Mouse Lymphoma Cell Line Research Articles

Caryophyllene-type sesquiterpenes from the endophytic fungus Pestalotiopsis lespedezae through an OSMAC approach.

Two new caryophyllene-type sesquiterpenes pestalotiopsins U and V (1 and 2) and three known compounds pestalotiopsin B (7), pestaloporinate B (8), and pestalotiopsin C (9) were isolated by the cultivation of the endophytic fungus Pestalotiopsis lespedezae on solid rice medium, while four additional new caryophyllene pestalotiopsins W-Z (3-6) were obtained when 3.5% NaI was added to the fungal culture medium. The structures of the new compounds were determined by HRESIMS and 1D/2D nuclear magnetic resonance data. Compounds 1-9 were tested for cytotoxicity against the mouse lymphoma cell line L5178Y, but only 6 displayed significant activity with an IC50 value of 2.4 μM.

Low-molecular-weight fucoidan increases telomere length and immunostimulatory effects on NK-92 cells following inhaled anesthetic injury

Inhaled anesthetics, such as isoflurane, may cause side effects, including short-term immunosuppression and DNA damage. In contrast, low molecular weight fucoidan (LMF), derived from brown seaweed, exhibits promising immunomodulatory effects. In this study, we determined the effect of isoflurane on telomeres and examined the potential of LMF to ameliorate the harmful effects of isoflurane. Male Lewis rats, the mouse lymphoma cell line YAC-1, and the human nature killer cell line NK-92 MI were exposed to isoflurane. The relative telomere length (T/S) ratio and mRNA expression were determined by quantitative PCR. The viability assay was used to assess cell viability. In vivo, 2% isoflurane exposure, which is a clinically relevant concentration, reduced telomere length, and correlated with exposure frequency and duration. Isoflurane concentrations above 2% shortened YAC-1 telomeres, with minimal impact on cell viability. LMF pre-treatment enhanced NK-92 MI cell survival resulting from isoflurane exposure and exerted superior telomere protection compared with LMF post-treatment. Furthermore, adding LMF during isoflurane exposure resulted in a significant increase in IFN-γ, TNF-α, and IL-10 mRNA compared with the untreated group. LMF protected against isoflurane-induced telomere shortening, enhanced NK cell viability, and modulated cytokine expression, thus mitigating postoperative immune suppression and risk of tumor metastasis.

Abstract A031: Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity

Abstract The transformative success of cancer immunotherapy has revolutionized cancer treatment and can induce long lasting responses in patients with cancers from a wide range of histologies. However, only a fraction of patients respond to immunotherapy and cancer cells escape immunosurveillance by downregulating antigen presentation through mechanisms that remain elusive. Proteasomes play a central role in the immune response by generating peptides from intracellular antigens which are presented on the cell surface for recognition by CD8+ cytotoxic T lymphocytes (CTLs). Immune cells contain a highly specialized variant of proteasomes, known as immunoproteasomes, in which the three constitutive catalytic subunits are replaced by cytokine-inducible, homologous catalytic subunits. Immunoproteasomes are specially adapted for a role in MHC class I antigen processing and presentation to CD8+ T-cells. Here, we performed a high-through screen (HTS) to detect novel molecular entities that activated proteasomal peptide-hydrolyzing activity. We identified a curated panel of molecules which not only enhanced proteasomal hydrolysis of the cell-permeable substrate LLVY-R110 but also enhanced the presentation of MHC class I antigens. E.G7-Ova is a mouse lymphoma cell line derived by electroporation of EL4 cells (C57BL/6, H-2b, T lymphoma) with chicken ovalbumin (OVA) cDNA. Proteasomes degrade OVA to generate the peptide SIINFEKL that is presented by MHC-class I molecules. Studies demonstrated that the hits identified in the screen increased SIINFEKL presentation on E.G7-Ova cells. The lead compound identified in the HTS, compound A, dramatically enhanced expression of the proteasome activator PA28, which is expressed by PSME1 and PSME2. Treatment of multiple myeloma (MM) cells with compound A enhanced the hydrolysis of Ac-ANW-MCA, which is selectively cleaved by the immunoproteasome beta5-associated catalytic subunits. Treatment of MM cells with compound A followed by mass spectrometry (MS) indicated that the relative presentation of individual antigenic peptides bound to MHC class I molecules on tumor cells was dramatically increased. Novel immunoproteasome-selective therapeutics have the potential to generate neoantigens and upregulate cspecific antigens on tumor cells to enhance CD8+ T-cell-mediated control of human cancers. Citation Format: James J. Driscoll, Priyanka S. Rana, James J. Ignatz-Hoover. Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A031.

