Ent-pimarane Diterpenoids Research Articles

Chemical constituents from Microlepia hancei Prantl and their chemotaxonomic significance

A phytochemical study on the Microlepia hancei Prantl yielded sixteen compounds including five flavonol glycosides (1–5), nine pterosin sesquiterpenes (6–14), and two ent-pimarane diterpenoids (15 and 16). Their structures were elucidated based on the ORD, CD, MS, and NMR data, as well as by comparison of the published data. This is the first report on the chemical constituents of M. hancei. Among them, compounds 1–5, 7, 8, and 13 were first reported from the family Dennstaedtiaceae, and compound 14 was first reported from the genus Microlepia. Meanwhile, the chemotaxonomic significance of these compounds was discussed.

Diterpenoids and Diacetylenes from the Roots of Aralia cordata with Inhibitory Effects on Nitric Oxide Production.

Bioactivity-guided isolation of a MeOH extract of Aralia cordata led to the isolation of four new ent-pimarane diterpenoids (1-4) and a diacetylene (5) together with 21 known compounds (6-26). Their structures were established based on the interpretation of one- and two-dimensional NMR and HRESIMS data. The absolute configurations of the new isolates were determined by electronic circular dichroism data analysis, single crystal X-ray diffraction, and Mosher's esterification method. All compounds exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages with IC50 values ranging from 1.1 to 69.4 μM.

Ent-Pimarane diterpenoids from Siegesbeckia glabrescens with anti-inflammatory activity.

Nine new ent-pimarane-type diterpenoids, siegesbeckia A-I (1-9), together with four known analogues ent-3α,15,16,19-tetrahydroxypimar-8(14)-ene (10), 15,16-dihydroxypimar-8(14)-en-3-one (11), 14β,16-epoxy-7-pimarene-3α,15β-diol (12) and darutigenol (13), were obtained from the aerial parts of Siegesbeckia glabrescens Makino. The structures of these compounds were elucidated by the interpretation of HRESIMS, 1D NMR and 2D NMR data. Their configurations were determined by ECD analysis and the structure of compound 1 was confirmed by X-ray crystallography. Putative biosynthetic pathways were proposed for 1-13. The anti-inflammatory effects of the compounds were evaluated by testing their inhibition of LPS-induced NO production in BV2 microglial cells. The results revealed that new compounds 2, 6 and 8 exhibited potent inhibitory activities with IC50 values of 33.07, 42.39 and 63.26 μM, which compared well with the positive control minocycline (IC50 32.84 μM).

Ent-abietane and ent-pimarane diterpenoids from Croton mubango (Euphorbiaceae)

Twelve ent-abietane and two ent-pimarane diterpenoids were isolated from the leaves of Croton mubango Müll. Arg. (Euphorbiaceae) collected in the Democratic Republic of the Congo. 2β-Hydroxy-ent-abieta-7,13-dien-3-one, 15-hydroxy-ent-abieta-7,13-dien-3-one, 13α,15-dihydroxy-ent-abieta-8(14)-en-3-one, 2β,9,13-trihydroxy-ent-abieta-7-en-3-one, 2β,7β-dihydroxy-ent-abieta-8,11,13-trien-3-one, 15-hydroxy-ent-abieta-8,11,13-trien-3-one and ent-pimara-8(14),15-dien-3-one and the ent-forms of the previously reported normal series diterpenoids, ent-abieta-8,11,13-trien-3-one, 7β-hydroxy-ent-abieta-8,11,13-trien-3-one, 3α-hydroxy-ent-abieta-8,11,13-triene, 15-hydroxy-ent-abieta-8,11,13-triene and 6β-hydroxy-ent-abieta-8,11,13-triene are reported here for the first time. Structures were established using HRESIMS, FTIR, NMR, DP4+ probability calculations and by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Ent-pimara-8(14), 15-dien-3-one, showed antiproliferative activity against melanoma (MALME-3M), renal (UO-31) and ovarian cancer cell lines (IGROV1) at a concentration of 10−5 M in the NCI 60 screen.

Isolation and characterization of ent-pimarane diterpenoids from Sigesbeckia pubescens

Five new ent-pimarane diterpenoids ent-16-nor-2-oxopimar-8(14)-ene-15,19-dial (1), ent-16-nor-2α,19-dihydroxypimar-8-en-15-al (2), 3-O-acetyldarutigenol (3), 19-O-acetylkirenol (4), ent-16-nor-3β,15-dihydroxypimar-8(14)-ene (5) were isolated and characterized from the ethanol extract of Sigesbeckia pubescens. Their structures were elucidated on the basis of spectroscopic analysis. The absolute configuration of C-15 in compounds 3 and 4 was assigned using Snatzke’s method. All these compounds were assessed for their anti-inflammatory potential by measuring the inhibitory effects on NO production in LPS-induced RAW 264.7 macrophage cells and compound 4 showed significantly inhibitory activity with IC50 value of 5.9 μM.

