Highly Oxygenated Triterpenoids and Diterpenoids from Fructus Rubi ( Rubus chingii Hu) and Their NF-kappa B Inhibitory Effects

During a phytochemical investigation of the unripe fruits of Hu (i.e., Fructus Rubi, a traditional Chinese medicine named "Fu-Pen-Zi"), a number of highly oxygenated terpenoids were isolated and characterized. These included nine ursane-type ( , , and - ), five oleanane-type ( , - ), and six cucurbitane-type ( - ) triterpenoids, together with five -kaurane-type diterpenoids ( - ). Among them, (4 ,5 ,8 ,9 ,10 ,14 ,17 ,18 ,19 ,20 )-2,19α,23-trihydroxy-3-oxo-urs-1,12-dien-28-oic acid (rubusacid A, ), (2 *,4 *,5 *,8 *,9 *,10 *,14 *,17 *, 18 *,19 *,20 *)-2α,19α,24-trihydroxy-3-oxo-urs-12-en-28-oic acid (rubusacid B, ), (5 ,8 ,9 ,10 , 14 ,17 ,18 ,19 )-2,19α-dihydroxy-olean-1,12-dien-28-oic acid (rubusacid C, ), and (3 ,5 ,8 ,9 , 10 ,13 ,16 )-3α,16α,17-trihydroxy- -kaur-2-one (rubusone, ) were previously undescribed. Their chemical structures and absolute configurations were elucidated on the basis of spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds and are rare naturally occurring pentacyclic triterpenoids featuring a special -unsaturated keto-enol (diosphenol) unit in ring A. Cucurbitacin B ( ), cucurbitacin D ( ), and 3 ,16 ,20( ),25-tetrahydroxy-cucurbita-5,23- dien-2,11,22-trione ( ) were found to have remarkable inhibitory effects against NF- B, with IC values of 0.08, 0.61, and 1.60 μM, respectively.