Purification, crystallization and anticancer activity evaluation of the compound alternariol methyl ether from endophytic fungi Alternaria alternata

AIMS

Medicinal plant-associated endophytic fungi are important sources of precious bioactive compounds, contributing more than 80% of the natural drugs for various ailments. The present study was aimed at evaluating the anticancer activity of the crystallized compound alternariol methyl ether (AME) against hepatocellular carcinoma (HCC) both in vitro and in vivo from an endophytic fungus residing in the medicinal plant Vitex negundo.

METHODS AND RESULTS

The secondary metabolites from the endophytic fungus Alternaria alternata MGTMMP031 were isolated. Purification and characterization of the compound was performed and the potential compound was identified as AME. The crystal structure of AME was unambiguously confirmed by X-ray analysis. AME has been checked for its antibacterial and anticancer properties which showed its effectiveness against various bacteria and demonstrated marked anti-proliferative activity against the human HCC cells (HUH-7) both in vitro and in vivo. Mode of actions included cell cycle arrest, reducing the level of markers enzymes of liver cancer and preventing tumour growth.

CONCLUSIONS

Alternariol methyl ether acts as a potential therapeutic target against HCC. The compound was isolated and the crystal structure was obtained for the first time from the endophytic fungus A. alternata MGTMMP031. In the present study, the crystallized structure of AME was obtained by slow evaporation technique. It can be concluded that AME acts as a potential therapeutic target against HCC.

SIGNIFICANCE AND IMPACT OF THE STUDY

Endophytic fungi residing in the medicinal plants have strong biological significance and bioactive compounds from these fungi provide better therapeutic targets against diseases.

Collective substitutions of selective rare earths (Yb3+, Dy3+, Tb3+, Gd3+, Eu3+, Nd3+) in ZrO2: an exciting prospect for biomedical applications

The study aims to understand the significance of collective rare earth (RE3+) substitutions in ZrO2 structures for biomedical applications. The RE3+ ions namely Yb3+, Dy3+, Tb3+, Gd3+, Eu3+, and Nd3+ were selected and their concentrations were adjusted to obtain three different combinations. The influence of RE3+ on the crystal structure of ZrO2 alongside the absorption, luminescence, mechanical, magnetic, computed tomography (CT), magnetic resonance imaging (MRI) properties was explored. The concomitant effect of the average ionic size and RE3+ concentration determines the crystallization behavior of ZrO2 at elevated temperatures. The collective RE3+ substitutions exhibit both up-conversion and down-conversion emissions with their respective excitation at 793 and 350 nm. Nevertheless, increment in the concentration of RE3+ is found to be detrimental to the mechanical stability of ZrO2. The collective characteristics of multiple RE3+ demonstrate the potential of the investigated system in multimodal imaging applications. The unique luminescence characteristics of Eu3+ and Tb3+ are promising for fluorescence imaging while the presence of Dy3+, Tb3+, Gd3+ and Nd3+ unveils a paramagnetic response required for MRI. In addition, Dy3+ and Yb3+ contribute to the high X-ray absorption coefficient values suitable for X-ray CT imaging.

Structure, luminescence, mechanical and in vitro behavior of zirconia toughened alumina due to terbium substitutions

The significance of Tb³⁺ inclusions at the zirconia toughened alumina (ZTA) structure was explored. The influence of Tb³⁺ content at the crystal structures of ZrO₂ and Al₂O₃ and the resultant optical, mechanical, magnetic and cytotoxicity properties were deliberated. The critical role of Tb³⁺ to attain a structurally stable ZTA until 1500 °C is ensured. Depending on the Tb³⁺ content, either tetragonal zirconia (t-ZrO₂) or cubic zirconia (c-ZrO₂) structures were stabilized while the propensity of Tb³⁺ reaction with Al₂O₃ to yield TbAlO₃ is transpired only after exceeding the occupancy limit in ZrO₂. The green emission and paramagnetic features are imparted by the Tb³⁺ inclusions at the ZTA structure. Dense and pore free microstructures with a direct impact on the improved mechanical features of ZTA is empowered by the presence of Tb³⁺. Further, the results from MTT assay and live/dead cell staining ensured the negligence of Tb³⁺ contained ZTA systems to induce toxicity.

