Diverse diterpenoids and a triterpenoid from Euphorbia spinidens Bornm. ex Prokh

Four previously unreported diterpenoids including three ent-atisanes (1-3) and one ent-abietane (4), along with one known linear triterpenoid (5) and five known diterpenoids including four myrsinanes (6-9), and one abietane (10) have been isolated from the roots of Euphorbia spinidens Bornm. ex Prokh. The structures were determined on the basis of extensive spectroscopic analyses including HR-ESI-MS, 1D and 2D NMR and comparison of the data with those reported in the literature. Antimicrobial potential of isolated compounds were also evaluated. Guionianol B (10) showed good antibacterial activity against Staphylococcus aureus and Bacillus subtilis with MIC value of 6.25 μg/mL.

Discovery of myrsinane-type Euphorbia diterpene derivatives through a skeleton conversion strategy from lathyrane diterpene for the treatment of Alzheimer's disease

A series of novel myrsinane-type Euphorbia diterpene derivatives (1-37) were synthesized from the abundant natural lathyrane-type Euphorbia factor L3, using a multi-step chemical process guided by a bioinspired skeleton conversion strategy, with the aim of discovering potential anti-Alzheimer's disease (AD) bioactive lead compounds. The synthesis process involved a concise reductive olefin coupling reaction through an intramolecular Michael addition with a free radical, followed by a visible-light-triggered regioselective cyclopropane ring-opening. The cholinesterase inhibitory and neuroprotective activities of the synthesized myrsinane derivatives were evaluated. Most of the compounds showed moderate to strong potency, highlighting the importance of ester groups in Euphorbia diterpene. In particular, derivative 37 displayed the most potent acetylcholinesterase (AChE) inhibition, with an IC50 value of 8.3 μM, surpassing that of the positive control, tacrine. Additionally, 37 also showed excellent neuroprotective effect against H2O2-induced injury in SH-SY5Y cells, with a cell viability rate of 124.2% at 50 μM, which was significantly higher than that of the model group (viability rate 52.1%). Molecular docking, reactive oxygen species (ROS) analysis, immunofluorescence, and immunoblotting were performed to investigate the mechanism of action of myrsinane derivative 37. The results indicated that derivative 37 may be a promising myrsinane-type multi-functional lead compound for the treatment of Alzheimer's disease. Furthermore, a preliminary SAR analysis was performed to study the acetylcholinesterase inhibitory and neuroprotective activities of these diterpenes.

Myrsinane-type diterpenes from Euphorbia gedrosiaca with cell growth inhibitory activity and apoptotic effects on melanoma cancer cells

Phytochemical analysis of Euphorbia gedrosiaca Rech.f., Aellen & Esfand., an Iranian endemic spurge, afforded the isolation of four myrsinane types diterpene polyesters. Two new compounds (1-2) were based on a myrsinane skeleton while the others (3-4) were known diterpenes based on a cyclomyrsinane backbone. Their chemical structures were elucidated by spectroscopic methods, including 1D and 2D NMR and HRESIMS. The isolated compounds were tested to evaluate their cell growth inhibitory activity and apoptotic effects on melanoma cell lines, B16F10 and A375. The IC₅₀ values for compounds 1-4 were 58.45, 55.43, 86.52 and 82.27 μM, respectively, on B16F10, and 20.66, 21.88, 36.21 and 39.87 μM, respectively, on A375 cells. Non-treated cells were used as negative control (100% cell growth) and 5 nM Taxol were considered as a positive control.