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Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae)and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae)were assessed. The phytochemical studies led to the isolation of eight compounds (1–8)from Diospyros conocarpa and six compounds (6, 9–13)from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12)and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value < 10 μg/mL for crude extracts and < 1 μg/mL for pure compounds. The hexane/ethyl acetate (1:1)fraction of A.klaineanum root bark (AKERF1)and the hexane/ethyl acetate (1:1)fraction of A.klaineanum trunk bark (AKETF1)presented the strongest antiplasmodial activities with IC50 values of 0.4 and 4.4 μg/mL, respectively. Aridanin (4)and antrocarine A(11), as well as the crude extract of D.conocarpa roots (EDCR), AKERF1 and AKETF1 showed moderate trypanocidal effects. The crude extract of A.klaineanum root bark (AKER)and AKETF1 exhibited attractive activities on HIV-1 integrase with IC50 values of 1.96 and 24.04 μg/mL, respectively. The results provide baseline information on the use of A.klaineanum and D.conocarpa extracts, as well as certain components, as sources of new antiplasmodial, antitrypanosomal and anti-HIV drugs., SCOPUS: ar.j, info:eu-repo/semantics/published

This study was designed to assess the cytotoxicity, anti-HIV and antibacterial efficacy of various solvent extracts of roots, stem and leaves of Alchornea laxiflora, as well as five compounds isolated from its methanolic stem extract viz.; ellagic acid (1); 3-O-methyl-ellagic acid (2), 3-O-β- d -glucopyranosyl-β-sitosterol (3), 3-O-acetyl-oleanolic acid (4) and 3-O-acetyl-ursolic acid (5). The tested crude extracts were prepared from several solvent polarities including: hexane (Hex), chloroform (CHCl3), ethyl acetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O). The anti-HIV properties were assessed on HIV-1 subtype C integrase while the cytotoxicity was tested against Hela cells. The antibacterial activity was studied on a panel of pathogens including gastrointestinal, skin, respiratory and urinary-tract infection causing Gram positive bacteria viz.; Bacillus cereus (ATCC 11778), Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 25923) and Staphylococcus saprophyticus (ATCC 15305)] and Gram-negative bacteria, i.e., Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13883), Moraxella catarrhalis (ATCC 23246). All the tested samples were determined to be non-toxic due to the low inhibitions observed. The most potent anti-HIV activity was observed for the methanolic extract of A. laxiflora root (ALR4) with an IC50 value of 0.21 ng/ml, which was more active than chicoric acid used as reference drug (6.82 nM). Roots, stem and leaves of A. laxiflora extracts exhibited antibacterial activities against most of the Gram-positive bacteria with the minimum inhibitory concentrations (MIC) ranging between 50 and 63 μg/ml. Compounds 1–5 displayed antibacterial activities against S. saprophyticus with MIC values as low as 4 μg/ml. The results inferred from this study demonstrate the potential of A. laxiflora root as a source for new anti-HIV drugs and scientifically validate the traditional use of A. laxiflora in the treatment of gastrointestinal, skin, respiratory and urinary tract related infections. These results reaffirm the ethnopharmacological significance of African traditional medicines.

Phytochemical investigation of the methanol extracts of the twigs of Manniophyton fulvum has led to the isolation and characterization of three new pentacyclic triterpenoids, designated as 3α,28-dihydroxyfriedelan-1-one (1), manniotaraxerol A (3) and manniotaraxerol B (4), along with fourteen known compounds, 3α-hydroxy-1-oxofriedelane (2), betulinic acid (5), friedelin (S1), taraxerol (S2), a mixture of stigmasterol (S3) and β-sitosterol (S4), herranone (S5), docosanoic acid (S6), ursolic acid (S7), nasutin B (S8), bergenin (S9), stigmasterol-3-O-β- d- glucopyranoside (S10), 1,2-di-O-palmitoyl-3-O-(6-sulfo-α- d -quinovopyranosyl)glycerol (S11), and aridanin (S12). The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI and ESI-MS). 3α,28-Dihydroxyfriedelan-1-one (1), 3α-hydroxy-1-oxofriedelane (2), manniotaraxerol A (3), manniotaraxerol B (4), and betulinic acid (5) were evaluated against HeLa (human cervix adenocarcinoma) cancer cells. Manniotaraxerol A (3) showed weak in vitro cytotoxicity with a cell viability value of 49.3%. Betulinic acid (5) also showed significant cytotoxicity against HeLa cell with a cell viability value of 4.0%; the other compounds were inactive in this test.

Liposomes are considered as potential vehicles for the delivery of anti-tuberculosis drugs (ATBD) due to their rapid uptake by alveolar macrophages, where the mycobacterium often resides. This may provide macrophage-targeting effects that would be key to site specific ATBD delivery using pH-sensitive liposomes, considering the pH-gradient found in the phagocytotic pathway. In this study, isoniazid (INH) was conjugated to 4-hydroxy-benzaldehyde via a hydrazone bond to yield isonicotinic acid (4-hydroxy-benzylidene)-hydrazide (INH-HB). This conjugate was encapsulated in crude soybean lecithin liposomes using film hydration method. INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering, transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. The release of INH from IHL was evaluated in media of different pH using a dialysis method. The particle size, Zeta Potential and encapsulation efficiency of IHL were about 945 nm, −62 mV and 89% respectively. In media of pH 7.4, 6.4, 5.4 and 4.4; the IHL exhibited respectively 22, 69, 83 and 100% of release over 12 h. In addition to possible targeted delivery, this pH-dependent release behavior may be suitable for minimizing the loss of INH by leakage from liposomes. The characteristics of IHL are promising for potential site-specific delivery of ATBD.