Insights into structural and inhibitory mechanisms of low pH-induced conformational change of influenza HA2 protein: a computational approach

Though oseltamivir and zanamivir are the active anti-influenza drugs, the emergence of different strains of influenza A virus with mutations creates drug-resistance to these drugs. Therefore, it is essential to find a suitable approach to stop the viral infection. The present study focuses on understanding the conformational changes of the HA2 protein at different pH levels (pH 7, pH 6, pH 5) and on blocking the low pH-induced conformational changes of the HA2 protein with a suitable ligand using molecular docking and molecular dynamics (MD) simulation methods. As the pH value decreases to pH 5, the protein undergoes large conformational changes with less stability in the order of pH 7 > pH 6 > pH 5. The fusion peptide (residues 1-20) and the extended loop (residues 58-75) deviate more at pH 5. The ligand stachyflin bound between the N- and C-terminal helix regions retains the stability of the HA2 protein at pH 5 and blocks the low pH-induced conformational transition. The performance of stachyflin is increased when it directly interacts with residues at the intramonomer binding site rather than the intermonomer binding site. The susceptibility of the HA2 protein of different subtypes to stachyflin is in the order of H1 > H7 > H5 > H2 > H3. Stachflin has a higher binding affinity for H1 (at pH 7, pH 6, pH 5) and H7 subtypes than others. Lys47, Lys58, and Glu103 are the key residues that favor the binding and highly stabilize the HA2 protein at low pH. Graphical abstract Low pH-induced conformational change of influenza HA2 protein.

Structural and bio-mineralization features of alumina zirconia composite influenced by the combined Ca2+ and PO43- additions

The structural and bioactivity features of alumina zirconia composite (AZC) due to Ca²⁺ and PO₄^3- additions are demonstrated. An in situ synthetic approach, starting from the solution precursors is devised for the powder synthesis in which the assorted range of Ca²⁺ and PO₄^3- additions were done to the equimolar concentrations of Al³⁺ and Zr⁴⁺ precursors. The results witnessed the unique crystallization of tetragonal zirconia (t-ZrO₂) at 1100 °C while Ca²⁺, PO₄^3- and Al₂O₃ remained in their amorphous state in the system. On further heat treatment, α-Al₂O₃ crystallized at 1200 °C, which enforced t- → m-ZrO₂ transformation while Ca²⁺ and PO₄^3- still retained their amorphous state. The immersion tests in simulated body fluid (SBF) solution validated the enhanced bio-mineralization activity of AZC due to Ca²⁺ and PO₄^3- additions. The results from the indentation tests demonstrated good uniformity in the elastic modulus and hardness data of the investigated specimens. Further, in vitro cell culture tests ascertained the bioactivity of all the AZC compositions.

Synergistic Complexes of Tributyl Phosphate and Dibutyl (Butyl) Phosphonate with Uranyl bis(β-diketonates). Synthesis, Characterisation and Molecular Structure of [UO2(TTA)2.TIBP]

Tributyl phosphate or dibutyl (butyl) phosphonate complexes of the type [UO2 (OO)2.X] (OO = TTA or DBM; X = TBP, TIBP or DBBP) have been prepared and characterised by 1H and 31P{1H} NMR, IR and elemental analyses. The structure of complex [UO2(TTA)2.TIBP] shows that the TIBP ligand coordinates through its phosphoryl oxygen atom to the uranyl ion.

