Loss Of Membrane Permeability Research Articles

Momordica balsamina acetone leaf extract induces apoptosis and inhibits the invasiveness and migration of MCF-7 breast cancer cells

Despite its well-documented nutritional and medicinal properties, Momordica balsamina has not received enough attention in cancer research. As a result, this study investigated whether a crude acetone leaf extract of Momordica balsamina could induce apoptosis and inhibit the migration and invasiveness of MCF-7 breast cancer cells. The MTT assay showed a significant decrease in cell viability after 48 h of treatment with concentrations from 100 – 200 µg/ml of the extract. Light microscopy, the acridine orange/ethidium bromide dual staining assay, and the Muse™ MitoPotential kit showed that the decrease in cell viability is associated with apoptotic cell death. Indeed, extract-treated cells showed signs of chromatin condensation, nuclear fragmentation, and loss of membrane permeability and mitochondrial membrane potential. The scratch wound-healing assay and transwell cell invasion kit showed that the extract inhibited the invasive and migratory abilities of MCF-7 cells, respectively. Also, the extract modulated the expression of proteins involved in the intrinsic and extrinsic pathways of apoptosis, as well as those involved in the regulation of cell invasiveness and migration. Based on these findings, we concluded that Momordica balsamina is a potential source of anticancer compounds.

Effect of Aqueous n-Butanol Treatments on Shelf-Life Extension of Longkong Fruit during Ambient Storage

The pericarp of the Longkong fruit rapidly browns during ambient storage, typically reducing its shelf life to between 3 and 7 days. Recently, n-butanol has demonstrated a promising effect in preventing this deterioration, extending the shelf life of tropical fruits to more than a week. The present study exploited this opportunity to examine the exogenous application of aqueous n-butanol at various concentrations (0.2–0.6%) in controlling pericarp browning and suppressing different oxidoreductase enzymes in the pericarp under prolonged ambient storage conditions (8 days). Every two days, the fruit pericarps were tested for color (lightness (L*), redness (a*), and yellowness (b*)), browning index (BI), membrane permeability loss (MPL), malondialdehyde (MDA) content, total phenolic content (TPC), and reactive oxygen species (ROS). Enzymes including phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), phospholipase D (PLD), lipoxygenase (LOX), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were also analyzed. All sample test results showed that increased storage significantly impacted color characteristics (decreased L*, b* and increased a*, and BI). MPL, MDA, and ROS also continuously increased. Furthermore, the browning-related enzymes (PAL and PPO), membrane-degrading enzymes (PLD and LOX), and antioxidant enzymes (SOD, CAT, and GPX) continuously increased in all pericarp samples throughout the storage. Among the samples, pericarp color, BI, MPL, MDA, PAL, PPO, PLD, and LOX were significantly high in the control samples, consequently adversely affecting the quality and shelf life of Longkong. On the other hand, the n-butanol-treated samples significantly controlled the loss and all problematic enzymes while improving the activities of SOD, CAT, and GPX in the pericarp. Furthermore, the positive effect of n-butanol application was dose-dependent; higher concentrations (0.4–0.6%) performed well in protecting the fruit from deterioration.

Physiological and Metabolic Responses of Gac Leaf (Momordica cochinchinensis (Lour.) Spreng.) to Salinity Stress.

Gac is a carotenoid-rich, healthful tropical fruit; however, its productivity is limited by soil salinity, a growing environmental stress. This study aimed to evaluate the effects of salinity stress on key physiological traits and metabolites in 30-day-old gac seedling leaves, treated with 0, 25-, 50-, 100-, and 150-mM sodium chloride (NaCl) for four weeks to identify potential alarm, acclimatory, and exhaustion responses. Electrolyte leakage increased with increasing NaCl concentrations (p < 0.05) indicating loss of membrane permeability and conditions that lead to reactive oxygen species production. At 25 and 50 mM NaCl, superoxide dismutase (SOD) activity, starch content, and total soluble sugar increased. Chlorophyll a, and total chlorophyll increased at 25 mM NaCl but decreased at higher NaCl concentrations indicating salinity-induced thylakoid membrane degradation and chlorophyllase activity. Catalase (CAT) activity decreased (p < 0.05) at all NaCl treatments, while ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) activities were highest at 150 mM NaCl. GC-MS-metabolite profiling showed that 150 mM NaCl induced the largest changes in metabolites and was thus distinct. Thirteen pathways and 7.73% of metabolites differed between the control and all the salt-treated seedlings. Salinity decreased TCA cycle intermediates, and there were less sugars for growth but more for osmoprotection, with the latter augmented by increased amino acids. Although 150 mM NaCl level decreased SOD activity, the APX and GPX enzymes were still active, and some carbohydrates and metabolites also accumulated to promote salinity resistance via multiple mechanisms.

