Isolation and Crystal Structure of Ent-kaurane Diterpenes from Rubus corchorifolius L. f.

In this study, ent-Kaurane-3β,16β,17-trioi （1） and ent-kaurane-2a,16β,17-triol （2）, were isolated from the leaves ofRubus corchorifolius L. f. Their structures were elucidated based on extensive spectroscopic analysis. NMR experiments identified the two compounds and X-ray crystallographic analysis confirmed their crystal structures. The crystal of 1 belongs to monoclinic with space group P21 and a = 10.7641（3）, b = 7.2789（3）, c = 11.7862（4） A, β = 95.275（3）°, V = 919.55（6） A3, Z = 2, C20H34O4, Mr = 322.49 g/mol, Dc = 1.230 g/m3, F（000） = 376, 2 = 1.54178 A,μ = 0.661 mm-1, R = 0.0319, and wR = 0.0811 for 10889 observed reflections （I〉 2σ（I））. The crystal of 2 is classified as orthorhombic with space group P212121 and a = 10.7641（3）, b = 12.72224（19）, c = 21.3929（3） A, V= 1748.94（4） A3, Z= 4, C20H3404, Mr = 322.47, De = 1.225 Mg/m3 F（000） = 712, λ = 1.54184 A,μ = 0.625 mm-1, R = 0.0303 and wR = 0.0759 for 10470 observed reflections （1〉 2σ（I））. Meanwhile, the compound revealed low inhibitory activities toward HepG2, MCF-7, and SCG-7901 cells.

New ent-kaurane diterpenes with chiral epoxyangelate moieties from Wedelia prostrata

Four new ent-kaurane diterpenes with chiral epoxyangelate moieties, (2′R,3′R)-3 a- (2′,3′-epoxyangeloyloxy)-kaur-16-en-19-oic acid (1), (2′S,3′S)-3 a- (2′,3′-epoxyangeloyloxy)-kaur-16-en-19-oic acid (2), (2′S,3′R)-3 a- (2',3'-epoxyangeloyloxy)-kaur-16-en-19-oic acid (3) and (2′R,3′S)-3α- (2′,3'-epoxyangeloyloxy)-kaur-16-en-19-oic acid (4), along with eight known diterpenes (5-12), were isolated from Wedelia prostrata. The absolute configurations of the new structures were determined by X-ray crystallography,ECD calculations and chemical methods. All compounds were evaluated for their cytotoxicity activities on human HepG-2 cells,with IC_(50) values of 11.72 ±0.22 μmol/L to 54.75±1.12 μmol/L.

Two new ent-kaurane diterpenoids from Isodon excisoides

Two new ent-kaurane diterpenoids taihangexcisoidesin A and B （1 and 2）, were isolated from the EtOAc extract of the leaves of lsodon excisoides. Their structures were determined on the basis of spectroscopic methods.

ent-Kaurane diterpenoids from the plant Wedelia trilobata

Four new ent-kaurane diterpenoids,namely,3α-tigloyloxypterokaurene L_(3)(1),ent-17-hydroxy-kaura-9(11),15-dien-19-oic acid(2),and wedelobatins A(3)and B(4),together with 11 known ent-kaurane diterpenoids(5-15),were isolated from the ethanol extract of Wedelia trilobata.All the structures of 1-15 were elucidated on the basis of spectroscopic studies.

New ent-kaurane-type diterpenoids from Isodon nervosus

Two new ent-kaurane-type diterpenoids,6β,7β,13α-trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one（1）and 15β- hydroxy-6,7-seco-6,11β：6,20-diepoxy-1α,7-olide-ent-kaur-16-ene（2）were isolated from the Isodon nervosus,and the structures were elucidated by spectroscopic analysis.

Two new ent-kaurane diterpenoids from Isodon henryi

Two new ent-kaurane diterpenoids, minheryins H （1） and I （2）, were isolated from the leaves of Isodon henryi. Their structures were elucidated by means of spectroscopic analysis, including 2D NMR spectra.

Isorosthornins A-C,new ent-kaurane diterpenoids from Isodon rosthornii

Three new ent-kauranoids,isorosthornins A-C(1-3),and a new natural product,dihydroponicidin(4),together with five known ones were isolated from the aerial parts of Isodon rosthornii.The structures were determined by means of extensive spectroscopic analysis.All diterpenoids isolated were evaluated for their cytotoxicity against HL-60,SMMC-7721,A-549,MCF-7,and SW480 cell lines,and compounds 5 and 7 showed significant inhibitory effects on all cell lines.

Two New ent-Kaurane Diterpenoids from Isodon xerophilus

Two new ent-kaurane diterpenoids, xerophilusin E (1) and xerophilusin F (2), were isolated from the leaves of Isodon xerophilus. Their structures were determined as 3, 20: 7, 20-diepoxy-ent-kaur-16-en-15-one and 7 beta, 14 beta, 20 (R)-trihydroxy-11 beta-acetoxy-7,20-cyclo-ent-kaur-16-en-6, 15-dione, respectively, by spectral methods and X-ray crystallographic analysis.

