Jatrophane Diterpenes as Modulators of Multidrug Resistance. Advances of Structure−Activity Relationships and Discovery of the Potent Lead Pepluanin A

Diterpenoids from Euphorbia peplus possessing cytotoxic and anti-inflammatory activities

Phytochemical investigation into the medium polar fraction of the ethanol extract of Euphorbia peplus led to the identification of 32 diterpenoids with five structural types. Compounds 1-5 and 7-11 are reported for the first time, while the configuration of 6,7-epoxy group of 6 was revised to be β-oriented. Compounds 1-5 feature a rare structural variation of the double bond at Δ1 migrating to Δ1(10) in the tigliane-type diterpenoid family. Biologically, compound 21 was found to be the only one to show moderate cytotoxic activity, associated with the presence of a benzoyloxy residue at C-16. Besides, compounds 4, 8, 12, 13, 16, and 19 show significant inhibitory activities against NO production induced by LPS in RAW264.7 macrophage cells, with IC50 values within 2-5 μM. Structure-activity relationship (SAR) analysis revealed that the ingenane-type diterpenoids have the best anti-inflammatory activity, and the esterification at 3-OH or 5-OH is crucial. Further biological researches demonstrated that 13, the predominant metabolite in this plant, exerts anti-inflammatory effects by blocking the activation of NF-κB and MAPK signaling pathways.

Integration of LC/MS, NMR and Molecular Docking for Profiling of Bioactive Diterpenes from Euphorbia mauritanica L. with in Vitro Anti-SARS-CoV-2 Activity

In spite of tremendous efforts exerted in the management of COVID-19, the absence of specific treatments and the prevalence of delayed and long-term complications termed post-COVID syndrome still urged all concerned researchers to develop a potent inhibitor of SARS-Cov-2. The hydromethanolic extracts of different parts of E. mauritanica were in vitro screened for anti-SARS-Cov-2 activity. Then, using an integrated strategy of LC/MS/MS, molecular networking and NMR, the chemical profile of the active extract was determined. To determine the optimum target for these compounds, docking experiments of the active extract's identified compounds were conducted at several viral targets. The leaves extract showed the best inhibitory effect with IC₅₀ 8.231±0.04 μg/ml. The jatrophane diterpenes were provisionally annotated as the primary metabolites of the bioactive leaves extract based on multiplex of LC/MS/MS, molecular network, and NMR. In silico studies revealed the potentiality of the compounds in the most active extract to 3CLpro, where compound 20 showed the best binding affinity. Further attention should be paid to the isolation of various jatrophane diterpenes from Euphorbia and evaluating their effects on SARS-Cov-2 and its molecular targets.

Jatrophane Diterpenoids from Euphorbia peplus Linn. as Activators of Autophagy and Inhibitors of Tau Pathology

Ten jatrophane diterpenoids were isolated from the whole plant Euphorbia peplus Linn. including seven new ones, named euphjatrophanes A-G (labeled compounds 1, 2, 4-8). Their structures were elucidated with a combination of spectroscopic and single-crystal X-ray crystallography, enabling the identification of compounds 3, 9, and 10 as the previously published euphpepluones G, K, and L, respectively. All compounds were evaluated for their bioactivity with flow cytometry in assays of autophagic flux in HM Cherry-GFP-LC3 (human microglia cells stably expressing the tandem monomeric mCherry-GFP-tagged LC3) cells. Euphpepluone K (9) significantly activated autophagic flux, an effect that was verified with confocal analysis. Moreover, cellular assays showed that euphpepluone K (9) induced autophagy and inhibited Tau pathology.

Gene discovery and virus-induced gene silencing reveal branched pathways to major classes of bioactive diterpenoids in Euphorbia peplus

SignificanceEuphorbia peplus, a member of the Euphorbia genus, is rich in jatrophane and ingenane diterpenoids. Using a metabolomics-guided transcriptomic approach to gene candidate identification, we have discovered a short-chain dehydrogenase gene involved in the production of the lathyrane jolkinol E. We have developed a virus-induced gene-silencing method in E. peplus that has allowed us to demonstrate the direct relationship between casbene and polycyclic diterpenoids and that jolkinol C acts as a key branch point intermediate in the production of ingenanes and jatrophanes. This work contributes both knowledge and tools for engineering production of bioactive diterpenoids in heterologous host systems, thus enabling their further evaluation and development.

