New Diterpenoids from Euphorbia sieboldiana

Ent-atisane diterpenoids from Euphorbia wallichii and their anti-influenza A virus activity

The study entailed the investigation of the roots of Euphorbia wallichii, which resulted in the isolation of 29 ent-atisane diterpenoids (1-29), 14 of which were previously unknown. These previously undescribed ones were named euphorwanoids A-N (3-5, 7, 9, and 10-18). Various techniques, including comprehensive spectroscopic methods and calculated electronic circular dichroism, were employed to determine their molecular structures. Additionally, the absolute configurations of ten ent-atisane diterpenoids (1, 2, 5, 6, 8, 9, 11, 12, 14 and 16) were established through X-ray crystallographic analyses. All isolated compounds' potential to inhibit the influenza A virus in vitro were evaluated. Compounds 18, 20, and 24 exhibited notable antiviral activity against the A/Puerto Rico/8/1934 strain. Their effective concentrations for reducing viral activity (EC50 values) were found to be 8.56, 1.22, and 4.97 μM, respectively. An intriguing aspect of this research is that it marks the first instance of ent-atisane diterpenes displaying anti-H1N1 activity. Empirical NMR rules were established with Δδ to distinguish the R/S configurations of C-13 and C-16 in ent-atisanes.

Terpenoids from Euphorbia helioscopia and Their Cytotoxic Activities against H1975 Cells

Three previously undescribed diterpenoids, helioscopnoids A-C, and eight known compounds were isolated from the whole plants of Euphorbia helioscopia. Their structures were established by extensive analysis of spectra and data comparison with previous literatures. Among them, compound 4 was identified as 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol with revised configurations of C-13, C-14, and C-17 (13R*, 14R*, 17R*). Cytotoxicity assays revealed that all compounds exhibited varying levels of cytotoxicity against H1975 cells, with compound 9 displaying the most potent activity, as indicated by cell viability rates of 18.13 % and 20.76 % at concentrations of 20 μM and 5 μM, respectively. This study expands the understanding of E. helioscopia terpenoids' structural diversity and biological activities, contributing to the exploration of potential therapeutic applications.

Diterpenoids with anti-inflammatory activity from Euphorbia wallichii

The Euphorbia plants are the focus of natural product drug discovery because of their fascinating structural diversity and broad biological activities. Here we reported the discovery of eight undescribed diterpenoids, including two ent-trachylobanes, five ent-atisanes, and one ent-abietane, together with 15 known ones from the whole plant of Euphorbia wallichii. Their chemical structures were elucidated by detailed spectrometry data analysis and X-ray crystallography. Among them, wallichane G represents a rare ent-atisane type pentacyclic diterpenoid featuring a tetrahydrofuran moiety. Furthermore, bioassays indicated that jolkinolide B exhibited potent inhibitory activities on the production of NO, with an IC₅₀ value of 3.84 ± 0.25 μM. Meanwhile, the mechanistic study revealed that jolkinolide B could obviously downregulate the expression of iNOS, COX-2, NF-κB, and phosphorylated IκBα in a dose-dependent manner and strongly upregulate the expression of Nrf2 and HO-1 protein, thereby suppressing the inflammatory process in macrophage cells induced by LPS.

Euphorfinoids E-L: Diterpenoids from the roots of Euphorbia fischeriana with acetylcholinesterase inhibitory activity

Eight undescribed diterpenoids, euphorfinoids E-L, together with twelve known analogues, were isolated from the roots of wild Euphorbia fischeriana. Their structures and absolute configurations were elucidated by a combination of NMR, MS, ECD, and X-ray diffraction analyses. The plausible biosynthetic pathway of 1 was also proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase (AChE) with 50% inhibiting concentration (IC₅₀) values of 6.23-192.38 μM.

ent-Atisane diterpenoids: isolation, structure and bioactivity

Covering: up to 2020 ent-Atisane diterpenoids are a class of over 150 members with diverse structures and valuable bioactivities. These compounds share a curious history in which the synthesis of the archetypal member preceded its isolation from natural sources. In this review, we provide a comprehensive summary of the isolation, structure, and bioactivity of ent-atisane diterpenoids from their discovery in 1965 to the present day.

New diterpenoids from the stems of Euphorbia antiquorum growing in Vietnam

Phytochemical analysis of Euphorbia antiquorum stem extracts afforded two new ent-atisane compounds, ent-3α-acetoxy-16β,17,18-trihydroxyatisane (1) and ent-3α,14,16β,17-tetrahydroxyatisane (2) together with three known compounds, 20-deoxy-16-hydroxyingenol (3), ent-14[S],16α,17-trihydroxyatisan-3-one (4), and agallochaol C (5). Their structures were elucidated by spectroscopic data analysis and comparison with published NMR data. Compounds 1-5 were evaluated for α-glucosidase inhibition and cytotoxicity. Compounds 1, 4, and 5 revealed significant inhibitory activity against α-glucosidase with the IC₅₀ values of 119.9, 135.5, and 134.3 µM, respectively. None showed activity in cytotoxicity assay.