Carbamoyl Methyl Sulfoxide Compounds of Lanthanum (III) Nitrate. Crystal and Molecular Structure of [La(NO3)3 {C6H5SOCH2CON(C4H9)2}2]

Carbamoyl methyl sulfoxide compounds of lanthanum (III) nitrate of the type [La(NO3)3L2] (where L = C6H5SOCH2CON(iC3H7)2, C6H5SOCH2CON(C4H9)2 C6H5SOCH2CON(iC4H9)2) have been synthesised and characterised. The structure of the compound [La(NO3)3(C6H5SOCH2CON(C4H9)2)2] shows that the C6H5SOCH2CON(C4H9)2 bonds through both the sulfoxo and carbamoyl oxygen atoms to the lanthanum(III) nitrate and acts as a bidentate chelating ligand.

Synthesis and characterization of [Bis (β-Diketonato) Uranium (Vi)] Malonamide Adducts

Malonamide (L) acts as monodentate ligand in [UO2(OO)2. L] complexes (where OO = a diketonate, HTTA = thenoyltrifluoroacetone [C4H3S.CO.CH2.COCF3]; HDBM = dibenzoylmethane [C6H5CO.CH2.COC6H5]; HBTA = benzoyltrifluoroacetone [C6H5CO.CH2.CO.CF3]) and coordinating through one of its amido oxygen atoms to the uranyl ion.

Syntheses and Characterisation of Amide Adducts of Uranyl Bis (β-Diketonates) the Molecular Structure of [UO2(DBM)2.C4H9CON(3-C5H11) (sec-C4H9)]

The first structurally characterised uranyl bis (β-diketonate)-amide adduct compound [UO2(DBM)2. C4H9CON ( 3-C5H11) ( sec-C4H9)] (DBM = dibenzoylmethanate) shows that the amide ligand bonded through its amido oxygen atom to the uranyl group. The average bond distances for U–O(uranyl), U–O(DBM) and U–O(amide) are 1.778(5), 2.346(5) and 2.411(5)Å respectively.

Abstract P2-02-17: Metabolism-driven cancer identification with GLUT5-specific molecular probes

Background: Current cancer imaging agents are limited in their ability to distinguish cancers from normal cells (low cancer-selectivity) and identify cancers at different stages of development (low cancer-specificity). This limitation makes biopsy mandatory for diagnosis and continuous treatment monitoring. Analysis of biopsy samples may also have some ambiguity in clearly identifying malignant and metastatic cells, resulting in cases of mischaracterization and overdiagnosis. Hence, cancer-selective and cancer-specific imaging agents are needed. Distinguishing cancer types and stages can be achieved by addressing differences in their nutrient uptake, manifested as changes in the expression of facilitative sugar transporters (GLUTs). Here, we present a novel approach to target the enhanced metabolism in breast cancers with sugar-like fluorescently labeled probes – ManCous - engineered for specific uptake by fructose transporter GLUT5. The differential accumulation of these probes in cancer cells parallels the differential activity of GLUT5 and results in active fluorescence accumulation within cancers with the highest levels observed in premalignant phenotypes.

Results: Locking fructose conformation in the furanose form was found to provide a sugar-like mimics recognized explicitly by GLUT5. The corresponding coumarin conjugates – ManCous (Figure 1A) - were found to exhibit GLUT5-specific uptake and work as reporters of GLUT5 activity in cells. Differential activity of GLUT5 in cells was found to parallel the differences in the uptake of ManCous. Significant differences in accumulation of ManCou-induced fluorescence were observed between normal and cancer cells and between cancer phenotypes (Figure 1A). Namely, an 8-fold difference in ManCou accumulation was observed between normal and adenocarcinoma MCF7 cells, and 70-fold difference was observed between normal and premalignant MCF10aNeoT cells. The uptaken ManCou were found to be metabolized by hexokinase to form phosphorylated analogs and effectively compete with glucose for hexokinase II (Figure 1B). The probes were found to be non-cytotoxic at concentrations below 100 μM, with higher cytotoxicity towards cancer cells at probe concentrations above 100 μM

Conclusions: The dependence of breast cancer cells on fructose provides a firm basis for developing imaging approaches to discriminate between normal and cancer cells as well as potentially between cancer phenotypes. While current probes are restricted to in-vitro imaging, further probe evolution is expected to lead to new in vivo agents, owing to a proper modification of the scaffold with the relevant radioactive (PET) or other imaging entity and retention of transporter specificity. The development of transporter-specific GLUT5 affinity probes could further contribute to enhancing the impact of fructose uptake inhibition for approaching cancer-specific therapies.

