Three New Diterpenoids from Euphorbia wallichii

Unprecedented nor-seco-diterpene lactones inhibited osteogenic differentiation of valve interstitial cells

The first examples of ent-atisane and ent-isopimarane diterpene lactones with an unusual 2,3-seco-2-nor-tetrahydro-2H-pyran-2-one nucleus, eufislactones A (1) and B (2), were isolated from the roots of Euphorbia fischeriana, together with a new (3) and fifteen known biosynthetic congeners (4-18). Their structures incorporating absolute configurations were elucidated via the comprehensive spectroscopic analyses, electronic circular dichroism (ECD) calculation, and single-crystal X-ray diffraction analyses. Biogenetically, compounds 1 and 2 were constructed by the plausible monomeric precursors, ent-atis-16-ene-3,14-dione (6) and ent-isopimara-8(14),15-dien-3-one (17), respectively, via key Baeyer-Villiger oxidation, decarboxylation, and semi-acetalization reactions to create a unique 2,3-seco-2-nor-tetrahydro-2H-pyran-2-one core. Our bioassays have revealed that eufislactone A (EFA, 1) displayed significant inhibitory effect on the osteogenic differentiation of human valvular interstitial cells (VICs), highlighting its potential as a preventive agent against the progression of human calcific aortic valve disease (CAVD).

Bioactive abietenolide diterpenes from Suregada procera

The phytochemical investigation of the leaves and the roots of Suregada procera afforded the new ent-abietane diterpenoid sureproceriolide A (1) along with the known secondary metabolites 8,14β:11,12α-diepoxy-13(15)-abietane-16,12-olid (2), jolkinolide A (3), jolkinolide E (4), ent-pimara-8(14),15-dien-19-oic acid (5), sitosterol (6), oleana-9(11):12-dien-3β-ol (7), and oleic acid (8). Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, and the structure of jolkinolide A (3) was confirmed by single-crystal X-ray diffraction analysis. Sureproceriolide A (1) showed modest activity against the Gram-positive bacterium Staphylococcus lugdunensis (MIC = 31.44 μM), and sitosterol (6) against the Gram-negative bacterium Porphyromonas gingivalis (IC50 = 45.37 μM). Jolkinolide A (3) and E (4) as well as sitosterol (6) inhibited the release of NOS (IMR-90 cells), TNF-α (HaCaT cells) and NF-κB (HaCaT cells), with IC50 values of 0.43, 3.21, and 10.32 μM, respectively. Compound 6 showed antitumoral activity against SK-MEL-28 (IC50 = 20.66 μM) and CCD-13Lu (IC50 = 24.70 μM) cell lines, with no cytotoxic effect against the prostate cells PrEC (CC50 > 300 μM).

Diterpenoids from Euphorbia fischeriana with Kv1.3 Inhibitory Activity

Euphorbia diterpenoids possess inhibitory effects of Kv1.3 ion channel, but most of this research has focused on diterpenoids with jatrophane-related or ingenane-related skeletons. In the present study, nine undescribed (1-9) and 16 known (10-25) diterpenoids, based on jatrophane, lathyrane, ingenane, abietane, and atisane skeletons, were identified from the methanol extract of the aerial parts of Euphorbia fischeriana. The structures were established by analysis of the spectroscopic data as well as by single-crystal X-ray diffraction analysis. Among the isolated diterpenoids, macrocyclic jatrophanes and lathyranes exerted Kv1.3 blocking activity. Compound 8 exhibited good selectivity on the inhibition of the Kv 1.3 channel rather than hERG channel, with a selectivity index over 7.0. The selective activity of lathyrane diterpenoids indicates that macrocyclic diterpenoids have the potential to be further investigated as therapeutic agents for the treatment of autoimmune diseases.

