Antimetabolic Activity Research Articles

In vitro antibacterial activity of photoactivated flavonoid glycosides against Acinetobacter baumannii

Acinetobacter baumannii’s extensive antibiotic resistance makes its infections difficult to treat, so effective strategies to fight this bacterium are urgently needed. This study aims to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) mediated by Rutin-Gal(III) complex and Quercetin against A. baumannii. Absorbance spectra, fluorescence spectra, and minimum inhibitory concentration (MIC) of Rutin-Gal(III) complex and Quercetin were determined. The intracellular reactive oxygen species (ROS), extracellular polymeric substances (EPS), cell membrane permeability, expression of ompA and blaOXA−23, anti-biofilm activity, and anti-metabolic activity of Rutin-Gal(III) complex- and Quercetin-mediated aPDT were measured. Rutin-Gal(III) complex and Quercetin revealed absorption peaks in the visible spectra. Quercetin and Rutin-Gal(III) complex displayed fluorescence peaks at 524 nm and 540 nm, respectively. MIC values for the Rutin-Gal(III) complex and Quercetin were 64 µg/mL and 256 µg/mL, respectively. Quercetin- and Rutin-Gal(III) complex-mediated aPDT significantly reduced the colony forming units/mL (58.4% and 67.5%), EPS synthesis (47.4% and 56.5%), metabolic activity (30.5% and 36.3%), ompA (5.5- and 10.5-fold), and blaOXA−23 (4.1-fold and 7.8-fold) genes expression (respectively; all P < 0.05). Quercetin- and Rutin-Gal(III) complex-mediated aPDT enhanced notable biofilm degradation (36.2% and 40.6%), ROS production (2.55- and 2.90-folds), and membrane permeability (10.8– and 9.6-folds) (respectively; all P < 0.05). The findings indicate that Rutin-Gal(III) complex- and Quercetin-mediated aPDT exhibits antibacterial properties and could serve as a valuable adjunctive strategy to conventional antibiotic treatments for A. baumannii infections. One limitation of this study is that it was conducted solely on the standard strain; testing on clinical isolates would allow for more reliable interpretation of the results.

A Green Bioactive By-Product Almond Skin Functional Extract for Developing Nutraceutical Formulations with Potential Antimetabolic Activity

(1) Background: almond peels are rich in polyphenols such as catechin and epicatechin, which are important anti-free-radical agents, anti-inflammatory compounds, and capable of breaking down cholesterol plaques. This work aims to evaluate the biological and technological activity of a “green” dry aqueous extract from Sicilian almond peels, a waste product of the food industry, and to develop healthy nutraceuticals with natural ingredients. Eudraguard® Natural is a natural coating polymer chosen to develop atomized formulations that improve the technological properties of the extract. (2) Methods: the antioxidant and free radical scavenger activity of the extract was rated using different methods (DPPH assay, ABTS, ORAC, NO). The metalloproteinases of the extracts (MMP-2 and MMP-9), the enhanced inhibition of the final glycation products, and the effects of the compounds on cell viability were also tested. All pure materials and formulations were characterized using UV, HPLC, FTIR, DSC, and SEM methods. (3) Results: almond peel extract showed appreciable antioxidant and free radical activity with a stronger NO inhibition effect, strong activity on MMP-2, and good antiglycative effects. In light of this, a food supplement with added health value was formulated. Eudraguard® Natural acted as a swelling substrate by improving extract solubility and dissolution/release (4) Conclusions: almond peel extract has significant antioxidant activity and MMP/AGE inhibition effects, resulting in an optimal candidate to formulate safe microsystems with potential antimetabolic activity. Eudraguard® Natural is capable of obtaining spray-dried microsystems with an improvement in the extract‘s biological and technological characteristics. It also protects the dry extract from degradation and oxidation, prolonging the shelf life of the final product.

2-Aminothiazole-Flavonoid Hybrid Derivatives Binding to Tau Protein and Responsible for Antitumor Activity in Glioblastoma.

