Minke Holwerda, BSc Biomedical Sciences
Unless you have been living under a rock, it has probably not escaped you that we are currently in the midst of a worldwide pandemic, caused by severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). While vaccines are being developed, produced, and injected in a (more or less) high tempo, a cure for coronavirus disease 2019 (COVID-19) has not yet been found.
In the race for the COVID-19 cure, some countries have turned to exploring the potential of plant-based medicine [1]. Plant-based medicine is an ancient practice which plays a role in traditional medicine as well as modern drug development [2, 3]. Plants produce secondary metabolites which assist in the survival of the plant, such as alkaloids, flavonoids, phenolic acids, and terpenoids[2, 4]. These compounds have, among others, anti-inflammatory, antioxidant, anticancerous, and – most importantly – antiviral properties [4]. Well-known examples of plant-based medicines are acetylsalicylic acid (aspirin), which is isolated from willow tree bark, and artemisinin, which is extracted from the plant Artemisia annua and used as treatment for malaria [2, 5].
A wide range of plants are currently being reviewed for their potential to treat COVID-19, including those that can be found in the average Dutch kitchen cabinet or garden. For example, research is being done into Anthemis hyaline, better known as chamomile. In one study, virus load decreased after adding extracts of Anthemis hyaline to CoV infected cells [6].
Curcuma Longa contains curcumin, which is a polyphenol that has previously been shown to have anti-viral activity against SARS coronavirus [7]. This name might sound familiar to you since curcuma, a spice currently very popular due to its superfood-status, is also made from this plant. A recent molecular docking study reported that curcumin binds and inhibits SARS-CoV-2 target receptors, supporting the use of this plant as prophylaxis against SARS-CoV-2 [8].
Another promising contender is a compound called ‘diammonium glycyrrhizinate’ found in Glycyrrhiza glabra, the plant from which liquorice is made. In traditional medicine, liquorice is used against colds, coughs, and to calm disturbed digestion, and diammonium glycyrrhizinate can be used to treat liver damage caused by hepatitis B due to its anti-inflammatory properties [9]. Recently, clinicals trials have been approved researching diammonium glycyrrhizinate in combination with vitamin C as therapy for COVID-19[10].
The use of plant-based medicine has many advantages. In countries with a rich tradition of herbal medicine, plant-based medicines have been used in a clinical setting for a long time, repeatedly proving their efficacy and safety. Theoretically, herbal medicines with known antiviral properties and established safety could immediately be used to treat COVID-19 patients [9]. This even more so because they are often widely available, in contrast to other medicines such as the recently approved remdesivir [11, 12]. In particular in low- and middle-income countries, where up to four billion people already depend on plant-based medicine as their primary source of healthcare, this is an attractive prospect [13] .
However, a lot has to happen before any traditional medicine is turned into a modern drug. Because plants contain multiple phytochemicals, the exact mechanism of action is often unclear, and it takes a long time to develop high-quality plant-based medicine with sufficient data on long-term safety and pharmacokinetics. In addition, developing reference standards is also more challenging for plant-based medicine than for synthetic drugs [1].
So, unfortunately, plant-based medicine is no quick fix for our COVID-19 cure conundrum. You might enjoy a calming cup of chamomile tea, curcuma in your food, and some liquorice to snack on, but this is no replacement for the vaccine or test needed to hit the clubs again!’
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