Euphorbia grandicornis Blanc is widely utilized in traditional medicine for a variety of ailments including body pains associated with skin irritations, inflammation, and snake or scorpion bites. Compounds from E. grandicornis were characterized using spectroscopic techniques, NMR, IR, MS, and melting points and alongside the extracts were evaluated for in vitro anticancer activity against several cancer cell lines. The root extract afforded known, β-glutinol (1), β-amyrin (2), 24-methylenetirucalla-8-en-3β-ol (3), tirucalla-8,25-diene-3β,24R-diol (4), stigmasterol (5), sitosterol (6), and hexyl (E)-3-(4‑hydroxy-3-methoxyphenyl)-2-propenoate (7) based on their NMR spectroscopic data for the first report in E. grandicornis. The extracts and isolated compounds were evaluated for anticancer activities against hormone receptor-positive breast cancer (MCF-7), triple-negative breast cancer (HCC70), and non-tumorigenic mammary epithelial (MCF-12A) cell lines. The CH2Cl2 extract exhibited potent, cytotoxicity against MCF-7, HCC70, and MCF-12A cells. The aerial extract exhibited IC50 values of 1.03, 0.301, and 1.68 µg/mL, and root extract displayed IC50 values of 0.83, 0.83 and 3.98 µg/mL against MCF-7, HCC70, and MCF-12A cells, respectively. The root extract thus showed selectivity for the cancer cell lines over the non-cancerous control cell line (SI = 4.80). Hexyl (E)-3-(4‑hydroxy-3-methoxyphenyl)-2-propenoate (7) showed significant activity with IC50 values of 23.41, 29.45 and 27.01 µM against MCF-7, HCC70 and MCF-12A cells, respectively, suggesting non-specific cytotoxicity.

We have attempted to prolong the circulation time and increase the solubility of 5-Fluorouracil by complexing it with cyclodextrin and then further conjugating onto the gold nanoparticle to form 5Fu ICAu. The 1H NMR and molecular docking studies suggested that 5-Fu was included within the 2HP-β-CD cavity and H-5 proton probably serves as the binding site for stabilization of the inclusion complex. The 5Fu-ICAu showed higher cell inhibition rate when studied on MDA-MB-231 and MCF-7 breast cancer cell lines due to the enhanced permeability and retention (EPR) effect by allowing the selective accumulation of nanoparticles at tumor site. This unique system can serve as a novel nanocarrier for delivery of hydrophobic drugs.

Unexpected substituent-dependent regioselectivty challenges in the synthesis of C-benzylated (N-arylcarbamoyl)phosphonate esters have been resolved. The C-benzylated N-furfurylcarbamoyl derivative showed low micromolar PfLDH inhibition, while one of the C-benzylated N-arylcarbamoyl analogues was active against Nagana Trypanosoma brucei parasites which are responsible for African trypanosomiasis in cattle.

Ethnopharmacological relevance Tetracera potatoria Afzel. Exg. Don (Dilleniaceae) is a medicinal plant used traditionally in Africa for the treatment of tuberculosis related ailments and respiratory infections. The antibacterial activity of the medium polar extracts of T. potatoria leaves and stem bark was recently reported against Mycobacterium smegmatis (MIC 25 µg/mL) and M. aurum (65 µg/mL), two fast-growing Mycobacterium strains used as model micro-organisms for the more pathogenic strain Mycobacterium tuberculosis ( Fomogne-Fodjo et al., 2014 ). The aim of this study was consequently to isolate the compounds possibly contributing to this activity, and which may therefore be promising precursors to be used for the development of novel anti-TB drugs. Materials and methods T. potatoria medium polar extract [MeOH/DCM (1:1, v/v)] was fractionated sequentially with petroleum ether to which EtOAC and MeOH were gradually added to increase the polarity. The examination of T. potatoria extract and its fractions was guided by bioassays for anti-mycobacterial activity against M. smegmatis (ATCC 23246) and M. aurum (NCTC 10437) using the minimum inhibitory concentration (MIC) method. All the isolated compounds were structurally elucidated using spectroscopic techniques and evaluated for their anti-mycobacterial activity. Results Two novel secondary metabolites (1, 2) named tetraceranoate and N-hydroxy imidate-tetracerane, together with five known compounds [β-stigmasterol (3), stigmast-5-en-3β-yl acetate (4), betulinic acid (5), betulin (6) and lupeol (7)] were isolated and identified. Tetraceranoate exhibited the best activity against M. smegmatis with a minimum inhibitory concentration (MIC) of 7.8 µg/mL, while β-stigmasterol, betulinic acid and betulin showed appreciable anti-mycobacterial activity against both strains (MIC 15 µg/mL). Conclusion Seven compounds were isolated from the medium polar extract [MeOH/DCM (1:1, v/v)] of T. potatoria stem bark. Only tetraceranoate one of the isolated compounds showed antibacterial activity against M. smegmatis having efficacy as high as rifampicin (one of a three drug regimen recommended in the initial phase short-course anti-tuberculosis therapy). Thus, tetraceranoate might be an interesting target for systematic testing of anti-TB treatment and management. This research supports the use of T. potatoria in African traditional medicine for the treatment of tuberculosis related symptoms.