Tau protein has been described for several decades as a promoter of tubulin assembly into microtubules. Dysregulation or alterations in Tau expression have been related to various brain cancers, including the highly aggressive and lethal brain tumor glioblastoma multiform (GBM). In this respect, Tau holds significant promise as a target for the development of novel therapies. Here, we examined the structure-activity relationship of a new series of seventeen 2-aminothiazole-fused to flavonoid hybrid compounds (TZF) on Tau binding, Tau fibrillation, and cellular effects on Tau-expressing cancer cells. By spectrofluorometric approach, we found that two compounds, 2 and 9, demonstrated high affinity for Tau and exhibited a strong propensity to inhibit Tau fibrillation. Then, the biological activity of these compounds was evaluated on several Tau-expressing cells derived from glioblastoma. The two lead compounds displayed a high anti-metabolic activity on cells related to an increased fission of the mitochondria network. Moreover, we showed that both compounds induced microtubule bundling within newly formed neurite-like protrusions, as well as with defection of cell migration. Taken together, our results provide a strong experimental basis to develop new potent molecules targeting Tau-expressing cancer cells, such as GBM.

The water fraction of Cantigi (Vaccinium varingiaefolium Bl. Miq.) fruits demonstrate the highest antimetabolic syndrome properties on enzyme assay

Vaccinium varingiaefolium, Cantigi (local name), is a member of the berries family that has various benefits to human health. It contains numerous biological compounds, including polyphenols, flavonoids, and anthocyanin. Although many studies reported the pharmacological activity of berries families, the pharmacological Cantigi’s activity is still limited. The research aims to examine the antimetabolic, inhibition of lipase, alpha-glucosidase (αGIA), and angiotensin-converting enzyme (ACE) of Cantigi. The fractionation process originates from a 70% ethanol extract that underwent treatment with the addition of HCl until reaching a pH of 3. To comprehensively analyze the diverse array of compounds present in the Cantigi water fraction, we employ non-targeted screening through HPLC-Q-TOF-MS. Additionally, the brine shrimp lethality test (BSLT) was applied to check the acute toxicity. The results clearly indicate that the water fraction of Cantigi’s extract exhibits the highest activity against Lipase, ACE, and αGIA with values of 27.74±3.66 μg/mL, 19.33±2.86 μg/mL, and 15.90±1.82 μg/mL, respectively. Furthermore, we found delphinidin was the major anthocyanin of the water fraction. Finally, the toxicity assay showed 196.56±14.8 mg/ml. In conclusion, the water fraction of Cantigi extract demonstrated the highest antimetabolic activity, and we propose that delphinidin contributes significantly to this observed activity as it serves as a major component.

DHFR Inhibitors Display a Pleiotropic Anti-Viral Activity against SARS-CoV-2: Insights into the Mechanisms of Action.

During the COVID-19 pandemic, drug repurposing represented an effective strategy to obtain quick answers to medical emergencies. Based on previous data on methotrexate (MTX), we evaluated the anti-viral activity of several DHFR inhibitors in two cell lines. We observed that this class of compounds showed a significant influence on the virus-induced cytopathic effect (CPE) partly attributed to the intrinsic anti-metabolic activity of these drugs, but also to a specific anti-viral function. To elucidate the molecular mechanisms, we took advantage of our EXSCALATE platform for in-silico molecular modelling and further validated the influence of these inhibitors on nsp13 and viral entry. Interestingly, pralatrexate and trimetrexate showed superior effects in counteracting the viral infection compared to other DHFR inhibitors. Our results indicate that their higher activity is due to their polypharmacological and pleiotropic profile. These compounds can thus potentially give a clinical advantage in the management of SARS-CoV-2 infection in patients already treated with this class of drugs.