Abstract A076: Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity

Abstract Evasion of immune destruction is a hallmark of cancer that thwarts the efficacy of immunotherapy and reduces patient benefit. The development of immunotherapies has sparked a revolution in oncology by releasing the power of the human immune system, but the identity of novel, actionable antigens exclusively presented on cancer cells remains elusive. Immune cells contain a highly specialized variant of proteasomes, known as immunoproteasomes, in which the three constitutive catalytic subunits are replaced by cytokine-inducible, homologous catalytic subunits. Immunoproteasomes are specially adapted for a role in MHC class I antigen processing and presentation to CD8+ T-cells. Here, we performed a high-through screen to detect novel molecular entities that activated proteasomal peptide-hydrolyzing activity. We identified a curated panel of molecules which not only enhanced proteasomal hydrolysis of the cell-permeable substrate LLVY-R110 but also enhanced the presentation of MHC class I antigens. E.G7-Ova is a mouse lymphoma cell line derived by electroporation of EL4 cells (C57BL/6, H-2b, T lymphoma) with chicken ovalbumin (OVA) cDNA. Proteasomes degrade OVA to generate the peptide SIINFEKL that is presented by MHC-class I molecules. Studies demonstrated that the hits identified in the screen increased SIINFEKL presentation on E.G7-Ova cells. The lead compound, compound A, dramatically enhanced the expression of the proteasome activator PA28a/b, expressed by PSME1/2. Treatment of multiple myeloma (MM) cells with compound A enhanced the hydrolysis of Ac-ANW-MCA, which is selectively cleaved by the immunoproteasome beta5-associated catalytic activity. Treatment of MM cells followed by mass spectrometry (MS) demonstrated that compound A modulated the relative presentation of individual antigenic peptides bound to MHC class I molecules on tumor cells. The identification of actionable tumor antigens is indispensable for the development of several cancer immunotherapies, including T cell receptor (TCR)–transduced T cells and patient-specific mRNA or peptide vaccines. MS-based immunopeptidomics enables the discovery of canonical and non-canonical antigens, i.e., antigens derived from sequences outside protein-coding regions or generated by non-canonical antigen-processing mechanisms. This method enables the rapid identification of non-canonical peptides, a fraction of which may be detected exclusively by cancer cells. Novel, immunoproteasome-selective therapeutics have the potential to contribute not only to CD8+ T-cell-mediated control of human cancers, but also intracellular infections, autoimmune diseases, neurodegenerative diseases and proteinopathies that are characterized by the pathologic accumulation of toxic, proteinaceous aggregates. Citation Format: James J. Driscoll, Priyanka S. Rana, James J. Ignatz-Hoover. Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A076.