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.

Jatrophane Diterpenoids from the Seeds of Euphorbia peplus with Potential Bioactivities in Lysosomal-Autophagy Pathway

Euphopepluanones F - K (1 - 4), four new jatrophane type diterpenoids were isolated from the seeds of Euphorbia peplus, along with eight known diterpenoids (5 - 12). Their structures were established on the basis of extensive spectroscopic analysis and X-ray crystallographic experiments. The new compounds 1 - 4 were assessed for their activities to induce lysosomal biogenesis through LysoTracker Red staining. Compound 2 significantly induced lysosomal biogenesis. In addition, compound 2 could increase the number of LC3 dots, indicating that it could activate the lysosomal-autophagy pathway.

Jatrophane Diterpenoids from Euphorbia peplus as Multidrug Resistance Modulators with Inhibitory Effects on the ATR-Chk-1 Pathway

Twelve undescribed jatrophane diterpenoids, euphpepluones A-L (1-12), together with seven known analogues (13-19), were isolated from the whole plant of Euphorbia peplus, and their structures were elucidated by spectroscopic studies. The absolute configurations of 1 and 4 were assigned by X-ray crystallographic analysis. All isolates were investigated for their inhibitory effects against the ATR-Chk1 pathway using a Western blotting assay. As a result, 1, 2, 5, 8, 10, and 16 were found to suppress the camptothecin (CPT)-induced phosphorylation of Chk1, indicating that these compounds inhibit the activation of the ATR-Chk1 pathway. A preliminary structure-activity relationship (SAR) study of the isolates was conducted. When compound 10 and CPT were combined, apoptosis was induced in A549 cells with PARP cleavage, while there was no apoptotic effect by treatment with CPT or 10 alone. The data obtained indicate that 10 potentiates the chemotherapeutic sensitivity of A549 cells to CPT.

Jatrophane and rearranged jatrophane-type diterpenes: biogenesis, structure, isolation, biological activity and SARs (1984-2019)

Diterpene compounds specially macrocyclic ones comprising jatrophane, lathyrane, terracinolide, ingenane, pepluane, paraliane, and segetane skeletons occurring in plants of the Euphorbiaceae family are of considerable interest in the context of natural product drug discovery programs. They possess diverse complex skeletons and a broad spectrum of therapeutically relevant biological activities including anti-inflammatory, anti-chikungunya virus, anti-HIV, cytotoxic, and multidrug resistance-reversing activities as well as curative effects on thrombotic diseases. Among macrocyclic diterpenes of Euphorbia, the discovery of jatrophane and modified jatrophane diterpenes with a wide range of structurally unique polyoxygenated polycyclic derivatives and as a new class of powerful inhibitors of P-glycoprotein has opened new frontiers for research studies on this genus. In this review, an attempt has been made to give in-depth coverage of the articles on the naturally occurring jatrophanes and rearranged jatrophane-type diterpenes isolated from species belonging to the Euphorbiaceae family published from 1984 to March 2019, with emphasis on the biogenesis, isolation methods, structure, biological activity, and structure-activity relationship.

Jatrophane Diterpenoids from Euphorbia glomerulans

In a phytochemical investigation of the whole plant of Euphorbia glomerulans, 17 new (1-17) and five known jatrophane diterpenoids (18-22) were identified. The X-ray crystallographic data of compounds 1, 4, and 21 permitted the definition of the absolute configurations of these compounds. The cytotoxicity and multidrug resistance reversal activities of the 17 new compounds were evaluated on multidrug-resistant MCF-7/ADR cells overexpressing P-glycoprotein. Several compounds showed different chemoreversal activities and considerably decreased cytotoxicity. Compounds 11 (IC₅₀ value of 5.0 ± 0.8 μM) and 12 (IC₅₀ value of 5.2 ± 2.0 μM) possessed MDR reversal activities that were as good as that of verapamil (IC₅₀ value of 4.7 ± 0.6 μM).