Ent-kauranes and ent-atisanes from Euphorbia wallichii and their anti-inflammatory activity

Phytochemical investigation on the whole plant of Euphorbia wallichii led to the identification of twelve diterpenoids, including nine undescribed ones, in which wallkauranes A-E (1-5) were classified as ent-kaurane diterpenoids and wallatisanes A-D (6-9) were assigned as ent-atisane diterpenoids. The biological evaluation of these isolates against NO production was conducted in the LPS-induced RAW264.7 macrophage cells model, resulting in the identification of a series of potent NO inhibitors, with the most active wallkaurane A showing an IC₅₀ value of 4.21 μM. The mechanistic study disclosed that wallkaurane A could inhibit pro-inflammatory cytokines generation such as TNF-α, IL-1β, and IL-6, and decrease the expression of iNOS and COX-2. Wallkaurane A could regulate the NF-κB signaling pathways and the JAK2/STAT3 signaling pathway to suppress the inflammatory reaction in LPS-induced RAW264.7 cells. Meanwhile, wallkaurane A could also inhibit the JAK2/STAT3 signaling pathway, thereby suppressing apoptosis in LPS-induced RAW264.7 cells.

Bioactive Compounds from Euphorbia usambarica Pax. with HIV-1 Latency Reversal Activity

Euphorbia usambarica is a traditional medicine used for gynecologic, endocrine, and urogenital illnesses in East Africa; however, its constituents and bioactivities have not been investigated. A variety of compounds isolated from Euphorbia species have been shown to have activity against latent HIV-1, the major source of HIV-1 persistence despite antiretroviral therapy. We performed bioactivity-guided isolation to identify 15 new diterpenoids (1–9, 14–17, 19, and 20) along with 16 known compounds from E. usambarica with HIV-1 latency reversal activity. Euphordraculoate C (1) exhibits a rare 6/6/3-fused ring system with a 2-methyl-2-cyclopentenone moiety. Usambariphanes A (2) and B (3) display an unusual lactone ring constructed between C-17 and C-2 in the jatrophane structure. 4β-Crotignoid K (14) revealed a 250-fold improvement in latency reversal activity compared to crotignoid K (13), identifying that configuration at the C-4 of tigliane diterpenoids is critical to HIV-1 latency reversal activity. The primary mechanism of the active diterpenoids 12–14 and 21 for the HIV-1 latency reversal activity was activation of PKC, while lignans 26 and 27 that did not increase CD69 expression, suggesting a non-PKC mechanism. Accordingly, natural constituents from E. usambarica have the potential to contribute to the development of HIV-1 eradication strategies.

Antimicrobial ent-abietane-type diterpenoids from the roots of Euphorbia wallichii

Three previously undescribed ent-abietane-type diterpenoids, designated as 11β-hydroxy-14-oxo-17-al-ent-abieta-8(9),13(15)-dien-16,12β-olide (1), 11β,17-dihydroxy-12-methoxy-ent-abieta-8(14),13(15)-dien-16,12ɑ-olide (2), and 14ɑ-hydroxy-17-al-ent-abieta-7(8),11(12),13(15)-trien-16,12-olide (3), were isolated from 95% ethanol extract of the roots of Euphorbia wallichii. The structures of the new compounds were elucidated by spectroscopic analysis (NMR, IR, UV, and MS). The isolated diterpenoids were tested in vitro for antimicrobial potentials against 6 pathogenic microorganisms. As a result, compounds 1-3 exhibited some antimicrobial activity against the tested Gram positive bacteria with minimum inhibitory concentration values less than 60 μg/ml.[Formula: see text].

Eupholides A-H, abietane diterpenoids from the roots of Euphorbia fischeriana, and their bioactivities

The roots of Euphorbia fischeriana known as "Langdu" in traditional Chinese medicine have been used for the treatment of tuberculosis in China. Through a bioactive phytochemical investigation of the roots of E. fischeriana, 15 diterpenoids were obtained by various chromatographic techniques. On the basis of wide spectroscopic data, including NMR, UV, IR, HR-ESI-MS, ECD and X-ray crystallography, all of the isolated compounds were elucidated to be ent-abietane diterpenoid analogs, including undescribed eupholides A-H and seven known diterpenoids. In the bioassay for anti-tuberculosis, eupholides F-H moderately inhibited the proliferation of Mycobacterium tuberculosis H37Ra, with the MIC determined to be 50 μM. Furthermore, eupholides G, ent-11α-hydroxyabieta-8(14), 13(15)-dien-16,12α-olide, and jolkinolide F significantly inhibited the lyase activity of human carboxylesterase 2 (HCE 2), with IC₅₀ values of 7.3, 150, and 34.5 nM, respectively.

