by 
Photo from Pexels by PhotoMIX Company
Herb- and plant-based medicines have been used for as long as 60,000 years, with the first written record dating to 7,000 years ago. While these medicines have survived scientific evaluation with varying success, one in four medications currently used has a plant-based origin. One of the most successful medications treats a vector-borne disease. With all this history, why aren’t we finding more success with herb- and plant-based medicines to treat vector-borne disease today?
The Bubonic Plague & Flea Repellants
A vector-borne disease we are all familiar with is bubonic plague. This infamous epidemic mainly affected Asia and Europe. Bubonic plague is caused by the bacteria Yersinia pestis, which is transmitted by infected fleas and rats. Researchers estimate that this illness killed about 20 million Europeans, roughly one-third of Europe’s population at the time.
One wave of bubonic plague struck during the 1300s. Medieval European medicine was not heralded for its efficacy and safety, and treatment for this infectious disease was often crude and dangerous. Practices like bloodletting were meant to remove the harmful illness, but without proper sanitation often caused even worse infections. Meanwhile, fleas had not yet been identified as the vector of the disease.
“Ring around the Rosie, a pocket full of posies, ashes ashes, we all fall down.” Many believe this classic nursery rhyme describes the bubonic plague. “Rosie” refers to a rosary used to pray, and the ashes and falling down refer to the death the plague brought. The posies refer to herbs kept on and around people during the plague.
At the time, doctors turned to plants and herbs to prevent infection. Many remedies were used, but the most notable one was a satchel of herbs worn around the face to clear out the “evil air”. Doctors also used garlic, chamomile, and lavender to support the body during the plague.
It wasn’t uncommon for a mixture of herbs to be used as a preventative measure against the bubonic plague. Four thieves’ vinegar was a mixture of herbs steeped in vinegar applied all over the body. It was thought to prevent the plague, but it more likely repelled fleas.
Plant-based repellants on the market today can be effective but come with their own risk and benefit profiles. Find out more about synthetic and plant-based repellants.
Malaria & Quinine
Another plant used for its medicinal properties is the bark of the cinchona tree, more specifically the alkaloid derived from the tree, which is known as quinine.
Scientists in the 1600s noted quinine’s effect against malaria. Malaria is a vector-borne disease caused by four parasites: Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. The disease is common around the world and affects an estimated 241 million people on a yearly basis.
Quinine was hailed as the first chemical compound to successfully treat an infectious disease. Traditionally, the bark of the cinchona tree was ground into powder and added to a liquid that was used as a treatment for malaria. As science progressed, researchers were able to derive the alkaloid quinine from the cinchona bark and use it as an oral treatment for malaria.
Up until the 1920s, quinine was the main treatment for malaria until more effective synthetic medicines were developed. Unfortunately, by the 1980s, the parasites had built up a resistance to the anti-parasitic medicines. Quinine was once again introduced as an effective treatment option for malaria.
In 2010, the World Health Organization (WHO) recommended quinine in combination with antibiotics like doxycycline, tetracycline, or clindamycin when antiparasitic medicines where not readily available. Thirty-eight African countries currently use quinine as a first line of treatment against malaria.
While quinine can be a relatively effective treatment against malaria, it can pose adverse health effects. Some side effects of quinine include nausea, headache, hearing loss, and in extreme cases death.
Lyme Disease & Pharmaceutical Development
New medicines and treatment need to go through extensive testing and study before they can be considered effective and safe. Before human testing is even considered, new drugs are developed in the laboratory. This can be a difficult process considering what illness is being targeted.
You can read more about bacteria and viruses and how they are treated here.
Modern pharmaceutical development focuses not only on a new cure itself but also on innovative processes to find new cures. At the turn of the last century, researchers ran clinical trials and validation studies on drugs that were already being used. Some medicines derived from plants, like quinine, passed this scrutiny. Many others did not. Using quinine and other plants as valid treatment for some illness led to more and more questions.
Can old remedies and plant-based medicines hold new answers for the treatment of illnesses? In an effort to discover and rediscover treatments, pharmaceutical development companies have built vast libraries of information about plants, natural molecules, and their benefits. They digitized ancient medical books to create a searchable database for “lost knowledge”. Their exploration of the past in pursuit of new medicines even led to the collection of fungus in soil in remote rain forests. Scientists have used these intricate digital databases to research target molecular matches between diseases and cures.
