Two novel casbane diterpenes 1-hydroxy-(2E,6Z,12E)-casba-2,6,12-triene-4,5-dione (1) and 6E,12E-casba-1,3,6,12-tetraen-1,4-epoxy-5-one (2) were isolated from the ethanol extract of the stems of Croton argyrophyllus. Structural characterization including the relative stereochemistry of all compounds was established on the basis of spectroscopic methods, mainly 1D and 2D NMR, and HRESIMS.
Um novo labdano glicosilado, 8α-hidroxilabd-14(15)-eno-13(S)-O-β-D-ribopiranosídeo, foi isolado das partes aéreas de Egletes viscosa Less, juntamente com o 13-epi-esclareol, barbatol, tarapacol, espinasterol, ternatina e triacontano. As estruturas dos compostos isolados foram elucidadas pelo uso de métodos espectrométricos e preparação de derivados químicos.A new labdane glycoside, 8α-hydroxylabd-14(15)-ene-13(S)-O-β-D-ribopyranoside, was isolated from the aerial parts of Egletes viscosa Less, along with 13-epi-sclareol, barbatol, tarapacol, spinasterol, ternatin and triacontane. The structures of the isolated compounds were elucidated by the use of spectrometric methods and preparation of chemical derivatives. Keywords: Asteraceae, Egletes viscosa, diterpene glycoside, 8α-hydroxylabd-14(15)-ene-13(S)-O-β-D-ribopyranoside IntroductionEgletes viscosa Less (Asteraceae) is an annual herb mostly native to intertropical Americas. It is known in the Northeast of Brazil as "macela" or "macela-da-terra" and grows throughout the margins of river and lakes as soon as the raining season ends. The flower buds are largely sold in the herbal stores and used in the folk medicine as emmenagogue, diaphoretic, 1 stomachic and antidiarrhoeal. 2 Previous studies with E. viscosa have reported the isolation of biologically active flavonoids and diterpenoids. [3][4][5][6][7][8][9][10][11][12][13][14] Recently, Lee et al reported the isolation of labdane diterpene glycosides and flavonoids from the entire plant native from Peru. 15 In continuation of the work with this species, we report now the isolation of the new labdane glycoside 8α-hydroxylabd-14(15)-ene-13(S)-O-β-D-ribopyranoside 1 in addition to 13-epi-sclareol, 16 barbatol, 17 tarapacol, 18 spinasterol, 19 ternatin, 7, 20-23 and triacontane from the aerial parts of E. viscosa. The complete proton and carbon assignments of the known compounds and of the new diterpene 1, including the unpublished 13 C and 1 H NMR data of the new derivatives 2-4 were accomplished by the use of a series of 2D NMR experiments such as 1 H-1 H COSY, HMQC and HMBC. Results and DiscussionCompound 1 was isolated as a white solid. Its molecular formula was determined as C 25 H 44 O 6 from the NMR and EImass spectroscopy measurements (m/z = 440). The absorption band in the IR spectrum at 3400 cm -1 was consistent with hydroxyl groups. Inspection of the 1 H NMR spectrum indicated the presence of three angular methyl groups at δ 0.81 (s, H-19 and H-20) and 0.88 (s, H-18), two methyls attached to oxygenated tertiary carbons at δ 1.11 (s, H-17) and 1.35 (s, H-16), and an anomeric hydrogen at δ 4.32 (d, J 6.4 Hz,. Moreover, the presence of a vinyl moiety was suggested by the signals at δ 5.92 (dd, J 17.8, 10.9, H-14); 5.22 (dd, J 17.8, 1.2, H-15a) and 5.17 (dd, J 10.9, 1.2, H-15b). The 13 C NMR spectral data of 1 confirmed 1375 Silva-Filho et al. Vol. 18, No. 7, 2007 the β-ribopyranosyl unit by the signals at δ 98.6 (C-1´), 73.1 (C-3´), 71.3 (C-2´), 68.2 (C-4´) and 65.1 (C-5´); 24 together with 20 carbon ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.