Study on the regulatory effect of liver X receptor in HEK293 cells by six main diterpene esters in Semen Euphorbiae

Background:To study the effects of the main diterpene esters in Euphorbia factor L_(1),L_(2),L_(3),L_(7a),L_(7b)and L_(8)on the transcriptional activity and protein expression of liver X receptor(LXR).Methods:The effect of the main diterpene ester components in Semen Euphorbiae on the viability of HEK293 cells were studied by MTT assay.The LXR-Luc plasmid vector was transfected into HEK293 cells and treated with Euphorbia factor L_(1),L_(2),L_(3),L_(7a),L_(7b)and L_(8)for 24 h.The effect of the main diterpene ester components of Semen Euphorbiae on LXR-Luc luciferase activity was investigated by dual luciferase reporter gene system,and the expression of LXRαprotein was detected by Western Blot.Results:Euphorbia factor L_(1),L_(2),L_(3),L_(7a),L_(7b)and L_(8)could significantly reduce the relative luciferase activity(RLU)of LXRα,and the expression level of LXRαprotein was significantly down-regulated.Conclusion:Euphorbia factor L_(1),L_(2),L_(3),L_(7a),L_(7b)and L_(8)can inhibit the expression of LXR protein level,which may be achieved by inhibiting the transcriptional activity of LXR.

Antitumor activityand mechanism of JD20,a newly synthetic analog of natural ent-kaurane diterpenoid

OBJECTIVE To study the anti-tumor activity and molecular mechanism of natural diter.pene derivative JD20 in vitro.METHODS Screening the sensitive of gastric carcinoma cell lines to JD20 by cytotoxicity test for 24 h.Cell morphology was evaluated by using DAPI.After staining of can.cer cells with PI or annexin V-FITC/PI respectively,the cell cycle and apoptosis induced by JD20 were detectded by flow cytometry.The change in cell membrane potential was detected by JC-1 test kit.Western blot method was used to detect the apoptosis-related protein.RESULTS The novel natural kaurane diterpene derivative JD20 had a significant inhibitory effect on tumor cells and was particularly active on gastric cancer cell lines HGC-27(IC50=4.72±1.37 μmol·L-1) and MGC-803(IC50=7.36±0.86 μmol·L^(-1)).Further studies found that JD20 resulted in thecell cycle arrest in the G2/M phase,and induced a significant apoptosis in HGC-27.In addition,JD20 also caused the drop of mitochondrial membrane potential of HGC-27 within a short time(3 h).Furthermore,the Western blotting analysis showed that JD20 could induce the up-regulation of p53,Bax and Bim protein expression in gastric can.cer cells,and the releasing of cytochrome c from the mitochondria into the cytoplasm,as well as the ac.tivation of casepase-9/3.CONCLUSION The natural kaurane diterpene derivative JD20 can inhibit the proliferation of various human cancer cells by blocking the cell cycle and inducing apoptosis,and its mechanism of inducing apoptosis may be related to the mitochondria-mediated apoptosis pathway.

Biological Template Based on ent-Kaurane Diterpenoid Glycosides for the Synthesis of Inorganic Porous Materials

Recent studies on the preparation of porous nano-materials revealed that the use of kaurane diterpenoids molecules from steviol as biological template favors the obtaining of metallic oxides with tubular morphology as nanorods or nanofibers. In this sense, the present contribution shows an analysis in order to understand how these glycosides of kaurane diterpenoids control the nucleation and growth of inorganic materials favoring the obtaining of these morphologies. For this purpose, it was necessary to carry out studies of the leaf aqueous extract of Stevia rebaudiana by HRTEM, FTIR and 1H-NMR.

Two Novel Myrinsol Diterpenes from Euphorbia prolifera

Two novel diterpenes, Euphorprolitherin A (1) and Euphorprolitherin B (2), were isolated from the roots of Euphorbia prolifera. Their structures were elucidated on the basis of spectroscopic methods.

Two new antitumor diterpenes from Pinus sylvestris

Two new diterpenes, 15-ethyl-18-methyl pinifolate （1） and 18-hydroxy-labda-8（17）, 13E-dien-15-acetate （2）, were isolated from the needles of Pinus sylvestris. Their structures were elucidated by spectroscopic methods, including 2D-NMR spectra. Compound 1 exhibited the significant cytotoxic activity against the human carcinoma cell lines Hela, SK-N-SH and BEL-7402 in vitro.

Characterization of phloroglucinol derivatives and diterpenes in Euphorbia ebracteolata Hayata by utilizing ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry

Euphorbia ebracteolata Hayata （E. ebracteolata） is a Chinese herbal medicine used for the treatment of tumor diseases. An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry （UPLC-Q-TOF/MS） based chemical profiling approach was established for the rapid separation and characterization on phloroglucinol derivatives and diterpenes in E. ebracteolata. Three phloroglucinol derivatives and nine diterpenes were identified by exact mass measurement and were further confirmed by Ms2 data. In addition, the chemical profiles of six compounds were acquired by reference standards. Furthermore, the fragmentation rules of phloroglucinol derivatives and diterpenes of E. ebracteolata were analyzed, and each chromatographic peak was classified.

FIVE NEW DITERPENES FROM EUPHORBIA SIEBOLDIANA

Five new diterpenes were isolated from Euphorbia sieboldiana and identified as atis-16-en-13(S)-hydroxy-3,14-dione(Ⅰ),atis-16-en- 14-oxo-13(S),3 β-diol(Ⅱ),atisane-3-oxo-16α,17-diol(Ⅳ),atisane-3β ,16α,17-triol(Ⅴ)and atisane-3β-acetyl-16α,17-diol(Ⅵ)based on the chemical,spectral evidences and X-ray diffraction.

A Concise Approach to the Synthesis of Carnosic Acid Type Diterpenes

vinyl-8,11,13-podocatriene 8, which is a model of Carnosic acid type diterpenes, has been synthesized by an expeditious convergent synthetic approach.

Two new brominated diterpenes from Laurencia decumbens

Two new brominated diterpenes, namely, laurendecumtriol and 11-deacetylpinnaterpene C, were isolated and identified from the marine red alga Laurencia decumbens. Their structures were established on the basis of various NMR spectroscopic techniques and HR-ESI-MS analyses.