Researchers also look at targets for treatments of disease and try to design molecules to fit. An example of a research target would be Borrelia burgdorferi, the principal bacteria that causes Lyme disease. More specifically, scientists are exploring the place where the bacteria adheres to human cells. Can this connection be disrupted? Is there a plant-based medicine or herb that accomplishes this? What other targets could combat Lyme disease? Asking these questions and having research to answer them shows the advancement of biotechnology at the turn of the century.
A 2018 study funded by the Bay Area Lyme Foundation, supported in part by the Steven & Alexandria Cohen Foundation, introduced 14 botanical extracts to B. burgdorferi in vitro (i.e., in petri dishes). These plants were identified by screening 1,581 candidates from a drug library. Researchers found that seven out of the 14 herbs may be effective against B. burgdorferi. The two most effective extracts were from Ghanaian quinine and Japanese knotweed.
While the extracts may have stopped B. burgdorferi from multiplying, the study was performed in vitro. This kind of controlled environment makes it difficult to determine how these extracts would interact with the target bacteria in a patient. How would they reach the bacteria in the same concentration that was in the petri dish? If that is even possible, how would that affect the patient’s other cells and microbiome?
In 2020, researchers did even more work on plant extracts, looking at them in the lab in small concentrations over a week. This is more like the environment that would occur in the treatment of a patient. To continue this development, tests need to be done in animals and in people to evaluate safety and efficacy.
Conclusion
Medical treatments developed from molecules found in nature make up a large part of current pharmaceutical treatments, yet progress remains elusive in the treatment of vector-borne pathogens. Advocacy group funding such as that provided by the Bay Area Lyme Foundation has been able to move the needle in a very real way, but further research is needed.
References
Petrovska, B. B. (2012). Historical review of medicinal plants’ usage. Pharmacognosy Review, 6(11), 1–5. https://doi.org/10.4103/09737847.95849 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3358962/ – Medicinal plant history
Yuan, H. et al. (2106). The traditional medicine and modern medicine from natural products. Molecules, 21, 559. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6273146/pdf/molecules-21-00559.pdf – 60000 stat
World Health Organization. (2022, March 25). WHO establishes the Global Centre for Traditional Medicine in India: Maximizing potential of traditional medicines through modern science and technology. https://www.who.int/news/item/25-03-2022-who-establishes-the-global-centre-for-traditional-medicine-in-india#:~:text=Around%2080%25%20of%20the%20world’s,estimated%20to%20use%20traditional%20medicine. – The WHO (not the band)
Cohut, M. (2020, February 23). Lyme disease treatment: 2 herbal compounds may beat antibiotics. MedicalNewsToday. https://www.medicalnewstoday.com/articles/lyme-disease-treatment-2-herbal-compounds-may-beat-antibiotics – Lyme disease study not a provider
Feng, J. et al. (2020). Evaluation of natural and botanical medicines for activity against growing and non-growing forms of B. burgdorferi. Frontiers in Medicine, 7, 6. https://doi.org/10.3389/fmed.2020.00006 https://www.frontiersin.org/articles/10.3389/fmed.2020.00006/full – Lyme disease study a provider
Centers for Disease Control and Prevention. (2022, March 22). Malaria. https://www.cdc.gov/malaria/about/faqs.html#:~:text=Malaria%20is%20a%20serious%20and,humans%3A%20Plasmodium%20falciparum%2C%20P.
Brittanica. (n.d.). Alkaloid. https://www.britannica.com/science/alkaloid
Bhambhani, S. et al. (2021). Diversity in chemical structures and biological properties of plant alkaloids. Molecules, 26, 3374. https://doi.org/10.3390/molecules26113374 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8199754/pdf/molecules-26-03374.pdf
Garcia, S. (2020). Pandemics and traditional plant-based remedies. A historical-botanical review in the era of COVID19. Frontiers in Plant Science, 11, 571042. https://doi.org/10.3389/fplas.2020.571042 https://www.frontiersin.org/articles/10.3389/fpls.2020.571042/full
History.com. (2021, November 23). Black death. https://www.history.com/topics/middle-ages/black-death
