Abstract
Euphorbia hirta (asthma weed) has been documented as an effective herb for the treatment of asthma and associated symptoms. This study was aimed at comparing the bioactive constituents and in vitro antiradical activity of asthma weed with other commonly growing anti-asthmatic plants such as Pergularia tomentosa, Dipterygium glaucum and Acalypha indica in Tabuk region of Saudi Arabia. The results showed that the total phenol and flavonoid content of methanolic leaf extract of E. hirta was highest compared to the other anti -asthmatic plants. E. hirta was also recorded to have the maximum total antioxidant capacity, 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) antiradical activity and nitric oxide (NOX) scavenging activity. However, hydrogen peroxide scavenging activities and metal chelating activities were as the highest for the methanolic extracts of D. glaucum and P. tomentosa, respectively compared to the other anti -asthmatic plants. It may be concluded that the abundance of phenol and flavonoids along with maximum antioxidant capacity, DPPH antiradical activity and NOX scavenging activity of E. hirta makes it worthy of using as an effective anti-asthmatic plant.