Metabolomic evaluation of Euphorbia pekinensis induced nephrotoxicity in rats

CONTEXT

Euphorbia pekinensis Rupr. (Euphorbiaceae) has long been used in the Orient, while its clinical use was limited due to its nephrotoxic effect.

OBJECTIVE

The possible mechanism of nephrotoxicity of Euphorbia pekinensis (EPR) and its related constituents were investigated.

MATERIALS AND METHODS

Petroleum ether (PE), acetic ether (AE) and n-butanol (BUT) extracted sections of EPR were separately given to Wistar rats by gavage at the dose of 3 g/kg/day for 10 weeks to determine the nephrotoxic section of EPR. Then, renal metabolic profiling of EPR after oral administration of nephrotoxic section was investigated and its related constituents were identified by LC/Q-TOF-MS method.

RESULTS

The average values of creatinine (CREA) in PE, AE, BUT and control groups were 76.54 ± 9.52, 54.12 ± 10.34, 51.33 ± 5.19 and 48.23 ± 6.67 μmol/L. The average values of blood urea nitrogen (BUN) in PE, AE, BUT and control groups were 15.25 ± 3.37, 8.32 ± 0.89, 9.22 ± 1.78 and 8.47 ± 1.33 mmol/L, respectively. Only kidney section of rats in PE group showed that glomeruli had cellular or fibrocellular crescents. Renal metabolic profiling showed disturbed metabolic pathways of purine, amino acid, phospholipids and sphingolipids in EPR nephrotoxicity. A total of 25 compounds [(-)-(1S)-15-hydroxy-18-carboxycembrene is a new compound] in PE section and 10 compounds in rat serum after administration of PE section were identified.

CONCLUSIONS

This is the first time that the toxic compounds of PER and action mechanism of EPR nephrotoxicity were explored to provide a new reference for studying the toxic components of Traditional Chinese Medicine (TCM).

Phytochemical profile of Euphorbia peplus L. collected in Central Italy and NMR semi-quantitative analysis of the diterpenoid fraction

In this work, the phytochemical profile of the ethanolic extract of Euphorbia peplus L. collected in Central Italy, was reported. This specimen had never been studied before and the analysis was accomplished by means of Column Chromatography for the separation procedure and by means of NMR Spectroscopy and Mass Spectrometry for the identification step. In particular, fourteen compounds were evidenced belonging to five different classes of natural compounds i.e. triterpenoids (pentacyclic and saponin), peculiar diterpenoids (jatrophanes and pepluanes), flavonoids (flavonols), caffeoyl-quinic acids and rare disaccharides. In addition to this, a semi-quantitative analysis on the diterpenoid fraction, by means of NMR Spectroscopy, was also performed in order to provide the real quantities of these compounds in the same fraction and in the total extract. Due to the pronounced chemo variability observed in Euphorbia spp., the availability of a reliable and quick analytical technique, such as that reported in the present study, could be a useful tool in the standardization of plant materials to be used in pharmacological studies or for ethnomedicinal purposes. The technical details for both the general phytochemical analysis and the specific quantitative one, were inserted in this paper. Moreover, the chemotaxonomic and ethnopharmacological relevance of these compounds was also discussed.

Environmentally Friendly Procedure Based on Supercritical Fluid Chromatography and Tandem Mass Spectrometry Molecular Networking for the Discovery of Potent Antiviral Compounds from Euphorbia semiperfoliata

A supercritical fluid chromatography-based targeted purification procedure using tandem mass spectrometry and molecular networking was developed to analyze, annotate, and isolate secondary metabolites from complex plant extract mixture. This approach was applied for the targeted isolation of new antiviral diterpene esters from Euphorbia semiperfoliata whole plant extract. The analysis of bioactive fractions revealed that unknown diterpene esters, including jatrophane esters and phorbol esters, were present in the samples. The purification procedure using semipreparative supercritical fluid chromatography led to the isolation and identification of two new jatrophane esters (13 and 14) and one known (15) and three new 4-deoxyphorbol esters (16-18). The structure and absolute configuration of compound 16 were confirmed by X-ray crystallography. This compound was found to display antiviral activity against Chikungunya virus (EC₅₀ = 0.45 μM), while compound 15 proved to be a potent and selective inhibitor of HIV-1 replication in a recombinant virus assay (EC₅₀ = 13 nM). This study showed that a supercritical fluid chromatography-based protocol and molecular networking can facilitate and accelerate the discovery of bioactive small molecules by targeting molecules of interest, while minimizing the use of toxic solvents.

