Ursane-type nortriterpenes with a five-membered A-ring from Rubus innominatus

Two five-membered A-ring nortriterpenes (1 and 2) and six triterpenes (3–8) along with 17 known triterpenes were isolated from the roots of Rubus innominatus. [Display omitted] •Separation and identification of 8 triterpenes from the roots of Rubus innominatus.•Two of the compounds have a distinctive contracted five-membered A-ring norursane-type skeleton.•Four compounds exhibited strong inhibitory effect on TNF-α, IL-1β, and IL-6 production in LPS-induced RAW 264.7 macrophages. Two nortriterpenes (rubuminatus A and B), which contain a distinctive contracted a five-membered A-ring ursane-type skeleton, and six triterpenes along with 17 known triterpenes were isolated from the roots of Rubus innominatus S. Moore. These structures were determined to be 19α-hydroxy-2-oxo-nor- A(3)-urs-12-en-28-oic acid, 1β,19α-dihydroxy-2-oxo-nor-A(3)-urs-12-en-28-oic acid, 1β,2α,3α,19α-tetrahy droxyurs-12-en-23-formyl-28-oic acid, 1β,2α,3α,19α,23- pentahydroxyurs-11-en-28-oic acid, 1-oxo-siaresinolic acid, 2α,3α-dihydroxyolean-11,13(18)-dien-19β,28-olide, 1β,2α,3α-trihydroxy-19-oxo- 18,19-seco-urs-11,13(18)-dien-28-oic acid, and 2-O-benzoyl alphitolic acid based on extensive spectroscopic analyses. In vitro anti-inflammatory abilities to modulate the production of TNF-α, IL-1β, and IL-6 in LPS-induced RAW 264.7 macrophages of the compounds were determined. Rubuminatus A and B, as well as 1-oxo-siaresinolic acid and 2α,3α-dihydroxyolean-11,13(18)-dien-19β,28-olide, exhibited significant inhibitory effects on these cytokines.