Hyperbranched polyethylenimine-modified polyethersulfone (HPEI/PES) and nAg@HPEI/PES membranes with enhanced ultrafiltration, antibacterial, and antifouling properties.

This study reports a simple fabrication of polyethersulfone (PES)-based membranes, their characterisation, and application. These membranes are modified with hyperbranched polyethyleneimine (HPEI) and -silver (nAg)-decorated HPEI. These were then compared for filtration, organic fouling, antifouling, and antibacterial properties against the neat PES membrane. The fabricated membranes were characterised for their chemistry using attenuated transmission reflectance-equipped Fourier transform infrared spectroscopy (ATR-FTIR) and x-ray photoelectron spectroscopy (XPS). As such, the presence of HPEI interactions between the nAg and HPEI in the membranes was confirmed. An energy-dispersive x-ray detector coupled with a scanning electron microscopy (SEM-EDS) and atomic force microscopy (AFM) were used to study morphological, compositional, topographical, and topological changes to the membrane due to the modifications. A thermogravimetric analyser (TGA) was also utilised to evaluate the effect of modification on thermal stability of the resulting membranes. Optical contact angle (OCA) interrogated the extent of membrane/water interactions which indicated enhanced hydrophilicity due to the modification. Dead-end filtration using these membranes indicated enhanced pure water permeate fluxes and protein rejection (bovine serum albumin, BSA). The results of the BSA rejection for the HPEI/PES membranes were a maximum of 98% while those of the nAg@HPEI/PES ranged between 30-87%. The membranes possessed high flux recoveries, indicating great potential for the membranes for antifouling applications in water treatment. Extensive antibacterial studies were carried out on the membranes to probe bioactivity. Enhanced activity was recorded (except for neat PES) with zone inhibitions of up to 7 mm against five bacterial strains including E. Coli and K. Pneumoniae as found in several wastewater streams. The antibacterial properties of these membranes mean they can prolong membrane operational lifetime by mitigating biofilming during water treatment.

Synthesis of substituted N-(2'-nitrophenyl)pyrrolidine-2-carboxamides towards the design of proline-rich antimicrobial peptide mimics to eliminate bacterial resistance to antibiotics.

The treatment of diseases is under threat due to the increasing resistance of disease-causing bacteria to antibiotics. Likewise, free radical-induced oxidative stress has been implicated in several human disease conditions, such as cancer, stroke and diabetes. In the search for amino acid analogues with antibacterial and antioxidant properties as possible mimics of antimicrobial peptides, substituted N-(2'-nitrophenyl)pyrrolidine-2-carboxamides 4a-4k and N-(2'-nitrophenyl)piperidine-2-carboxamides 4l-4n have been synthesized via a two-step, one-pot amidation of the corresponding acids, using thionyl chloride with different amines in dichloromethane. The carboxamides were characterized by infrared and nuclear magnetic resonance spectroscopy, mass spectrometry and elemental analysis. Carboxamides 4a-4n were assayed against five Gram-positive and five Gram-negative bacterial strains using the broth micro-dilution procedure and compared to standard antibiotic drugs (streptomycin and nalidixic acid). 4b showed the highest antibacterial activity with a minimum inhibitory concentration (MIC) value of 15.6 µg/mL against Staphylococcus aureus. Pertinently, 4b and 4k are promising candidates for narrow-spectrum (Gram-positive) and broad-spectrum antibiotics, respectively. The antioxidant properties of the carboxamides were also evaluated using the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation. 4a and 4k recorded the lowest IC50 values of 1.22 × 10-3 mg/mL (with DPPH) and 1.45 × 10-4 mg/mL (with ABTS), respectively. Notably, 4k recorded about 2.5 times better antioxidant capacity than the positive controls - ascorbic acid and butylated hydroxyanisole. These results bode well for N-aryl carboxamides as good mimics and substitutes for antimicrobial peptides towards mitigating bacterial resistance to antibiotics as well as ameliorating oxidative stress-related diseases.

