Terpenoids from the Aerial Parts of Parasenecio deltophylla

Abstract

Five new modified eremophilane-type sesquiterpenes (1-5), including three norsesquiterpenes (1-3), and one new monoterpene (6) were isolated from the aerial parts of Parasenecio deltophylla. Their structures were established on the basis of HRMS and NMR methods. The cytotoxicity of compounds 1-4 and 6 against selected cancer cell lines, including human promyelocytic leukemia (HL-60) and human hepatoma (Hep-G2), was evaluated. Antioxidant activities of these compounds were assessed by ABTS and DPPH methods.

Modified Eremophilanes from Parasenecio hastatus and Their Neuroprotective Activities

“…The 1 H NMR data (Table 3) suggested three ortho-benzenoid proton signals [H-1 (δ H 8.08, 1H, d, J = 8.4 Hz), H-2 (δ H 7.38, 1H, t, J = 7.6 Hz), and H-3 (δ H 7.29, 1H, d, J = 6.9 Hz)] and three methyl groups [Me-13 (δ H 1.81, 3H, s), Me-14 (δ H 3.02, 3H, s), and Me-15 (δ H 2.94, 3H, s)], together with one lactone carbonyl C-12 (δ C 177.4) in the 13 C NMR data (Table 2), indicating that compound 10 was a modified eremophilane lactone that was similar to 14-angeloyloxy-11α-hydroxy-Omethyl-1,2,3,4-tetrahydrocacalolide, except for lacking an angeloyloxy group at C-14. 4 These conclusions were verified by the HMBC correlations from Me-14 to C-5 (δ C 132.7), C-6 (δ C 130.8), and C-7 (δ C 130.4). The OH group at C-11 was confirmed to be β-oriented by comparing the specific rotation of 10 ([α] D +17) with those of 3-hydroxycacalolide ([α] D −18) and epi-3-hydroxycacalolide ([α] D +35).…”

“…3 The most obvious distinction was the chemical shift value of H-3 (δ H 4.83, 1H, m), which indicated the presence of a hydroxy group at C-3 (δ C 71.6) for 2 instead of a methylene group for cacalohastine. 3 The 1 H− 1 H COSY correlations (Figure 1) from H-1 through H- 4 Furthermore, the correlation between Me-15 and Me-14 in the NOESY experiment confirmed the β-orientation at Me-15, 15 and the correlation between H-3 and H-4 confirmed the β-orientation for the hydroxy group at C-3 (Figure 4). The (4R) absolute configuration was identified based on the chiroptical data of both cacalol and compound 2, which showed a positive Cotton effect at approximately 287 nm in the ECD spectrum.…”

“…Compound 9 had the molecular formula C 15 H 16 O 3 , as evidenced by the HRESIMS protonated molecular ion at m/z 245.1173 ([M + H] + , calcd for C 15 H 17 O 3 , 245.1172). The 1 H (Table 3) and 13 C NMR (Table 2) data of 9 resembled those of 8, with the only difference being the presence of a Δ 3 (4) olefinic bond [H-3 (δ H 7.17, 1H, d, J = 7.0 Hz), C-3 (δ C 128.9), and C-4 (δ C 139.7)] in 9 instead of an OH group at C-3 in 8. This structure was confirmed by the cross-peaks of Me-14 (δ H 2.88, 3H, s) with C-3, C-4, and C-5 (δ C 135.2) in the HMBC spectrum, together with the cross-peaks of Me-12 (δ H 2.52, 3H, s) with C-11 (δ C 205.3), thereby establishing the 2D structure of hastatusin I (9).…”

“…A phytochemical investigation of the acetone extract of P. hastatus afforded 11 new modified eremophilanes, 1−11, and 13 known compounds, 12−24, that were identified as 14angeloyloxy-3β-hydroxy-1,2-dehydrocacalolmethyl ether (12), 14 deltonorcacalol (13), 15 14-angeloyloxy-3β-hydroxydeltonorcacalol (14), 4 radulifolin D (15), 8 cacalonol (16), 16 maturinone (17), 17 deltocacalone (18), 15 5-hydroxy-9-methoxy-3,4,5-trimethylnaphtho [2,3-b]furan-6(5H)-one (19), 18 14-nordehydrocacalohastine (20), 19 dehydrocacalohastine (21), 3 dehydrocacalohastin-14-ol (22), 20 cacalohastin (23), 21 and 14-ethoxydehydrocacalohastine (24) 20 by comparison of the observed and reported data (Chart 1).…”

“…The 1 H (Table 1) and 13 C NMR (Table 2) data of 7 were similar to those of 6. They differed mainly in the presence of an epoxide moiety involving C-2 and C-3 4,23 The correlation between H-3 and Me-15, together with the correlation between H-2 and H-3 in the NOESY experiment, indicated that H-2, H-3, and Me-15 were all β-oriented (Figure 4). The (1S,2R,3S,4R) absolute configurations of 7 was established by comparison of the experimental and calculated ECD spectra (Figure 6).…”