Microwave-assisted extraction of bioactive saponins from chickpea (Cicer arietinum L)

Growing interest in plant secondary metabolites has brought with it the need for economical, rapid and efficient extraction protocols. Microwave-assisted extraction (MAE) was used to extract saponins from chickpea (Cicer arietinum). Several MAE conditions were tested, and the method proved to be superior to Soxhlet extraction with regard to amounts of solvents required, time and energy expended. The use of a butanol/H₂O mixture showed selectivity towards saponin extraction. Using TLC, two distinct saponins were observed in the various chickpea extracts. The identification of the major saponin as a DDMP-conjugated saponin was verified using ¹H and ¹³C NMR, for the first time in chickpea. The MAE procedure most likely contributed to the conservation of the heat-sensitive DDMP moiety. The pure chickpea saponin exhibited significant inhibitory activity against Penicillium digitatum and additional filamentous fungi. Two Fusarium strains tested were highly tolerant to the saponin. The potential for using MAE for the efficient extraction of natural products may assist in expediting the chemical analysis and characterization of the biological activities of such compounds.