Ring-opening polymerization of lactides and ε-caprolactone catalyzed by Zn(II) aryl carboxylate complexes supported by 4-pyridinyl schiff base ligands.

Synthesis and catalytic studies of aryl carboxylate Zn (II) complexes is reported. Reaction of substituted (E)-N-phenyl-1-(pyridin-4-yl)methanimine with a methanolic solution of Zn(CH3COO)2 and substituted aryl carboxylate co-ligands gave heteroleptic Zn(II) complexes; [Zn(C6H5COO)2(L1)]2 (1), [Zn(C7H7COO)2(L1)]2 (2), [Zn (4-F-C6H4COO)2(L1)]2 (3), [Zn(C6H5COO)2(L2)]2 (4), [Zn(C7H7COO)2(L2)]2 (5), [Zn (4-F-C6H4COO)2(L2)]2 (6), [Zn(C6H5COO)2(L3)]2 (7), [Zn(C7H7COO)2(L3)]2 (8), [Zn (4-F-C6H4COO)2(L3)]2 (9). The molecular structures of complexes 1 and 4 are dinuclear with the zinc atom in complex 1 adopting a distorted trigonal bipyramidal geometry in a bi-metallacycle while complex 4 is square pyramidal where all four benzoate ligands bridge the zinc metals in a paddle wheel arrangement. All complexes successfully initiated mass/bulk ring-opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) and lactides (LAs) monomers with or without alcohol co-initiators at elevated temperatures. Complexes 1, 4 and 6 containing the unsubstituted benzoate co-ligands were the most active in their triad; with complex 4 being the most active (k app) of 0.3450 h-1. The physicochemical properties of the polymerization products of l-lactide and rac-lactide in toluene revealed melting temperatures (Tm) between 116.58 °C and 188.03 °C, and decomposition temperatures between 278.78 °C and 331.32 °C suggestive of an isotactic PLA with a metal capped end.

Copper(II)-N-hydroxy-N,N'-diarylformamidine complexes: Synthesis, crystal structures, antibacterial and molecular docking studies.

A series of Cu(II) complexes were synthesized by using N-hydroxy-N,N'-diarylformamidine ligands: N-hydroxy-N,N'-(phenyl)formamidine (L1), N-hydroxy-N'-(4-methylphenyl)formamidine (L2), N-hydroxy-N,N'-(2,6-dimethylphenyl)formamidine (L3), N-hydroxy-N,N'-(2,6-diisopropylphenyl)formamidine (L4). Reaction of ligands L1-L4 with hydrated copper acetate furnished mononuclear Cu(II) complexes 1-4 with general formula [Cu-(L)2]. The molecular structures of complexes 3 and 4, as determined by single crystal X-ray diffraction, showed both to have square planar geometry with a near C2 symmetry. The antimicrobial potency of all four complexes was evaluated against three gram-(-) bacteria (S. typhimurium, P. aeruginosa, and E. coli) and two gram-(+) bacteria (Methicillin-resistant S. aureus (MRSA) and S. aureus), with ciprofloxacin as the reference drug. All tested complexes were inactive against gram-(+) bacteria strains except for complex 1, which displayed excellent activity when compared to the reference. Molecular docking studies showed that hydrogen bonding, pi-sigma and van der Waals interactions are prominent complex-protein connections, with complex 2 displaying good binding affinities with the studied biological targets.

Highlights of the 3rd ISCB Africa Student Council Symposium 2019 in Ghana.

The article elaborates on the program highlights of the 3rd African Student Council Symposium 2019. The one-day symposium was held in Kwame Nkrumah University of Science and Technology (KNUST), Ghana, on 11 November 2019 during the 6th joint international bioinformatics conference of the ISCB and ASBCB. It consisted of three sessions that included keynote talks by Prof Christine Orengo and Dr. Amel Ghouila, and seven selected student speaker talks from different areas of bioinformatics. The students benefited from networking and learning about ongoing research work by their peers hailing from different countries of the African region. The symposium proved to be pivotal to strengthen connections in the African bioinformatics student community.

Architecture and synthesis of P,N-heterocyclic phosphine ligands.

Diverse P,N-phosphine ligands reported to date have performed exceptionally well as auxiliary ligands in organometallic catalysis. Phosphines bearing 2-pyridyl moieties prominently feature in literature as compared to phosphines with five-membered N-heterocycles. This discussion seeks to paint a broad picture and consolidate different synthetic protocols and techniques for N-heterocyclic phosphine motifs. The introduction provides an account of P,N-phosphine ligands, and their structural and coordination benefits from combining heteroatoms with different basicity in one ligand. The body discusses the synthetic protocols which focus on P-C, P-N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands.