Antibacterial activity of colloidal copper nanoparticles against Gram-negative (Escherichia coli and Proteus vulgaris) bacteria.

Antibacterial activities of as-synthesized nanoparticles have gained attention in past few years due to rapid phylogenesis of pathogens developing multi-drug resistance (MDR). Antibacterial activity of copper nanoparticles (CuNPs) on surrogate pathogenic Gram-negative bacteria Escherichia coli (MTCC no. 739) and Proteus vulgaris (MTCC no. 426) was evaluated under culture conditions. Three sets of colloidal CuNPs were synthesized by chemical reduction method with per batch yield of 0·2, 0·3 and 0·4 g. As-synthesized CuNPs possess identical plasmonic properties and have similar hydrodynamic particle sizes (11-14 nm). Antibacterial activities of CuNPs were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests, cytoplasmic leakage and reactive oxygen species (ROS) assays. MIC and MBC tests revealed dose dependence bactericidal action. Growth curves of E. coli show faster growth inhibition along with higher cytoplasmic leakage than that of P. vulgaris. This might be because of increased membrane permeability of E. coli. CuNP-microorganism interaction induces oxidative stress generated by ROS. Leakage of cytoplasmic components, loss of membrane permeability and ROS generation are the primary causes of CuNP-induced bacterial cell death. As-synthesized CuNPs exhibiting promising antibacterial activities and could be a promising candidate for novel antibacterial agents.

Cantharis 200c counters heat stress in germinating seeds of Vigna unguiculata (L.) Walp.

Background&#x0D; Thermal stress during early imbibitional phase of germination causes disruption of redox-homeostasis by increasing accumulation of ROS Reactive Oxygen species (assessed in terms of hydrogen peroxide) and significant reduction of antioxidative defense (assessed in terms of catalase and peroxidase) in germinating tissues of cowpea (Vigna ungiculata). It also induces oxidative damage to newly assembled membrane system by aggravating membrane lipid peroxidation [measured in terms of thiobarbituric acid reactive substances (TBARS)]. Cantharis is a homeopathic remedy used for treating burn injuries in humans. The objective is to see whether potentized Cantharis could ameliorate heat stress in germinating seeds of cowpea.&#x0D; &#x0D; Methodology&#x0D; Seeds, imbibed in water overnight, were divided into four groups (n=50/group): Control I (Water 200c), Control II (Ethanol 200c), treated with Cantharis 200c and untreated and unstressed. Water soaked seeds were dipped in control/drug solution for 5 min and then washed. Control II and Cantharis 200c were diluted with water 1:1000 to minimize the ethanol effect. Except the fourth group, all other groups were subjected to heat stress (450C for 8 hours). All the groups were allowed to germinate for 5 days in germination chamber at 25 ± 20C. Groups 1 and 2 (Control I and II) served as systematic negative controls throughout the experiment. Ten independent replications were performed for each group in parallel. All experiments were randomized and blinded. &#x0D; &#x0D; &#x0D; Results&#x0D; The systematic negative controls (I, II) did not produce any significant effect. The results in terms of germination, growth, soluble sugar, protein, accumulation of reactive oxygen species and loss of membrane permeability clearly exhibit that Cantharis 200c could mitigate heat stress significantly (p

Integration of oxalic acid chelation and Fenton process for synergistic relaxation-oxidation of persistent gel-like fouling of ceramic nanofiltration membranes