DNA-aptamer-nanographene oxide as a targeted bio-theragnostic system in antimicrobial photodynamic therapy against Porphyromonas gingivalis

The aim of this study was to design and evaluate the specificity of a targeted bio-theragnostic system based on DNA-aptamer-nanographene oxide (NGO) against Porphyromonas gingivalis during antimicrobial photodynamic therapy (aPDT). Following synthesis and confirmation of NGO, the binding of selected labeled DNA-aptamer to NGO was performed and its hemolytic activity, cytotoxic effect, and release times were evaluated. The specificity of DNA-aptamer-NGO to P. gingivalis was determined. The antimicrobial effect, anti-biofilm potency, and anti-metabolic activity of aPDT were then assessed after the determination of the bacteriostatic and bactericidal concentrations of DNA-aptamer-NGO against P. gingivalis. Eventually, the apoptotic effect and anti-virulence capacity of aPDT based on DNA-aptamer-NGO were investigated. The results showed that NGO with a flaky, scale-like, and layered structure in non-cytotoxic DNA-aptamer-NGO has a continuous release in the weak-acid environment within a period of 240 h. The binding specificity of DNA-aptamer-NGO to P. gingivalis was confirmed by flow cytometry. When irradiated, non-hemolytic DNA-aptamer-NGO were photoactivated, generated ROS, and led to a significant decrease in the cell viability of P. gingivalis (P < 0.05). Also, the data indicated that DNA-aptamer-NGO-mediated aPDT led to a remarkable reduction of biofilms and metabolic activity of P. gingivalis compared to the control group (P < 0.05). In addition, the number of apoptotic cells increased slightly (P > 0.05) and the expression level of genes involved in bacterial biofilm formation and response to oxidative stress changed significantly after exposure to aPDT. It is concluded that aPDT using DNA-aptamer-NGO as a targeted bio-theragnostic system is a promising approach to detect and eliminate P. gingivalis as one of the main bacteria involved in periodontitis in periopathogenic complex in real-time and in situ.

Quorum quenching of Streptococcus mutans via the nano-quercetin-based antimicrobial photodynamic therapy as a potential target for cariogenic biofilm

BackgroundQuorum sensing (QS) system can regulate the expression of virulence factors and biofilm formation in Streptococcus mutans. Antimicrobial photodynamic therapy (aPDT) inhibits quorum quenching (QQ), and can be used to prevent microbial biofilm. We thereby aimed to evaluate the anti-biofilm potency and anti-metabolic activity of nano-quercetin (N-QCT)-mediated aPDT against S. mutans. Also, in silico evaluation of the inhibitory effect of N-QCT on the competence-stimulating peptide (CSP) of S. mutans was performed to elucidate the impact of aPDT on various QS-regulated genes.MethodsCytotoxicity and intracellular reactive oxygen species (ROS) generation were assessed following synthesis and confirmation of N-QCT. Subsequently, the minimum biofilm inhibitory concentration (MBIC) of N-QCT against S. mutans and anti-biofilm effects of aPDT were assessed using colorimetric assay and plate counting. Molecular modeling and docking analysis were performed to confirm the connection of QCT to CSP. The metabolic activity of S. mutans and the expression level of various genes involved in QS were evaluated by flow cytometry and reverse transcription quantitative real-time PCR, respectively.ResultsSuccessful synthesis of non-toxic N-QCT was confirmed through several characterization tests. The MBIC value of N-QCT against S. mutans was 128 μg/mL. Similar to the crystal violet staining, the results log10 CFU/mL showed a significant degradation of preformed biofilms in the group treated with aPDT compared to the control group (P < 0.05). Following aPDT, metabolic activity of S. mutans also decreased by 85.7% (1/2 × MBIC of N-QCT) and 77.3% (1/4 × MBIC of N-QCT), as compared to the control values (P < 0.05). In silico analysis showed that the QCT molecule was located in the site formed by polypeptide helices of CSP. The relative expression levels of the virulence genes were significantly decreased in the presence of N-QCT-mediated aPDT (P < 0.05).ConclusionsThe combination of N-QCT with blue laser as a QQ-strategy leads to maximum ROS generation, disrupts the microbial biofilm of S. mutans, reduces metabolic activity, and downregulates the expression of genes involved in the QS pathway by targeting genes of the QS signaling system of S. mutans.

Antimicrobial effects and mechanical properties of poly(methyl methacrylate) as an orthodontic acrylic resin containing Curcumin-Nisin-poly(L-lactic acid) nanoparticle: an in vitro study.