An Immunoproteasome Activator That Increases MHC Class I Antigen Presentation to Enhance Anti-Tumor Immunity

Evasion of immune destruction is a hallmark of cancer that thwarts the efficacy of immunotherapy and reduces patient benefit. The development of immunotherapies has sparked a revolution in oncology by releasing the power of the human immune system, but the identity of novel, actionable antigens exclusively presented on cancer cells remains elusive. Proteasomes are multi-subunit proteolytic complexes that selectively degrade intracellular proteins. Proteasomes play a critical in controlling myriad cellular processes including metabolism, cell cycle progression, signal transduction, protein quality control and differentiation. Importantly, proteasomes are also the source of most antigenic peptides presented to the immune system on major histocompatibility complex (MHC)-class I molecules. In this process, intracellular and viral proteins are degraded in the cytosol to 8 and 9-amino acid peptides, which are then transported into the endoplasmic reticulum, where they associate with MHC-class I molecules and are presented to the cell surface. Immune cells contain a highly specialized, cytokine-inducible proteasome variant, known as the immunoproteasome, in which the three constitutive catalytic subunits are replaced by homologous catalytic subunits. Immunoproteasomes are specially adapted for a role in MHC class I antigen processing and presentation to CD8 + T-cells. Here, we performed a high-through screen (HTS) to detect novel molecular entities that activated immuno-proteasomal catalytic activity. We identified a curated panel of molecules which not only enhanced hydrolysis of the cell-permeable substrate LLVY-R110 but also enhanced the presentation of MHC class I antigens. E.G7-Ova is a mouse lymphoma cell line derived by electroporation of EL4 cells (C57BL/6, H-2b, T lymphoma) with chicken ovalbumin ( OVA) cDNA. Proteasomes degrade OVA to generate the peptide SIINFEKL that is presented by murine MHC-class I H-2Kb molecules. E.G7-Ova cells were pretreated with compound A and co-cultured with the T-cell hybridoma B3Z that had been genetically-engineered to express a SIINFEKL-restricted t-cell receptor (TCR). Pretreatment of E.G7-Ova cells with compound A significantly increased tumor cell lysis by B3Z cells. The treatment of multiple myeloma (MM) cells with compound A also dramatically enhanced the expression of pan-MHC class I antigens. Treatment of MM cells with compound A increased the intracellular level of the proteasome activator PA28α/β, which is expressed by PSME1/2. Compound A treatment also enhanced hydrolysis of the fluorogenic peptide substrate Ac-ANW-AMC, which is selectively cleaved by the immunoproteasome β5-associated catalytic activity. Treatment of MM cells with compound A followed by mass spectrometry (MS) revealed that immunoproteasome activation modulated the relative presentation of individual antigenic peptides bound to MHC class I molecules. Pre-treatment of MM cells with compound A also significantly enhanced the anti-myeloma activity of human cytotoxic T-cells. Taken together, our results demonstrate that immunoproteasome activation has the potential to overcome immune escape and promote host immunity. In addition, our model systems now allows us to identify actionable tumor antigens on patient tumor cells as an indispensable tool for the development of cancer immunotherapies, e.g., T cell receptor (TCR)-transduced T-cells and patient-specific mRNA and peptide vaccines. Finally, immunoproteasome activators have the potential to contribute not only to cytotoxic T-cell mediated tumor lysis but also the treatment of intracellular infections and autoimmune and neurodegenerative proteinopathies characterized by the pathologic accumulation of toxic, proteinaceous aggregates.

Nypa fruticans endophytic fungus Cichorin A displays a weak cytotoxic activity against mouse lymphoma

A keen interest and attention have been given to studies on Endophytic fungus as a substitute or an alternative to the traditional source of drugs which is principally plant as a result of its interesting bioactive products. This may be an additional means of increasing the yields of those already obtained from plants or a source of entirely new ones. In essence, it is a treasure trove of therapeutically active metabolites. The aim of the study was to challenge Cichorin A isolated from Pestalotiopsis sp. against mouse lymphoma cell line. The result showed that it has a weak activity with a growth inhibitory effect of 31.2%

Differential cytotoxic effects of fenbendazole on mouse lymphoma EL-4 cells and spleen cells

