Rubiyunnanins C-H, cytotoxic cyclic hexapeptides from Rubia yunnanensis inhibiting nitric oxide production and NF-κB activation

Six new (1-6) and five known (7-11) cyclic hexapeptides were isolated from the roots of Rubia yunnanensis. This is the first time it is being reported that compounds 2 and 7-10 significantly inhibited TNF-α-induced NF-κB pathway activation.