Polycyclic Polyprenylated Acylphloroglucinols (PPAPs) Kouytchin A‐B and a Tetramethoxydibenzo[1,4]Dioxin From Hypericum kouytchense : Isolation and Cytotoxic Evaluation

Three new compounds, kouytchin A ( 1 ), kouytchin B ( 2 ), and 2,4,5,10‐tetramethoxydibenzo[1,4]dioxin ( 3 ), along with nine known compounds ( 4 ‐ 12 ), were isolated and purified from the ethyl acetate extract of Hypericum kouytchense H Lév. The known compounds were identified as uraloidin A ( 4 ), uralione D ( 5 ), biyoulactones B ( 6 ), xanthone derivatives ( 7 ‐ 11 ), and 3‐hydroxy‐1,4,7‐trimethoxydibenzofuran ( 12 ). The structures of new compounds were elucidated based on comprehensive spectroscopic analysis, including 1D NMR ( 1 H, 13 C and DEPT), 2D NMR (HMBC, COSY and HSQC), HRMS, and electronic circular dichroism (ECD). Furthermore, compounds 4 and 5 exhibited potent cytotoxic activity against the gastric cancer cell MKN‐45, with half‐maximal inhibitory concentration (IC 50 ) values of 16.00 ± 0.86 µM and 18.47 ± 0.95 µM, respectively. These findings enrich the phytochemical knowledge of H. kouytchense and highlight the potential of its constituents as leads for anticancer drug discovery.