Ingenane and jatrophane-type diterpenoids from Euphorbia kansui with multidrug resistance reversal activity

20-Deoxyingenol ester and ether derivatives: Synthesis, properties and cytotoxicity

The C-3 and C-5 substituted 20-deoxyingenol monoesters are important active components in Euphorbiaceae plants. Nonetheless, their similar physical properties make them difficult to distinguish. The present study developed fast and efficient rules for identifying the esterification sites of 20-deoxyingenol based on a series of chemical syntheses of monoesters and literature research, utilizing NMR spectroscopy, optical rotation analysis, and chromatographic retention behavior. In addition, a series of 20-deoxyingenol ether derivatives, including 1,3,4-oxadiazole derivatives, were synthesized. The cytotoxic activities of 20-deoxyingenol derivatives were evaluated on A549 and HepG2 cell lines. Notably, 20-deoxyingenol 1,3,4-oxadiazole derivative 22 (IC50 = 8.8 μM) exhibited significant anticancer activity against HepG2 cells with low toxicity to normal cells (IC50 > 50 μM), making it a promising compound. We investigated the potential anticancer mechanism of compound 22 by examining protein expression changes in HepG2 cells using quantitative proteomics. Our findings indicated that 22 induced G1/S phase cell cycle arrest and, In a dose-dependent manner, inhibited CDK4 and CyclinD1 expression while upregulating P21. Moreover, 22 promoted the accumulation of autophagosomes and the proteins LC3 and PINK1, enhancing autophagy and mitophagy in HepG2 cells. Collectively, compound 22 might serve as a novel autophagy agonist with anticancer properties.

Ingenane diterpenoids with anti-inflammatory activity from Euphorbia antiquorum

The Euphorbia plants are famous for their diterpenoid constituents with diverse structures and broad biological activities. Herein, the discovery of 15 ingenane diterpenoids including 10 previously unreported ones (1-10) from Euphorbia antiquorum was presented. Structures of the undescribed compounds were established via detailed spectroscopic analyses. Meanwhile, a preliminary anti-inflammatory screening revealed that compound 6 showed significant inhibitory activity against the production of nitric oxide, as well as downregulated the expression of COX-2 and IL-6, in lipopolysaccharide-stimulated RAW264.7 macrophages. Further mechanistical exploration revealed that compound 6 could exert its anti-inflammatory effect by inhibiting NF-κB and activating Nrf2 signaling pathways.

An Ingenane-Type Diterpene from Euphorbia kansui Promoted Cell Apoptosis and Macrophage Polarization via the Regulation of PKC Signaling Pathways

Euphorbia kansui, a toxic Chinese medicine used for more than 2000 years, has the effect of "purging water to promote drinking" and "reducing swelling and dispersing modules". Diterpenes and triterpenes are the main bioactive components of E. kansui. Among them, ingenane-type diterpenes have multiple biological activities as a protein kinase C δ (PKC-δ) activator, which have previously been shown to promote anti-proliferative and pro-apoptotic effects in several human cancer cell lines. However, the activation of PKC subsequently promoted the survival of macrophages. Recently, we found that 13-hydroxyingenol-3-(2,3-dimethylbutanoate)-13-dodecanoate (compound A) from E. kansui showed dual bioactivity, including the inhibition of tumor-cell-line proliferation and regulation of macrophage polarization. This study identifies the possible mechanism of compound A in regulating the polarization state of macrophages, by regulating PKC-δ-extracellular signal regulated kinases (ERK) signaling pathways to exert anti-tumor immunity effects in vitro, which might provide a new treatment method from the perspective of immune cell regulation.

Cycloartane-type triterpenoids and steroids from Trichilia connaroides and their multidrug resistance reversal activities

Four undescribed cycloartane-type triterpenoids (1-4) and seven undescribed steroids (6-12), along with five known analogues (5 and 13-16), were isolated from the leaves of Trichilia connaroides. Their structures were identified based on the NMR data and HRESIMS, and the absolute configurations were determined through single-crystal X-ray diffraction analysis, Mosher's method, and ECD calculations. The multidrug resistance (MDR) reversal activities of all the isolates were assessed, and compounds 10 and 11 showed significant activities to reverse the MDR of MCF-7/DOX cells with IC50 values of 2.90 and 3.76 μM, respectively. These bioactive compounds may bring fresh insights into the research and development of MDR reversal agents.

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.

Diterpenoids from Euphorbia lactea and their anti-HIV-1 activity

Nine undescribed diterpenoids, euphlactenoids A-I (1-9), including four ingol-type diterpenoids (1-4) with a 5/3/11/3-tetracyclic framework and five ent-pimarane-type diterpenoids (5-9), together with thirteen known diterpenoids (10-22), were identified from the leaves and stems of Euphorbia lactea Haw. The structures and absolute configurations of compounds 1-9 were unequivocally elucidated on the basis of spectroscopic analysis, ECD calculations and single crystal X-ray diffraction. Compounds 3 and 16 showed anti-HIV-1 effects with IC₅₀ values of 1.17 μM (SI = 16.54) and 13.10 μM (SI = 1.93), respectively.

