Noxious and Invasive Weeds as Medicine

An Alternative for the pesticide treadmill and a way to reduce use of At-Risk Medicinal Plants

by Autumn Arvidson and Kelly Kindscher

Introduction:

kudzu
Figure 1. Kudzu (Pueraria montana),
trying to cover a house

The use of medicinal plants is gaining popularity in the health industry as more individuals are recognizing the risks associated with modern pharmaceuticals and the benefits of many herbal products. While this may be considered a step in the right direction for individuals seeking low side effect treatments, it is worrisome for those trying to manage populations and preserve the integrity of at risk native medicinal plants. Perhaps a way to reduce harvesting of at risk native plant species would be to find alternative medicinal plants which offer some of the same healing properties; we would like to recommend consideration of noxious and/or invasive plants. There is an abundance of non-native invasive and noxious weeds that have promising medicinal uses that could be used alternatively. This would not only allow for the harvesting of some native medicinal plants to be reduced but would encourage an eco-friendlier way of managing populations of noxious and invasive weeds.

With the abundance of non-native weeds in the United States remaining constant or increasing and the increasing toxicity of the herbicides used to remove them, changing the negative relationship people have with weeds would have many positive impacts. There is significant research published showing numerous medicinally promising non-native plants present in the United States. These plants include kudzu (Pueraria montana), purple loosestrife (Lythrum salicaria), and creeping Charlie (Glechoma hederacea), all of which were introduced to North America intentionally for their ecological benefits, such as preventing soil erosion. For the purposes of this literature review, the plants listed above were focused on as examples due to the abundance of peer-reviewed research which determined the chemical components of the plants and their respective potential as medicinal tools.

invasive-weeds-chart

Discussion:

Kudzu (figure 1.), which is so predominate in the South and coined; “the plant that ate the South,” is very hardy and can grow where almost nothing else will. The plant produces several useful compounds (see Fig.4) and shows promise of being a medicinally significant plant containing the isoflavones, daidzein and genistein. These isoflavones have been found to reduce the occurrence of breast, uterine, and prostate cancers; lessen the risk of coronary disease and heart disease; and reduce menopause symptoms (June, 2003). Another compound found in kudzu, puerarin, is effective at reducing symptoms and side effects of alcoholism, including over consumption, dependency, and withdrawal symptoms. One study found puerarin extracted from kudzu to be effective at reducing binge drinking in all participants in a study, even when consumed shortly before alcohol consumption began. This study demonstrated that kudzu would be a safe and effective adjunctive tool in the treatment of alcohol abuse and dependency (Penetar, 2015).

purple-loosestrife
Purple Loosestrife (Lythrum salicaria) in wetland ecosystem

Purple loosestrife is a non-native plant that invades wetland habitats. Purple loosestrife has many medicinal properties, as the whole plant from root to flower contains useful medicinal chemical compounds, which can be used both externally and internally. It can be used in several forms including powdered, infusion, and liquid extract for health ailments such as diarrhea, dysentery, inflammation of intestines, nose bleeds, and severe menstrual cramps. The plant’s flowers and roots can be used for their astringent, styptic, antibiotic, hypoglycemic, or vulnerary effects on burns, snake bites, and pain management (Šutovská, 2012). Due to the plant’s astringent properties the extract has been shown to be very effective at treating conditions such as eye inflammation, sinusitis, varicose veins, hemorrhoids, and ulcers (Piwowarski, Granica, & Kiss, 2015).

Creeping Charlie, which while only classified as noxious in Connecticut has begun to raise concern in other states as its presence is ever increasing. However, as a medicine this plant would be very useful as it has been found to contain several promising compounds, one of which being rosmarinic acid, as well as some of its analogues, which can be used in the treatment and prevention of inflammation related diseases such as allergies, arthritis, and fibrosis (Kim, et al, 2011). Creeping Charlie has also been found to contain significant concentrations of oleanolic and ursolic acids, which have been found to promote tumor inhibiting effects. In a study monitoring papilloma (tumor) bearing mice which were treated with a topical ointment containing both oleanolic and ursolic acids, researchers observed that the number of papillomas per mouse decreased significantly when compared to the control group of mice who received no topical treatment containing the two acids (Liu, 1995). Furthermore, a study investigating the medicinal potential of oleanolic and ursolic acids found that the intake of these compounds elevated the circulating insulin level and alleviated diabetes-induced hyperphagia; which is characterized by hyperglycemia, weight loss, and increased food intake (Wang, Hsu, Cheng-Chin & Yin, 2010).