Ceramic nanofiltration (NF) is a newly-developed technology for water recycling, but is still limited to pilot-scale applications. Lacking efficient and eco-friendly strategies for cleaning ceramic NF membrane impedes its scaling-up in industries. Forward flush, backwash and acidic/caustic cleaning are not efficient enough. In this work, a novel oxalic acid-aided Fenton process was proposed for synergistic relaxation/oxidation of persistent Ca2+-mediated gel-like fouling of ceramic NF membrane. A reactive catalyst layer was online pre-coated on top of the membrane via a pressure-driven cross-flow pre-filtration of Fe3O4 hydrosols. The gel-like fouling was simulated by alginate in the presence of Ca2+ ions. Results show that the Fe3O4 loading could be readily tuned from 0.16 to 1.34 g m−2 by altering the permeate flux during the pre-coating. The membrane permeability loss due to the pre-coating was minimal (<10%). The combination of oxalic acid chelation and Fenton-based oxidation resulted in high flux recovery (85.07%) for the iron-oxide pre-coated membrane, whereas the single treatment by hydrogen peroxide (H2O2) or oxalic acid was inefficient. This synergistic effect was attributed to relaxation of the Ca2+-mediated gel layer via oxalic acid/Ca2+ chelation, which presumably facilitated H2O2 diffusion at the Fe3O4/foulant interface. The iron-oxide pre-coated membrane maintained stable initial normalized fluxes (83.33–90.15%) through the oxalic acid/H2O2 cleaning over five cycles, with no need of refreshing the iron-oxide pre-coat. Additionally, the leaching of iron from the iron-oxide pre-coat by oxalic acid was suppressed by the oxalic acid/H2O2 combination, owing to a reactive shielding by competitive sorption of H2O2 onto the Fe3O4 surface. Overall, the synergistic relaxation/oxidation method, demonstrated in this study, provides new insights into improving reactivity of Fenton-based processes on hybrid catalytic ceramic membranes for water treatment or fouling control.

A Performance Comparison of Pilot-Scale Sand Filtration and Membrane Filtration of Glafkos River Water

Surface-water treatment plants use the flocculation–precipitation method followed by gravity filters to remove suspended solids. In the present work, the replacement of gravity filters with ultrafiltration membrane units is suggested to improve the efficiency of water treatment and to reduce fixed and operational costs. A parametric pilot-scale study was conducted to compare the filtration efficiency of a deep bed and a membrane module for water-simulating river water of various turbidity degrees. Suspensions of kaolinite were prepared to simulate turbidity of the Glafkos River, Achaia Region of Greece and were filtered using a laboratory sand-bed column and a pilot ultrafiltration (UF) membrane unit. Operational parameters such as the particle concentration ratio, the flow rate, and the filter head loss were studied in the case of the granular bed. In the case of membrane filtration, the permeate flux, turbidity, and membrane permeability loss due to fouling were tested. A discussion in terms of the operational cost and environmental impacts was performed. Filtration capacity of the sand filter is a decreasing function of the flow rate and it was found less efficient than membrane ultrafiltration for increased turbidity or increased particle concentration values. Membrane ultrafiltration could achieve long-term economic profit while it is characterized by minimum environmental impact since the use of chemical reagents and the production of waste sludge are limited.

Influence of macro‐perforated polyethylene terephthalate and low‐density polyethylene packaging films on quality and storability of strawberries

Perishable nature of strawberry poses serious challenges in maintaining quality and extending its market life. In this study, efficacy of macro-perforated polyethylene terephthalate polyester (PET), low-density polyethylene (LDPE), and composite film packaging (PET + LDPE) was evaluated to inhibit fungal decay and retain nutritional and organoleptic attributes of strawberries stored at 2 ± 0.5°C. Strawberries packed in LPDE exhibited better moisture retention, least fungal infection, and delayed loss of membrane permeability compared to PET + LDPE and PET. The LDPE film was also more effective in delaying increase in pH and total soluble solids and decline in fruit dry weight, titratable acids, ascorbic acid, and organoleptic acceptability. Overall, marketable life of strawberries packed in LDPE film was 2- and 1.5-fold higher than strawberries packed in either PET or LDPE + PET, respectively. Higher levels of antioxidant enzymes catalase, superoxide-dismutase, and peroxidase in LDPE-packed strawberries suggest that LDPE retained strawberry quality was partly through maintaining ROS-scavenging mechanism in fruits. Practical applications Low-density polyethylene film effectively preserves physical and biochemical properties of fresh strawberry fruit and extends its storability under low temperature conditions, an important aspect for long-distance local marketing and export. Findings of this research can be translated to other highly perishable crops and, with basic research support, local packaging industry can be involved to manufacture commodity-specific flexible film packaging.

