With the 1918 pandemic influenza specter lurking at the doorstep of another worldwide outbreak, the avian flu, naturopathic physicians are renewing their interest in various antiviral herbs. Preeminent among these are two members of the Apiaceae family native to the western part of North America: Ligusticum spp (oshá) and Lomatium dissectum (lomatium). Those interested in these plants should read Michael Moore’s discussions of them in his books, Medicinal Plants of the Mountain West, revised edition, and Medicinal Plants of the Pacific West. A review and discussion of topics not covered by Moore are provided here.
The Three Musketeers
Most practitioners think of Ligusticum porteri when they think of oshá (pronounced o-SHAW). This species is native to mountainous regions of the southeastern United States (in and around the southern Rocky Mountains). Another potent species native to the Cascades and Sierra Nevada mountains of the Pacific Northwest is L. grayi (oshala). Lomatium is found in the same general region as oshala.
All three species are most well known for being antiviral. However, they have broader antimicrobial effects than this. For instance, (Z)-ligustilide, a key constituent in all three species, has been shown to be antibacterial and antifungal in vitro. One older study found that an oil extract of lomatium root (then called Leptotaenia multifida) inhibited several bacteria as effectively as penicillin at similar concentrations.
Tinctures of the fresh roots of large, mature plants of all three herbs are used as medicine. The major active constituents in these plants, furanocoumarins and closely related ligustilides and phthalides, are not particularly water soluble, so higher ethanol levels (50-60%) are needed to extract them optimally.
Typical tincture doses for adults with acute problems are 2-3 mL every 2-3 hours. For those with chronic problems, the dose is 2-3 mL three times per day. It cannot be stated strongly enough that frequency of dose is as important as size of dose, due to the relatively rapid excretion of constituents—one of the attributes that makes these herbs so safe. This pharmacokinetic characteristic requires that these herbs be given frequently to maintain therapeutic blood and tissue concentrations of their constituents.
Cytokine Storm
Based on clinical observation, oshá, oshala, and lomatium have some degree of immune stimulating activity. Specifically it is believed they activate phagocytic cells, mostly macrophages and possibly neutrophils. (No research documentation could be found to substantiate this claim, leaving it in urgent need of substantiation.) This activation is one of the ways natural antimicrobials differ significantly from synthetic agents, as has been documented for many other plants, such as Echinacea spp.
The possible immunostimulant effects of these herbs raise concerns about their use in treating people with influenza. Growing evidence suggests that people who die from influenza infection have an extreme immune response to the virus, known as cytokine storm. If these herbs do stimulate macrophages and increase the cytokines they release, it is theoretically possible that they could exacerbate mortality due to influenza.
The historical record suggests the opposite is the case (whether it is because these herbs are not immune stimulants, are actually immune modulators, or for some other reason is unknown). According to one report, the Washoe Indians of Nevada used lomatium root extensively during the 1918 pandemic and suffered no mortality. Other physicians in Nevada subsequently tried the treatment and found it highly effective. Reportedly the Washoe would use a decoction of the root, using one full pound over a period of three days given frequently. This makes sense given our knowledge of lomatium chemistry, as a much higher dose would be needed to compensate for the low water solubility of crucial constituents.
The Chinese Surprise
Most Westerners would not think of Angelica sinensis (dong quai, danggui) when they think of oshá or lomatium. However, these plants are in the same botanical family, share remarkably similar chemical profiles, and at least in the case of the Asian species Ligusticum wallichii (Sichuan lovage) are considered substitutes for dong quai in traditional Chinese medicine.
Dong quai is of course primarily used to support women’s health, but it and Sichuan lovage are also commonly used in Chinese medicine for their vasodilatory effects, particularly for the coronary and cerebral arteries. Sichuan lovage extract has been shown to be significantly better than aspirin for treating patients with transient ischemic attacks in a randomized clinical trial in China. The potential for using oshá, oshala, and/or lomatium for these same situations needs to be investigated to determine whether or not we have been overlooking a critical aspect of these herbs.
A Rash of Rashes
Ligusticum spp. and Lomatium spp. are generally quite safe. However, all these plants contain furanocoumarins that can, in susceptible individuals, cause a photosensitivity rash. Lomatium has been most consistently reported anecdotally among practitioners for causing a rash. This phenomenon is well documented with many species in the Apiaceae family. The type and nature of the rash seen in people who react to lomatium (both orally and topically) is completely consistent with furanocoumarin-induced problems. The apparent mystery is why some people get the rash and some do not. The standard explanation says it is purely a dose-dependent phenomenon (i.e. everyone would get it with sufficiently high exposure), but clearly there must be some genetic component, as some people do not react even at high levels of exposure. It is possible that other constituents in lomatium play a role in this variation. Some people may be better able to catabolize the furanocoumarins to harmless forms, others may have stronger antioxidant defenses (the furanocoumarins become free radicals when they interact with UV light), or there may be a yet unrecognized genetically related immunological component to the problem.
There is the theoretical danger that these herbs may cause or worsen bleeding since they appear to be platelet aggregation inhibitors. No such cases involving oshá, oshala, or lomatium have been reported. Monitoring is warranted if these herbs are used in combination with vitamin K antagonist anticoagulant drugs.
The Environmental Imperative
Any discussion of Ligusticum and Lomatium must give thought to environmental sustainability. To satisfy demand for the medicine, L. porteri has been significantly over harvested in the southeastern United States, to the point of threatened existence in wild areas of some regions (in and around Santa Fe and other large cities). Lomatium and oshala have not yet suffered this fate and remain locally abundant, but increasing their popularity could lead to over harvesting and even extinction in the worst-case scenario.
All three species discussed here have not yet been successfully cultivated on a large scale. However, some entrepreneurs have begun to successfully cultivate oshá for the first time. It appears that this notoriously finicky plant requires a highly specific soil mycorrhiza (companion fungi) in order to be healthy and flourish. Determining this has made it possible to cultivate. Lomatium does not appear to be as finicky, but all three species do grow in relatively narrow climate ranges, further complicating attempts at cultivation. Any cultivated material should be grown as close to wild conditions as possible to insure good quality medicine.
