Simiranes A and B: erythroxylanes diterpenes and other compounds fromSimira eliezeriana(Rubiaceae)

Abstract

The first phytochemical study of Simira eliezeriana Peixoto (Rubiaceae) allowed the isolation and structural determination of two new diterpenes named simirane A [(5R,6R,8R,9R,10S,11S,13S)-6β,11β-dihydroxy-2,4(18),15-erythroxylatrien-1-one] (1) and simirane B [(5S,8R,9R,10S,11S,13S)-11β-hydroxy-2,4(18),15-erythroxylatrien-1-one] (2), together with seven known compounds: sitosterol (3), stigmasterol (4), campesterol (5), coniferaldehyde (6), vanillin (7), pinoresinol (8) and harman (9) from the bark of the plant. The structures of the compounds were established on the basis of spectroscopic methods, including 1-D and 2-D NMR, HRESI-MS and CD analysis and comparisons with available literature data of known compounds.

Angelocunhol: New Erythroxylane Diterpene and Other Compounds fromSimira sampaioana(Rubiaceae)

“…The molecular formula was assigned as C 20 .60). Thus, these data were used to postulate the structure of a diterpene with erythroxylane skeleton, 6 corroborated by long-range correlations of (Figure 2). The value corresponding to vicinal interaction ( 3 J H,H ) between the hydrogens H-11 and H-12 (J 9.0 Hz) is consistent with axial-axial interaction 7 as appear in Figure 1, H nuclear Overhauser effect spectroscopy (NOESY) spectrum through the cross-peaks assigned to corresponding dipolar interaction (special proximity) shown in Figure 2 (1a and 1b) which indicates the axial positions for these hydrogens.…”

“…The known simirane B (2), 6 harman (3), 6,8 maxonine (4), isomalindine (5), malindine (6), 9 sitost-4-en-6-ol-3-one (7), estigmast-4,22-dien-6-ol-3-one (8), campest-4-en-6-ol-3-one (9), sitost-4-en-3-one (10), stigmast-4,22-dien-3-one (11), campest-4-en-3-one (12), 10,11 β-sitosterol (13), stigmasterol (14), 12 and stigmast-4,22-dien-3-ol (15) were identified by spectral data, involving mainly 1D and 2D 1 H and 13 C NMR spectra and comparison with literature values.…”

Other compounds isolated from Simira glaziovii and the ¹H and 13C NMR chemical shift assignments of new 1-epi-castanopsol

“…The structures of 1-3, 4, 5, 7, 8, 9, 10+11 and 12 were defined by NMR and mass spectra analyses and comparison with literature data. 5,7,[9][10][11][12] The 1 H and 13 C NMR spectra, together with GC/MS data analysis, were used to identify the steroids Table 1. 8,9 The signal correlations of 1 J CH of δ H /δ C 3.27/75.9 and δ H /δ C 3.43/79.6, observed in HSQC spectrum, confirmed the presence of two carbinolic carbons.…”

“…The FrB2 (0.45 g) was fractionated on a flash chromatographic column of silica gel, using the system hexane/acetone (9:1, v/v) as mobile phase, resulting in the isolation of 1-epi-castanopsol (6, 22.5 mg) and simirane B (7, 15 mg). 5,8 The fraction FrB3 (0.27 g) was submitted to the same chromatographic procedure as FrB2 and led to isolation of the lignan syringaresinol (8, 25 mg) and 6,7,8-trimethoxycoumarin (9, 7.0 mg). 10,11 The fraction FrC (1.5 g) was submitted to a silica gel column, using hexane/acetone in gradient of polarity as mobile phase, resulting in the isolation of the coumarin mixture isofraxidin + scopoletin (10+11, 8.0 mg) and the chemotaxonomic marker of Simira genus, the harman alkaloid (12, 10 mg).…”

“…4 The diterpenes simirane A and simirane B, besides other compounds, were isolated from S. eliezeriana. 5 The harman alkaloid is considered a chemotaxonomic marker of Simira genus. 6,7 In addition, this paper reports the isolation and structural identification of other compounds, campesterol, lupeol, lupenone, lignan syringaresinol, three coumarins and 1-epi-castanopsol, besides the diterpene simirane B, identified by the additional study of S. glaziovii.…”