A New Tricyclic Alkaloid from Portulaca oleracea L.

A new tricyclic alkaloid named portulacatone ( 1 ), i.e. , 5,6‐dihydro‐8,9‐dihydroxy‐11 H ‐pyrrolo[2,1‐ b ] [3]benzazepin‐11‐one, together with eight known compounds, methyl 4‐hydroxyphenylacetate ( 2 ), p ‐hydroxybenzaldehyde ( 3 ), vanillin ( 4 ), protocatechualdehyde ( 5 ), p ‐hydroxybenzoic acid ( 6 ), iseluxine ( 7 ), oleracein E ( 8 ), and (+)‐( R )‐feruloyl malate ( 9 ) were isolated from aerial parts of Portulaca oleracea L. Their structures were elucidated based on spectroscopic analyses. Among them, compounds 1 – 7 and 9 were isolated from this medicinal plant for the first time. Compounds 1 and 7 showed dose‐dependent scavenging activities against DPPH (2,2‐diphenyl‐1‐picryl‐hydrazyl) free radical, with EC 50 values of 14.36 μ M and 9.98 μ M , respectively, more potent than the natural antioxidant vitamin C ( EC 50 20.72 μ M ).