New ent-kaurane and ent-pimarane diterpenoids from Siegesbeckia pubescens

Phytochemical investigation of the aerial parts of Siegesbeckia pubescens afforded two new ent-kaurane diterpenoids (1-2), together with sixteen known ent-kaurane and ent-pimarane diterpenoids (3–18). Their structures were elucidated on the basis of extensive spectroscopic methods The absolute configurations of 1–2 and 12 were determined by single-crystal X-ray diffraction analyses. All compounds were evaluated for their cytotoxic activities against two human cancer cell lines A375 and HCT-116.

Diterpenoids from aerial parts of Flickingeria fimbriata and their nuclear factor-kappaB inhibitory activities

Chemical investigation of the aerial parts of Flickingeria fimbriata (Bl.) Hawkes resulted in isolation of sixteen ent-pimarane diterpenoids, including five rare 16-nor-ent-pimarane diterpenoids, two 15,16-dinor-ent-pimarane diterpenoids and one ent-pimarane diterpenoid. Structures were mainly elucidated by extensive spectroscopic analysis, and their absolute configurations were unequivocally determined by the exciton chirality method, the modified Mosher’s method, the CD experiments (including Snatzke’s method) and chemical transformations, respectively. All the isolated compounds were screened for inhibitory effects on the nuclear factor-kappaB (NF-κB) in lipopolysaccharide (LPS) induced murine macrophage RAW264.7 cells, using a NF-κB-dependent luciferase reporter gene assay. Several of these compounds displayed comparable or even better activities than the positive control pyrrolidinedithiocarbamate (PDTC) (IC50=26.3μM) with IC50 values in the range of 14.7–29.2μM and structure–activity relationships are briefly proposed.

Ent-Kaurane and ent-Pimarane Diterpenoids from Siegesbeckia pubescens

Phytochemical investigation of the above-ground parts of Siegesbeckia pubescens yielded 25 diterpenoids, including five new ent-pimarane diterpenoids (1-3, 11, and 12) and four new ent-kaurane diterpenoids (13-16). The structures and relative configurations of the new compounds were elucidated by comprehensive spectroscopic analysis and by comparison of their NMR data with those of related compounds. Single-crystal X-ray diffraction analysis confirmed the structures of 8, 13, and 14. Seven of these diterpenoids were evaluated for cytotoxic activity against HSC-T6, HeLa, and B16 cell lines. Compounds 11 and 14 exhibited moderate cytotoxicity.

Ent-Pimarane Diterpenoids from Siegesbeckia orientalis and Structure Revision of a Related Compound

Six new ent-pimarane diterpenoids, namely, ent-14beta,16-epoxy-8-pimarene-3beta,15alpha-diol (1), 7beta-hydroxydarutigenol (2), 9beta-hydroxydarutigenol (3), 16-O-acetyldarutigenol (4), 15,16-di-O-acetyldarutoside (5), and 16-O-acetyldarutoside (6), were isolated from the ethanol extract of Siegesbeckia orientalis. Their structures were elucidated on the basis of spectroscopic studies, and the absolute configuration of 1 was established by the modified Mosher's method. Furthermore, the structure of ent-12beta,16-epoxy-8-pimarene-2alpha,15beta,19-triol, recently isolated from the same plant, should be revised as ent-14beta,16-epoxy-8-pimarene-2alpha,15alpha,19-triol (10).

Novel diterpenoids and diterpenoid glycosides from Siegesbeckia orientalis.

Eight new ent-pimarane diterpenoids and diterpenoid glycosides, namely, ent-12alpha,16-epoxy-2beta,15alpha,19-trihydroxypimar-8-ene (1), ent-12alpha,16-epoxy-2beta,15alpha,19-trihydroxypimar-8(14)-ene (2), ent-2alpha,15,16,19-tetrahydroxypimar-8(14)-ene, ent-15-oxo-2beta,16,19-trihydroxypimar-8(14)-ene, ent-2-oxo-15,16-dihydroxypimar-8(14)-en-16-O-beta-glucopyranoside, ent-2-oxo-15,16,19-trihydroxypimar-8(14)-ene, ent-2-oxo-3beta,15,16-trihydroxypimar-8(14)-en-3-O-beta-glucopyranoside, and ent-2beta,15,16,19-tetrahydroxypimar-8(14)-en-19-O-beta-glucopyranoside, together with seven known diterpenes were isolated from Siegesbeckia orientalis. Compounds 1 and 2 are novel ent-pimarane diterpenoids with an unprecedented 12alpha,16-epoxy group. Their structures were established by spectral methods, especially 1D and 2D NMR spectral methods.