Chemical and biologically active constituents of Pteris multifida

A new compound, 4-caffeoyl quinic acid 5-O-methyl ether (2), together with 12 known compounds—identified as (2R,3R)-pterosin L 3-O-β-d-glucopyrannoside (3), β-sitosterol β-d-glucopyranoside (4), apigenin 7-Ο-β-d-glucopyranoside (5), luteolin 7-Ο-β-d-glucopyranoside (6), sucrose (7), caffeic acid (8), pterosin C 3-Ο-β-d-glucopyranoside (9), pteroside C (10), 4,5-dicaffeoyl quinic acid (11), pteroside A (12), wallichoside (13) and (2S)-5,7,3′,5′-tetrahydroxyflavanone (14)—were isolated from Pteris multifida. The structure of the new compound was determined by means of physical, chemical and spectroscopic evidence. Compounds 5 and 6 were the main constituents of the plant, with yields of 0.19% and 0.16%, respectively. The cytotoxic activities of 2, 3, and 9–13 were evaluated against a human cell line (KB cells). Among the isolated compounds, pterosin C 3-Ο-β-d-glucopyrannoside (9) and 4,5-dicaffeoylquinic acid (11) showed a significant selective cytotoxicity (IC₅₀ 2.35 and 5.38, respectively), while moderate activity was observed for compound 2 (IC₅₀ 12.3). The chemosystematics of Pteris species is also discussed.