Euphonoids A-G, cytotoxic diterpenoids from Euphorbia fischeriana

Seven previously undescribed polycyclic diterpenoids, euphonoids A-G, including four ent-abietanes, two ent-atisanes, and one ent-kaurene, along with 26 known analogues were isolated from the roots of Euphorbia fischeriana. The structures of the undescribed compounds were elucidated by spectroscopic analysis, ECD calculations, and single crystal X-ray diffraction. Besides, the structure of a previously reported ent-abietane diterpenoid, fischeriabietane A, was revised. All the isolates were screened for the cytotoxicities against five cancer cell lines. Euphonoid A, fischeriabietane A, 11-oxo-ebracteolatanolide B, caudicifolin, jolkinolide B, and methyl-8,11-3-dihydroxy-12-oxo-ent-abietadi-13,15(17)-ene-16-oate showed significant inhibitory activities against human prostate cancer C4-2B and C4-2B/ENZR cell lines, with IC₅₀ values being less than 10 μM. The brief structure-activity relationships (SARs) of these diterpenoids were also discussed.

Diterpenoids from the roots of Euphorbia ebracteolata and their inhibitory effects on human carboxylesterase 2

A chemical investigation of the roots of Euphorbia ebracteolata identified eighteen diterpenoids and glycosides. On the basis of spectroscopic data, they were determined to be ent-kauranes, ent-atisanes, tigliane derivatives, ingenane, and ent-abietanes, among which were eleven previously undescribed diterpenoids. The inhibitory effects of the isolated compounds against human carboxylesterase 2 (hCE-2) were evaluated in vitro, which revealed moderate inhibitory effects with IC₅₀ values < 50 μM. Next, the inhibitory kinetics were evaluated for the putative hCE-2 inhibitor 4β,9α,16,20-tetrahydroxy-14(13 → 12)-abeo-12αH-1,6-tigliadiene-3,13-dione (IC₅₀ 3.88 μM), and results indicated competitive inhibition with K_i 4.94 μM. Additionally, none of the diterpenoids showed cytotoxic effects against five human tumor cell lines as determined by MTT assays.

Chemical constituents from Euphorbia wallichii and their biological activities

One rare diterpenoid which was an unusual phorbol derivative possessing a 5-ene-7-oxo functional group, wallichiioid A (1), and 17 known compounds (2-18) were isolated from the aerial parts of Euphorbia wallichii. The structures and relative configuration of these compounds were elucidated on the basis of extensive spectroscopic interpretation. All the known compounds were isolated from E. wallichii for the first time. Diterpenoids 1-5 were tested for their cytotoxicity against five cancer cell lines (A-549, MCF-7, Hep G2, HeLa, and P388) and showed IC(50) values in the range of 8.19-29.72 μg/mL. The antiangiogenic activities of diterpenoids 1-5 were also evaluated using a zebrafish model.

Preliminary evaluation for cancer chemopreventive and cytotoxic potential of naturally growing ethnobotanically selected plants of Pakistan

CONTEXT

Natural products are a very productive source of leads for the development of medicines. Six Pakistani plants were chosen for study based on ethnobotanical data.

OBJECTIVE

Exploration of important medicinal plants of Pakistan for cancer treatment.

MATERIALS AND METHODS

The crude extracts of the six plants and their fractions were tested for inhibition of nuclear factor κB (NFκB), aromatase, and nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells, induction of quinone reductase 1 (QR1), agonism of retinoid X receptor, and growth inhibition with MCF-7, LU-1 and MDA-MB-231 cancer cells.