Citation Format: Ghosh A, Kannan S, Begoyan VV, Weselinski LJ, Rao S, Tanasova M. Metabolism-driven cancer identification with GLUT5-specific molecular probes [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-02-17.

Remarkably enhanced direct dissolution of plutonium oxide in task-specific ionic liquid: insights from electrochemical and theoretical investigations

The present work envisages an approach for direct dissolution of PuO2 in a task-specific ionic liquid (TSIL). An attractive possibility to electrodeposit plutonium from the mixture of TSIL and PuO2 has been explored further. The carboxyl functional group attached to the TSIL plays a key role in facilitating the dissolution of plutonium ions.

Structural, charge density and bond length variations in c-Y2O3 influenced by progressive cerium additions

Cerium occupancy induces expansion of the cubic Y₂O₃ unit cell and yields a dense microstructure alongside enhanced mechanical properties.

Prevalence of FVIII inhibitors in severe haemophilia A patients: Effect of treatment and genetic factors in an Indian population

INTRODUCTION

Factor replacement therapy in treatment of haemophilia A is complicated by the production of neutralising antibodies known as inhibitors. The formation of inhibitors is multifactorial being associated with both genetic and environmental factors.

AIM

To document the prevalence of inhibitors in severe haemophilia in the community where most patients receive only infrequent episodic replacement therapy and evaluate the factors which could be contributing to it.

METHODS

Community based camps were conducted in different parts of the country. Patients were assessed through a structured questionnaire and blood samples were obtained for laboratory evaluation of inhibitors and defined immunological parameters.

RESULTS

Inhibitors were present in 87/447 (19.5%) of the evaluated patients. High-titre inhibitor (>5 Bethesda Units [BU]) was identified in 31 (35.6%) patients. HLA DRB1-13-positive cases (RR = 2.04; 95% CI 1.06-3.911; P = 0.033) had an increased risk of inhibitor formation which was retained in the high-titre subset. A decreased risk of inhibitor formation was noted with heterozygous IL4-590 C/T allele (RR = 0.22; 95% CI 0.108-0.442: P = 0.000). There were no significant correlations between any of the evaluated environmental factors and the development of inhibitors in this study.

CONCLUSION

The overall prevalence of inhibitors in patients with severe haemophilia A is similar to that reported among patients receiving regular replacement therapy. The data from this study, limited by its retrospective and cross-sectional study design, would suggest that genetic rather than environmental are more likely to impact the development of inhibitors.

Mitochondrial Dysfunction–Induced Apoptosis in Breast Carcinoma Cells Through pH-Dependent Intracellular Quercetin NDDS of PVPylated-TiO2NPs