creeping-charlie
Creeping Charlie (Glechoma hederacea) flowering

While these non-native plants may currently be considered nuisances and largely unwelcome in the ecosystems they inhabit, they may be an innovative tool that could be used in improving the health of citizens and reducing the harvesting of native medicinal plants. Improving the health and abundance of native medicinal plants may be one of many positive side effects that would result from the use of weeds as medicinal products. This would also help to reframe the ways in which people view plants that are considered invasive and/or noxious, which would only further propagate the shift from thinking certain plants are inherently bad to viewing these plants as unproductive in their current environment, but if utilized could be beneficial in advancing treatments for certain health conditions.

Conclusion:

Further consideration should be given to how non-native invasive and noxious plants are being controlled and/or removed from ecosystems using ecologically degrading herbicides. The chemicals used to remove these weeds include 2,4-D, Dicamba, Picloram, and other broad leaf herbicides. Unfortunately, the use of these potent and toxic herbicides can be considerably harmful to non-target organisms, including native plants and insects. It is also worth noting that these herbicides have only limited success.

The effectiveness of these chemical control methods should be considered and reevaluated. Since the Noxious Weed Act was enacted in 1974, we do not know of one noxious weed that has been successfully eradicated and removed from the list. This may show that the current methods of eradicating these plants have not been, and will likely not be, effective, and this may lead to even more toxic herbicides being used in the future. It is a perfect scheme to have perpetual herbicide use.

The continued use of toxic herbicides will only further and exaggerate ecological degradation already being caused to the ecosystems of some native medicinal plants by invasive and noxious weeds. The lack of data showing the long-term effects of herbicide use in ecosystem health and functionality should be concerning. The prolonged use of herbicides on invasive and noxious weeds may cause irreversible damage to soil, water, and macroinvertebrates that are integral components to the health and success of ecosystems. However, harvesting these plants for further testing and medicinal product production would be a mutually beneficial solution to the current weed-pesticide paradigm while allowing some at risk native medicinal plant populations the opportunity to improve both in abundance and health. But if even a portion of the acreage of noxious weeds could be harvested for beneficial herbal product use, this would be an important demonstration of an alternative paradigm.

So, we would like to propose the following: In clean environments (those that do not have a history of being sprayed), the funds that have been used by the state and county governments to buy pesticides and hiring staff to spray noxious weeds should as a pilot project, be replaced with hiring herbalist and wild-crafters to harvest and prepare medicine from these noxious weeds. The research funding for noxious weed research and State Extension program funding related to noxious weeds could also be altered to include funding that would promote the techniques of harvest and most effective and healthful use of many of these plants. The results would likely be equally effective, while managing these noxious weeds. In addition, there would be healthful benefits for the environment and for people alike, including providing jobs for herbalists (yes, a jobs program for herbalists). We believe that developing this approach could benefit the health of ecosystems, while also reducing the use of some at-risk medicinal plants. And we believe it is time for a paradigm shift.

References:

  • Jun, M. 2003. Comparison of antioxidant activities of isoflavones from kudzu root (Pueraria Lobata Ohwi). Journal of food science, 68, 6, 2117-22.
  • Kim, J, Song, S, Lee, I, Kim, Y, Yoo I, Ryoo, I, & Bae, K. 2011. Anti-inflammatory activity of constituents from Glechoma hederacea var. longituba. Bioorganic & Medicinal Chemistry Letters, 21, 11, 3483-87.
  • Penetar, D, Toto, L, Lee, D, & Lucas, S. 2015. A single dose of kudzu extract reduces alcohol consumption in a binge drinking paradigm. Drug and Alcohol Dependence, 153, 194-200.
  • Piwowarski, J, Granica, S, & Kiss, A. 2015. Lythrum salicaria L.- underestimated medicinal plant from European traditional medicine. A review. Journal of Ethnopharmacology, 170, 226-50.
  • Šutovská, M, P., Fraňová, S, Pawtaczyk, I. & Gancarz R. 2012. Antitussive and bronchodilatory effects of Lythrum salicaria polysaccharide-polyphenolic conjugate. International journal of biological macromolecules, 51, 5, 794-99.
  • Wang, Z, Hsu, C, Huang, C, Yin, Mei-Chin. 2010. Anti-glycative effects of oleanolic acid and ursolic acid in kidney of diabetic mice. European Journal of harmacology, 628, 1-3, 255-60.