Discovery of a novel highly potent and low-toxic jatrophane derivative enhancing the P-glycoprotein-mediated doxorubicin sensitivity of MCF-7/ADR cells.

Use of novel modulators targeting P-glycoprotein (P-gp, ABCB1 transporter) is among the most accepted strategies for overcoming multidrug resistance in cancer chemotherapy. In the current study, we pursued our structure-activity relationship studies of jatrophane derivatives by structural modification of compound 1, a natural jatrophane isolated from Euphorbia. sororia A. Nine compounds exhibited higher reversal activity in P-gp/ABCB1-mediated MCF-7/ADR cells than verapamil (VRP). The cytotoxicity and doxorubicin (DOX) intracellular accumulation effects of jatrophane derivatives were assessed in normal HEK293T cells and DOX-resistant MCF-7/ADR cells. The most potent compound 17 merits multiple activities, including (1) high efficiency (EC50 = 182.17 ± 32.67 nM) in reversing P-gp-mediated resistance to DOX, low cytotoxicity, and a high therapeutic index; and (2) increasing the accumulation of Rhodamine123 (Rho123) and DOX in a dose-dependent manner compared to verapamil in MCF-7/ADR cells. Our results indicated that the reversal activity of 17 was due to the stimulation of the P-gp ATPase activity instead of the direct inhibition of P-gp protein expression. A docking study demonstrated that 17 has a high binding affinity toward the DOX recognition site of P-gp. This resulted in 17 enhancing the sensitivity of DOX to MCF-7/ADR cells by stimulating P-gp ATPase activity, increasing intracellular DOX and Rho123 concentrations, inhibiting the phosphoinositide 3-kinase/serine-threonine kinase mediated by DOX and further reducing the expression of P-gp. This study provides a promising P-gp inhibitor for reversing multidrug resistance and provides a basis for further research.

Jatrophane diterpenoids from Euphorbia microcarpa (prokh.) krylov with multidrug resistance modulating activity.

Eight undescribed jatrophane diterpenoids, namely euphomicrophane A-H, together with thirteen known diterpenes were isolated from the whole plant extracts of Euphorbia microcarpa (Prokh.) Krylov. Among them, euphomicrophane C and F were possessed the endo-type core structure that naturally rarely appeared. The structures of the purified undescribed compounds were established by extensive spectroscopic and spectrometric analysis, and the single-crystal X-ray diffraction analysis was used to determine the absolute configuration of euphomicrophane E, elusone A and euphorbesulin G. All the isolates were screened for their reversal abilities on P-glycoprotein-mediated multidrug resistant cancer cell line MCF-7/ADR. Compounds euphomicrophane G-H and 3ß,7ß,8α,9α,15ß-pentaacetoxy-5ß-benzoyloxyjatropha-6(17)-11E-dien-14-one were showed potential chemoreversal effect with reversal fold values 18.67, 17.15, and 16.76 at a concentration of 10.0 µM, being equal to or stronger than the positive drug verapamil (16.68).

Diterpenoids from Euphorbia glomerulans with potential reversal activities against P-glycoprotein-mediated multidrug resistance.

The development of collateral sensitivity agents that are able to modulate P-glycoprotein (P-gp) is the most promising approaches to overcome multidrug resistance (MDR) in cancer. In this study, eight new diterpenoids of jatrophane and ingenane type, 1-8, and three known ones (9-11) were isolated from Euphorbia glomerulans. Their structures were elucidated by spectroscopic analysis and electronic circular dichroism (ECD) calculations. The MDR reversal activity evaluation of these isolates on breast cancer MCF-7/ADR cells demonstrated the four potent MDR modulators (3, 4, 5, and 9) with great chemoreversal ability and low cytotoxicity. The structure-activity relationship (SAR) analysis indicated that the presence of isobutanoyloxy group at C-8 significantly enhance reversal efficiency. Compound 5 exhibited high efficacy (EC50 = 159.5 nM) in reversing MDR resistance, being stronger than verapamil (EC50 = 302.9 nM). The MDR reversal mechanism assays revealed that 5 could promote the accumulation of Rh123 and DOX in drug-resistant cells in a certain dose-dependent manner, and inhibit P-gp transport function. In addition, the possible recognition mechanism of compound 5 and verapamil (VRP) with P-gp was predicted by molecular docking.