Offline two-dimensional normal-phase × reversed-phase liquid chromatography coupled with high-resolution mass spectrometry for comprehensive analysis of chemical constituents in Euphorbia kansui

Euphorbia kansui is the dried root of Euphorbia kansui T. N. Liou ex T.P. Wang. Its main chemical components are diterpenoids, triterpenes, and volatile oil. In this study, an offline two-dimensional (2D) normal-phase × reversed-phase liquid chromatography method coupled with quadrupole time-of-flight mass spectrometry was established to comprehensively analyze the chemical constituents in E. kansui. A total of 240 compounds were identified from the E. kansui extract, including 218 diterpenoids (77 known, 141 new), 16 known volatile oils, and six known triterpenes. The relationship between the structural characteristics and tandem mass spectroscopy fragments of diterpenoids was further analyzed. Based on the characteristic fragment ions, 141 new diterpenoids were determined as 118 ingenane diterpenoids and 23 jatrophane diterpenoids. The newly identified diterpenoids may provide lead compounds for drug discovery, improving the medicinal value of E. kansui.

Triterpenoids, steroids and other constituents from Euphorbia kansui and their anti-inflammatory and anti-tumor properties

Six undescribed triterpenoids (euphokanols A-F), two undescribed C21-steroidal glycosides (euphokanosides A and B), together with fifty-four known compounds were isolated from the roots of Euphorbia kansui. Their structures were demonstrated by extensive spectroscopic data (1D, 2D NMR and HR-ESI-MS), and the absolute configuration of euphokanol A was elucidated based on electronic circular dichroism (ECD) calculation. Among them, euphokanol A was a tetracyclic triterpenoid with a 5,10-epoxy moiety and concurrent rearrangement of Me-19(10 → 9) and Me-30 (14 → 8), while euphokanols B and C were rare 19(10 → 9) abeo-tirucallane-type triterpenoids with Δ5(10) double bonds and 7,8-epoxy moieties. In addition, ten C21-steroidal glycosides were isolated from Euphorbia plants for the first time. Moreover, cynotophylloside B, caudatin, 5α,8α-epidioxy-22E-ergosta-6,22-diene-3β-ol, 6β,7β-epoxy-3β,4β,5β-trihydroxyl-20-deoxyingenol, 13-hydroxyingenol-3-(2,3- dimethylbutanoate)-13-dodecanoate, ingenol, 3-O-benzoyl-13-O-dodecanoateingenol, 3-O-(2'E,4'Z-decadienoyl)-20-O-acetylingenol, 20-O-acetylingenol and 20- deoxyingenol exhibited significant inhibition on NO production with IC50 values of 9.10, 17.38, 1.71, 0.55, 0.57, 12.22, 0.56, 0.30, 11.21 and 2.98 μM, respectively. Furthermore, wilfoside KIN, cynsaccatol L, kanesulone A, and 3β,7β,15β-triacetyloxy-5α-benzoyloxy-2α,8α-dihydroxyjatropha-6(17),11E-diene-9, 14-dione showed cytotoxicity against HepG2 cell line, with IC50 values of 12.55, 12.61, 18.24 and 18.26 μM, respectively. 13-Hydroxyingenol-3-(2,3-dimethylbutanoate)-13- dodecanoate exhibited anti-proliferation activity on MCF-7 cell line with an IC50 value of 17.12 μM. Specifically, euphol selectively inhibited the growth of human glioma stem cells (GSC-3# and GSC-12#), with IC50 values of 8.89 and 13.00 μM, respectively.

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.

Research Progress on Natural Diterpenoids in Reversing Multidrug Resistance

Multidrug resistance (MDR) is one of the main impediments in successful chemotherapy in cancer treatment. Overexpression of ATP-binding cassette (ABC) transporter proteins is one of the most important mechanisms of MDR. Natural products have their unique advantages in reversing MDR, among which diterpenoids have attracted great attention of the researchers around the world. This review article summarizes and discusses the research progress on diterpenoids in reversing MDR.

Diterpenoids with Rearranged 9(10→11)-abeo-10,12-Cyclojatrophane Skeleton and the First (15S)-Jatrophane from Euphorbia helioscopia: Structural Elucidation, Biomimetic Conversion, and Their Immunosuppressive Effects

Two novel diterpenoids, one with a rearranged trans,trans-fused tricyclo[10.3.0.04,6]pentadecane framework (1) and the other with an unprecedented 15S configuration (2), were isolated from Euphorbia helioscopia. Their structures were elucidated by extensive analysis of HR-ESI-MS, NMR, quantum-chemical calculation, and X-ray crystallographic data. Biosynthetically, 1 has a unique "cyclopropane-shift-like" biogenesis involving an oxa-di-π-methane (ODPM) rearrangement, which inspired us to accomplish the biomimetic conversion of 3 to 1. Moreover, compound 1 displayed a potent immunosuppressive effect by inhibiting Kv1.3 voltage-gated channels.