Antioxidant and prooxidant effects of Piptadeniastrum africanum as the possible rationale behind its broad scale application in African ethnomedicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Piptadeniastrum africanum is widely used in treating oxidative stress related diseases. Oxidative stress, defined as the disturbance in the balance between the production of free radicals and antioxidant defenses, is the root cause of many pathophysiological conditions. Based on the dual properties of prooxidants as toxic and beneficial compounds, both prooxidants and antioxidants may be effective in the treatment of these conditions when the right dose is given to the right subject at the right time for the right duration. AIM OF THE STUDY: This study was aimed at investigating the in vitro and ex vivo anti- and pro-oxidative effects of P. africanum. MATERIALS AND METHODS: Total phenolic and flavonoid contents of methanol and aqueous extracts of P. africanum stem back were quantified spectrophotometrically. The methanol extract, ascorbate radicals and reactive oxygen species in brain and liver homogenates of mice treated with the methanol stem bark extract were analyzed by electron paramagnetic resonance (EPR) spectroscopy. Free radical scavenging of DPPH was determined by spectrophotometric and EPR assays. RESULTS: The methanol extract was richer in both phenolic and flavonoid contents compared to the aqueous extracts and also showed better DPPH radical scavenging capacity. The EPR spectroscopy in vitro analysis exhibited high DPPH scavenging capacity before and after UV irradiation (99.5% and 98.76%) at 40 µg/ml extract. The ex vivo EPR spectroscopy studies demonstrated increased levels of ascorbate radicals (•Asc) in liver and brain homogenates of healthy mice treated with P. africanum in comparison with those of the non treated controls (0.6141 ±â€¯0.026 vs 0.1800 ±â€¯0.0073 arb. units for liver homogenates and 0.9605 ±â€¯0.0492 vs 0.3375 ±â€¯0.0062 arb. units for brain homogenates, correspondingly). Considerably, higher levels of reactive oxygen species (ROS) were measured in mice liver and brain homogenates after treatment with P. africanum extract compared to the control group, as well (1.9402 ±â€¯0.1200 vs 0.6699 ±â€¯0.062 arb. units for liver homogenates and 1.7325 ±â€¯01503 vs 0.3167 ±â€¯0.0403 arb.units, respectively). CONCLUSION: Therefore, P. africanum exhibited antioxidant and pro-oxidant properties which may explain its broad spectrum use in a wide variety of ailments.

(2,4,6-Trimethyl-phen-yl){2-[N-(2,4,6-trimethyl-phen-yl)formamido]-eth-yl}ammonium chloride.

In the title salt, C21H29N2O(+)·Cl(-), the benzene rings form a dihedral angle of 6.13 (1)°. In the crystal, N-H⋯Cl hydrogen bonds link the cations and anions into chains extending along the c axis.

1,3-Bis(1-adamant-yl)imidazolium tetra-chloridoferrate(III).

The crystal structure of the title compound, (C(23)H(33)N(2))[FeCl(4)], consists of 1,3-bis-(1-adamant-yl)imidazolium (BAIM) cations and tetra-hedral tetra-chloridoferrate(III) (TCF) anions. The BAIM cation possesses m symmetry, with the central imidazole ring and four C atoms of each terminal adamantyl group located on a mirror plane. The Fe and two Cl atoms of the TCF anion are also located on the mirror plane. The cyclo-hexane rings of the adamantyl groups adopt normal chair conformations.

1,3-Bis(2,6-diisopropyl-phen-yl)-4,5-dihydro-1H-imidazol-3-ium triiodide.

In the crystal structure of the title compound, C(27)H(39)N(2) (+)·I(3) (-), the imidazolidinium ring is perpendicular to a mirror plane which bis-ects the cation. The dihedral angle between the imidazolidinium ring and the benzene ring is 89.0 (2)°. The triiodide anion also lies on a mirror plane and is almost linear with an I-I-I bond angle of 178.309 (18)°.