Cyclodextrins (CDs) have widely been used as component of drug delivery systems. However unmodified cyclodextrins are associated with cytotoxicity and poor water solubility thus limiting their use in pharmaceutical industry. The cationic-β-cyclodextrin (Cat-β-CD) polymer cores were synthesized using β-CD, epichlorohydrin and choline chloride via a one-step polycondensation process. The main aim of this study was to synthesize hierarchical nanoflowers composed of cationic-β-CD as polymeric core along with alginate and chitosan "petals" (Cat-β-CD/Alg-Chi nanoflowers) as carriers for oral delivery of 5-Fluorouracil (5-FU) via an ionic-gelation technique. The drug loading capacity, particle size, zeta potential and surface morphology of the synthesized nanoflowers were determined. The prepared nanoflowers were formed with an average size of 300nm and a zeta potential of +9.90mV with good encapsulation efficiency of up to 77.3%. In vitro release of 5-FU from the loaded nanoflowers showed controlled and sustained release compared to the inclusion complex alone. Cat-β-CD/Alg-Chi nanoflowers were assessed against L929 cells and found to be effectively inhibiting the growth of L929 cells in a concentration dependent manner.

A series of novel and readily accessible N-benzylated (N-arylcarbamoyl)alkylphosphonate esters and related compounds have been prepared as potential antimalarial agents. Bioassays reveal that some of these compounds exhibit promising activity against Plasmodium falciparum, and exhibit no significant growth inhibition of HeLa cells.

In this study, solvent dependence of electronic and nonlinear optical properties of a new Schiff base, 2-(((5-aminonaphthalen-1-yl)imino)methyl) phenol (DANOHB), has been investigated. Electronic and optical properties of the Schiff base studied using Uv-visible absorption and fluorescence spectroscopic techniques in solution show that the Schiff base exhibits fluorescence with a quantum yield of 0.21 and a Stokes shift of 39 nm. Quantum chemical calculations were performed on the Schiff base at time-dependent density functional level of theory using Becke-3-Lee-Yang-Parr method with 6-311++G(d,p) basis set. Solvent dependence of the excited state energies (EE), energy gap (ΔE), first-order (β) and second-order (γ) hyperpolarizabilities were studied in gas, cyclohexane and ethanol. The medium perturbed the energy levels which implies that the reactivity, activity and stability of the system are solvent sensitive. The γ is more than thirty times higher than urea (standard NLO material) and this property is further enhanced in less polar medium. Small ΔE and large hyperpolarizabilities obtained for this system suggest its good potential in photonics and nonlinear optical devices.

This work entails the study of electronic and nonlinear optical (NLO) properties of two synthesized Schiff bases namely 3-(((2-methyl-4-nitrophenyl)imino)methyl)phenol (MMP) and 3-(((2,4-dinitrophenyl)imino)methyl)phenol (DMP). Electronic absorption properties studied using UV–Visible spectrophotometry in ethanol reveal low-energy absorption indicating a low band gap. Time-dependent density functional calculations on their excited state properties with ωB97X-D/6-311++G(d,p) method show comparable transition energies and intensities with the experimental results. Energy gaps (ΔE) and NLO properties were evaluated from the frontier orbitals and hyperpolarizabilities (βtot and γ) in gas, cyclohexane and ethanol. Low ΔE obtained shows the potentials of the systems as organic semiconductor with remarkable band gap stabilization in ethanol. Higher βtot and γ than urea imply that the Schiff bases possess potentials for NLO applications. The solvatochromic shift in transition energies and perturbation of electronic properties reveal the solvent dependence of the electronic and optical properties of MMP and DMP due to solute-solvent interactions.

The recurrent development of resistance to antimicrobial agents threatens the ability for successful treatment of infectious diseases. Hydrophobic antibiotics such as rifampicin (Rif) are particularly affected due to poor bioavailability. On the other hand, proteins play important roles in drug delivery and release. Further, the combination of antimicrobials with therapeutic proteins and their encapsulation in liposomes seems a promising approach for improvement of antimicrobial efficacy. This study aimed to encapsulate Rif simultaneously with a large protein, Human Serum Albumin (HSA) in liposomes made from an inexpensive crude soy lecithin (CSL). Dual liposomes (Rif-HSA-lip) were prepared using a reverse phase evaporation method. The effect of lipid composition and HSA concentration on Rif loading was also investigated. Physicochemical properties, stability of Rif-HSA-lip and Rif release profiles were evaluated. A good encapsulation efficiency was observed (59% for Rif), despite the presence of bulky HSA. This paves the way for encapsulation strategies of other “biologics”. The in vitro release profile for Rif from the Rif-HSA-lip was improved and the freeze-dried formulation exhibited good shelf stability over liposomes with no HSA. The presence of HSA in the liposomal membrane is encouraging for potential targeted delivery studies. This study represents an illustrative example of co-loading of antibiotics and proteins into liposomes, which could lead to the development of novel therapeutic tools for tackling antimicrobial resistance.

A series of N2,N2′-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC50 = 3.5 μM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 μM) activity.