Chemical profile and defensive function of the latex of Euphorbia peplus

Plant latex is an endogenous fluid secreted from highly specialized laticifer cells and has been suggested to act as a plant defense system. The chemical profile of the latex of Euphorbia peplus was investigated. A total of 13 terpenoids including two previously unknown diterpenoids, (2S*,3S*,4R*,5R*,6R*,8R*,l1R*,13S*,14S*,15R*, 16R*)-5,8,15-triacetoxy-3-benzoyloxy-11,16-dihydroxy-9-oxopepluane and (2R*,3R*, 4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,8,9,14-pentaacetoxy-3-benzoyloxy-15-hydroxy-7-isobutyroyloxyjatropha-6(17),11E-diene), ten known diterpenoids, and a known acyclic triterpene alcohol peplusol, were identified, using HPLC and UPLC-MS/MS analyses and through comparison with the authentic compounds isolated from the whole plant. The diterpenoids exhibited significant antifeedant activity against a generalist plant-feeding insect, the cotton bollworm (Helicoverpa armigera), with EC₅₀ values ranging from 0.36 to 4.60 μg/cm². In particular, (2R*,3R*,4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,9,14-tetraacetoxy-3-benzoyloxy-8,15-dihydroxy-7-isobutyroyloxyjatropha-6(17),11E-diene and (2R*,3R*, 4S*,5R*,7S*,8S*,9S*,l3S*,14S*,15R*)-2,5,14-triacetoxy-3-benzoyloxy-8,15-dihydroxy-7-isobutyroyloxy-9-nicotinoyloxyjatropha-6(17),11E-diene had EC₅₀ values of 0.36 and 0.43 μg/cm², respectively, which were approximately 7-fold more potent than commercial neem oil (EC₅₀ = 2.62 μg/cm²). In addition, the major peplusol showed obvious antifungal activity against three strains of agricultural phytopathogenic fungi, Rhizoctonia solani, Colletotrichum litchi and Fusarium oxysporum f. sp. niveum. The results indicated that terpenoids in the latex of E. peplus are rich and highly diversified, and might function as constitutive defense metabolites against insect herbivores and pathogens for the plant.

Evaluation of Jatrophane Esters from Euphorbia spp. as Modulators of Candida albicans Multidrug Transporters

Twenty-nine jatrophane esters (1-10, 12-30) and one lathyrane (11) diterpenoid ester isolated from Euphorbia species were evaluated for their capacity to inhibit drug-efflux activities of the primary ABC transporter CaCdr1p and the secondary MFS transporter CaMdr1p of Candida albicans, in yeast strains overexpressing the corresponding transporter. These diterpenoid esters were obtained from Euphorbia semiperfoliata (1-10), E. insularis (11), and E. dendroides (12-30) and included five new compounds, euphodendroidins P-T (26-30). The jatrophane esters 12 and 23 were found to inhibit the efflux of Nile Red (NR) mediated by the two multidrug transporters, at 85-64% for CaCdr1p and 79-65% for CaMdr1p. In contrast, compound 21 was selective for CaCdr1p and induced a strong inhibition (92%), whereas compound 8 was selective for CaMdr1p, with a 74% inhibition. It was demonstrated further that potency and selectivity are sensitive to the substitution pattern on the jatrophane skeleton. However, these compounds were not transported and showed no synergism with fluconazole cytotoxicity.