Fenbendazole (FBZ) is a benzimidazole anthelmintic widely used to treat parasitic infections. The anticancer effect of FBZ has been recently highlighted leading to its consideration as a potential anticancer agent. Although previous studies have demonstrated the effect of FBZ on cancer cells, there is a paucity of studies on the effect of FBZ on lymphoma cells and normal immune cells. Herein, we investigated the effects of FBZ on a mouse lymphoma cell line, EL-4 cells, and spleen cells, using vincristine as a positive control. The cellular metabolic activity of EL-4 cells was decreased by FBZ, but that of the spleen cells was not decreased. Moreover, FBZ reduced the mitochondrial membrane potential and induced reactive oxygen species production in EL-4 cells, but not in spleen cells. FBZ induced G2/M phase arrest and increased the sub G0/G1 phase ratio, indicating apoptosis. Furthermore, compared to the control cells, the reactivity of spleen cells pretreated with FBZ to lipopolysaccharide was maintained. In summary, FBZ is cytotoxic to EL-4 cells, but not to spleen cells. This study provides experimental evidence that FBZ exerts an anticancer effect, and less cytotoxic effects and functional damage to normal spleen cells.

S1PR1/S1PR3-YAP signaling and S1P-ALOX15 signaling contribute to an aggressive behavior in obesity-lymphoma

BackgroundExcess body weight has been found to associate with an increased risk of lymphomas and some metabolic pathways are currently recognized in lymphomagenesis. Bioactive lipid metabolites such as sphingosine-1-phosphate (S1P) have been proposed to play an important role linking obesity and lymphomas. However, the underlying mechanism(s) of S1P signaling in obesity-lymphomagenesis have not been well addressed.MethodsThe gene expression of sphingosine kinase (SPHK), lymphoma prognosis, and S1P production were analyzed using Gene Expression Omnibus (GEO) and human lymphoma tissue array. Obesity-lymphoma mouse models and lymphoma cell lines were used to investigate the S1P/SPHK-YAP axis contributing to obesity-lymphomagenesis. By using the mouse models and a monocyte cell line, S1P-mediated polarization of macrophages in the tumor microenvironment were investigated.ResultsIn human study, up-regulated S1P/SPHK1 was found in human lymphomas, while obesity negatively impacted progression-free survival and overall survival in lymphoma patients. In animal study, obesity-lymphoma mice showed an aggressive tumor growth pattern. Both in vivo and in vitro data suggested the existence of S1P-YAP axis in lymphoma cells, while the S1P-ALOX15 signaling mediated macrophage polarization towards TAMs exacerbated the lymphomagenesis. In addition, treatment with resveratrol in obesity-lymphoma mice showed profound effects of anti-lymphomagenesis, via down-regulating S1P-YAP axis and modulating polarization of macrophages.ConclusionS1P/S1PR initiated the feedback loops, whereby S1P-S1PR1/S1PR3-YAP signaling mediated lymphomagenesis contributing to tumor aggressive growth, while S1P-ALOX15 signaling mediated TAMs contributing to immunosuppressive microenvironment in obesity-lymphoma. S1P-targeted therapy could be potentially effective and immune-enhancive against obesity-lymphomagenesis.Graphical

Ingol, ent-atisane, and stachane-type diterpenoids from Euphorbia deightonii with multidrug resistance reversing activity

Nine previously undescribed ingol-type diterpenoid polyesters with eighteen known ingol esters, two ent-atisane, and one stachane diterpenoid were isolated from the methanol extract of Euphorbia deightonii Croizat. The structures were established by extensive spectroscopic analysis involving 1D (1H, 13C J-modulation) and 2D NMR experiments, HRESIMS measurements, and the comparison of the spectroscopic data with reported literature values. The cytotoxic concentrations of 13 isolated compounds were determined, and the compounds were investigated for multidrug resistance modulating activity on an L5178 mouse lymphoma cell line using a rhodamin 123 accumulation assay. Six ingol esters demonstrated the significant inhibition of P-glycoprotein, while the two ent-atisane diterpenoids were found to be inactive. The measured activities allowed to establish some structure–activity relationships. Notably, lower and higher-type diterpenoids simultaneously occurred in E. deightonii.