BackgroundThe porous surface of acrylic orthodontic removable appliances creates a niche for microbial plaque accumulation, and changes the oral flora by raising cariogenic bacteria including Streptococcus mutans. In this study, we evaluated the mechanical properties and antimicrobial activities of incorporating different concentrations of Curcumin-Nisin-poly(l-lactic acid) nanoparticle (CurNisNps) into orthodontic acrylic resin against Streptococcus mutans and Candida albicans.MethodsFollowing synthesis and characterization of CurNisNps, acrylic resin specimens with different concentrations of CurNisNps (0, 1, 2, 5, and 10% w/w) were fabricated. Flexural strength values, antimicrobial effects, anti-biofilm potential, and anti-metabolic activity against S. mutans and C. albicans were assessed at different time intervals. Also, the expression of the virulence-factor-related genes of S. mutans and C. albicans was assessed by quantitative real-time polymerase chain reaction following treatment with CurNisNps.ResultsAcrylic resin containing 10% CurNisNps (30.76 ± 3.91 MPa) showed flexural failure in comparison with acrylic resin specimens without CurNisNps (50.67 ± 1.82 MPa) as the control group (P < 0.05). There was no significant decrease in the flexural strength values in samples containing 1, 2, and 5% of CurNisNps in comparison to the control group (P > 0.05). Acrylic resin with 5% CurNisNps showed the highest concentration of CurNisNps and clinically accepted flexural strength value (14.89 ± 3.26 MPa, P < 0.05) simultaneously. In the disc agar diffusion assay, 5% CurNisNps showed a high level of inhibitory activity for the test microorganisms. The reduction of growth inhibition zones of the different concentrations of CurNisNps against test microorganisms was positively associated with the time, in such a way that it was reduced significantly after 60 days. The anti-biofilm and anti-metabolic activities of acrylic resin specimens containing a 5% concentration of CurNisNps against S. mutans and C. albicans could significantly decrease the expression levels of gtfB (6.8-fold) and HWP (3.4-fold) in S. mutans and C. albicans, respectively.ConclusionsOur data support that 5% (w/w) of CurNisNps can serve as an excellent orthodontic acrylic resin additive against S. mutans and C. albicans biofilm without adverse effects on its mechanical property.

High-Dose Bendamustine, Etoposide, Cytarabine and Melphalan (BeEAM) Conditioning Prior to Autologous Transplantation for Patients with Multiple Myeloma: Results of a Prospective Phase II Trial

Single-agent high-dose melphalan followed by autologous stem cell transplantation (ASCT) remains a standard of care in eligible patients with multiple myeloma (MM). Efforts to improve transplant outcomes by intensifying transplant conditioning have mostly failed, with the exception of a sole phase III study showing improved progression-free survival (PFS) with the addition of busulfan to melphalan (Lancet Haematology 2019, 6:266-75). Bendamustine is a synthetic agent that combines the alkylating properties of a mustard-group with the antimetabolic activity of a purine analog. It can induce responses in MM resistant to other alkylators and is therefore a promising agent to test synergy in conditioning regimens. The high-dose chemotherapy combination of bendamustine, etoposide, cytarabine and melphalan (BeEAM) has been shown to be a safe and effective transplant regimen for lymphoma patients (Blood 2011, 118:3419-25). We performed a phase II study to test the safety and efficacy of BeEAM in MM patients, 18-70 years of age, with adequate organ function (EF≥40% predicted, CrCl ≥40ml/min) and within 9 months of starting induction therapy. Results were compared to a contemporaneously treated control group receiving a single high-dose melphalan 200mg/m2 transplant (Mel200) but otherwise meeting study eligibility criteria. Study patients (n=65) had a median (range) age of 59 (40, 69) years and were transplanted from 2015-2020. Other characteristics included KPS<80%, HCT-CI≥3, ISS III, and high-risk FISH in 35%, 46%, 26% and 44% respectively. Pre-BMT status was (s)CR1, VGPR1, PR1 and <PR1 in 26%, 43%, 26% and 5% respectively. ASCT following BeEAM was well tolerated with no non-relapse deaths through one-year post-transplant. Although at least one non-hematologic grade 3 toxicity was reported in 32 (49%) patients, there were no grade ≥3 renal or hepatic toxicity and no grade ≥4 non-hematologic toxicity. With a median f/u of 44 (13, 70) months, three-year OS and PFS was 92% and 57% respectively. When BeEAM patients were compared to contemporaneously treated Mel200 patients, there were no significant differences in baseline characteristics, induction regimen or use of post-transplant maintenance therapy. Neutrophil and platelet engraftment was faster following BeEAM (11 vs. 12 days, 17 vs 18 days, p<0.001 and p=0.007 respectively), when compared to Mel200 patients. One-year non-relapse mortality was 0% with both BeEAM and Mel200. No significant differences were seen in quality of response, PFS or OS between BeEAM and Mel200, when analyzing either the whole cohort (see figure) or by genetic risk stratification. In multivariate analysis, controlled for genetic risk and year of transplantation, the use of BeEAM conditioning offered no benefit to Mel200 in terms of OS, PFS or risk of relapse/progression. In summary, BeEAM was shown to be a safe and effective conditioning regimen prior to up-front autologous transplant for MM. However, BeEAM conditioning appears to offer no significant advantage when compared to conventional Mel200 conditioning. [Display omitted] DisclosuresSolh: Jazz Pharmaceuticals: Consultancy; BMS: Consultancy; Partner Therapeutics: Research Funding; ADCT Therapeutics: Consultancy, Research Funding. OffLabel Disclosure:Bendamustine for Multiple Myeloma

