Hypercohones A–C, acylphloroglucinol derivatives with homo-adamantane cores from Hypericum cohaerens

Abstract

Abstract:Three new homo-adamantanyl type natural products were derived from polyprenylated polycyclic acylphloroglucinol. Hypercohones A-C (1-3), along with five other known hypercohones (4-8), were isolated from the aerial parts of Hypericum cohaerens. The structures of 1-3 were elucidated on the basis of comprehensive spectroscopic analysis. The inhibitory activities of these isolates against five human cancer cell lines in vitro were tested.

Homoadamantane and Adamantane Acylphloroglucinols from Hypericum hirsutum

“…Compounds 13 and 14 were isolated as a mixture of 2 diastereomers, and their formula was assigned to be C 31 4) yielded the same carbon skeleton as for 12. Conspicuous was a more or less distinct chemical shift of some carbon atoms, especially C-7, C-10, C-13, and C-14.…”

“…Hence, compound 11 was identified as a hitherto unknown homoadamantane acylphloroglucinol derivative with an additional cyclopentane ring and trivially named hirsutusal A. Structurally related substances could be found in the literature [27,30,31].…”

“…The relative configuration of H-2‴ was ascertained by NOE cross-peaks between H 3 -14 (δ H 1.21) and both H-7a and H-6 and between H 3 -13 (δ H 0.89) and H-7b (δ H 1.57), H-10b (δ H 1.77), and H-2‴ (δ H 2.47) as β-oriented. This configuration is known from sampsonione C [29,30], attenuatumione A [32], and plukenetione B [28,31]. Comparable to 11 and 12, the NOESY spectrum showed for 14 correlations of H-10a (δ H 2.37) and H 3 -16 (δ H 1.26), H 3 -15 (δ H 1.26), and H-7a (δ H 1.91) and also of H-6 (δ H 1.82) and H-10b (δ H 2.10), which established the relative β orientation of H-6.…”

“…56S-57 aS, Supporting Information). The hitherto undescribed derivatives 13 and 14 were trivially named hirsutusals C and D. Related compounds were isolated from H. cohaerens N. Robson [31], H. henryi H. Lév. & Vaniot [27], and H. attenuatum Fischer ex Choisy [32].…”

“…Thus, compound 18 was assigned as a hitherto unknown tetracyclic adamantan type acylphloroglucinol with isobutyryl side chain and named hyperihirsolin A. An analogous acylphloroglucinol is hyperisampsin A from H. sampsonii Hance[34].Compound 19 was isolated as a colorless oil, and its molecular formula was assigned to be C31 H 46 O 6 by positive-ion ESI-HRMS showing a pseudomolecular ion at m/z 537.3188 [M + Na] + . Comprehensive NMR analyses (▶ Table…”