The photocatalytic degradation of eosin yellow over N, Ir co-doped TiO 2 was studied over an Ir loading concentration range of 0–1%. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV–vis, SEM, EDS and TEM. All the samples existed mainly in the anatase phase except for the N, Ir TiO 2 (1.0% Ir) which showed presence of some rutile phase. There was a gradual decrease in band gaps with increasing amount of Ir in all the samples which did not correlate with the visible light photoactivity. The materials consisted of nearly spherical particles of 20–30 nm in size. The photodegradation kinetic data were explained using the Langmuir–Hinshelwood model with most of the samples giving best fit in the first 90 min of the experiment. Initial rate constants were a function of Ir loadings as well as the phase composition of the samples. The N doped TiO 2 showed superior photoactivity with near complete dye degradation (99.6%) being realised in about 150 min. The N, Ir TiO (0.8% Ir) was the least effective.

An easily prepared solid state colorimetric probe for detecting the neurotransmitter dopamine (DA) was developed. The probe, in the form of an electrospun Nylon−6 (N6) nanofibre with embedded un−functionalized gold nanoparticles (UF−AuNPs) produces a clear colour change in the presence of a DA that is detectable by the naked eye. Characterisation of the nanofibre using UV/vis spectroscopy and electron microscopy (TEM) confirmed the formation of the AuNPs in the polymer solution, and that the AuNPs were completely encapsulated within the composite nanofibres before exposure to the analytes. The probe exhibited very high sensitivity towards DA resulting in colour change of the composite fibres from purple to navy blue/black even under low concentrations of DA. The probe was also selective to DA since the colour remained unchanged in the presence of commonly encountered interfering species such as ascorbic acid, uric acid, catechol, epinephrine and norepinephrine. Moreover, the colour change was observed rapid, occurring either immediately on contact with higher concentrations (5 x10 −4 M) or within about 3−5 min for the lower concentrations (e.g. 5 x10 −7 M). Since this probe does not require the use of any instruments, and is both rapid and stable over time, it can be applied in the field by an inexperienced person.

Poly(vinylidene fluoride) (PVDF) nanocomposite materials filled with a hybrid of organoclay and/or copper nanoparticles were successfully prepared. The synthesis of copper nanoparticles was achieved without the use of a conventional chemical stabilizer, only the organoclay surface serving as a stabilizing agent for the nanoparticles. The results showed the size of the nanoparticles decrease as the organoclay amount increases and less aggregation of the nanoparticles is observed when the particles are on the organoclay surface. Physical and chemical properties were probed using a host of analytical techniques. X-ray Diffraction (XRD) showed successful formation of copper nanoparticles as shown by peaks at 2θ = 460 of the orientation. The prepared hybrids were then used to produce the PVDF nanocomposites membrane sheets. The morphologies of the fabricated nanocomposites sheets were compared using scanning electron microscope (SEM). Atomic force microscope (AFM) showed the change in surface properties and roughness as the hybrid materials were added.. Addition of the hybrid into the PVDF polymer didn’t affect the chemical structure of the polymer as confirmed by the Fourier Transform Infrared Spectroscopy (FT-IR) even when the organoclay content was increased.

Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae) and Pentanisia prunelloides (Klotzsch ex Eckl. & Zeyh.) Walp. (Rubiaceae) are two medicinal plants used extensively in southern Africa to treat various ailments. Often, decoctions and infusions from these two plants are used in combination specifically for stomach ailments. The antimicrobial activities of the methanol and aqueous extracts of the rhizomes of the two plants, as well as the two active ingredients from the plants [(−)-epicatechin and palmitic acid] have been determined apart and in combination against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739) and Bacillus cereus (ATCC 11778). The minimum inhibitory concentration (MIC) values for the aqueous (0.50–16.00 mg/mL) and methanol (0.20–16.00 mg/mL) extracts independently demonstrated varied efficacies depending on the pathogen of study. When the two plants were combined in 1:1 ratios, synergistic to additive interactions (ΣFIC values 0.19–1.00) were noted. Efficacy for the two major compounds ranged between 0.13–0.63 mg/mL and mainly synergistic interactions were noted against E. faecalis and E. coli . The predominantly synergistic interactions noted between E. elephantina and P. prunelloides and major compounds, when tested in various ratios against these pathogens, provide some validation as to the traditional use of these two plants to treat bacterial gastrointestinal infections.

An improved photocatalyst consisting of a nanocomposite of exfoliated graphite and titanium dioxide (EG-TiO2) was prepared. SEM and TEM micrographs showed that the spherical TiO2 nanoparticles were evenly distributed on the surface of the EG sheets. A four times photocatalytic enhancement was observed for this floating nanocomposite compared to TiO2 and EG alone for the degradation of eosin yellow. For all the materials, the reactions followed first order kinetics where for EG-TiO2, the rate constant was much higher than for EG and TiO2 under visible light irradiation. The enhanced photocatalytic activity of EG-TiO2 was ascribed to the capability of graphitic layers to accept and transport electrons from the excited TiO2, promoting charge separation. This indicates that carbon, a cheap and abundant material, can be a good candidate as an electron attracting reservoir for photocatalytic organic pollutant degradation.