Impact of hydraulic retention time and organic matter concentration on side-stream aerobic granular membrane bioreactor

This study investigated the effect of hydraulic retention time (HRT) and chemical oxygen demand (COD) concentration on membrane fouling in aerobic granular membrane bioreactor (AGMBR) in a systematic approach. Changes in HRT (7, 10, and 15 h) and COD (500, 1000 and 1500 mg/L) were applied in five operational phases, to determine the most significant parameters to control membrane fouling for enhanced AGMBR performance. Membrane permeability loss was dramatically intensified with increase in HRT from 7.5 to 15 h and COD from 500 to 1000 mg/L. The highest polysaccharide content of loosely bound EPS (0.41 mg PS/mg VSS) and soluble microbial products (SMPs) (27 mg PS/L) occurred alongside poor AGMBR performance. Variations in membrane fouling were accompanied with considerable changes in Flavobacterium, Thauera and Paracoccus populations. Analysis of variance (ANOVA) demonstrated that HRT and interaction between HRT and COD were the most significant parameters in controlling membrane fouling.

Iron catalyzed degradation of an aromatic polyamide reverse osmosis membrane by free chlorine

The catalytic effect of iron on the degradation of a polyamide (PA) reverse osmosis (RO) membrane by free chlorine was evaluated by measuring the permeability, P, and salt rejection, R, at circumneutral pH, cumulative exposures (CT) of 6000 and 3000 ppm-h, varying free chlorine concentrations, and exposure times. The chemical transformations of the polyamide layer were characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The role of free radicals was probed by studying the effect of the short-chained alcohols of increasing size (methanol (MeOH), ethanol (EtOH) and tertiary-butyl alcohol (tBuOH) on membrane performance and transformation. In the absence of iron, CT up to 6000 ppm-h caused N-chlorination (up to 4.9%), disrupted intra-molecular hydrogen bonding and caused membrane tightening. A one-time-addition of iron nitrate (Fe(NO3)3) (1 mg/L) to the recirculating feed water significantly accelerated oxidation and increased P and decreased R. The proposed membrane degradation mechanism involves Fe precipitates lodged on the membrane surface catalyzing the formation of hydroxyl radical by Fenton-like reactions. MeOH accelerated membrane degradation, apparently because the secondarily formed hydroxymethyl radical diffused into the separation layer. By contrast, tBuOH inhibited membrane degradation likely because tBuOH quenched hydroxyl radical and secondary radicals of tBuOH were prevented from diffusing into the separation layer due to their large size. In the initial loss of membrane permeability and the rejection after CT of 3000 ppm-h were proportional to the free chlorine concentration. Results highlight the potential significance of radical formation and quenching processes when evaluating membrane degradation by oxidants to under field conditions.

Cryopreservation Induced Sperm Cryoinjuries in Hariana Bull Semen

Cryopreservation causes breach in the plasma membrane which culminates into loss of membrane permeability, change in membrane fluidity, exudation of acrosomal enzymes, and modification in mitochondrial membrane potential. Keeping these views in mind the current study was conducted to evaluate the apoptosis like changes or cryoinjuries in spermatozoa during cryopreservation. In the present study we collected semen from 4 Hariana bulls and after dilution semen was evaluated for various parameters, thereafter semen was cryopreserved. Various sperm characteristics were further evaluated 24 hrs after cryopreservation. The findings of the current study revealed that there is significant reduction in progressive motility, viability, acrosomal integrity, plasma membrane integrity and mitochondrial membrane potential of spermatozoa after semen cryopreservation. Thus we concluded that cryopreservation induced cryoinjuries in spermatozoa and investigation regarding mechanism involved in these changes is key factor to improve the success of semen cryopreservation.