In Vitro Phytobiological Investigation of Bioactive Secondary Metabolites from the Malus domestica-Derived Endophytic Fungus Aspergillus tubingensis Strain AN103.

Endophytic fungi including black aspergilli have the potential to synthesize multiple bioactive secondary metabolites. Therefore, the search for active metabolites from endophytic fungi against pathogenic microbes has become a necessity for alternative and promising strategies. In this study, 25 endophytic fungal isolates associated with Malus domestica were isolated, grown, and fermented on a solid rice medium. Subsequently, their ethyl acetate crude extracts were pretested for biological activity. One endophytic fungal isolate demonstrated the highest activity and was chosen for further investigation. Based on its phenotypic, ITS ribosomal gene sequences, and phylogenetic characterization, this isolate was identified as Aspergillus tubingensis strain AN103 with the accession number (KR184138). Chemical investigations of its fermented cultures yielded four compounds: Pyranonigrin A (1), Fonsecin (2), TMC 256 A1 (3), and Asperazine (4). Furthermore, 1H-NMR, HPLC, and LC-MS were performed for the identification and structure elucidation of these metabolites. The isolated pure compounds showed moderate-to-potent antibacterial activities against Pseudomonas aeruginosa and Escherichia coli (MIC value ranged from 31 and 121 to 14.5 and 58.3 μg/mL), respectively; in addition, the time–kill kinetics for the highly sensitive bacteria against isolated compounds was also investigated. The antifungal activity results show that (3) and (4) had the maximum effect against Fusarium solani and A. niger with inhibition zones of 16.40 ± 0.55 and 16.20 ± 0.20 mm, respectively, and (2) had the best effect against Candida albicans, with an inhibition zone of 17.8 ± 1.35 mm. Moreover, in a cytotoxicity assay against mouse lymphoma cell line L5178Y, (4) exhibited moderate cytotoxicity (49% inhibition), whereas (1–3) reported weak cytotoxicity (15, 26, and 19% inhibition), respectively. Our results reveal that these compounds might be useful to develop potential cytotoxic and antimicrobial drugs and an alternative source for various medical and pharmaceutical fields.

Azapodophyllotoxin Causes Lymphoma and Kidney Cancer Regression by Disrupting Tubulin and Monoglycerols.

A natural compound screen identified several anticancer compounds, among which azapodophyllotoxin (AZP) was found to be the most potent. AZP caused decreased viability of both mouse and human lymphoma and renal cell cancer (RCC) tumor-derived cell lines. Novel AZP derivatives were synthesized and screened identifying compound NSC750212 to inhibit the growth of both lymphoma and RCC both in vitro and in vivo. A nanoimmunoassay was used to assess the NSC750212 mode of action in vivo. On the basis of the structure of AZP and its mode of action, AZP disrupts tubulin polymerization. Through desorption electrospray ionization mass spectrometry imaging, NSC750212 was found to inhibit lipid metabolism. NSC750212 suppresses monoglycerol metabolism depleting lipids and thereby inhibits tumor growth. The dual mode of tubulin polymerization disruption and monoglycerol metabolism inhibition makes NSC750212 a potent small molecule against lymphoma and RCC.

Prenylated cyclohexene-type meroterpenoids and sulfur-containing xanthones produced by Pseudopestalotiopsis theae

Chemical investigation of the fungal endophyte Pseudopestalotiopsis theae isolated from leaves of Caloncoba welwitschii, collected in Cameroon, resulted in two previously undescribed sulfur-containing xanthone derivatives sydoxanthones D and E, in addition to three previously undescribed monomeric diisoprenyl-cyclohexene-type meroterpenoids biscognienynes D-F and five known natural products. The structures of the undescribed compounds were unambiguously identified by their mass spectra and by extensive 1D and 2D NMR spectroscopic analysis. Mosher's reaction was performed to determine the absolute configuration of sydoxanthones D and E while TDDFT-ECD calculations were used to assign the configuration of biscognienyne D. Biscognienynes B and D showed significant cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values of 7.7 and 6.7 μM and against the human leukemic cell lines HL60, and Hal-01 with IC50 values ranging from 4.3 to 12.1 μM.

