Antioxidant activity of devil’s claw cell biomass and its active constituents

A cell suspension culture of devil’s claw (Harpagophytum procumbens  ), an African plant with high medicinal value, was induced from previously obtained callus cultures, cultivated in shake-flasks, and a purification scheme to isolate the main active constituents that accumulated in the biomass was developed. The antioxidant activities of total methanol extracts, collected fractions (phenylethanoids, terpenoids and sugars) and specific active constituents (β-OH-verbascoside, verbascoside and leucosceptoside A) were then evaluated in 2,2-diphenyl-1-picrylhydrazyl (DPPH·) and superoxide anion (O2-) radical scavenging and oxygen radical absorbance capacity (ORACFL) assays. The most active compounds were found to be β-OH-verbascoside (in DPPH· and superoxide radical scavenging assays) and leucosceptoside A (in ORAC assays). The phenylethanoid fraction may be attractive for various commercial purposes since it displayed significant antioxidant activity and it can be conveniently and economically prepared by a single-step column separation of extracts.