RESULTS

Two samples of Withania coagulans (Stocks) Dunal (Solanaceae) demonstrated inhibition of TNF-α induced activity of NFκB with IC₅₀ values of 2.6 and 4.3 µg/mL, respectively. Two fractions from W. coagulans and Euphorbia wallichii Hook F. (Euphorbiaceae) aerial parts inhibited aromatase with IC₅₀ values of 17.0 and 17.7 µg/mL, respectively. A total of 13 samples (five from E. wallichii, one from Acer oblongifolium Hort. ex Dippel (Aceraceae), one from Aster thomsonii C. B. Clarke (Asteraceae) and six from W. coagulans aerial parts with fruits) inhibited NO production with IC₅₀ values ranging from 1.3 to 15.6 µg/mL. Fourteen samples demonstrated induction of QR1 with CD ranging from 1.0 to 20.6 µg/mL, and a total of eight extracts and fractions inhibited the proliferation of cancer cells in culture with IC₅₀ values ranging from 1.2 to 7.8 µg/mL.

DISCUSSION AND CONCLUSION

Selected plants can be a valuable source of chemopreventive and anticancer products. W. coagulans aerial parts showed the strongest activity.

Tandem mass spectrometric analysis and density functional theory calculations on the fragmentation behavior of two tetradecanoylingenol regioisomers from Euphorbia wallichii

RATIONALE

Two structurally similar bioactive regioisomers, 3-O-tetradecanoylingenol and 20-O-tetradecanoylingenol, from Euphorbia wallichii presented quite different fragmentation behaviors. Revealing the related fragmentation pathways may improve the efficiency of characterization and identification of such type of compounds.

METHODS

The two regioisomers were subjected to collision-induced dissociation (CID) on Finnigan LCQ(DECA) and LTQ Orbitrap XL instruments. Based on the CID results, the possible fragmentation pathways were proposed and investigated with density functional theory (DFT) calculations.

RESULTS

Elimination of C(14)H(28)O(2) (tetradecanoic acid) for 3-O-tetradecanoylingenol and the sequential losses of C(4)H(8) (butylene) for 20-O-tetradecanoylingenol were observed in ESI-MS/MS, witnessed also by HR-ESI-MS/MS. The fragmentation pathways were proposed and verified by calculating the activation energy of their transition states by DFT calculations.

CONCLUSIONS

Based on the observations, fragmentation pathways for the two regioisomers were proposed and verified by calculating the energy of the reactants, products and the corresponding transition states using DFT. This report should have value in rapid identification of the derivatives of ingenol and other regioisomers in natural products.

Spirowallichiione: a rearranged multiflorane from Euphorbia wallichii Hook F. (Euphorbiaceae)

Euphorbia wallichii of the family Euphorbiaceae yielded a new rearranged pentacyclic triterpene of the multiflorane class which we have named spirowallichiione. The structure of this natural spirocompound was elucidated with the aid of modern spectroscopic techniques, including 2D-NMR.

A new guaiane diterpenoid fromEuphorbia wallichii

A new guaiane-type diterpenoid, (1alpha,5beta,7alpha)-3,10(18),11-dictytriene-19-acid, was obtained from the roots of Euphorbia wallichii. This is the first isolation of guaiane diterpene from this genus of Euphorbia. The structure was elucidated by spectral methods. And the compound was tested for the cytotoxicities on the cancer cell line P-388 and A-549 in vitro.

Microbial Transformations of Gelomulide G: A Member of the Rare Class of Diterpene Lactones

Microbial transformation of gelomulide G (3beta,6beta-diacetoxy-8beta,14beta-epoxyabiet-13(15)-en-16,12-olide, 1) was carried out. Incubation of 1 with Aspergillus niger afforded two new metabolites, 3beta,6beta-diacetoxy-8beta,14beta-dihydroxyabiet-13(15)-en-16,12-olide (2) and 3beta,6beta-diacetoxy-14beta-hydroxyabieta-8(9),13(15)-dien-16,12-olide (3). While Cunninghamella elegans afforded the 14-epimer of 2, i.e., 3beta,6beta-diacetoxy-8beta,14alpha-dihydroxyabiet-13(15)-en-16,12-olide (4), along with 3beta-acetoxy-6beta-hydroxy-8beta,14beta-epoxyabiet-13(15)-en-16,12-olide (5). The structures of the transformed products 2-5 were deduced to be new on the basis of MS and NMR data.