Isolation, identification and antioxidative capacity of water-soluble phenylpropanoid compounds from Rhodiola crenulata

► Six water-soluble phenylpropanoids including a new phenylpropanoid (compound 1) were isolated from Rhodiola crenulata. ► Compound 1 was mainly elucidated by its 1D and 2D NMR spectral data and chemical method. ► The contents of six water-soluble phenylpropanoids from the crude extract of R. crenulata were simultaneously analysed by HPLC. ► Free radical scavenging capacities of the six water-soluble phenylpropanoids were first evaluated by DPPH test. ► The four phenylpropanoids from R. crenulata had potentials as natural antioxidants.