Bioassay-guided isolation of terpenoids from Rubus rosifolius

Rubus rosifolius S.Vidal, a plant from the Rosaceae family, is a traditional Chinese herbal medicine utilized as an adjunctive therapy for cancer, and its bioactive chemical constituents need further unearthing. In this work, seven sesquiterpenoids (1 – 7) and eight triterpenoids (8 – 15), including an undescribed compound (1), are bioassay-guidedly isolated from the decoction of the whole herb of Rubus rosifolius. Their structures are elucidated via detailed HR-ESI-MS, extensive spectroscopic analyses, and modified Mosher ester method, and the absolute configuration of (-)-hyptishumulene I (2) was revised. In bioassay, corosolic acid (10) and maslinic acid (11) exhibit moderate cytotoxicity against all tested human cancer cell lines, A549, MDA-MB-435, and SNB19, with IC₅₀ values in the range of 16.20 – 33.63 μM. Additionally, corosolic acid and maslinic acid have been reported to be capable of inhibiting STAT3 and NF-κB, or increasing membrane permeability of cancer cells and inducing apoptosis, which suggests they are the important bioactive anti-cancer components of the decoction of Rubus rosifolius.