A new cyclic peptide from the fibrous root of Pseudostellaria heterophylla

A new cyclic peptide, Pseudostellarin K (1), together with thirteen known compounds, including two cyclic peptides (2 and 3), one β-carboline alkaloid (4), two amides (5 and 6), three phenylpropanoids (7–9) and other compounds (10–14), were isolated from the fibrous root of Pseudostellaria heterophylla. Their structures were elucidated by extensive spectroscopic analysis. Compounds 1, 4–6, 10 were isolated from the genus pseudostellaria for the first time. All compounds were evaluated for cytotoxic activities against MCF-7, A549, HCT-116 and SGC-7901 cell lines by MTT assay. Unfortunately, all these compounds displayed weak cytotoxic activities.