Abstract IA23: PI3K inhibitors as a backbone for combination treatments for breast and ovarian cancer

Abstract PI3K inhibitors reduce glucose uptake and utilization by tumors. Yet in solid tumor clinical trials the efficacy of PI3K -inhibitors as single agents has been limited. Therefore, we have focused on harnessing the antimetabolic efficacy of PI3K inhibitors to augment the efficacy of antineoplastic treatments. A recently completed clinical trial (NCT01623349) examined the combination of PI3Ki BYL719 and the PARPi olaparib in ovarian cancer (EOC). Of the 28 EOC patients, 10 (35.7%) had partial response (PR), 14 (50%) had stable disease (SD), 3 (10.7%) had progressive disease (PD), and 1 (3.6%) patient was unevaluable. ORR was 33.3% and 31.3% in platinum resistant/refractory gBRCAmut and gBRCAwt patients, respectively. These data show that combining BYL719 and olaparib is feasible with no unexpected toxicities and that the activity of olaparib/BYL719 in gBRCAwt platinum-resistant EOC appears significantly higher than expected compared to either olaparib or BYL719 monotherapies. Next-generation sequencing did not identify markers of responsiveness to this combination. To assess responsiveness to this combination functionally, we have developed novel methods to monitor the antimetabolic activity of PI3K inhibitors in vivo using functional MRI of tumors based on the interconversion of 13C-pyruvate to 13C-lactate as well as NMR spectroscopy of tumoral ATP stores. Citation Format: Gerburg Wulf, Panos Konstantinopoulos, William Barry, Olmo Sonzongi, Julia Eismann, Bose Kucherlapati, Ursula Matulonis. PI3K inhibitors as a backbone for combination treatments for breast and ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr IA23.

High synergistic antibacterial, antibiofilm, antidiabetic and antimetabolic activity of Withania somnifera leaf extract-assisted zinc oxide nanoparticle.

Nanotechnology is currently gaining immense attention to combat food borne bacteria, and biofilm. Diabetes is a common metabolic disease affecting majority of people. A better therapy relies on phytomediated nanoparticle synthesis. In this study, W. somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) was synthesized and characterized. From HR-TEM analysis, it has been found that the hexagonal wurtzite particle is 15.6 nm in size and - 12.14 mV of zeta potential. A greater antibacterial effect of Ws-ZnO NPs was noticed against E. faecalis and S. aureus at 100 µg mL-1. Also, the biofilm of E. faecalis and S. aureus was greatly inhibited at 100 µg mL-1 compared to E. coli and P. aeruginosa. The activity of α-amylase and α-glucosidase enzyme was inhibited at 100 µg mL-1 demonstrating its antidiabetic potential. The larval and pupal development was delayed at 25 µg mL-1 of Ws-ZnO NPs. A complete mortality (100%) was recorded at 25 µg mL-1. Ws-ZnO NPs showed least LC50 value (9.65 µg mL-1) compared to the uncoated ZnO NPs (38.8 µg mL-1) and leaf extract (13.06 µg mL-1). Therefore, it is concluded that Ws-ZnO NPs are promising to be used as effective antimicrobials, antidiabetic and insecticides to combat storage pests.