We present the application of a bismuth modified exfoliated graphite electrode in the detection of arsenic in water. Bismuth film was electrodeposited onto an exfoliated graphite (EG) electrode at a potential of −600 mV. The modification of EG resulted in an increase in the electroactive surface area of the electrode and consequently peak current enhancement in Ru(NH 3 ) 6 2+/3+ redox probe. Square wave anodic stripping voltammetry was performed with the modified electrode (EG-Bi) in As (III) solutions at the optimum conditions of pH 6, deposition potential of −600 mV and pre-concentration time of 180 s. The EG-Bi was able to detect As (III) to the limit of 5 μg L −1 and was not susceptible to many interfering cations except Cu (II). The EG-Bi is low cost and easy to prepare.

Buccal films (BFs) were prepared using a solvent casting method using the liposomal suspension as the dispersing medium. Optimization of some physical properties of the films containing different amounts of polymers was done using digital Vernier calliper and digital weighing balance. The physiochemical properties of the best optimized properties were characterized using Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscopy (SEM). Permeation study of the BFs composed of Carbopol (CP) alone and CP to Pluronic 127 (PF127) demonstrated better bio-adhesive properties than the films made of other polymers such as HPMC (hydroxyl propyl methyl cellulose) and HPMC-PF127. These CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2.16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50% for CP and 78% for CP-PF127. The cumulative amount of drug that permeated through the buccal epithelium after 24 h was about 66% from CP and 75% from CP-PF127.

Ethnopharmacological relevance Anthocleista vogelii Planch (Loganiaceae) is used in African Traditional Medicine for the treatment of pain and inflammatory disorders as well as sleeping sickness. Aim of the study To determine the in vivo anti-inflammatory and in vitro anti-trypanosomal activities of the extracts of A. vogelii stem bark and identify the phytochemical classes of the fractions responsible for the activities. Materials and methods The in vivo anti-inflammatory activity of the extracts was evaluated using the egg albumin-induced rat paw oedema model while the in vitro anti-trypanosomal activity was assessed on Trypanosoma brucei brucei. The in vitro cytotoxicity was assessed on HeLa (human cervix adenocarcinoma) cell line. Results The methanolic extract of A. vogelii stem bark, with 11.2% yield, gave LD50 > 5000 mg/kg. The n-hexane fraction of the extract contains steroids, terpenes and fatty acids and yielded non-cytotoxic terpenoidal column fraction with anti-trypanosomal IC50 of 3.0 μg/mL. The ethylacetate fraction at 100 mg/kg dose significantly (p Conclusion The study demonstrated that the anti-inflammatory and anti-trypanosomal activities of A. vogelii are probably due to non-cytotoxic terpenoids and validated the traditional use of A. vogelii in the treatment of inflammation and sleeping sickness.

The removal of natural organic matter (NOM) by polysulfone/β-cyclodextrin polyurethane (PSf/β-CDPU) mixed matrix membranes (MMMs) was investigated in order to establish the effect of the addition of β-cyclodextrin polyurethane (β-CDPU) in polysulfone (PSf) membrane on the rejection of NOM (humic acid) and the fouling resistance of MMMs. It was found that the effective pore sizes and molecular-weight-cut-off (MWCO) of hand-cast PSf membranes were improved by β-CDPU addition due to its large pore size and its conical structure being capable of allowing easy passage of water molecules. An increase in pure water flux was achieved with increase in β-CDPU concentration in the PSf MMMs. Furthermore, the pure water flux of the hand-cast PSf membrane improved from 12 to 137 l/m2 h when the applied pressure was increased from 0.62 to 2.41 MPa. The highest NOM removal efficiency achieved was 69% based on TOC measurements whereas a 76% NOM removal efficiency was attained as calculated from UV254 analysis. Fourier transform infrared (FT-IR) spectroscopy analyses confirmed the absence of OH and CH groups on all membranes after NOM rejection. This accounted for the increase in contact angle obtained after rejection tests. It is suggested that solution–diffusion mechanism is responsible for NOM filtration/rejection process. In addition, scanning electron microscopy (SEM) micrographs (after NOM rejection tests) revealed that the addition of β-CDPU in PSf resulted in improved antifouling properties based on the agglomeration of NOM on the membrane surfaces.

Chlorination disinfection by-products (DBPs) in water pose a health threat to humans and the aquatic environment. Their detection in water sources is therefore vital. Herein we present the detection of chloroform, a DBP, using a molecular fluorescent probe. The detection was based on the quenching of fluorescence of the probe by chloroform due to host–guest complex formation between β-cyclodextrin in the probe and the chloroform molecule. The stability constant for the host–guest complex was high at 3.825 × 104 M−1. Chloroform quenched the fluorescence of the copolymer the most compared to the other small chlorinated compounds studied, suggesting that the probe was more sensitive to chloroform, with a sensing factor of 0.35 compared to as low as 0.0073 for dichloromethane. There was no interference from other chloroalkanes on the quenching efficiency of chloroform. The probe was used to detect chloroform in dam water as well as in bottled water. Detection of chloroform in both water samples using the probe was possible without chemically treating the water samples which may introduce other pollutants.

