A new amide (1), two new phenylpropanoid derivatives (2, 3), along with three new natural products, including three nitrogen chirality compounds, N-(3-methoxy-1,3-dioxopropyl)-D-phenylalanine methyl ester (4), N-(3-methoxy-1,3-dioxopropyl)-L-phenylalanine methyl ester (5), and N-acetyl-L-phenylalanine methyl ester (6), as well as dimethyl (2R,3R)-2-hydroxy-3-(((E)-3-(4-hydroxyphenyl)acryloyl)oxy)succinate (7) and dimethyl (S,E)-2-((3-(4-hydroxy-3-methoxyphenyl)acryloyl)oxy)succinate (8) were isolated from Delphinium kamaonense Hunth. Their structures were elucidated by extensive analysis of 1D and 2D NMR, and HR-ESI-MS experiments, and the absolute configurations were determined by comparative analysis of specific optical rotation. Compound 1 exhibited a moderate cytotoxicity effect against Hep-3B cancer cell lines (IC50 41.39±0.13 μM) and an excellent antioxidant activity (IC50 0.527±0.06 μM in ABTS assay, and 1.235±0.09 μM in DPPH assay, respectively), which was superior to vitamin C in ABTS (IC50 1.670±0.07 μM) and DPPH (IC50 19.10±0.40 μM) methods.
Keywords: Delphinium kamaonense; amide alkaloids; antioxidant activity; cytotoxicity; phenylpropanoids.
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