Scientists investigate estonian medicinal plants for lyme disease treatment

Ticks in Estonia, particularly in Tallinn, carry bacteria that cause borreliosis at a rate of approximately one in three and up to one in four ticks, respectively. To combat this issue, researchers from TalTech are exploring the potential of medicinal plants found in Estonia to fight Lyme disease and eliminate the bacteria responsible for it.

With the arrival of warmer weather and increased outdoor activities, it becomes crucial to address the associated risks. Ticks, known carriers of various pathogens, can latch onto human skin in natural areas. Over the past decade, Estonia has witnessed a significant rise in tick population and the prevalence of tick-borne diseases.

A recently published project called ‘Mail a Tick!’ by the National Institute for Health Development revealed that out of the six major viruses and bacteria studied, at least one pathogen was detected in 62.3% of all examined ticks. Among the well-known tick-borne illnesses are tick-borne encephalitis and borreliosis.

More and more causes of Lyme disease

Encephalitis, being a viral disease, can be prevented through vaccination, and contracting the disease leads to the development of immunity. On the other hand, there is currently no preventive treatment available for Lyme disease. Once infected, individuals do not acquire immunity, and the consequences of the disease can be severe. Lyme disease is caused by a group of bacteria called Borrelia burgdorferi sensu lato, which enter the human bloodstream through tick bites.

The initial indication of infection is often the appearance of a reddish patch that expands around the tick bite site, although this symptom is absent in approximately one-third of cases. Scientific articles published in reputable journals like Frontiers in Neurology, Pain, The Lancet, and Clinical Microbiology and Infection have reported that in later stages, Lyme disease can lead to joint damage, nervous system complications, skin problems, and heart issues.

According to the National Institute of Health, around 28% of ticks in Estonia carry B. burgdorferi, and more than 2,500 people contract Lyme disease annually. Comparing recent data with surveys conducted between 2006-2009 and 2012-2014 reveals a two to threefold increase in the prevalence of Lyme disease in ticks across various locations in Estonia.

It is important to note that tick-borne diseases can also be contracted within urban areas. A survey conducted in 2018 by the National Institute for Health Development on green areas in the capital city found that an average of 35% of ticks collected from urban areas carried at least one pathogen, with the prevalence of bacteria causing Lyme disease reaching as high as 25% in certain locations.

Innovative treatments are needed

Antibiotics serve as the primary treatment for Lyme disease, effectively addressing the acute stage of the illness. However, if the disease goes undetected and treatment is delayed, it can progress into a chronic condition.

Persistent symptoms in chronic Lyme disease stem from more resilient forms of B. burgdorferi bacteria, such as round body forms and biofilm, which exhibit reduced sensitivity to antibiotics compared to their original corkscrew-shaped spirochete form.

To combat these antibiotic-resistant bacteria, innovative treatments are necessary. Numerous studies in the research literature highlight the effectiveness of various plant-derived compounds or phytochemicals against Lyme disease.

TalTech’s instrumental analysis research group has long been engaged in studying Estonian plants, with a recent focus on identifying phytochemicals that effectively combat B. burgdorferi and discovering new lead compounds suitable for treating chronic Lyme disease.

While several Estonian plants are renowned as medicinal herbs with antibacterial properties, their alleged benefits often lack scientific confirmation. Chemical analysis of Estonian plants facilitates the identification of specific plant compounds responsible for various therapeutic properties.

Plantago lanceolata is one of the plants expected to contain phytochemicals with antibacterial properties. Credit: Pille-Riin Laanet and Merike Vaher

Which plants are studied by chemists?

The instrumental analysis research group is actively studying various plants found in Estonia, many of which are known for their medicinal properties. Through their research, they aim to provide a comprehensive overview of the chemical composition and beneficial characteristics of local plant extracts. The initial phase of the study involves analyzing the chemical makeup of the selected plant species, identifying the main groups of compounds present, and assessing the antioxidant properties of the plant extracts.

The antioxidant activity exhibited by these extracts suggests their potential therapeutic applications as antibacterial agents and in the treatment of conditions associated with oxidative stress, such as certain types of cancers. By utilizing appropriate solvents and extraction protocols, the researchers hope to isolate compounds from these plants that possess antibacterial properties, with the goal of identifying those suitable for treating Lyme disease.

A detailed account of this research can be found in a recent article published in the special issue of Molecules. The article specifically focuses on the identification and characterization of phytochemicals present in various Galium species that grow in Estonia.

Significant antioxidant properties were observed in extracts derived from Galium verum, Galium aparine, and Galium mollugo. The main compounds identified in these extracts belonged to the polyphenol and iridoid classes. Both polyphenols and iridoids have exhibited a wide range of therapeutic benefits in previous scientific studies. Polyphenols are recognized for their potential in preventing and treating oxidative stress-related diseases, while iridoids are known for their anti-inflammatory properties and their ability to inhibit bacterial, viral, and fungal growth. Among the Galium species examined, the extract derived from Galium verum flowers displayed the strongest antioxidant properties. Additionally, volatile compounds present in Estonian Galium species were identified, some of which have previously been confirmed as inhibitors of bacterial and fungal growth across all three plant species.

The beneficial properties of Dipsacus fullonum L. are confirmed

The research team has made a significant breakthrough by confirming the anti-Borrelia properties of a plant found in Estonia, specifically Dipsacus fullonum L. This groundbreaking research was published in a special issue of the journal Pharmaceuticals last year, highlighting its significance in the field. The team successfully isolated an iridoid-glycoside fraction from the extract of Dipsacus fullonum L., which exhibited strong activity against Borrelia while posing a low risk to mammalian cells.

With approximately 15% of the total extract consisting of compounds that demonstrate activity against Borrelia, the leaves of Dipsacus fullonum L. serve as an excellent natural source for extracting novel lead compounds for the treatment of Lyme disease. This finding holds great promise for the development of new and effective treatments against this challenging disease.

Plantagos and honey are also examined

The instrumental analysis research group at TalTech, comprising scientists Merike Vaher, Piret Saar-Reismaa, Pille-Riin Laanet, Piia Jõul, and Olga Bragina, will persist in their endeavors related to the chemical characterization of Estonian plants and the development of extraction methods suitable for isolating compounds with therapeutic potential.

Currently, their focus lies on investigating the activity of different Plantago species, as well as various types of Estonian honeys and pollen, against Borrelia. Ongoing trials have yielded promising results in both areas of research. The TalTech researchers are hopeful that these findings could contribute to the exploration of new treatment options for medical professionals and their patients, ultimately paving the way for future clinical trials aimed at assisting individuals with chronic Lyme disease.

Source: Estonian Research Council

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