This paper discusses the modification of polyamide thin-film composite (TFC) membranes with amino- and diethylamino-cyclodextrins (CDs). An in situ modification procedure was carried out using different concentrations of amino and diethylamino functionalised CDs (both α- and β-CDs) dispersed in m-phenylenediamine in water. These aqueous solutions were then reacted with trimesoyl chloride on polyethersulphone (PES) ultrafiltration support membranes through the interfacial polymerisation process. Contact-angle measurements demonstrate that the TFC membranes have improved hydrophilic properties due to additional OH functional groups of the CDs. The incorporation of the amino- and diethylamino-CDs within the membrane selective layer improved water permeability which was rationalised by the increased hydrophilicity and additional water channels in the modified membranes. Modified membranes exhibited significantly improved water permeability (33.92 ± 2.00 l m−2 h−1) and maintained a high NaCl rejection (99.21% ± 0.65%). The unmodified membranes, however, had a flux of 1.12 ± 0.5 l m−2 h−1 and a NaCl rejection of 95.69% ± 0.87%, at 6.89 bar. Membranes modified with diethylamino-CDs had a smoother surface while the unmodified membranes and membranes modified with amino-CDs had rough surfaces. The membranes modified with diethylamino-CDs had a compact and dense cross-linked polyamide thin-film structure while membranes modified with amino-CDs had a less compact cross-linked structure. This is due to the C C chain of the diethylamino functionality that allowed for a maximum exposure of the pendent group to the trimesoyl chloride during the interfacial polymerisation; as a result, the diethylamino-CDs were less subjected to steric hindrance than the amino-CDs. The pendent group of the amino-CDs was close to the molecule, making it difficult to reach during the interfacial polymerisation due to steric hindrance.

This paper discusses the solute and structural properties of polysulfone (PSf)/β-cyclodextrin (β-CD) polyurethane (PU) mixed-matrix membranes. Relative to a commercial PSf membrane, β-CD polyurethane (β-CDPU) was blended with PSf at concentration levels of 0–10% to prepare mixed-matrix membranes using a convectional phase-inversion technique. The surface morphology and the porous structure were evaluated by scanning electron microscopy (SEM). Dynamic mechanical analysis was used to determine the mechanical stability (stiffness) of the membranes: mixed-matrix membranes (MMMs) were found to be mechanically stable even at elevated temperatures (30–350 °C). Pure water sorption results show a Fickian diffusion mode mechanism for the PSf membrane ( n =0.50), PSf/5% β-CDPU shows an anomalous transport mechanism ( n =0.80) while the PSf/8 %β-CDPU and PSf/10% β-CDPU membranes followed a non-Fickian diffusion mode ( n =1.1). Pure water permeability and glucose rejection characteristics were carried out using a cross-flow system. These results reveal that pure water and solute permeability increase with an increase in pressure. The hydrophilicity and surface energy of the MMMs were determined using a sessile-drop (contact-angle) method. Mixed-matrix PSf/β-CDPU membranes were found to be more hydrophilic (

Synthetic methods for high-quality monodispersed nanoparticles in organic solvents are well-developed, but their biological applications are restricted due to the lack of water solubility and tailored surface chemistry. Herein we report on the synthesis of water soluble nanocrystals of CuS and CdS via the direct use of hydrophilic glucuronic and thioglycolic acid ligands. The employed method successfully derived water-soluble particles. The solubility test revealed that the glucuronic acid was a more effective ligand for rendering the nanocrystals water soluble. However the morphologies of the glucuronic acid-capped nanocrystals showed a higher degree of agglomeration thought to be as a result of the interaction between the OH groups. The thioglycolic acid ligand was less effective than the glucuronic acid and this was attributed to the non-aromatic nature of the ligand and the presence of fewer polar groups. Nevertheless, both the CuS and CdS thioglycolic acid-capped nanocrystal showed better dispersity.

Triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNT) were prepared in aprotic media and under anhydrous conditions by treating bromo-arylated-MWCNT with potassium diphenylphosphine (Tpp-MWCNT (1)), or with chlorodiphenylphosphine and butyllithium (Tpp-MWCNT (2)). Tpp-MWCNT were characterised by various techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The presence of the expected elements (C and P) is evident in the XPS spectra. Furthermore XPS results showed the presence of phosphorus with average concentrations of 0.7% and 2.6% in Tpp-MWCNT (1) and Tpp-MWCNT (2), respectively. TGA results revealed the following thermal decomposition order: Tpp-MWCNT (2)

Copper sulphide has interesting chemistry as it is capable of forming various stoichiometries and couple to that, it has excellent electrical, optical and magnetic properties. Its optical and magnetic attributes renders it a suitable candidate in a nano-regime for biological applications. We therefore report on the synthesis of single-phase, water soluble CuS nanoparticles using a simple colloidal route with alanine as the stabilizing and compatibility ligand. We further report on the optical and morphological properties of CuS nanoparticles as a function of temperature. The employed synthetic method successfully yielded water soluble CuS nanoparticles with a single crystal phase. The binding mode of alanine on the surface of the nanoparticles was shown to be pH dependent. The temperature had an effect on both the optical and morphological properties of the particle. The highest synthetic temperature (100 °C) resulted in particles with properties superior to the ones synthesized at lower temperatures and the surface coverage of the nanoparticles with alanine improved with increasing temperature.

