The "Maori painkiller" taking on fungal diseases

Historically, Maori medicine involved 200-odd plants, with harakeke, kawakawa, rata and koromiko in particular being used in a range of ways, from helping to heal cuts and wounds to soothing stomach aches. Today, native botanicals are attracting renewed interest.

In Golden Bay, for example, Peter Butler has been interested in horopito (Pseudowintera colorata) since the early 1980s when he was looking for another use for a property occupied by an unprofitable organic kiwifruit orchard.

He had considered growing medicinal herbs, but his research showed that most of those used commercially originated in Europe or North America. “My property, west of Golden Bay, was surrounded by bush and I was more interested in the benefits of native plants,” he says.

He came across a 1982 University of Canterbury paper showing that horopito extract had strong anti-fungal properties and was more effective against the yeast Candida albicans than the pharmaceutical product it was compared with.

Candida is normally found in small amounts in the body, but is also one of the most common causes of fungal infections. An overgrowth can result in various conditions, including oral and vaginal thrush, urinary tract infections and gastro­intestinal problems. More than half of women develop vaginal thrush at some point in their lives, often for no ­apparent reason, although antibiotic use, diabetes or poor immune ­function increase the chances. Horopito has been found to be effective in treating even recurrent cases.

The source of its anti-fungal properties is the active ingredient polygodial, which also gives it the hot, peppery taste that makes it popular as a culinary herb. Horopito contains at least 20 other terpenes (organic compounds found in plants) and at least four flavonoids.

“It is one of the oldest flowering plants on Earth, and has survived so long because of its natural bioactive compounds,” says Butler.

The plant prefers damp areas and flourishes in most regions, aside from the Far North. In the 19th century, Maori bruised its leaves then steeped them in water to use as a treatment for skin complaints or chewed it for toothache. European settlers brewed it into a tea to help stomach ­dis­orders. It became known as “Maori painkiller”.

However, after Butler started testing the leaves, he discovered horopito’s potency varies greatly depending on where it is grown. “We found a five-fold difference between the most active and the least active.”

He also learnt that just because a plant grows vigorously in the wild doesn’t mean it is easy to cultivate.

“There was a lot of work in learning how to grow it sustainably,” he says. “Some varieties didn’t want to be harvested; you’d try a few times and then the plants would die. I also spent a lot of time working out how to best make extractions and test them.”

His company, Forest Herbs Research, now has a commercial plantation of 30,000 horopito plants and is expanding with the aim of quadrupling the number of mature plants by 2020.

The horopito-based products, including capsules, topical creams and a tea, are marketed under the name Kolorex. The products are targeted at thrush, digestive care and athlete’s foot, but may have ­potential for other conditions. When a customer claimed the foot cream had also cleared up an outbreak of Herpes simplex (cold sores), the company collaborated with the University of Otago to get scientific data to back it up.

“We’ve done a small trial in humans and found encouraging results so far,” says Butler.

Clinical research has continued to prove that this Kiwi product outperforms other natural ingredients, such as tea tree and manuka honey, and stacks up against the pharmaceutical alternatives used to treat fungal conditions. Among its advantages are that it is stable and non-toxic and has minimal reported side effects.

Forest Herbs Research exports to 10 countries, with horopito remedies especially popular in Italy.

“Originally, we planned to look at using other herbs and there were two or three others on our shortlist that I’m sure will be developed even­tually,” says Butler. “But for now we’re focusing on this one, as it stands out in terms of efficacy.”

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