NMR structure and dynamics of inhibitory repeat domain variant 12, a plant protease inhibitor from Capsicum annuum, and its structural relationship to other plant protease inhibitors

Although several plant protease inhibitors have been structurally characterized using X-ray crystallography, very few have been studied using NMR techniques. Here, we report an NMR study of the solution structure and dynamics of an inhibitory repeat domain (IRD) variant 12 from the wound-inducible Pin-II type proteinase inhibitor from Capsicum annuum. IRD variant 12 (IRD12) showed strong anti-metabolic activity against the Lepidopteran insect pest, Helicoverpa armigera. The NMR-derived three-dimensional structure of IRD12 reveals a three-stranded anti-parallel β-sheet rigidly held together by four disulfide bridges and shows structural homology with known IRDs. It is interesting to note that the IRD12 structure containing ∼75% unstructured part still shows substantial amount of rigidity of N–H bond vectors with respect to its molecular motion.Communicated by Ramaswamy H. Sarma

Pyrazinib (P3), [(E)-2-(2-Pyrazin-2-yl-vinyl)-phenol], a small molecule pyrazine compound enhances radiosensitivity in oesophageal adenocarcinoma

Oesophageal adenocarcinoma (OAC) is an aggressive disease with 5-year survival rates of <20%. Only 20–30% OAC patients show a beneficial response to neoadjuvant therapy. Altered mitochondrial function is linked with radioresistance in OAC. We identified pyrazinib (P3), a pyrazine phenol small molecule drug with anti-angiogenic and anti-metabolic activity in-vivo in zebrafish and in-vitro isogenic models of OAC radioresistance. Pyrazinib (P3) significantly inhibited blood vessel development in zebrafish (p < 0.001). In-vivo in zebrafish and in-vitro in an isogenic model of OAC radioresistance, pyrazinib (P3) significantly reduced measures of oxidative phosphorylation and glycolysis. Pyrazinib (P3) significantly reduced the surviving fraction in OE33P; radiation-sensitive and OE33R; radiation-resistant cells following irradiation. Under hypoxic conditions pyrazinib (P3) significantly reduced OE33R cell survival following 4 Gy irradiation (p = 0.0216). Multiplex ELISA showed significantly higher secreted levels of 9 of 30 detected inflammatory and angiogenic factors in OE33R radioresistant cells compared to OE33P cells; IL-8, IL-4, IL-6, IL-2, IL-12p70, IL-10, MCP-1, IP-10, ICAM (p < 0.05). Pyrazinib (P3) significantly reduced the secretions of IL-6 (p = 0.0006), IL-8 (p = 0.0488), and IL-4 (p = 0.0111) in OE33R cells. Collectively, these findings support further development of pyrazinib (P3) as a novel therapeutic radiosensitiser in OAC.

Molecular Networking Reveals Two Distinct Chemotypes in Pyrroloiminoquinone-Producing Tsitsikamma favus Sponges.

The temperate marine sponge, Tsitsikamma favus, produces pyrroloiminoquinone alkaloids with potential as anticancer drug leads. We profiled the secondary metabolite reservoir of T. favus sponges using HR-ESI-LC-MS/MS-based molecular networking analysis followed by preparative purification efforts to map the diversity of new and known pyrroloiminoquinones and related compounds in extracts of seven specimens. Molecular taxonomic identification confirmed all sponges as T. favus and five specimens (chemotype I) were found to produce mainly discorhabdins and tsitsikammamines. Remarkably, however, two specimens (chemotype II) exhibited distinct morphological and chemical characteristics: the absence of discorhabdins, only trace levels of tsitsikammamines and, instead, an abundance of unbranched and halogenated makaluvamines. Targeted chromatographic isolation provided the new makaluvamine Q, the known makaluvamines A and I, tsitsikammamine B, 14-bromo-7,8-dehydro-3-dihydro-discorhabdin C, and the related pyrrolo-ortho-quinones makaluvamine O and makaluvone. Purified compounds displayed different activity profiles in assays for topoisomerase I inhibition, DNA intercalation and antimetabolic activity against human cell lines. This is the first report of makaluvamines from a Tsitsikamma sponge species, and the first description of distinct chemotypes within a species of the Latrunculiidae family. This study sheds new light on the putative pyrroloiminoquinone biosynthetic pathway of latrunculid sponges.

