If people ponder the origin of medicinal herbs, the image of the village shaman or a medicine hunter trekking deep in the jungle likely comes to mind. After days of scouring the rain forest he returns triumphant, plant in hand. But this isn?t exactly how it works. Recent research by John Richard Stepp, Ph.D., at the University of Florida, Gainesville, shows that many medicinal botanicals come from weeds—those pesky plants that take root in every backyard and vacant lot. And the next botanical superstars may be weeds, says Stepp. Through his research he discovered that although only about 3 percent of the world?s quarter-million plant species are weeds, they make up more than a third—36—of the 101 plant species used in pharmaceuticals. The Natural Foods Merchandiser talked with Stepp about the medicinal importance of weeds.
NFM: What gave you the idea that backyard weeds might be a rich source of medicinal botanicals?
JRS: Just what I was seeing with what traditional people were using. I had been working for the past 10 years in southern Mexico in the state of Chiapas with the Highland Maya. When I first started working there I went in with the assumption that there was a lot of use of mature forest—that people would go trek back into the jungle to find plants. But what I found was that this wasn?t happening. People were almost entirely using plants that were located close by. In fact, the most productive area where they were getting these plants was the area immediate to their houses.
NFM: How do you define weed?
JRS: It sounds like a simple question, but it?s not. It?s used in a lot of different ways but generally I adopt the definition that?s used by weed scientists—a plant that thrives in disturbed areas, generally grows aggressively and reproduces rapidly.
NFM: What?s a ?disturbed? area?
JRS: A disturbed area is where people come in and cut down the trees—an abandoned field, any place that?s undergone significant human modification or impact, and weeds grow really fast there.
NFM: Why do weeds possess such medicinal characteristics compared with other plants?
JRS: It?s tied into why they grow so well: They tend to have a lot of secondary bioactive compounds in order to combat other species coming in, and these particularly bioactive compounds are potential sources of medicinal substances.
NFM: You studied weeds around railroad tracks in Athens, Ga. What did you find?
JRS: I wanted to further explore the idea that weeds are a significant source of medicinals. We used the largest plant database of the medicinals used by the Native Americans, which had been developed by Dan Moerman at the University of Michigan in Dearborn, and we collected every plant we could find in a forest and along a railroad track. What we found was that a significant number of the plants that came from the disturbed area—by the railroad track—were medicinal and had been used by native North Americans as medicinal plants. In contrast, we found only a few of the forest plants had medicinal properties.
NFM: Will developers use this research to support rain forest deforestation?
JRS: That is certainly something that I wouldn?t want to see happen. I am not making the claim that there are not medicinal plants in the rain forest. The point is that there are other significant areas where medicinal herbs exist. The nature of the tropics is such that there is a lot of diversity, and it?s a highly competitive environment so that you tend to see a lot of plants with bioactive compounds. But, if we?re going to go out looking for new compounds for medicine, the [jungle] may not be the best place that we can go looking. Maybe we can go looking a lot closer in disturbed areas.
NFM: What are some well-known weeds with medicinal properties?
JRS: A wide range of painkillers have been made from the opium poppy. Echinacea shows very weedy characteristics; in fact most plants in that family tend to be pretty weedy. Dandelion, calendula and periwinkle are all weeds. Periwinkle is used in the pharmaceutical anticancer drugs vincristine and vinblastine.
NFM: How do you think your research might affect naturals manufacturers?
JRS: The nature of the natural products industry seems to be to give a lot of attention to one species at a time and then move on. Will the next one be a weed? It?s hard to say. I think it will be directed by what people need for a cure at the time. [For example,] kava became popular, I think, because Americans needed something to help calm them down.
NFM: What about pharmaceutical manufacturers?
JRS: There are natural products developments by pharmaceutical companies, but it?s not a very large area simply because arrogance says it?s easier simply to make up [new drugs]. So the amount of money that pharmaceutical companies actually spend on looking at plants is very insignificant; however, they are still doing it. Prior to World War II it was all plants. There wasn?t synthetic chemistry of any significance. There are lots of medicinal plants here in our backyard. Are they waiting to be discovered? No. Native Americans have been using them for years, but they are being overlooked by researchers.
NFM: Do you use herbs?
JRS: I do, [but] not very often because I don?t get sick very often. When I?m doing fieldwork I?ll try anything once. In fact, I?ve had a lot of success using the same medicinal plants that the Mayans use. And it?s not surprising; they?ve lived for a very long time by using medicinal plants. They don?t have Western-trained doctors.
Natural Foods Merchandiser volume XXV/number 10/p. 104, 110