Bisfischoids A and B, dimeric ent-abietane-type diterpenoids with anti-inflammatory potential from Euphorbia fischeriana Steud

Naturally Occurring [4+2] Type Terpenoid Dimers Assembled through Unmatched-electron-demand Cycloaddition

Terpenoid dimers of the [4+2] type, which are naturally occurring compounds biosynthetically derived from the [4+2] cycloaddition of two precursors, have garnered considerable attention due to their complex molecular structures, diverse biological activities, and intriguing biosynthetic pathways. We have previously summarized the advancements in three types of [4+2] terpenoid dimers. In this review, we will focus on the lesser-explored class of [4+2] terpenoid dimers which assembled from two electron-deficient precursors via the unmatched-electron-demand Diels-Alder reaction (UMEDDA). We will summarize their sources, biological activities, proposed biosynthesis, and chemical syntheses. Finally, a summary and outlook for this fascinating class of compounds will be presented.

Anti-Inflammatory and Cytotoxic Compounds Isolated from Plants of Euphorbia Genus

Euphorbia is a large genus of the Euphorbiaceae family. Around 250 species of the Euphorbia genus have been studied chemically and pharmacologically; different compounds have been isolated from these species, especially diterpenes and triterpenes. Several reports show that several species have anti-inflammatory activity, which can be attributed to the presence of diterpenes, such as abietanes, ingenanes, and lathyranes. In addition, it was found that some diterpenes isolated from different Euphorbia species have anti-cancer activity. In this review, we included compounds isolated from species of the Euphorbia genus with anti-inflammatory or cytotoxic effects published from 2018 to September 2023. The databases used for this review were Science Direct, Scopus, PubMed, Springer, and Google Scholar, using the keywords Euphorbia with anti-inflammatory or cytotoxic activity. In this review, 68 studies were collected and analyzed regarding the anti-inflammatory and anti-cancer activities of 264 compounds obtained from 36 species of the Euphorbia genus. The compounds included in this review are terpenes (95%), of which 68% are diterpenes, especially of the types ingenanes, abietanes, and triterpenes (approximately 15%).

Antiproliferative ent-abietane diterpenoids from Euphorbia fischeriana

Euphorfinoids M and N (1 and 2), two previously undescribed ent-abietane diterpenoids, together with seven known analogues (3-9), were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by spectroscopic analysis, including extensive NMR, HR-ESIMS, ECD, and comparison with structurally related known analogues. Bioassays against proliferative effects of HeLa cell line showed that compound 1 was the most active with IC50 3.62 ± 0.31 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.

Yuexiandajisu diterpenoids from Euphorbia ebracteolata Hayata (Langdu roots): An overview

The roots of the plant Euphorbia ebracteolata Hayata (Yue Xian Da Ji) are commonly used in traditional Chinese medicine to treat multiple diseases such as chronic liver diseases, oedema, pulmonary diseases and cancer. It is the main ingredient of the TCM called Langdu which can be prepared also from roots of E. fischeriana Steud. and occasionally from Stellera chamaejasme species. Numerous bioactive natural products have been isolated from E. ebracteolata including a large diversity of diterpenoids with anti-inflammatory and anticancer properties. One little series of compounds has been named yuexiandajisu (A, B, C, D, D₁, E, F) which comprises two casbane-, one isopimarane-, two abietane-, and two rosane-type diterpenes including a dimeric molecule. The origin, structural diversity and properties of these little-known natural products is discussed here. Several of these compounds have been identified in the roots of other Euphorbia species, notably the potent phytotoxic agent yuexiandajisu C. The abietane diterpenes yuexiandajisu D-E exhibit marked anticancer properties but their mechanism of action remains unresolved. The dimeric compound, renamed yuexiandajisu D₁, also exhibit anti-proliferative properties against cancer cell lines, unlike the rosane diterpene yuexiandajisu F. The structural or functional analogy with other diterpenoids is discussed.

Phytochemical Analysis, Antioxidant Activities In Vitro and In Vivo, and Theoretical Calculation of Different Extracts of Euphorbia fischeriana

Euphorbia fischeriana has a long-standing history of use in traditional medicine for the treatment of tuberculosis diseases. However, the plant's therapeutic potential extends beyond this specific ailment. The present study aimed to investigate the antioxidant properties of Euphorbia fischeriana and lay the groundwork for further research on its potential therapeutic applications. Phytochemical tests were performed on the plant, and 11 types of phytochemicals were identified. Ultraviolet-visible spectrophotometry was used to evaluate the active components and antioxidant properties of eight different solvent extracts, ultimately selecting acetone extract for further research. UHPLC-ESI-Q-TOF-MS identified 43 compounds in the acetone extract, and chemical calculations were used to isolate those with high content and antioxidant activity. Three stability experiments confirmed the extract's stability, while cell viability and oral acute toxicity studies demonstrated its relatively low toxicity. In rats, the acetone extract showed significant protective effects against D-galactosamine-induced liver damage through histopathological examination and biochemical analysis. These results suggest that Euphorbia fischeriana's acetone extract has potential in treating diseases related to oxidative imbalances. Therefore, this study highlights the plant's potential therapeutic applications while providing insight into its antioxidant properties.