Jatrophane diterpenoids as multidrug resistance modulators from Euphorbia sororia.

Eight new jatrophane diterpenoids, Euphosorophane F-M (1-8), as well as fourteen known jatrophane diterpenoids (9-22) were separated and purified from the fructus of Euphorbia sororia, and the chemical structures were determined based on extensive spectroscopic analysis, 1D, 2D NMR and HRESIMS data included. Their absolute configurations of compounds 1, 2, 9, and 22 were elucidated by X-ray crystallographic analysis. These jatrophane diterpenoids showed lower cytotoxicity and compounds 3, 4, 11, 12, 13, 14, and 20 revealed promising multidrug resistance (MDR) reversal ability as modulators compared to verapamil (VRP) by MTT assay. The structure-activity relationship (SAR) exhibited that the absence of keto-carbonyl at C-9 and C-14 was essential to MDR reversal activity and the acyloxies substitution at C-5, C-7, C-8, and C-14 also made the activity difference. Euphosorophane I (4) particularly unfold greater potency (EC50 = 1.82 µM) in reversing P-gp-mediated resistance to doxorubicin (DOX). As shown by fluorescence microscopy, 4 promoted intracellular accumulation of rhodamine 123 (Rh123) and DOX in a dose-dependentmanner than VRP. Flow cytometry indicated that 4 inhibitedP-glycoprotein (P-gp) -dependentRh123 efflux in drug-resistant MCF-7/ADR cells. 4 stimulated P-gp-ATPase activity in a concentration-dependent way and inhibited DOX transport activity. Western blot and real-time qPCR results further illustrated that 4 exhibited superior MDR reversal effect in MCF-7/ADR cells attributed to the activation of ATPase rather than the upregulation of P-gp expression and mRNA levels. In addition, 4 bond to the drug-binding site of P-gp predicted by the molecular docking analysis. Collectively, these results indicated that 4 efficiently reversed P-gp-mediated MDR via inhibiting the ABCB1 drug efflux function. 4 with the advantage of low toxicity and efficient could be used as an adjuvanttherapy drug for breast cancer.

Crystal and mol-ecular structure of jatrophane diterpenoid (2R,3R,4S,5R,7S,8S,9S,13S,14S,15R)-2,3,8,9-tetra-acet-oxy-5,14-bis-(benzo-yloxy)-15-hydroxy-7-(iso-butano-yloxy)jatropha-6(17),11(E)-diene.

The structure of the jatrophane diterpenoid (ES2), C46H56O15, has ortho-rhom-bic (P212121) symmetry. The absolute configuration in the crystal has been determined as 2R,3R,4S,5R,7S,8S,9S,13S,14S,15R [the Flack parameter is -0.06 (11)]. The mol-ecular structure features intra-molecular O-H⋯O and C-H⋯O hydrogen bonding. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules into supra-molecular columns parallel to the a axis. One of the acet-oxy substituents is disordered over two orientations in a 0.826 (8):0.174 (8) ratio.

Ancient Chemistry "Pharaoh's Snakes" for Efficient Fe-/N-Doped Carbon Electrocatalysts.

The method of fabricating nonprecious metal electrocatalysts with high activity and durability through a facile and eco-friendly procedure is of great significance to the development of low-cost fuel cells and metal-air batteries. Herein, we present that an ancient chemical reaction of "Pharaoh's snakes" can be a fast and convenient technique to prepare Fe-/N-doped carbon (Fe/N-C) nanosheet/nanotube electrocatalysts with sugar, soda, melamine, and iron nitrate as precursors. The resultant Fe/N-C catalyst has a hierarchically porous structure, a large surface area, and uniformly distributed active sites. The catalyst shows high electrocatalytic activities toward both the oxygen reduction reaction with a half-wave potential of 0.90 V (vs reversible hydrogen electrode) better than that of Pt/C and the oxygen evolution reaction with an overpotential of 0.46 V at the current density of 10 mA cm-2 comparable to that of RuO2. The activity and stability of the catalyst are also evaluated in primary and rechargeable Zn-air batteries. In both conditions, three-dimensional Fe/N-C exhibited performances superior to Pt/C. Our work demonstrates a success of utilizing an ancient science to make a state-of-the-art electrocatalyst.