Zuiderveen, Grady H. and Eric P. Burkhart. Pennsylvania State University, State College, PA.
(Presented at The Future of Ginseng and Forest Botanicals Symposium, July 12-14, 2017, Morgantown, WV)
Abstract
Goldenseal (Hydrastis canadensis) is an Appalachian forest herb whose rhizome is used to treat inflammation and digestive disorders. Due to overexploitation concerns and significant demand, goldenseal is a crop option for forest farming. Despite its popularity as an herbal medicine, there is little information on the effects of harvest timing and habitat-related production factors on its medicinal constituents (i.e., Berberine, Hydrastine, and Canadine). The need to satisfy market demand with sustainably harvested, quality assured product requires a better understanding of goldenseal chemistry. Results (using High Performance Liquid Chromatography) in central Pennsylvania suggest that time of harvest can dramatically influence the alkaloid content in the dried root and rhizomes. Alkaloid content was found to peak in July (fruiting stage) and October (senescent stage), while samples between those times fell well below current recommended therapeutic and industry constituent levels (c.f., United States Pharmacopeia). My current research further examines harvest timing effects by expanding the range of the previous study to include (1) aerial and root portions; (2) time of day harvested; (3) full seasonal phenology; and (4) drying temperature. Additionally, I am conducting more exhaustive geographic sampling for associated habitat conditions in Pennsylvania and nearby states. The results of this study will identify production, harvest and post-harvest factors that can influence quality control in forest farmed goldenseal. This, in turn, may help forest farmers garner higher prices and a stronger market edge compared with wild crafted product –contributing to conservation of remaining wild populations by creating a more desirable product.
Keywords: Forest Farming, Goldenseal, Medicinal Plant Chemistry, Isoquinoline Alkaloids, Quality Control
Introduction
Plants have long played a critical role in treating human ailments in cultures around the world. In North America, early European settlers quickly adopted many natural remedies from the Native Americans that were well accustomed to making use of North America’s rich array of natural remedies – many of which grew under the canopy of the vast forested landscape at the time. While herbal popularity faded in the 20th century with the advent of “modern medicine,” it has made a resurgence in recent decades due to public interest in “natural” medicine along with academic interests in new medicinal compounds that can be developed into pharmaceutical drugs.
One medicinal plant that has been particularly popular in North American has been goldenseal (Hydrastis canadensis). Historically, Native Americans used goldenseal root for the treatment of numerous maladies including whooping cough, diarrhea, stomachache, tuberculosis, fever, earaches, and general weakness as well as a tonic and wash for inflammation (Moerman, 2003) . Among early European settlers, the most common medicinal uses for goldenseal include an eye wash (hence the common names eye balm and eye root), a bitter tonic, a digestive aid and appetite stimulant, and a treatment for mucus membrane inflammation (Lloyd and Lloyd, 1884). Today, goldenseal is one of the most popular plants in the herbal medicinal market, and is found in many formulations used to treat numerous ailments, and is known to have antibacterial, antimicrobial, anticancer, and immune-stimulant properties (Le et al., 2013). Goldenseal’s medicinal properties are largely attributed to a synergistic action of the alkaloids berberine, hydrastine, and canadine (Avula et al. 2012, Scazzocchio et al., 2001, Weber et al. 2003).
Goldenseal was introduced into cultivation in the United States more than a century ago (Van Fleet 1914) but the adoption of goldenseal as a specialty crop has been hindered by volatile prices and demand, and associated profitability concerns (Burkhart and Jacobson 2009, Person and Davis 2005). It is generally believed that most goldenseal on the market today originates from harvesting from wild populations in the United States (c.f., AHPA 1999, 2003, 2006, 2007) and thus the species is included in Appendix 2 of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) due to conservation concerns surrounding continued wild harvests. The timing of harvests, allowing an adequate recovery interval, and attention to site influences are all important components for sustainable harvesting from wild populations (Albrecht and McCarthy 2006, Sanders and McGraw 2005, Sinclair and Catling 2004).
The United States Pharmacopeia alkaloid minimum standards for goldenseal dictate 2.5% for berberine, and 2.0% for hydrastine. However, reports on alkaloid content range from 0.5-6.0% berberine, 1.5-4.0% hydrastine, and 0.5-1.0% canadine, with a total alkaloid range of 2.5-6.0% (Upton, 2001). Studies of other North American medicinal forest plants such as bloodroot, Sanguinaria canadensis L. (c.f. Salmore and Hunter 2001), American mayapple, Podophyllum peltatum L. (c.f., Zheljazkov et al. 2009) and American ginseng, Panax quinquefolius L. (c.f., Lim et al. 2005) have shown that there are often differences in chemistry resulting from when and where plants are harvested, and that these differences can be important qualitative considerations for herb buyers, consumers and herbal practitioners. This study examined alkaloid content – in particular the three major alkaloids berberine, hydrastine and canadine – in wild-harvested goldenseal roots and rhizomes in relation to plant colony and harvest date to evaluate (1) alkaloid variation in wild-harvested roots from colonies co-occurring on a single forested site; and (2) the best post-reproductive phenological stage during which harvest should occur for purposes of maximizing root alkaloid content.