A myrsinol diterpene isolated from a traditional herbal medicine, LANGDU reverses multidrug resistance in breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

LANGDU, a Chinese traditional herbal medicine, was the dried roots of Euphorbia prolifera Buch-Ham. The herbal medicine has been used as anti-cancer and anti-inflammatory drug in local folk medicine for several hundred years.

AIM OF THE STUDY

P-glycoprotein (P-gp) is a transmembrane exporter, which can expel a variety of anti-cancer drugs. Over-expressed P-glycoprotein in cancer cells impairs the effect of cancer chemotherapy and results in multidrug resistance (MDR). To elucidate the effect of LANGDU on MDR cancer cells, the constituents of Euphorbia prolifera Buch-Ham were analyzed. We found that a myrsinol diterpene, J196-10-1 could reverse multidrug resistance.

MATERIALS AND METHODS

Cytotoxicity assays were performed to measure reversal efficiency of J196-10-1. Efflux assay, ATPase assay, and real-time PCR were used to elucidate the mechanism of the chemical.

RESULTS

J196-10-1 could reverse the resistance to daunorubicin, vincristine, and topotecan effectively. The diterpene inhibited P-gp mediated efflux and did not alter transcription of the target gene significantly. The compound stimulated ATP hydrolysis at a low concentration and inhibited it at a high concentration.

CONCLUSIONS

J196-10-1 inhibits P-gp competitively and reverses P-gp induced MDR in breast cancer cells.

Synthesis of an Orthogonally Protected Polyhydroxylated Cyclopentene from l-Sorbose

The use of l-sorbose in the synthesis of functionalized cyclopentene derivatives was accomplished. These cyclopentene derivatives are related to those found in naturally occurring jatrophane frameworks and in other bioactive compounds. The formation of allyl α-l-sorbopyranoside was a key synthetic step. Regioselective introduction of protecting groups was followed by the hydrolysis of the allyl glycoside to furnish a fully protected acyclic l-sorbose derivative. This acyclic intermediate was subsequently used to give an orthogonally protected polyhydroxylated cyclopentene, which has potential for further synthesis of bioactive compounds. The protected cyclopentene itself showed a clear cytotoxic activity when tested against a panel of human cancer cell lines (HT29, LS174T, SW620, A549, and HeLa cells).

Complementary and alternative medicine use among cancer patients in Palestine with special reference to safety-related concerns

ETHNOPHARMACOLOGICAL RELEVANCE

The use of CAM including herbal medicine as the most preferred CAM modality, among cancer patients who are taking prescription medications has shown to be highly prevalent worldwide as well as in several Middle Eastern countries, with a high percentage of the patients do not disclose their CAM use to treating physician.

AIM OF THE STUDY

The current study aimed to evaluate the patterns of CAM use among two cohorts of cancer patients in Palestine over a three-year period, and to identify socio-demographic factors that are associated with CAM use.

MATERIALS AND METHODS

Across-sectional survey of patients attending outpatient cancer clinics. The method was based on a semi-structured questionnaire. In order to identify safety-related concerns associated with the products listed, a literature search was conducted using different databases (PubMed, Micromedex, AltMedDex, and the Natural Medicine Comprehensive Database).

RESULTS

In 472 cancer patients including 372 of the 2011 cohort; and 100 of the 2014 cohort, the overall prevalence of CAM use was 69.5%. CAM users were more likely to be ≤65 years old, village resident, being in the midst of chemotherapy, to have high interest spiritual quest, and to have no other chronic diseases. A significant number of CAM users reported using herbal preparations (98.3%, and 89.6% in the two study cohorts, respectively). In the current study, a total of 40 plant taxa belonging to 23 botanical families were reported by ≥3 cancer patients in the two cohort groups. The top most commonly used plant in the 2011 cohort group was Arum palaestinum (43.5%), while Ephedra foeminea emerged as the top most commonly utilized plant (from 0.0% in 2011 to 55.2% in the 2014 cohort), mainly due to a recent publicizing and portraying of the plant in the local media as an effective cancer herbal remedy. Safety-related concerns were associated with 33 (82.5%) herbs, including herb-drug interactions with altered pharmacokinetics (8, 20% herbs), direct toxic effects (16, 40% herbs), and increased in vitro response of cancer cells to chemotherapy (30, 75% herbs).

