Kudzu research
One area of herbal medicine that I find exciting is the stream of new basic research that seeks to explore the actions associated with traditional medicinal herbs. I think this research is important for a number of reasons. Clinical herbalists need to have a modern perspective when considering safety of traditional herbs, one example of this is comfrey, the use of which continues to be controversial. Anotther reason to stay appraised of basic research is that this flow of research serves as the wellspring that ensures that Western Herbal Medicine continues to evolve and grow it’s materia medica.
Pueraria lobata (Willd.), kudzu is a notorious invasive species in North America. In the early 1900’s over a million acres of kudzu were planted in the southeastern United States. Initially as garden ornamentals and later to combat soil erosion where it quickly began to outcompete and kill the local plant species including trees. The entire southeastern quarter of the United States is considered infested with kudzu.
The silver lining in this story is that P. lobata, also known as gé gēn is both edible and one of the 50 fundamental herbs of Traditional Chinese Medicine (TCM). In that modality, it has been used for millennia as a heat and toxin dispelling herb that protects the liver and kidney useful for migraine and cluster headaches tinnitus, vertigo and to mitigate the effects of moderate or even excess alcohol consumption. It’s use dates back to at least the time of Shen Nong’s “Herbal Classic”.
The isoflavone daidzein (DA) and it’s glucosides puerarin (PE) and daidzin are the current kudzu constituents of active research.
An animal model (and therefore ethically flawed) study produced results that suggest that PE treatment ameliorates renal fibrosis by inhibiting oxidative stress damaged caused by rapid oxidation species induced-epithelial cell apoptosis through modulating the mitogen-activated protein kinase signaling pathways (Zhou et al., 2017). Another small double blind cross over study found that 1200mg of PE daily altered alcohol consumption in humans, resulting in decreased sip size and number of sips to finish a beer. Subjects also and took longer to consume each beer and latency to opening the next beer was increased (Penetar et al., 2012). This alcohol modulating effect was also observed in another small, between-subject, double-blind, placebo controlled study that reported a 34-57% reduction in number of drinks consumed each week in the intervention group (Lukas et al., 2013).
A heartbreaking randomized placebo controlled study assessed the effect of a PE coated dressing on burn victims. The study found that interleukin-1 levels were decreased and interleukin-4 levels were increased. Furthermore the pro-inflammatory P2X7 receptor gateway and peripheral blood mononuclear cell concentrations were reduced in the group treated with PE. Overall the inflammation and associated pain involved in dressing changes of burn patients were relieved by PE treatment (Zhang et al., 2013)
Cytotoxic effects have also been attributed in-vitro to constituents of P. lobata as well. Puerarin 6″-O-xyloside demonstrated anti-tumor effects on the human lung carcinoma A549 cell line (Chen, Chen, Wang, & Zhang, 2016).
While larger studies are needed, in this small sampling of studies we see modern results that corroborate the traditional understandings of kudzu’s nephroprotective, heat dispersing, and anti-inflammatory effects. There is evidence that backs up kudzu’s use as a modulator of alcohol consumption as well. Preliminary results of cytotoxic effects of constituents in kudzu are promising as well. These recent studies are exciting because they recontextualize the narrative around this plant from “folk” wisdom to modern research. These studies also provide tantalizing glimpses into the wisdom of the traditional Chinese materia medicas and their venerable authors.
References:
Chen, T., Chen, H., Wang, Y., & Zhang, J. (2016). In vitro and in vivo antitumour activities of puerarin 6″-O-xyloside on human lung carcinoma A549 cell line via the induction of the mitochondria-mediated apoptosis pathway. Pharmaceutical Biology, 54(9), 1793–1799. https://doi.org/10.3109/13880209.2015.1127980
Jung, H. W., Kang, A. N., Kang, S. Y., Park, Y.-K., & Song, M. Y. (2017). The Root Extract of Pueraria lobata and Its Main Compound, Puerarin, Prevent Obesity by Increasing the Energy Metabolism in Skeletal Muscle. Nutrients, 9(1). https://doi.org/10.3390/nu9010033
Lukas, S. E., Penetar, D., Su, Z., Geaghan, T., Maywalt, M., Tracy, M., … Lee, D. Y.-W. (2013). A standardized kudzu extract (NPI-031) reduces alcohol consumption in nontreatment-seeking male heavy drinkers. Psychopharmacology, 226(1), 65–73. https://doi.org/10.1007/s00213-012-2884-9
Penetar, D. M., Toto, L. H., Farmer, S. L., Lee, D. Y.-W., Ma, Z., Liu, Y., & Lukas, S. E. (2012). The isoflavone puerarin reduces alcohol intake in heavy drinkers: a pilot study. Drug and Alcohol Dependence, 126(1–2), 251–256. https://doi.org/10.1016/j.drugalcdep.2012.04.012
Ulbricht, C., Costa, D., Dam, C., D’Auria, D., Giese, N., Isaac, R., … Windsor, R. C. (2015). An evidence-based systematic review of kudzu (Pueraria lobata) by the Natural Standard Research Collaboration. Journal of Dietary Supplements, 12(1), 36–104. https://doi.org/10.3109/19390211.2014.904123
Zhang, J., Li, X., Gao, Y., Guo, G., Xu, C., Li, G., … Liang, S. (2013). Effects of puerarin on the inflammatory role of burn-related procedural pain mediated by P2X(7) receptors. Burns: Journal of the International Society for Burn Injuries, 39(4), 610–618. https://doi.org/10.1016/j.burns.2012.08.013
Zhou, X., Bai, C., Sun, X., Gong, X., Yang, Y., Chen, C., … Yao, Q. (2017). Puerarin attenuates renal fibrosis by reducing oxidative stress induced-epithelial cell apoptosis via MAPK signal pathways in vivo and in vitro. Renal Failure, 39(1), 423–431. https://doi.org/10.1080/0886022X.2017.1305409