Fighting inflammation with dog’s mercury

As early as the fifth century BC, Mercurialis perennis, or dog's mercury, was being used as a remedy to treat purulent wounds and eczema. WALA researchers have tasked themselves with using modern technology to reveal the plant’s mechanism of action. While their work is providing new insights, it is also raising additional questions.

Dog’s mercury (Mercurialis perennis) is one of the first plants to cover the forest floor in spring
Photo: Arne Schneider

It is late March and we are taking a stroll through the woods. The birds sing of the coming spring, while the plants are still half asleep in hibernation. But not all of them. On the dappled forest floor, some small green plants can be seen pushing their way through the carpet of dry leaf matter. They resemble wild garlic, though the leaves have finely toothed edges and appear bluish green in the sunlight. We are looking at dog’s mercury – a plant that makes the most of this still sparse woodland season to flourish abundantly without competition from other vegetation.

Dr. Peter Lorenz has taken a liking to this inconspicuous plant. For him, as a chemist, it holds a lot of secrets. Lorenz is the most experienced phytochemical researcher at WALA Heilmittel GmbH, and has been investigating this old Euphorbiaceae (spurge family) medicinal plant since 2009. Together with the doctoral students in his research group, he has largely been working on uncovering new substances within the plant. Over a period of ten years, seven publications on dog’s mercury have come out of the WALA laboratories.

One of the team’s unexpected discoveries was that the plant contains lipids known as n-alkylresorcins. This class of compounds is one of the secondary plant substances that the plant develops as a defence mechanism against predators. In humans, these lipids have anti-inflammatory properties. This was the first time that the presence of n-alkylresorcins had been recorded in spurge plants.¹

Research that paves the way

We asked Peter Lorenz why he finds it so interesting to investigate unrecorded plant substances. “Our team’s primary task is conducting basic research that generates knowledge. We can use our very specific findings to ask broader questions. Sometimes, the initial relevance of certain results is unclear. But later, they can lead us somewhere completely different.” Many of the great discoveries, he explains, have developed out of seemingly insignificant results. "Sometimes we have to look at things in isolation before we can pan out and understand the bigger picture.”

But where do these findings find application? “We work closely with our in-house Clinical Research Department, which produces proof of the efficacy of WALA drugs,” explains Lorenz. “The team there finds it helpful to understand the mechanisms of action of the medicinal plants that are used.” And this was precisely the idea behind the research team’s investigations. They focused on the aqueous-fermented extract of dog’s mercury that is contained in WALA’s anti-inflammatory drugs.

Inhibiting inflammation isn’t always the goal

Inflammation can actually be a good sign. The heating and reddening of inflamed tissue shows us that our immune cells have jumped on pathogenic invaders and are working up a sweat as they fight them. In order to determine in laboratory tests whether the dog’s mercury extract is indeed anti-inflammatory, its effect on immune cells must be investigated. This is exactly what Peter Lorenz and his research colleagues did, using isolated immune cells. At first, they were amazed by the results: the aqueous-fermented dog’s mercury extract did not reduce the activity of the immune cells, but actually increased it.²

Upon further consideration, however, this finding makes sense. WALA medicines that contain dog’s mercury extract help to heal poorly healing, purulent wounds. In these cases, the immune cells have basically run out of steam. To further inhibit them would therefore be the wrong approach. Activating them, on the other hand, would have the desired effect. Used locally, dog’s mercury extract stimulates the immune system directly at the site of inflammation and thus stimulates the stagnant healing process of chronic inflammations. What is now unclear is precisely which substances have this stimulating effect on the immune system. And so, with one question answered, another arises.

¹ Lorenz P, Knödler M, Berger M et al. n-Alkylresorcinol occurence in Mercurialis perennis L. (Euphorbiaceae). Z Naturforsch C 2010; 65: 174–179.

² Lorenz P, Beckmann C, Felenda J et al. Das Waldbingelkraut (Mercurialis perennis L.). Z Phytother 2013; 34: 40–46.