Toxicity Reduction of Euphorbia kansui Stir-Fried with Vinegar Based on Conversion of 3-O-(2'E,4'Z-Decadi-enoyl)-20-O-acetylingenol

The dried roots of Euphorbia kansui S.L.Liou ex S.B.Ho have long been used to treat edema in China. However, the severe toxicity caused by Euphorbia kansui (EK) has seriously restricted its clinical application. Although EK was processed with vinegar to reduce its toxicity, the detailed mechanisms of attenuation in toxicity of EK stir-fried with vinegar (VEK) have not been well delineated. Diterpenoids are the main toxic ingredients of EK, and changes in these after processing may be the underlying mechanism of toxicity attenuation of VEK. 3-O-(2′E,4′Z-decadienoyl)-20-O-acetylingenol (3-O-EZ) is one of the diterpenoids derived from EK, and the content of 3-O-EZ was significantly reduced after processing. This study aims to explore the underlying mechanisms of toxicity reduction of VEK based on the change of 3-O-EZ after processing with vinegar. Based on the chemical structure of 3-O-EZ and the method of processing with vinegar, simulation experiments were carried out to confirm the presence of the product both in EK and VEK and to enrich the product. Then, the difference of peak area of 3-O-EZ and its hydrolysate in EK and VEK were detected by ultra-high-performance liquid chromatography (UPLC). Furthermore, the toxicity effect of 3-O-EZ and its hydrolysate, as well as the underlying mechanism, on zebrafish embryos were investigated. The findings showed that the diterpenoids (3-O-EZ) in EK can convert into less toxic ingenol in VEK after processing with vinegar; meanwhile, the content of ingenol in VEK was higher than that of EK. More interestingly, the ingenol exhibited less toxicity (acute toxicity, developmental toxicity and organic toxicity) than that of 3-O-EZ, and 3-O-EZ could increase malondialdehyde (MDA) content and reduce glutathione (GSH) content; cause embryo oxidative damage by inhibition of the succinate dehydrogenase (SDH) and superoxide dismutase (SOD) activity; and induce inflammation and apoptosis by elevation of IL-2 and IL-8 contents and activation of the caspase-3 and caspase-9 activity. Thus, this study contributes to our understanding of the mechanism of attenuation in toxicity of VEK, and provides the possibility of safe and rational use of EK in clinics.

Ingenane Diterpenoids

Despite a more recent isolation and chemical characterization when compared to phorbol, along with its chemical instability, limited distribution in Nature, and scarce availability, ingenol is the only Euphorbia diterpenoid that has undergone successful pharmaceutical development, with ingenol 3-angelate (ingenol mebutate, Picato(®)) entering the pharmaceutical market in 2012 for the treatment of actinic keratosis. The phytochemical, chemical, and biological literature on members of the ingenane class of diterpenoids is reviewed from their first isolation in 1968 through 2015, highlighting unresolved issues both common to phorboids (biogenesis, relationship between molecular targets, and in vivo activity) and specific to ingenol derivatives (two-dimensional representation, in-out stereoisomerism, versatility of binding mode to PKC, and inconsistencies in the structural elucidation of some classes of derivatives). The biogenesis of ingenol is discussed in the light of the Jakupovic proposal of a dissection between the formation of the macrocyclic Euphorbia diterpenoids and the phorboids, and the clinical development of ingenol mebutate is chronicled in the light of its "reverse-pharmacology" focus.

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.

Antifeedant and Antiviral Diterpenoids from the Fresh Roots of Euphorbia jolkinii

The perennial herbaceous plant Euphorbia jolkinii (Euphorbiaceae) is a noxious weed widely distributed in the grasslands of northwestern Yunnan and has greatly threatened the local biodiversity. Phytochemical investigation on the fresh roots of E. jolkinii afforded six new diterpenoids 1, 2, 4-6, and 8, together with fifteen known diterpenoids. Their structures were elucidated on the basis of 1D and 2D NMR and other spectroscopic methods. Casbane, lathyrane, abietane, and ent-kaurane diterpenoids were reported from this plant for the first time. Selected compounds were evaluated for their antifeedant and anti-RSV (respiratory syncytial virus) activities. Compound 2 and ingenol (3) exhibited moderate antifeedant activity against a generalist insect herbivore, Spodoptera exigua, with EC50 values of 17.88 and 17.71 μg/cm(2) respectively. Compound 19 showed significant anti-RSV activity, with 50 % inhibition (IC50) value of 10.0 μM and selective index of 8.0. Compounds 1 and 2 were less active against RSV virus, both with IC50 value of 25 μM, and with selective indices of 1.0 and 3.2 respectively. These findings provided new evidence for the biological functions and utilization of the diversified diterpenoid metabolites in the roots of this rich but harmful plant.