The bushfires in Australia have worsened since I wrote about them a couple of weeks ago. Frequent exposures to hazy skies containing tiny airborne pollutants that are damaging to our lungs, have been incurred by millions of Australians, and also by many New Zealanders due to drift across the Tasman. Smoke from the Australian fires has also travelled to Argentina and across to the Atlantic, a stark reminder of how climatic events in one part of the world can have significant impacts on those living in completely different continents.
In addition to mucilaginous (polysaccharide hydrocolloid rich) and expectorant herbs such as Marshmallow (Althaea officinalis), Mullein (Verbascum thapsus) and the New Zealand native Hoheria (Hoheria populnea), evidence suggests that other herbal medicines can be beneficial for those forced to live or work in environments where exposure to smoke or fine-particulate matter containing and toxic haze from bush or forest fires, is unavoidable. Herbs with protective actions against airborne lung damaging and potentially carcinogenic compounds, are of particular interest.
One of the most promising herbs in this regard, is Elecampane (Inula helenium), the roots of which have long been traditionally used in treatments for coughs, chest infections, asthma and other lung conditions. Elecampane is an anti-inflammatory, antimicrobial and antioxidant herb, and contains various constituents exhibiting lung protective effects.
Research showing in vitro activity by elecampane against various forms of human cancer cell lines was first reported in 2002(1), and several further investigations into anticancer properties of elecampane and other Inula species, have produced favourable results(2-8). While having antitumour activity against cancer cells, no harmful effects have been measured on normal cells(3).
The sesquiterpene lactones alantolactone and isoalantolactone, key sesquiterpene lactone constituents in elecampane roots, undoubtedly contribute to these effects, having inhibitory effects against human lung, breast, prostate, colon and pancreatic cancer cells through a range of different mechanisms(10-13). Alantolactone also increases the sensitivity of lung cancer cells to the effects of the chemotherapy drugs doxorubicin and gemcitabine(9,10), suggesting a possible role as adjunctive therapy.
Isoalantolactone has also been shown to have marked anti-inflammatory effects and to reduce the extent of lung injury following exposure to lung damaging compounds in animal studies. Beneficial effects included suppression of pulmonary pathological changes, neutrophil infiltration, pulmonary permeability, and pro-inflammatory cytokine expression(14).
However, isoalantolactone and alantolactone seem to have low bioavailability when given orally to rats, possibly due to poor stability in gastrointestinal fluids and being subject to significant degradation by the liver after absorption through the so-called “first pass effect”(15,16). As such, alternative means of administration of elecampane apart from the usual oral route, particularly when the lungs are the target organ, are worth considering.
Many traditional applications of herbal medicine including Maori Medicine (Rongoā Māori), Ayurvedic, Chinese and European herbal medicine, utilised inhalation through the lungs as a popular method of administration. This pulmonary route of administration through inhalation or sprays, is also used widely in modern drug-based medicine as a means of treating conditions such as asthma or sore throats, or as a way to deliver drugs to the general blood circulation and treat other systemic conditions. Well-known examples include the pronounced bronchodilatory or anti-inflammatory effects through inhaling bronchodilatory or anti-inflammatory asthma drugs, relaxant and calming effects through inhalation of essential oil-rich preparations such as lavender or chamomile, and the well-known effects through inhaling preparations of plants such as cannabis and tobacco. The high permeability and large absorptive surface area of the lung alveolar epithelium, its good blood supply, the rapid onset of action and capacity for overcoming first-pass metabolism, can provide significant advantages of a pulmonary rather than oral route of administration(17-18).
With increasing evidence that acute or chronic environmental or occupational exposure to airborne carcinogens or lung-damaging compounds can have serious effects on human health, not only in an era of increasing bushfires but also amongst farmers handling pesticides, firefighters, painters and others working in dusty environments, the possible application of chemo-preventive and lung protecting herbs such as elecampane through the pulmonary route as an inhalation or spray, deserves more attention.
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