Combining the IAP Antagonist Tolinapant with a DNA Hypomethylating Agent Enhances Immunogenic Cell Death in Preclinical Models of T-Cell Lymphoma

Introduction: Tolinapant is a potent, non-peptidomimetic antagonist of cIAP1, cIAP2 and XIAP. In ongoing Phase 2 trial (NCT02503423), tolinapant has shown activity against highly pre-treated peripheral and cutaneous T-cell lymphoma (Samaniego et al., Hematological Oncology, 2019). Hypomethylating agents (HMAs) have also shown clinical responses in some subsets of PTCL (Lemonnier et al., Blood, 2019). Both HMAs and IAP antagonists show immunomodulatory anti-cancer potential in pre-clinical studies. A Phase 1 clinical study investigating the combination of tolinapant and ASTX727 (oral decitabine) in AML is currently in progress (NCT04155580). Here we have undertaken a biomarker-driven approach to understand the potential for induction of immunogenic forms of cell death (ICD), such as necroptosis, by rational combination of our clinical compounds in pre-clinical models of T-cell lymphoma (TCL).Methods: On-target effects of decitabine and tolinapant were measured by analysing levels of DNMT1 and cIAP1, respectively, by Western blotting in mouse and human cell lines. Levels of key apoptosis, necroptosis or pyroptosis biomarkers were also monitored by Western blotting to provide evidence of lytic cell death contributing to a potential immune response. RIPK3- or MLKL-knockout cell lines were generated by CRISPR to demonstrate involvement of necroptosis in drug-induced cell death in a T-cell lymphoma cell line (BW5147.G.1.4) in vitro. Cell death was monitored by viability (CellTiterGlo) or real-time microscopy (IncuCyte) assays. Levels of key inflammatory mediators or DAMPS were measured in tissue culture supernatants and mouse plasma by Luminex assay (Ampersand).Results: Combined treatment of tolinapant and decitabine led to depletion of cIAP1 and DNMT1 in TCL cell lines, demonstrating on-target activity of tolinapant and decitabine, respectively. The combination of tolinapant and decitabine acted synergistically in mouse and human T-cell lymphoma cell lines to reduce viability in proliferation assays.Necroptosis was induced by decitabine or tolinapant alone in mouse TCL cell lines with robust activation of the RIPK1/RIPK3/MLKL necroptosis pathway when caspase activity was inhibited, and the combination of both agents enhanced loss of viability.Furthermore, we demonstrated decitabine treatment led to re-expression of both RIPK3 and MLKL in mouse cell lines, supporting published evidence that methylation can silence these key biomarkers (Koo et al., Cell Research, 2015; Koch et al., Neoplasia, 2021). Enhanced release of chemokine, cytokine and DAMPs was demonstrated with the combination of agents in vitro and in vivo.By removal of key necroptosis pathway components using CRISPR, we confirmed the importance of this lytic cell death pathway by demonstrating that RIPK3 -/- and MLKL -/- T-cell lymphoma (BW5147.G.1.4) cell lines had reduced necroptosis potential after treatment with tolinapant or decitabine alone or in combination; and demonstrate reduced release of inflammatory mediators in vitro.Finally, our in vivo evaluation of the combination of agents in mouse syngeneic models suggested that increased anti-tumour activity and immune-potentiating systemic biomarker modulation can be achieved with a tolerated dosing regimen of both compounds.Conclusion: These data demonstrate that decitabine enhances immunogenic cell death induced by tolinapant through the re-expression of genes in the necroptotic pathway. This finding provides strong rationale to explore this combination clinically. DisclosuresSims: Astex Pharmaceuticals: Current Employment. Davis: Astex Pharmacueticals: Current Employment. Smyth: Astex Pharmaceuticals: Current Employment.

