Asthma, Euphorbia hirta and its anti-inflammatory properties

EUPHORBIA HIRTA IS A PLANT USED IN TRADItional medicine for a variety of diseases, such as cough, asthma, colic dysentery and genito-urinary infection. This plant, belonging to the family Euphorbiaceae, is also known as the Australian asthma herb or Queensland asthma weed, and is not toxic when taken in typical dosages. In South Africa, it is commonly used for asthma, which is one of the most common respiratory complaints. Although corticosteroids are considered the best means of defence against this debilitating illness, many people, especially in poor countries, rely on herbal remedies for its treatment. We discuss recently published results to assess the effect of the plant using the BALB/c murine asthma model. We also review the different compounds found in plant extracts, in an attempt to understand the reason for its anti-inflammatory properties. We conclude that the flavonoids quercitrin (converted to quercetin in the alimentary canal) and myricitrin, as well as the sterols 24-methylene-cycloartenol and -sitosterol, exert noteworthy and dose-dependent anti-inflammatory activity. The triterpene β-amyrin also seems to exert a similar anti-inflammatory activity. Tannins and tannic acid derivatives, also present in the plant, have antiseptic effects and the two triterpenoids, taraxerone (EH-1) and 11α, 12α-oxidotaraxerol (EH-2), in E. hirta demonstrate antibacterial and antifungal properties. The effectiveness of E. hirta in treating asthma may lie predominantly in the synergistic relationships between the flavonoids, sterols and triterpenoids.