Methods
Three spatially distinct goldenseal colonies were sampled in a forested hollow in central Pennsylvania. Colony 1 was situated at the lowermost position in the hollow (elevation 305 m); colony 2 at a middle-upper location; and colony 3 occurred at the upper end on the hollow (elevation 370 m). Each colony was spatially distinct with a distance of approximately 450 m between colonies 1 and 3. Soil conditions varied slightly between colonies, although all soils had a pH between 6 and 7, were low in fertility (by agronomic standards), and had moderately high levels of calcium. Due to conservation concerns, exact locations are withheld from this publication but Global Position System (GPS) coordinates are on-file with the PA DCNR Wild Plant Management Program. Voucher specimens for study populations were deposited in herbaria at the Carnegie Museum of Natural History (Pittsburgh, PA) and the Morris Arboretum of the University of Pennsylvania (Philadelphia, PA).
Goldenseal roots and rhizomes were harvested from mature, reproductive stems (i.e., stems bearing 2-3 leaves) on four dates corresponding with the following phenological stages of interest: (July 2) Fruit present and fully mature, foliage green; (August 7) Post fruit bearing, foliage green; (September 8) Post fruit bearing, foliage beginning to yellow; and (October 12) Foliage yellow, plants senescing with ~50% of each colony fully senesced. Root and rhizome material was not differentiated in collecting and processing samples, and samples are hereafter simply referred to as root samples. For each sample date, three root samples were collected from each of the three colonies for a total of nine samples per date and 36 samples total. Roots were washed and dried at 35°C for 24-36 hours until they were dry enough to break cleanly. Root samples were ground to approximately 60 mesh and analyzed using High Performance Liquid Chromatography.
Results and Discussion
There was considerable variation observed both within and between colonies for all three alkaloids (Figure 1). Total root alkaloid content varied from a low of 3.2% in August (represented by a single sample from Colony 1) to a high of 4.8% in July and October (samples both collected from Colony 3). Average root alkaloid content was highest in colony 3 on all sample dates (Figure 2), suggesting that local growing conditions and/or genetic predilections could be influential factors in goldenseal alkaloid production. Both of these potential influences have been highlighted in wild chemistry studies of other North American medicinal forest plants (c.f., Lim et al. 2005, Zheljazkov et al. 2009).
Total alkaloid content was highest at plant senescence (Figure 3), which corroborates the long-held belief among wild-crafters that roots and rhizomes should be harvested during the fall months. Total root alkaloid content averaged between 4.0% and 4.7% on the final harvest date (Oct 12) compared with an average of 3.7%-3.8% obtained from samples harvested in August. Goldenseal is included in the United States Pharmacopeia (USP) and USP standards require a minimum alkaloid content of 2.5% berberine and 2.0% hydrastine for dried goldenseal roots and rhizomes (USP 2013). Out of the 36 wild harvested goldenseal root samples analyzed in this study, slightly more than half (53%, n = 19) met this threshold for berberine while only one sample (<1%) met the hydrastine threshold.
The harvest of goldenseal from the wild is inherently of concern because it is the underground roots and rhizomes that are harvested, and this can lead to population declines if proper stewardship behaviors are not followed (such as allowing for recovery time between harvests). Over a century ago, there were reported noticeable declines in populations (Lloyd and Lloyd, 1884), and it is common to see statements such as “declining due to excessive collection” in some regional floras today (e.g., Plants of Pennsylvania, 2007). One course of action that has been identified as a viable option for helping sustain goldenseal in the future is to promote forest farming as an alternative for digging the plant from the wild. In order to be successful, it is important to have a more comprehensive understanding of the effects of habitat and harvest timing on alkaloid production in goldenseal.
Results indicate that colonies of goldenseal can vary significantly, and support a fall harvest of goldenseal roots/rhizomes which is in agreement with traditional lore as well as current understandings of sustainable wild-harvest practices (c.f., Albrecht and McCarthy 2006, Sanders and McGraw 2005). Total alkaloid content – and the levels of the individual alkaloids berberine, hydrastine and canadine – were all greatest at plant senescence (early October). However, our inability to distinguish what could be influencing the differences observed between colonies and our finding that alkaloid levels were nearly as high at fruit maturity (early July) as they were at plant senescence (early October) suggests further research is needed to examine additional goldenseal populations and early season alkaloid levels particularly during the period between flowering and fruiting. It may be that alkaloid levels fluctuate during the growing season in relation to key reproductive phenological stages, and that total alkaloid levels – or individual alkaloids – are in equal or greater concentration in roots/rhizomes during this time. While early (pre-fruit maturation) season harvests would negatively impact reproduction in wild populations, early season harvests from cultivated or forest farmed populations would not present such ethical dilemmas.
My current research further examines harvest timing effects by expanding the range of the previous study to include (1) aerial and root portions; (2) time of day harvested; (3) full seasonal phenology; and (4) drying temperature. Additionally, I am conducting more exhaustive geographic sampling for associated habitat conditions in Pennsylvania to illicit more detailed factors that may have an influence on the average alkaloid content in a given colony. The results of this study will identify production, harvest, and post-harvest factors that can influence quality control in forest farmed goldenseal. This, in turn, may help forest farmers garner higher prices and a stronger market edge compared with wild crafted product – contributing to conservation of remaining wild populations by creating a more desirable product.
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