Laser induced fluorescence (LIF) technique visualizes and characterizes concentration polarization and fouling layer in the cross-flow nanofiltration

In-situ non-invasive observation of concentration polarization (CP) and fouling layer is of vital importance to understanding membrane filtration process and membrane permeability loss. This study developed a novel real-time technique, laser induced fluorescence (LIF) technique, to visualize CP development and fouling layer formation, and to measure solute concentration field on the membrane surface directly during cross-flow nanofiltration, which helped to quantitatively evaluate the effect of various operation conditions on membrane permeability. The solute concentration distribution on the membrane surface was successfully determined from the LIF images, and the fouling layer thickness was measured by series of processed images after binary subtraction. LIF results demonstrated that the fouling development experienced approximate two stages, i.e. rapid growth phase and consolidation phase, and visualized the transition from initial CP to the later fouling layer formation. Afterwards, the formed fouling layer tend to be steady with nearly unchanging concentration and thickness. Quantitative analysis proved that the operational hydraulic condition has a significant influence on the formation and stabilization of fouling layer. The developed method and obtained results were very useful to in-depth recognize the nanofiltration process and to understand the membrane fouling mechanism.

Fast polydopamine coating on reverse osmosis membrane: Process investigation and membrane performance study

We report a novel membrane surface modification method using a fast polydopamine coating (fPDAc) strategy. Specifically, NaIO4 was introduced in the coating process to accelerate the polydopamine deposition rate. Surface properties and separation performances of fPDAc-coated reverse osmosis membranes were characterized and compared to those obtained using the conventional slow polydopamine coating (sPDAc) strategy. Quartz crystal microbalance measurements showed greatly increased polydopamine deposition rate using the fPDAc method, resulting in a reduction of 97% coating time to reach an areal mass of 2000 ng/cm2. Both fPDAc and sPDAc enhanced the surface hydrophilicity and reduced the membrane surface charge. At relatively low areal mass deposition (<1000 ng/cm2), fPDAc-coated membranes showed improved NaCl rejection together with only mild loss of pure water flux. Nevertheless, this rejection enhancement effect was not noticeable when extensive polydopamine coating was applied due to the undesirable cake-enhanced concentration polarization effect. The extensive polydopamine coating was further accompanied with severe loss of membrane permeability, suggesting that shorter coating time (e.g., 4 min) is preferred using the fPDAc method. Our study provides a more rapid and effective membrane surface coating method compared to the conventional sPDAc method.

Amphiphobic surface modification of electrospun nanofibrous membranes for anti-wetting performance in membrane distillation

Membrane distillation (MD) works as a promising alternative of RO to desalinate hypersaline water owing to its unique advantages including high concentration brine tolerance, 100% theoretical solute rejection, and low operating pressure. Hydrophobic MD membranes face critical challenge to treat industrial wastewaters containing low surface tension substances because these substances led to membrane wetting with loss of membrane permeability and rejection. In this study, we report a simple and facile approach to fabricate amphiphobic polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) electrospun nanofibrous membranes with anti-wetting property. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS) was used to fluorinate PVDF-HFP fibers and was then crosslinked to form a network upon dealcoholization under thermal treatment. The FAS-coated PVDF-HFP nanofibrous membranes exhibited great stable amphiphobicity with high contact angles against both water and oil, even challenged under critical conditions including boiling water, and strong base and acid etchings. Surface fluorination of PVDF-HFP nanofibrous membrane with the FAS coating did not sacrifice its permeate flux and salt rejection much. The fabricated amphiphobic nanofibrous membrane exhibited robust MD performance in the long-term operation and also in the presence of surfactant sodium dodecyl sulfate in the feed saline solution.

Oxidized Mutant Human Hemoglobins S and E Induce Oxidative Stress and Bioenergetic Dysfunction in Human Pulmonary Endothelial Cells.