CONCLUSIONS

CAM use, especially herbal medicine in cancer is highly prevalent in Palestine. This study has demonstrated the role of the media on the emergence of new CAM herbal therapies among cancer patients in Palestine, and discussed its potential implications on patients and for oncologists who are treating them. Some of the most widely used herbal medicines by cancer patients in the present work are known to interact with conventional anticancer drugs. Hence, the disclosure of the use of herbal remedies by patients to health professionals with sufficient training in CAM use is important for the later in order to assess whether there are any possible herbal drug interactions and/or harmful drug reactions.

Pepluane and Paraliane Diterpenoids from Euphorbia peplus with Potential Anti-inflammatory Activity

Twelve new diterpenoids based on two rare skeletal types, namely, paralianones A-D (1-4) and pepluanols A-H (5-12), along with five known compounds, were isolated from an acetone extract of Euphorbia peplus. Their structures were proposed based on 1D and 2D NMR spectroscopic data analysis. These diterpenoids were evaluated for potential anti-inflammatory activity in a lipopolysaccharide-stimulated mouse macrophage cellular model. Compounds 3, 4, 11, 13, and 16 displayed moderate inhibitory effects on NO inhibition, with IC50 values ranging from 29.9 to 38.3 μM.

Biodiversity characteristics of Teucrium polium species in Saudi Arabia

Teucrium (Lamiaceae) is a large and polymorphic genus distributed mainly in Europe, North Africa and in the temperate parts of Asia. In this study, the anatomical features of the leaf and stem of Teucrium polium are investigated. Teucrium has 19 taxa in Iran, which mainly grow in the Irano-Turanian region between 700 and 2000 m above sea level. T. polium belonging to sect. Polium, is a perennial herb growing on Lorestan province. The leaves clearly exhibit xeromorphy due to features such as thick cuticle layer, thick outer epidermal cell wall, high density of trichomes and thick palisade layer of the mesophyll. Anatomical studies on T. polium revealed that the stem shares the general characteristics of the Labiatae family. The aim of our approach was to study the morphological and taxonomical parameters for T. polium in Saudi Arabia. The results of this study showed that there was no influence of environment on the structure of stomata and trichomes as studying species with T . polium. In conclusion our study shows we have studied the geographical distribution of the species in Saudi Arabia and in the world.

Jatrophanes from Euphorbia squamosa as potent inhibitors of Candida albicans multidrug transporters

A series of structurally related jatrophane diterpenoids (1-6), including the new euphosquamosins A-C (4-6), was purified from the Iranian spurge Euphorbia squamosa and evaluated for its capacity to inhibit drug efflux by multidrug transporters of Candida albicans. Three of these compounds showed an interesting profile of activity. In particular, deacetylserrulatin B (2) and euphosquamosin C (6) strongly inhibited the drug-efflux activity of the primary ABC-transporter CaCdr1p, an effect that translated, in a yeast strain overexpressing this transporter, into an increased sensitivity to fluconazole. These compounds were transported by CaCdr1p, as shown by the observation of an 11-14-fold cross-resistance of yeast growth, and could also inhibit the secondary MFS-transporter CaMdr1p. In contrast, euphosquamosin A (4) was selective for CaCdr1p, possibly as a result of a different binding mode. Taken together, these observations suggest jatrophane diterpenes to be a new class of potent inhibitors of multidrug transporters critical for drug resistance in pathogenic yeasts.