Copper is one of the heavy metals that have been recognized as essential for living organisms in trace amounts as a cofactor for crucial enzymes. However, excess amount of this trace element can have serious health effects. It is therefore important to monitor Cu in drinking water as it can easily be overlooked due to its biological functions. An electrochemical technique using re-compressed exfoliated graphite modified with cobalt oxide nanoparticles was evaluated as an electrochemical sensor for the detection of Cu2+ in spiked water samples. The analysis involved an accumulation step at −500 mV while stirring followed by square wave-anodic stripping voltammetry (SW-ASV). The accumulation step resulted in the reduction of Cu2+ ions in solution onto the electrode surface which were subsequently stripped off on the second step resulting in an analytical current signal. The electrodeposition time and potential were first optimised and the best conditions were used to get a detection limit of 94 μg L−1. This sensor was used for Cu analysis in real water samples using standard addition method with percentage recoveries of between 99% and 101%.

Water-pollution problems worldwide have led to an acute shortage of clean and pure water for both domestic and human consumption. Various technologies and techniques are available for water treatment which includes the use of activated carbon. In this study activated carbons used for the removal of lead (II) ions from water samples were prepared from maize tassels (an agricultural waste residue) which were modified using physical and chemical activation. In the physical activation CO2 was used as the activating agent, while in chemical activation H3PO4 with an impregnation ratio ranging from 1 to 4 was employed. The maize tassel was pyrolysed at different temperatures ranging from 300 °C to 700 °C in an inert atmosphere for a period of 60 min and activated at 700 °C for 30 min. The effects of activation temperature, impregnation ratio and duration were examined. The resultant modified tassels were characterised by measuring their particle-size distribution, porosities, pore volume, and pore-size distribution using scanning electron microscopy (SEM). The activated carbon produced by chemical activation had the highest BET surface area ranging from 623 m2 g−1 to 1 262 m2 g−1. The surface chemistry characteristics of the modified tassels were determined by FT–IR spectroscopy and Boehm’s titration method. The experimental data proved that properties of activated carbon depend on final temperature of the process, impregnation ratio and duration of the treatment at final temperature. The adsorption studies showed that chemically prepared activated carbon performed better than physically prepared activated carbon.

The synthesis of a porous CNTs–CoO–TiO 2 nanocomposite was successfully achieved using a two step method. Samples were characterized with X-ray powder diffraction (XRD), to determine the crystallinity and phase of titania and cobalt in the composite as well as to estimate the particle size. Laser Raman spectroscopy was employed to confirm the nature of TiO 2 . Morphological properties such as, particle size and distribution of the particles on CNTs were probed using electron microscopic techniques (such as field emission electron microscopy (FESEM) and transmission electron microscopy (TEM)). Each of these microscopes was coupled to detectors to qualitatively measure the elemental composition of the nanocomposite by energy dispersive X-ray (EDX) analyses. Surface area measurements were determined by BET.

Managing the removal of Natural Organic Matter (NOM) or problematic components from water has become increasingly important. NOM is a heterogeneous mixture of organic compounds of human origin and derived from plant and microbial residues. The inadequate removal of NOM has a bearing on the capacity of the other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. In addition the action of certain disinfection processes has been shown to lead to the formation of harmful disinfection by-products (DBPs). Owing to the complexity, in composition and structure, of NOM, the techniques currently employed for its characterization have a number of limitations, both in terms of quantification and removal of the NOM within short periods of time. The dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC) and Fluorescence Emission Excitation Matrices (FEEM) were used to characterize NOM from various water samples collected around South Africa. Characterization results gave an indication of the character of NOM present in all the water samples. FEEM and UV–Vis results indicated that most of the water samples were aromatic in nature, since they had high hydrophobic and humic acid-like materials content. Generally, the characterization data indicated a varying composition of NOM amongst the various sampling points. The polarity rapid assessment method (PRAM) was then employed as a rapid NOM characterization tool. The characterization under PRAM is based on preferential adsorption of dissolved organic matter (DOM) fractions onto solid phase extraction (SPE) sorbents. The PRAM also allows the separation of DOM into fractions by polarity, hence reducing the molecular heterogeneity of NOM and thus aiding the removal of specific NOM fractions from water. The PRAM provided a quick characterization of the NOM character. However, DOC quantification by the PRAM analysis was hindered by excessive carbon leaching from the SPE cartridges. The BDOC method of analysis is based on the bacteria fixed on the biologically active sand and gives a ratio of the biodegradable NOM versus the non-biodegradable NOM. For the BDOC analysis, the percentage DOC removal for the samples ranged from 12% to 61%.

Indium is the choice of material for cryogenic joining applications. It is superior under repeated wide temperature excursions including extreme cold temperatures (below −55 °C) because of its excellent electrical conductivity and ductility at cryogenic temperatures. In particular, it is being considered for die/substrate attaches in low temperature SiGe BiCMOS modules for Martian and Lunar exploration. An efficient and systematic assessment was conducted to evaluate the reliability of indium solder under thermal fatigue and extended cold temperature mechanical fatigue conditions encountered in space exploration missions. In addition, fatigue failure sites, modes and mechanisms in indium solder at low temperature were investigated. A fatigue model was also calibrated for indium solder joint at cryogenic temperatures.

Branched multi-walled carbon nanotubes (b-CNTs) were deposited in a collar around the cathode in a DC arc-discharger in the presence of hydrogen and copper catalysts. Irrespective of the gas pressure or oxidation state of the catalysts, common morphologies (compartmentalization/segmentation, branching, partial metal filling) were observed when raw samples from the collar were analyzed by TEM. EDX confirmed the presence of metallic copper in the tips, in the branches and in the partially filled b-CNTs. These features have led to the proposal of a common growth model, in which reactions between metallic copper nanoparticles and gaseous carbon species that were formed in hydrogen, were used to rationalize the various CNT structures synthesised.