Cell free hemoglobin (Hb), becomes oxidized in the circulation during hemolytic episodes in sickle cell disease (SCD) or thalassemia and may potentially cause major complications that are damaging to the vascular system. Hemolytic anemias are commonly associated with pulmonary hypertension (PH) and often result from dysfunction of lung endothelial cells. The aim of this study was to determine the effect of different Hbs on cultured human lung endothelial function. Toward this goal, endothelial permeability, oxidative stress response parameters, glycolytic and mitochondrial bioenergetic functions were monitored in cultured human pulmonary arterial endothelial cells (HPAEC) following incubation with human adult Hb (HbA), and Hb isolated from patients with sickle cell Hb (HbS, βV6E) and HbE (βE26K) that commonly co-exist with β-thalassemia. These mutant Hbs are known for their distinct oxidative profiles. HPAEC treated with the ferrous forms of HbE, HbS for 24 h showed higher loss of endothelial monolayer integrity with concomitant rise in reactive oxygen radical production, lipid hydroperoxide formation and higher expressions of oxidative stress response proteins including heme oxygenase-1 (HO-1) accompanied by a rise in uncoupled mitochondrial respiration. Loss of membrane permeability was diminished in part by haptoglobin (Hp, protein scavenger), hemopexin (Hpx, heme scavenger) or ascorbate (reducing agent). To understand the role of Hb oxidation, HPAEC were exposed to ferric or ferryl states of the mutant Hbs. Ferryl forms of all proteins caused a significant damage to the endothelial monolayer integrity at a higher degree than their respective ferric Hbs. Ferryl forms of HbS and HbE also caused a loss of respiratory chain complex activities in isolated endothelial mitochondria and basal oxygen consumption in HPAEC. However, longer incubation with ferryl Hbs produced bioenergetic reprogramming including higher degree of uncoupled respiration and glycolytic rate. The data in this report collectively indicate that higher oxidation forms of HbS and HbE cause endothelial dysfunction through distinct damaging mechanisms involving mitochondrial bioenergetic function.

Nanofiltration fouling propensity caused by wastewater effluent organic matters and surface-water dissolved organic matters

ABSTRACTRejection of dissolved organic matters (DOMs) from wastewater treatment plant effluent (EfOM) and surface reservoir water (RW-DOM) by nanofiltration (NF) was comparatively studied to evaluate their influence on membrane fouling and to unveil the major causations. EfOM and RW-DOM were fractionated to determine the major components that preferentially form fouling layer and initiate biofouling. The results indicated that EfOM induced a rapid membrane permeability loss and a more complicated biofilm diversity than RW-DOM did. Hydrophilic components with small molecular weight (<3 kDa), and SMP in EfOM made a crucial contribution to membrane flux decline, while the hydrophobic large-molecular-weight components (>50 kDa) resulted in initially quick membrane fouling. The complex biofouling resulted from EfOM closely related with significant retention of SMP on the non-porous NF membrane surface, where the Proteobacteria phylum dominated the biofouling formed by microbial community growth and accumulation that gave rise to serious irreversible membrane fouling.

The effect of high pressure processing on clingstone and freestone peach cell integrity and enzymatic browning reactions

Abstract HPP-treated fruits and vegetables may undergo undesirable enzymatic browning reactions due to loss of membrane permeability and sub-cellular compartmentalization. Clingstone and freestone peaches were treated from 100 to 500 MPa for 10 min and evaluated for polyphenol oxidase (PPO) activity, color, total phenols, and for cell integrity using light microscopy and 1 H NMR. Significant changes in membrane integrity following HPP above 200 MPa were determined by T 2 shifts in the vacuolar compartment from initial levels of 0.79 (clingstone) or 0.88 (freestone) to approximately 0.60–0.68. Clingstone peaches treated at 300, 400 and 500 MPa showed significant decreases (5, 12 and 7%) in % water of the vacuolar compartment and simultaneous increases in the cytoplasmic compartment (4, 8 and 5%). Additionally, there was a reduction in the number of viable cells from an initial 57–58% to 0 and 14% in clingstone and freestone peaches, respectively. These results correlated with the development of increased browning. Industrial relevance Clingstone peaches are firm-textured and therefore are preserved primarily through canning, which desirably softens the texture. In this study we evaluated the use of high pressure processing – at a range of MPa levels – for preservation, and found that enzymatic browning took place after 2 weeks in refrigerated storage if processing occurred above 200 MPa. Analytical tools were developed to follow the onset of the browning, and in future work preventative measures will be studied to minimize this reaction.

Isolation, Purification and Characterization of a Novel Steroidal Saponin Cholestanol Glucoside from Lasiodiplodia theobromae that Induces Apoptosis in A549 Cells.

