Bioactive Phenylpropanoids, Phenolic Acid and Phytosterol from Landolphia owariensis P. Beauv Stringy Seed Pulp

Landolphia owariensis P. Beauv is economically important for latex/rubber and folklore medicine. Its stringy seed pulp is freely eaten by humans and animals. Thus, L. owariensis stringy seed pulp was extracted serially with hexane and acetone to isolate and characterize its active pharmaceutical ingredients. Solvent/solvent partition and chromatographic separations afforded four bioactive compounds, (E)-3-(3,4-Dihydroxylcinnamoyl)quinic acid [(E)-Chlorogenic acid], I; (E)-3-(3,4-Dihydroxylcinnamoyl)quinic acid methyl ester [(E)-Chlorogenic acid methyl ester], II; 3,4-Dihydroxylbenzoic acid, (Protocatechuic acid), III; and 22,23-Dihydrostigmaster-3β-ol (3β-Sitosterol) (IV). Structures of I, II and III were assigned by combinations of high-performance liquid chromatography-ultraviolet-visible spectroscopy, 1D and 2D nuclear magnetic resonance spectroscopy, high-performance liquid chromatography-mass spectrometry and reference to published literatures, while compound IV was identified by chemical methods and gas chromatography-mass spectrometry. The phenylpropanoids and phenolic acid (compounds I, II and III) are notable standard antioxidants with confirmed hepatic-protective activity and other exciting biological activities. Compound IV has been reported to possess anti-inflammatory activity, anti-colon cancer action and a cholesterol-lowering effect. The described compounds are important medicinal constituents of L. owariensis stringy seed pulp, and this is the first major report on the phytochemistry of L. owariensis P. Beauv.