Deterrence in metabolic and biofilms forming activity of Candida species by mycogenic silver nanoparticles

Candida, a commensal and opportunistic fungal pathogen has been typically known for its biofilm forming ability and device-associated hospital acquired infections in human. The study aimed at exploring the in vitro anti-biofilm and anti-metabolic activity of AgNPs against C. albicans (n=2), C. tropicalis (n=2) and C. parapsilosis (n=2) isolated from urine samples. Broth dilution method revealed greater than 50% inhibition at 100ppm against Ag NPs in 24h. An overall reduction of 55–86% in biomass (crystal violet staining assay) and 20–73% in metabolic activity (XTT assay) was observed in 24h old biofilms. However, C. albicans proved to be more susceptible to AgNPs compared to C. tropicalis and C. parapsilosis. Scanning Electron Microscopy revealed patchy growth and deterrence in biofilm biomass when Ag NPs were coated on urinary catheter. Furthermore, viable cell counts of Candida were significantly reduced on AgNPs coated catheter compared to control.

A case of Pneumocystis jiroveci pneumonia after bendamustine-based chemotherapy for refractory diffuse large B-cell lymphoma.

A case of Pneumocystis jiroveci pneumonia after bendamustine-based chemotherapy for refractory diffuse large B-cell lymphoma.

A method to investigate the anti-metabolic activity of anti-cancer agents on ovarian cancer cells cultured in a 96-well high throughput format.

BackgroundAn early step of advanced ovarian cancer begins when floating cancerous cells as single cells or small clusters grow on the peritoneal surface. This surface is rich in extracellular matrix (ECM) proteins, which have profound effects on cellular behaviour and can facilitate cancer progression. Subsequently, this ECM may alter cellular metabolism making cancer cells susceptible to chemotherapeutic agents differently. Therefore, generating a cell culture tool in vitro that includes the interaction between ECM and cancer cells will facilitate our understanding of how cancer cells behave during cancer treatment. There is some evidence to suggest that in an in vitro model that includes ECM components such as collagens will provide a better predictive tool for drug evaluation than a traditional cell monolayer (2D) culture model.FindingsAs a proof -of- concept, we made a collagen gel in a 96-well plate format and utilised this to evaluate the efficacy of clinical cytotoxic drugs, a targeted drug, and food compounds in single and combination treatments. The primary endpoints were to measure the reduction of cellular metabolism and secretion of vascular endothelial growth factor (VEGF). The invasive capacity of cancer cells was observed in collagen gels and it was cell line-dependent. The responses to drugs were prominently observed in collagen gels, but they had little effect on 2D cell monolayers. These responses were cell line- and type of drug-dependent.ConclusionsThe collagen gel in a 96 well plate format was easy to set up and could have potential to identify drug sensitivity in the clinical management of women with platinum resistant ovarian cancer.

Introduction of a Fluorine Atom at C3 of 3-Deazauridine Shifts Its Antimetabolic Activity from Inhibition of CTP Synthetase to Inhibition of Orotidylate Decarboxylase, an Early Event in the de Novo Pyrimidine Nucleotide Biosynthesis Pathway