In vitro and in vivo assessment of CYP2C9-mediated herb-herb interaction of Euphorbiae Pekinensis Radix and Glycyrrhizae Radix

According to traditional Chinese medicine theories, Euphorbiae Pekinensis Radix and Glycyrrhizae Radix should not be used together in one prescription, because their interaction leads to an unexpected consequence. However, the mechanism remains unclear. The purpose of this study was to find out whether CYP2C9 was involved in this herb–herb interaction by using tolbutamide as a probe substrate in vivo and in vitro. Both Euphorbiae Pekinensis Radix and Glycyrrhizae Radix showed induction activity toward CYP2C9, while the combination of them showed a more potent induction activity toward CYP2C9 in vivo. In vitro study revealed only the combination of the herbs could induce the activity of CYP2C9. Thus, both in vivo and in vitro study indicated combination of Glycyrrhizae Radix and Euphorbiae Pekinensis Radix could induce the activity of CYP2C9 to a high level, which may result in decreased plasma levels of major active ingredients of these two herbs, as well as other herbs in the prescriptions. Further research also appears to be necessary to identify the main enzymes involved in the metabolism of the active ingredients in Glycyrrhizae Radix and Euphorbiae Pekinensis Radix.

Jatrophane diterpenes from Euphorbia mellifera and their activity as P-glycoprotein modulators on multidrug-resistant mouse lymphoma and human colon adenocarcinoma cells

Three new macrocyclic jatrophane diterpenes, named euphomelliferine (1) and euphomelliferenes A (2) and B (3), and one new tetracyclic triterpene, 19(10→9)-abeo-8α,9β,10α-tirucalla-5,25-diene-3β,24-diol (6, C-24 epimers), were isolated from the methanolic extract of Euphorbia mellifera. A known ingenane (7) and two jatrophane diterpenes (4 and 5) were also isolated. Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D homo- and heteronuclear NMR experiments. Jatrophane diterpenes 1-3 and 5 were evaluated for their effects on the reversion of multidrug resistance (MDR) mediated by P-glycoprotein, by using the rhodamine-123 exclusion test, on human MDR1 gene-transfected mouse lymphoma cells (L5178Y MDR) and on human colon adenocarcinoma cells (COLO 320). The apoptosis-inducing activity of these compounds was also tested on COLO 320 cells, using the annexin-V/propidium iodide assay. Diterpenes 1 and 2 displayed significant MDR reversing activity, in a dose-dependent manner, on both cancer cell models. The tested compounds did not induce apoptosis in the COLO 320 cells.

Reversal of multidrug resistance by morning glory resin glycosides in human breast cancer cells

Reversal of multidrug resistance (MDR) by thirty resin glycosides from the morning glory family (Convolvulaceae) was evaluated in vinblastine-resistant human breast carcinoma cells (MCF-7/Vin). The effects of these amphipathic compounds on the cytotoxicity and P-glycoprotein (P-gp)-mediated MDR were estimated with the sulforhodamine B colorimetric assay. Active noncytotoxic compounds exerted a potentiation effect of vinblastine susceptibility by 1- to over 1906-fold at tested concentrations of 5 and 25 μg/mL. Murucoidin V (1) enhanced vinblastine activity 255-fold when incorporated at 25 μg/mL and also, based on flow cytometry, significantly increased the intracellular accumulation of rhodamine 123 with the use of reserpine as a positive control for a MDR reversal agent. Incubation of MCF-7/Vin cells with 1 caused an increase in uptake and notably lowered the efflux rate of rhodamine 123. Decreased expression of P-glycoprotein by compound 1 was detected by immunofluorescence flow cytometry after incubation with an anti-P-gp monoclonal antibody. These results suggest that resin glycosides represent potential efflux pump inhibitors for overcoming MDR in cancer therapy.

Selective modulation of P-glycoprotein activity by steroidal saponines from Paris polyphylla

Bio-guided fractionation of the roots of Paris polyphylla (Trilliaceae), based on inhibition of P-glycoprotein-mediated daunorubicin efflux in K562/R7 cell line, led to isolation and identification of the three saponins 3-O-Rha(1-->2)[Ara(1-->4)]Glc-pennogenine, gracillin and polyphyllin D, and the two ecdysteroids 20-hydroxyecdysone and pinnatasterone. These compounds were tested for multidrug reversion on P-glycoprotein (ABCB1) with both drug-selected and transfected cell lines, and also on Breast Cancer Resistance Protein (BCRP/ABCG2). By contrast to a weak efficiency on BCRP, the three saponins displayed significant effects as inhibitors of P-glycoprotein-mediated drug efflux.