Phytochemical Exploration and Anti-asthmatic Activity of Crude Methanol Extract and Derived Fractions of Sonchus asper (L.) Hill

Asthma is a chronic inflammatory airway disease with limited curative therapies. Sonchus asper, traditionally used in Pakistan for asthma, was investigated for its phytochemical profile and in vivo anti-asthmatic potential.

The whole plant was extracted with 80% methanol, fractionated, followed by phytochemical screening, HPLC analysis, and total phenolic and flavonoid quantification. Anti-asthmatic activity was evaluated using an ovalbumin-induced asthma model following oral administration of extracts and fractions. Bronchoalveolar lavage fluid analysis, total and differential leukocyte counts, and lung histopathology were performed. The most active fraction (chloroform) was subjected to column chromatography and GC-MS analysis.

Alkaloids, flavonoids, saponins, tannins, and phenolics were detected, with the chloroform fraction exhibiting the highest phenolic and flavonoid contents. HPLC analysis identified quercetin, catechin, and rutin. The chloroform fraction displayed the most potent anti-asthmatic activity, significantly reducing total inflammatory cells by 73.2% (p ˂ 0.001), 63% (p ˂ 0.01) and 57.7% (p < 0.01) at 300, 150 and 75 mg/kg respectively, with marked suppression of eosinophils, neutrophils, lymphocytes and macrophages, and improved histopathology, while the ethyl acetate fraction produced comparable reductions (72.61%, 61.90%, 56.54%) across the same dose range. GC-MS identified caryophyllenyl alcohol and phytol.

The significant anti-asthmatic activity of Sonchus asper , particularly the chloroform and ethyl acetate fractions, supports existing evidence on flavonoid and phenolic-rich medicinal plants, although the lack of cytokine profiling and molecular mechanistic validation remains a limitation.

These findings support the traditional use of Sonchus asper in asthma and identify it as a promising source of anti-inflammatory agents.