Biscroyunoid A, an Anti-Hepatic Fibrotic 19-nor-Clerodane Diterpenoid Dimer with a C-16-C-12' Linkage from Croton yunnanensis

Biscroyunoid A (1), a 19-nor-clerodane diterpenoid dimer featuring a unique C-16-C-12' linkage and containing an unusual 4,7-dihydro-5H-spiro[benzofuran-6,1'-cyclohexane] motif, together with its biosynthetic precursor, croyunoid A (2), were isolated from Croton yunnanensis. Their structures were determined by spectroscopic, computational, and single-crystal X-ray diffraction methods. Compound 1 exerted an antihepatic fibrosis effect in LX-2 cells via inhibition of TGFβ-Smad2/3 signaling.

Euphorbia diterpenoids: isolation, structure, bioactivity, biosynthesis, and synthesis (2013-2021)

Covering: 2013 to 2021As the characteristic metabolites of Euphorbia plants, Euphorbia diterpenoids have always been a hot topic in related science communities due to their intriguing structures and broad bioactivities. In this review, we intent to provide an in-depth and extensive coverage of Euphorbia diterpenoids reported from 2013 to the end of 2021, including 997 new Euphorbia diterpenoids and 78 known ones with latest progress. Multiple aspects will be summarized, including their occurrences, chemical structures, bioactivities, and syntheses, in which the structure-activity relationship and biosynthesis of this class will be discussed for the first time.

Biogenetic and biomimetic synthesis of natural bisditerpenoids: hypothesis and practices

Covering: up to March 2022Bisditerpenoids, or diterpenoid dimers, are a group of natural products with high structural variance, deriving from homo- or hetero-dimeric coupling of two diterpenoid units. They usually possess complex architectures resulting from the diversity of monomeric diterpenoids as building blocks and the dimerization processes. These compounds have attracted the attention of synthetic and biological scientists owing to the rarity of their natural origin and their significant biological activities. Herein, we provide a review highlighting some of the interesting bisditerpenoids reported since 1961 and showcase the chemical diversity in both their structures and biosynthesis, as well as their biological functions. This review focuses on the biosynthetic dimerization pathways of interesting molecules and their biomimetic synthesis, which may act as useful inspiration for the discovery and synthesis of more bisditerpenoids and further pharmacological investigations.

Chemical Composition, Anti-Breast Cancer Activity and Extraction Techniques of Ent-Abietane Diterpenoids from Euphorbia fischeriana Steud

Ent-abietane diterpenoids are the main active constituents of Euphorbia fischeriana. In the continuing search for new anti-breast cancer drugs, 11 ent-abietane diterpenoids (1–11) were isolated from E. fischeriana. The structures of these compounds were clearly elucidated on the basis of 1D and 2D NMR spectra as well as HRESIMS data. Among them, compound 1 was a novel compound, compound 10 was isolated from Euphorbia genus for the first time, compound 11 was firstly discovered from E. fischeriana. These compounds exhibited varying degrees of growth inhibition against the MCF-10A, MCF-7, ZR-75-1 and MDA-MB-231 cell lines in vitro. The experimental data obtained permit us to identify the roles of the epoxy group, hydroxyl group and acetoxyl group on their cytotoxic activities. Extraction is an important means for the isolation, identification, and application of valuable compounds from natural plants. To maximize yields of ent-abietane diterpenoids of E. fischeriana, 17-hydroxyjolkinolide B, jolkinolide B, 17-hydroxyjolkinolide A and jolkinolide A were selected as quality controls to optimize the salting-out-assisted liquid–liquid extraction (SALLE) by response surface methodology (RSM). The optimized conditions for SALLE were 0.47 g sodium dihydrogen phosphate, 5.5 mL acetonitrile and 4.5 mL water at pH 7.5. The experimental values of 17-hydroxyjolkinolide B, jolkinolide B, 17-hydroxyjolkinolide A and jolkinolide A (2.134, 0.529, 0.396, and 0.148 mg/g, respectively) were in agreement with the predicted values, thus demonstrating the appropriateness of the model.