Preclinical study of 212Pb alpha-radioimmunotherapy targeting CD20 in non-Hodgkin lymphoma.

Despite therapeutic advances, Non-Hodgkin lymphoma (NHL) relapses can occur. The development of radioimmunotherapy (RIT) with α-emitters is an attractive alternative. In this study, we investigated the potential of α-RIT in conjunction with 212Pb-rituximab for the treatment of NHL. EL4-hCD20-Luc cells (mouse lymphoma cell line) were used for in vitro and in vivo studies. Biodistribution and efficacy studies were performed on C57BL/6 mice injected intravenously with 25 × 103 cells. 212Pb-rituximab (0.925-7.4 kBq/mL) inhibit proliferation of EL4-hCD20-Luc cells in vitro. Biodistribution of 203/212Pb-rituximab in mice showed a significant tumour uptake and suggested that the liver, spleen, and kidneys were the organs at risk. For efficacy studies, mice were treated at either 11 days (early stage) or 20-30 days after injection of tumour cells (late stage). Treatment with 277.5 kBq 212Pb-rituximab significantly prolonged survival. Even at an advanced tumour stage, significant tumour regression occurred, with an increase in the median survival time to 28 days, compared with 9 days in the controls. These results show the efficacy of 212Pb-rituximab in a murine syngeneic lymphoma model, in terms of significant tumour regression and increased survival, thereby highlighting the potency of α-RIT for the treatment of NHL.

Antibacterial Activity and Reversal of Multidrug Resistance of Tumor Cells by Essential Oils from Fresh Leaves, Flowers, and Stems of Montanoa quadrangularis Schultz Bipontinus (Asteraceae) Collected in Mérida-Venezuela.

Essential oils obtained by hydrodistillation of Montanoa quadrangularis leaves, flowers, and stems were analyzed by GC and GC/MS techniques revealing myrcene, limonene, β-phellandrene, and sabinene among the main components. The aim of the present study was to evaluate the MDR modulator activity on human MDR1 gene transfected mouse lymphoma cell line and the antimicrobial activity on the essential oils obtained from different parts of the species under investigation. The results revealed that MQL caused a similar increase in the fluorescence activity of the cells at 0.02 μL/mL comparing to the Verapamil® value. The antimicrobial assay was carried out according to the disc diffusion method. Five different bacterial strains (Staphylococcus epidermidis, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli AG 100, and Escherichia coli AG100A) were treated with the essential oils and the zones of inhibition were determined on TSA plates and TSA agar plates supplemented with Tween 20. MQF and MQL showed activity against B. subtilis, S. epidermidis, and E. coli AG 100A while MQS was only active against E. coli AG 100A on TSA agar plates experiment. In case of TSA agar plates supplemented with 0.1 v/v% Tween 20 detergent, MQF showed inhibition on B. subtilis, S. epidermidis, and E. coli AG 100A; MQL was active against B. subtilis, E. coli AG 100, and E. coli AG 100A while MQS was only active against E. coli AG 100A.

Induction of ambuic acid derivatives by the endophytic fungus Pestalotiopsis lespedezae through an OSMAC approach

Ten new ambuic acid derivatives, pestallic acids H–Q including one new iodinated natural product along with two known compounds, ambuic acid and ambuic acid 18-acetate, were obtained through fermentation of the endophytic fungus Pestalotiopsis lespedezae on solid rice medium with 3.5% NaI. Pestallic acids H–Q were undetectable in cultures of the fungus grown on solid rice medium lacking NaI or in those where NaI had been replaced by NaCl or NaBr. The structures of the new metabolites were established on basis of 1D/2D NMR and HRESIMS data. Their absolute configurations were determined by Mosher’s method and TDDFT-ECD calculations. The compounds failed to show antibacterial activity against S. aureus (ATCC29213), drug-resistant Acinetobacter baumannii (BAA1605) or Mycobacterium tuberculosis , as well as cytotoxicity against the mouse lymphoma cell line L5178Y. • Fermentation of Pestalotiopsis lespedezae yielded ten new ambuic acid derivatives. • One new iodinated natural product was induced. • ECD calculations were performed to determine the absolute configuration.