Background: The conventional chemotherapy has some noticeable drawbacks, such as lack of specificity, the requirement of high drug-dose, adverse effects, and gradual development of multidrug resistance (MDR), that reduce the efficacy of cancer therapy. Aim: To achieve intracellular drug delivery, strategies for overcoming various biologic barriers from the system level to the organ level, to the cellular level. To win through over these challenges in chemotherapy is to be achieving high drug loading combination with low leakage at physiologic pH, minimal toxicity toward healthy cells, and tunable controlled release at the site of action is an ongoing challenge. Methods: To assist drug delivery, we have prepared PVPylated-TiO2NPs consisting of Qtn with high loading efficiency (26.6% w/w) for NDDS. Qtn-PVPylated-TiO2NPs uptake via endocytosed by cancer cells able to generate intracellular ROS, to decrease the mitochondrial membrane potential loss (Δψm) to release cytochrome- c, Bcl-2 dysregulation into the cytosol and then activating caspase-3 to induce cancer cell apoptosis. Results: These novel nanocombinations can be used to improve cancer nanotherapy by induction of apoptosis in vitro. Analysis at molecular level revealed that Qtn-PVPylated-TiO2NPs nanocombination induced Δψm-mediated apoptotic signaling pathway. Conclusion: To our knowledge, this is a novel report using Qtn-PVPylated-TiO2NPs nanocombinations to study the pH-dependent intracellular NDDS to cancer cells. This new nanoformulations of this study may further advance the use of Qtn-PVPylated-TiO2NPs based nanotherapeutic of biomaterials for various biomedical applications, especially cancer nanotherapy.

Design and structural investigations of Yb3+ substituted β-Ca3(PO4)2 contrast agents for bimodal NIR luminescence and X-ray CT imaging

The quest for the development of bone substitutes with contrast agents for diagnostic imaging subsists to distinguish synthetic bone from native human tissue. To this aim, ytterbium (Yb³⁺) substitutions in β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) as contrast agents has been developed to differentiate implant materials thereby, facilitating as host for bimodal imaging application by means of NIR luminescence and X-ray computed tomography techniques. A facile aqueous chemical precipitation route with the aid of surfactant is used for the synthesis of Yb³⁺ substitutions in β-Ca₃(PO₄)₂. The characterization results affirms the ability of β-Ca₃(PO₄)₂ to host 4.36 mol% of Yb³⁺ while the excess Yb³⁺ crystallizes as YbPO₄. The structure refinement results favour the occupancy of Yb³⁺ at the Ca²⁺(5) site of β-Ca₃(PO₄)₂. The absorption and photoluminescence spectra in the near infrared region with emission intensity ~1024 nm in the second biological window correspond to ²F_5/2 → ²F_7/2 transitions of Yb³⁺. The designed Yb³⁺ substituted β-Ca₃(PO₄)₂ does not exhibit any toxicity in human osteosarcoma cell lines and delivers an excellent in vitro CT contrast ability allied by the enhanced signal intensity and high X-ray absorption coefficient.

Lanthanide phosphate (LnPO4 ) rods as bio-probes: A systematic investigation on structural, optical, magnetic, and biological characteristics

The proposed work involves an exclusive study on the synthesis protocol, crystal structure analysis, and imaging contrast features of unique lanthanide phosphates (LnPO₄ ). XRD and Raman spectra affirmed the ability of the proposed synthesis technique to achieve unique LnPO₄ devoid of impurities. The crystal structure analysis confirms the P121/c1 space setting of NdPO₄ , EuPO₄ , GdPO₄ , and TbPO₄ that all uniformly crystallizes in monoclinic unit cell. In a similar manner, the tetragonal crystal setting of DyPO₄ , ErPO₄ , HoPO₄ , and YbPO₄ that unvaryingly possess the I41/amd space setting is confirmed. Under the same synthesis conditions, the monoclinic (Eu) and tetragonal (Ho) lanthanide phosphates displayed uniform rod-like morphologies. Absorption and luminescence properties of unique LnPO₄ were determined. In vitro biological studies demonstrated low toxicity levels of LnPO₄ and clearly distinguished fluorescence of TbPO₄ and EuPO₄ in Y79, retinoblastoma cell lines. The paramagnetic response of GdPO₄ , NdPO₄ , DyPO₄ , TbPO₄ , and HoPO₄ facilitated excellent magnetic resonance imaging (MRI) contrast features. Meanwhile, GdPO₄ , DyPO₄ , HoPO₄ , and YbPO₄ possessing higher X-ray absorption coefficient than clinical contrast Omnipaque™ exhibited high computed tomography (CT) efficiency. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1372-1383, 2019.