Natural organic matter (NOM) consists of a complex mixture of naturally occurring organic compounds. Although it is not considered toxic by itself, NOM present during water disinfection may result in the formation of disinfection by-products (DBPs), many of which are either carcinogenic or mutagenic. Although it is difficult to completely characterize NOM due to its complex and large structure, a consideration of its structure is necessary for a better understanding of the mechanism of NOM removal from water. In this study, water from the Vaalkop water treatment plant was characterized for its NOM composition by fractionation over ion-exchange resins. Fractionation at different pH with different resins resulted in the isolation of the neutral, basic and acidic fractions of both the hydrophobic and hydrophilic NOM. The hydrophilic basic fraction was found to be the most abundant fraction in the source water. Each of the isolated NOM fractions were percolated through cyclodextrin (CD) polyurethanes, resulting in an adsorption efficiency of between 6% and 33%. The acidic fractions were the most adsorbed fractions by the CD polyurethanes, while the neutral fractions being the least adsorbed. The water samples were then subjected to an ozonation regime at the treatment plant and then fractionated as before. As expected there were decreases of the neutral and basic fractions after ozonation. The application of CD polyurethanes to the fractions after ozonation resulted in a removal efficiency of up to 59%, nearly double that of the non-treated sample. Also, in the case of the ozone pre-treated samples, it was mainly the hydrophilic basic fraction which was removed. All the fractions were subjected to a chlorination test to determine the trihalomethane (THM) formation potential. All six NOM fractions resulted in THM formation, but the hydrophilic basic fraction was found to be the most reactive and formed the highest THM concentration. The effect of the combination of ozone and cyclodextrin polyurethane resulted in a relatively good capability to remove NOM from water as evidenced by an up overall 88% reduction of the hydrophilic acidic fraction.

The prevalence of nitrosamines, especially N-nitrosodimethylamine (NDMA), was monitored in three South African water supplies. NDMA a disinfection by-product (DBP) and potent carcinogen, has recently been detected in many drinking water supplies internationally. Besides direct industrial or human-derived contamination, nitrosodimethylamine can be formed through a chemical reaction between monochloroamine and an organic based compound such as dimethylamine which is frequently detected in surface water. It has been suggested that chloramination of surface waters with a high concentration of dissolved organic carbon (DOC) could result in elevated NDMA formation. Growing evidence suggests that NDMA occurs more frequently and at higher concentrations in drinking water systems that practise chloramination compared to systems that use chlorination. In gauging the extent of water contamination by nitrosamines in water distribution systems, especially NDMA, water samples collected from three different water treatment plants that practise chemical drinking water disinfection were qualitatively analysed for the presence of nitrosamines. Solid phase microextraction (SPME) was employed in the extraction of nitrosamines from the water samples and gas chromatography–mass spectrometry (GC–MS), was used in the analysis of the water samples. Trace amounts of NDMA were detected at one of the water treatment plants and in the distribution network. The application of water-insoluble cyclodextrin (CD) polymers in the removal of nitrosamines and potential amine precursors from the water samples was tested. Quantitative removal of NDMA (based on peak area) from the water samples was achieved which suggests that in the water treatment train the use of these nanosponges can be applied in the mitigation of trace contaminants such as NDMA.

Insoluble cyclodextrin polymers co-polymerized with multi-walled carbon nanotubes were synthesized by polymerizing β-cyclodextrin with acid-functionalized multi-walled carbon nanotubes and diisocyanate linkers; hexamethylene- and toluene-2,4-diisocyanate. The polymers are useful in removing some organic pollutants from water, and we now report the full characterization of these polymers using infrared spectroscopy (IR), Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and thermal techniques such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymers could be synthesized as either powders or amorphous solids. Results of the IR analysis showed the presence of functional groups such as C O, C C, C H and C O, indicating that polymerization indeed took place. Characterization of the polymers by scanning electron microscopy and BET analysis showed that these polymers had a spongy appearance indicating a hierarchical pore structure. Incorporation of small amounts (

Quantum-dot sized range generation 2 and 3 poly(propylene imine) dendrimer encapsulated NiFe nanoalloy have been successfully synthesised via the co-complexation route. The HRTEM micrograph for the nanoalloy showed an average size range of 1 to 4 nm; while energy dispersive spectroscopy confirmed the presence of Ni and Fe as the alloy. The dendrimer capped NiFe nanoalloy exhibited photoluminescence properties and FTIR analysis confirmed the presence of the dendrimer as the capping agent.

We report here the formation of silicon carbide (SiC) nanorods from organic–inorganic hybrid of the commercially available lignin and sol-gel derived nanosized silica. The SiC nanorods were identified by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface morphology shows the formation of continuous nanorods of diameter in the range of 50–200 nm. The X-ray diffraction (XRD) pattern show peaks at 2 θ = 35.5° and 60.2° indicate the formation of β-SiC and a sharp peak at 2 θ = 22.1° suggests the presence of unreacted crystalline silica (crystoballite). The characteristic vibration of SiC at 791 cm − 1 in Fourier transform infrared spectroscopy (FTIR) was also observed.