Search for novel anticancer lead molecules continues to be a major focus of cancer research due to the limitations of existing drugs such as lack of tumor selectivity, narrow therapeutic index and multidrug resistance of cancer types. Natural molecules often possess better pharmacokinetic traits compared to synthetic molecules as they continually evolve by natural selection process to interact with biological macromolecules. Microbial metabolites constitute nearly half of the pharmaceuticals in market today. Endophytic fungi, owing to its rich chemical diversity, are viewed as attractive sources of novel bioactive compounds. In the present study, we report the purification and characterization of a novel steroidal saponin, cholestanol glucoside (CG) from Saraca asoca endophytic fungus Lasiodiplodia theobromae. The compound was assessed for its cytotoxic potentialities in six human cancer cell lines, A549, PC3, HepG2, U251, MCF7 and OVCAR3. CG exhibited significant cytotoxicities towards A549, PC3 and HepG2 among which A549 cells were most vulnerable to CG treatment. However, CG treatment exhibited negligible cytotoxicity in non malignant human lung fibroblast cell line (WI-38). Induction of cell death by CG treatment in A549 cells was further investigated. CG induced the generation of reactive oxygen species (ROS) and mitochondrial membrane permeability loss followed by apoptotic cell death. Mitochondrial membrane depolarization and apoptotic cell death in CG treated A549 cells were completely blocked in presence of an antioxidant, N-acetyl cysteine (NAC). Hence it could be concluded that CG initiates apoptosis in cancer cells by augmenting the basal oxidative stress and that the generation of intracellular ROS is crucial for the induction of apoptosis.

Hybridization of physical cleaning and quorum quenching to minimize membrane biofouling and energy consumption in a membrane bioreactor

Membrane fouling and energy consumption are interconnected and considered as a bottleneck in membrane bioreactor (MBR) applications. This study investigated synergistic combinations of quorum quenching (QQ) and physical cleaning under different cleaning conditions and aeration intensities with respect to fouling control and energy saving. The MBR operated with periodic air backpulsing had a lower fouling tendency compared with the reactor operated with relaxation. Frequent physical cleanings mitigated the membrane fouling, but irreversible fouling inevitably occurred over time. A significant improvement in fouling control was accomplished when QQ was coupled with physical cleanings, particularly in the filtration/relaxation mode. The submerged QQ vessel helped operate the MBRs stably even at the lowest end of aeration intensity (51 s−1 in G value), without any significant loss of membrane permeability. The specific membrane filtration energy of the QQMBR remained low and independent of aeration intensities tested, whereas that of the normal MBR sharply increased with decreased aeration rates. The QQMBR with low aeration intensity (51 s−1) reduced approximately 27% of the specific aeration energy required for the MBR operated at high aeration intensity (103 s−1). QQ bacteria should hamper the formation of a biofilm on the membrane surface, but mixed liquor properties and treatment performances were not affected by the QQ activity.

Hydrophilic fraction of natural organic matter causing irreversible fouling of microfiltration and ultrafiltration membranes

Although membrane filtration is a promising technology in the field of drinking water treatment, persistent membrane fouling remains a major disadvantage. For more efficient operation, causative agents of membrane fouling need to be identified. Membrane fouling can be classified into physically reversible and irreversible fouling on basis of the removability of the foulants by physical cleaning. Four types of natural organic matter (NOM) in river water used as a source of drinking water were fractionated into hydrophobic and hydrophilic fractions, and their potential to develop irreversible membrane fouling was evaluated by a bench-scale filtration experiment together with spectroscopic and chromatographic analyses. In this study, only dissolved NOM was investigated without consideration of interactions of NOM fractions with particulate matter. Results demonstrated that despite identical total organic carbon (TOC), fouling development trends were significantly different between hydrophilic and hydrophobic fractions. The hydrophobic fractions did not increase membrane resistance, while the hydrophilic fractions caused severe loss of membrane permeability. These results were identical with the case when the calcium was added to hydrophobic and hydrophilic fractions. The largest difference in NOM characteristics between hydrophobic and hydrophilic fractions was the presence or absence of macromolecules; the primary constituent causing irreversible fouling was inferred to be “biopolymers”, including carbohydrates and proteins. In addition, the results demonstrated that the extent of irreversible fouling was considerably different depending on the combination of membrane materials and NOM characteristics. Despite identical nominal pore size (0.1 μm), a polyvinylidene fluoride (PVDF) membrane was found to be more rapidly fouled than a PE membrane. This is probably explained by the generation of strong hydrogen bonding between hydroxyl groups of biopolymers and fluorine of the PVDF membrane. On the basis of these findings, it was suggested that the higher fouling potential of the hydrophilic fraction of the dissolved NOMs from various natural water sources are mainly attributed to macromolecules, or biopolymers.