The antimetabolite prodrug 3-deazauridine (3DUrd) inhibits CTP synthetase upon intracellular conversion to its triphosphate, which selectively depletes the intracellular CTP pools. Introduction of a fluorine atom at C3 of 3DUrd shifts its antimetabolic action to inhibition of the orotidylate decarboxylase (ODC) activity of the UMP synthase enzyme complex that catalyzes an early event in pyrimidine nucleotide biosynthesis. This results in concomitant depletion of the intracellular UTP and CTP pools. The new prodrug (designated 3F-3DUrd) exerts its inhibitory activity because its monophosphate is not further converted intracellularly to its triphosphate derivative to a detectable extent. Combinations with hypoxanthine and adenine markedly potentiate the cytostatic activity of 3F-3DUrd. This is likely because of depletion of 5-phosphoribosyl-1-pyrophosphate (consumed in the hypoxanthine phosphoribosyl transferase/adenine phosphoribosyl transferase reaction) and subsequent slowing of the 5-phosphoribosyl-1-pyrophosphate-dependent orotate phosphoribosyl transferase reaction, which depletes orotidylate, the substrate for ODC. Further efficient anabolism by nucleotide kinases is compromised apparently because of the decrease in pK(a) brought about by the fluorine atom, which affects the ionization state of the new prodrug. The 3F-3DUrd monophosphate exhibits new inhibitory properties against a different enzyme of the pyrimidine nucleotide metabolism, namely the ODC activity of UMP synthase.

Interaction of an amphiphilic squalenoyl prodrug of gemcitabine with cellular membranes

We have designed an amphiphilic prodrug of the anticancer agent gemcitabine (dFdC), by covalent coupling to squalene. This bioconjugate, which self-assembled into nanoparticles (NPs) in water, was previously found to display an impressive anticancer activity both in vitro and in vivo. The present study aims to investigate the impact of SQdFdC nanoparticles on cellular membranes. MTT assays showed that, in the nanomolar range, squalenoyl gemcitabine (SQdFdC) was slightly less active than dFdC on a panel of human cancer cell lines, in vitro. However, above 10 μmol L −1 SQdFdC was considerably more cytotoxic than dFdC. Contrarily to its parent drug, SQdFdC also induced cell lysis in a few hours, as evidenced by LDH release assays. Erythrocytes were used as an experimental model insensitive to the antimetabolic activity of dFdC to further investigate the putative membrane-related cytotoxic activity of SQdFdC. The bioconjugate also induced hemolysis in a time- and dose-dependent fashion, unlike squalene or dFdC, which clearly proved that SQdFdC could permeabilize cellular membranes. Structural X-ray diffraction and calorimetry studies were conducted in order to elucidate the mechanism accounting for these observations. They confirmed that SQdFdC could be transferred from NPs to phospholipid bilayers and that the insertion of the prodrug within model membranes resulted in the formation of nonlamellar structures, which are known to promote membrane leakage. As a whole, our results suggested that due to its amphiphilic nature, the cell uptake of SQdFdC resulted in its insertion into cellular membranes, which could lead to the formation of nonlamellar structures and to membrane permeation. Whether this mechanism could be the source of toxicity in vivo, however, remains to be established, since preclinical studies have clearly proven that squalenoyl gemcitabine displayed a good toxicity profile.

Protein digestion in cereal aphids (Sitobion avenae) as a target for plant defence by endogenous proteinase inhibitors

Gut extracts from cereal aphids (Sitobion avenae) showed significant levels of proteolytic activity, which was inhibited by reagents specific for cysteine proteases and chymotrypsin-like proteases. Gut tissue contained cDNAs encoding cathepsin B-like cysteine proteinases, similar to those identified in the closely related pea aphid (Acyrthosiphon pisum). Analysis of honeydew (liquid excreta) from cereal aphids fed on diet containing ovalbumin showed that digestion of ingested proteins occurred in vivo. Protein could partially substitute for free amino acids in diet, although it could not support complete development. Recombinant wheat proteinase inhibitors (PIs) fed in diet were antimetabolic to cereal aphids, even when normal levels of free amino acids were present. PIs inhibited proteolysis by aphid gut extracts in vitro, and digestion of protein fed to aphids in vivo. Wheat subtilisin/chymotrypsin inhibitor, which was found to inhibit serine and cysteine proteinases, was more effective in both inhibitory and antimetabolic activity than wheat cystatin, which inhibited cysteine proteases only. Digestion of ingested protein is unlikely to contribute significantly to nutritional requirements when aphids are feeding on phloem, and the antimetabolic activity of dietary proteinase inhibitors is suggested to result from effects on proteinases involved in degradation of endogenous proteins.