In vitro adjuvant antitumor activity of various classes of semi-synthetic poststerone derivatives

Various classes of semi-synthetic analogs of poststerone, the product of oxidative cleavage of the C20-C22 bond in the side chain of the phytoecdysteroid 20-hydroxyecdysone, were synthesized. The analogs were obtained by reductive transformations using L-Selectride and H2-Pd/C, by molecular abeo-rearrangements using the DAST reagent or ultrasonic treatment in the NaI-Zn-DMF system, and by acid-catalyzed reactions of poststerone derivatives with various aldehydes (o-FC6H4CHO, m-CF3C6H4CHO, CO2Me(CH2)8CHO). The products were tested on a mouse lymphoma cell line pair, L5178 and its ABCB1-transfected multi-drug resistant counterpart, L5178MDR, for their in vitro activity alone and in combination with doxorubicin, and for the ability to inhibit the ABCB1 transporter. Among the tested compounds, new 2,3-dioxolane derivatives of the pregnane ecdysteroid were found to have a pronounced chemosensitizing activity towards doxorubicin and could be considered as promising candidates for further structure optimization for the development of effective chemosensitizing agents.

Azacoccones F-H, new flavipin-derived alkaloids from an endophytic fungus Epicoccum nigrum MK214079

Three new flavipin-derived alkaloids, azacoccones F-H (1–3), along with six known compounds (4–9) were isolated from the endophytic fungus Epicoccum nigrum MK214079 associated with leaves of Salix sp. The structures of the new compounds were established by analysis of their 1D/2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS) data. The absolute configuration of azacoccones F-H (1–3) was determined by comparison of experimental electronic circular dichroism (ECD) data with reported ones and biogenetic considerations. Epicocconigrone A (4), epipyrone A (5), and epicoccolide B (6) exhibited moderate antibacterial activity against Staphylococcus aureus ATCC 29213 with minimal inhibitory concentration (MIC) values ranging from 25 to 50 μM. Furthermore, epipyrone A (5) and epicoccamide A (7) displayed mild antifungal activity against Ustilago maydis AB33 with MIC values of 1.6 and 1.8 mM, respectively. Epicorazine A (8) showed pronounced cytotoxicity against the L5178Y mouse lymphoma cell line with an IC50 value of 1.3 μM.

Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii

Five sesterterpenes (1–5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 μM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong cytotoxicity against the L5178Y cell line, as well as against human Jurkat J16 and Ramos cells with IC50 values of 0.4, 5.8, and 4.4 μM, respectively. Mechanistic studies indicated that 7 induces apoptotic cell death. In addition, compounds 3, 4 and 7 showed low antibacterial activities against Mycobacterium tuberculosis H37Rv and compound 6 against Staphylococcus aureus, respectively, with MICs of 100 μM. Preliminary structure-activity relationships are discussed.

Polyketide Derivatives from Mangrove Derived Endophytic Fungus Pseudopestalotiopsis theae.

Chemical investigation of secondary metabolites from the endophytic fungus Pseudopestalotiopsis theae led to the isolation of eighteen new polyketide derivatives, pestalotheols I–Q (1–9) and cytosporins O–W (15–23), together with eight known analogs (10–14 and 24–26). The structures of the new compounds were elucidated by HRMS and 1D and 2D NMR data, as well as by comparison with literature data. Modified Mosher’s method was applied to determine the absolute configuration of some compounds. Compound 23 showed significant cytotoxicity against the mouse lymphoma cell line L5178Y with an IC50 value of 3.0 μM. Furthermore, compounds 22 and 23 showed moderate antibacterial activity against drug-resistant Acinetobacter baumannii (ATCC BAA-1605) in combination with sublethal colistin concentrations.