicoletti, M., Rakotosaona, R., & Rasoanaivo, P. (2017). Not ordinary antimalarial drugs: Madagascar plant decoctions potentiating the chloroquine action against Plasmodium parasites. Industrial Crops and Products, 103, 19–38. doi:10.1016/j.indcrop.2017.03.032
- Chakraborty, P. (2018). Herbal genomics as tools for dissecting new metabolic pathways of unexplored medicinal plants and drug discovery. Biochimie Open, 6, 9–16. doi:10.1016/j.biopen.2017.12.003
- Dar, RA., Shahnawaz, M., Qazi, PH. (2017) Natural product medicines: A literature update. Journal of Phytopharmacology, 6(6):349-351.
Further Reading