[Show abstract][Hide abstract] ABSTRACT: Four new serratene triterpenoids, 3β,21β,24-trihydroxyserrat-14-en-24-(4'-hydroxybenzoate) (1), 3β,21α,24-trihydroxyserrat-14-en-3-(4'-hydroxybenzoate) (2), 3β,14α,15α,21α-tetrahydroxyserrat-14-en-3-(3'-methoxyl-4'-hydroxybenzoate) (3), and 3β,14α,15α,21α-tetrahydroxyserrat-14-en-21-acetyl-3-(4'-hydroxybenzoate) (4), together with two known ones, 5 and 6, were isolated from whole plants of Palhinhaea cernua. The structures of these new compounds were elucidated by spectroscopic methods. All the six compounds were tested for their in vitro cytotoxicity against three human cancer cell lines (K562, SMMC-7721, and SGC7901). Compound 5 showed cytotoxicity against the three test cell lines with IC₅₀ values of 20.3, 34.0, and 22.5 ug/mL, respectively. Compound 1 showed slight cytotoxicity against K562 cell lines with IC₅₀ value of 56.1 ug/mL, while no obvious inhibitory effects were detected for other compounds.
[Show abstract][Hide abstract] ABSTRACT: Four homoisoflavonoids named portulacanones A-D, identified as 2'-hydroxy- 5,7-dimethoxy-3-benzyl-chroman-4-one, 2'-hydroxy-5,6,7-trimethoxy-3-benzyl-chroman-4-one, 5,2'-dihydroxy-6,7-dimethoxy-3-benzyl-chroman-4-one, and 5,2'-dihydroxy-7-methoxy-3-benzylidene-chroman-4-one, were isolated from aerial parts of the plant Portulaca oleracea along with nine other known metabolites. Their structures were established on the basis of extensive spectroscopic analyses. Portulacanones A-D is the first group of homoisoflavonoids so far reported from the family Portulacaceae. They represent a rare subclass of homoisoflavonoids in nature with a structural feature of a single hydroxyl group substituted at C-2' rather than at C-4' in ring B of the skeleton. Three homoisoflavonoids and the known compound 2,2'-dihydroxy-4',6'-dimethoxychalcone selectively showed in vitro cytotoxic activities towards four human cancer cell lines. Especially 2,2'-dihydroxy-4',6'-dimethoxychalcone showed cytotoxic activity against cell line SGC-7901 with an IC₅₀ value of 1.6 μg/ml, which was more potent than the reference compound mitomycin C (IC₅₀ 13.0 μg/ml).