Determination of the chemical and functional properties of yam bean (Pachyrhizus erosus (L.) Urban) flour for food systems.

Many plant species that are suitable for food across the world are neglected and underutilized. In order to increase their diversified food uses and thus help enhance food and nutrition security, we studied the chemical and functional properties of Pachyrhizus erosus (yam bean), which is a neglected and underutilized legume species. The chemical properties of flour produced from the yam bean include 5.8% moisture content, 5.7% crude fat, 6.2% crude fiber, and 85% available carbohydrate, indicating appropriate shelf-stable flour, low fat, and abundant energy. The results also showed a reducing sugar content of 2.0% and 21.0% starch. Pasting temperature was 70.6°C with peak viscosity of 14.5 BU, which supports ease of cooking of the flour. The swelling power obtained was 752.9 g/100 g at 85°C with a solubility index of 54%. Water holding capacity (WHC) obtained for the flour was 363.88%, whereas swelling volume was 14.0 ml and makes the flour appropriate for the production of infant foods. The P. erosus flour therefore exhibits good functional and chemical properties that would make the flour quite suitable as a substitute for other flours in food systems.

Structural and functional effects of nucleotide variation on the human TB drug metabolizing enzyme arylamine N-acetyltransferase 1.

The human arylamine N-acetyltransferase 1 (NAT1) enzyme plays a vital role in determining the duration of action of amine-containing drugs such as para-aminobenzoic acid (PABA) by influencing the balance between detoxification and metabolic activation of these drugs. Recently, four novel single nucleotide polymorphisms (SNPs) were identified within a South African mixed ancestry population. Modeling the effects of these SNPs within the structural protein was done to assess possible structure and function changes in the enzyme. The use of molecular dynamics simulations and stability predictions indicated less thermodynamically stable protein structures containing E264K and V231G, while the N245I change showed a stabilizing effect. Coincidently the N245I change displayed a similar free energy landscape profile to the known R64W amino acid substitution (slow acetylator), while the R242M displayed a similar profile to the published variant, I263V (proposed fast acetylator), and the wild type protein structure. Similarly, principal component analysis indicated that two amino acid substitutions (E264K and V231G) occupied less conformational clusters of folded states as compared to the WT and were found to be destabilizing (may affect protein function). However, two of the four novel SNPs that result in amino acid changes: (V231G and N245I) were predicted by both SIFT and POLYPHEN-2 algorithms to affect NAT1 protein function, while two other SNPs that result in R242M and E264K substitutions showed contradictory results based on SIFT and POLYPHEN-2 analysis. In conclusion, the structural methods were able to verify that two non-synonymous substitutions (E264K and V231G) can destabilize the protein structure, and are in agreement with mCSM predictions, and should therefore be experimentally tested for NAT1 activity. These findings could inform a strategy of incorporating genotypic data (i.e., functional SNP alleles) with phenotypic information (slow or fast acetylator) to better prescribe effective treatment using drugs metabolized by NAT1.

Development and quality characteristics of shelf-stable soy-agushie: a residual by-product of soymilk production.

A process was developed for the production of a high-protein food ingredient, soy-agushie, from the residual by-product of soymilk production. The product, with a moisture content of about 6%, was evaluated for its quality characteristics and performance in traditional dishes. The protein content was about 26% with similar amino acids content as that of the whole soybean. Lysine remained high in the dehydrated product (6.57 g/16 g N). While over 60% of the original B vitamins content in the beans was extracted with the milk, high proportions of the minerals were found to be retained in the residual by-product. The process adequately reduced the trypsin inhibitor levels in the beans from 25 to 1.5 mg/g. High sensory scores were obtained for recipes developed with soy-agushie in traditional dishes. The scope of utilization of the soy-agushie could be widened to include several traditional foods and bakery products for maximum nutritional benefits.

Screening respiratory samples for detection of human rhinoviruses (HRVs) and enteroviruses: comprehensive VP4-VP2 typing reveals high incidence and genetic diversity of HRV species C.

Rhinovirus infections are the most common cause of viral illness in humans, and there is increasing evidence of their etiological role in severe acute respiratory tract infections (ARTIs). Human rhinoviruses (HRVs) are classified into two species, species A and B, which contain over 100 serotypes, and a recently discovered genetically heterogeneous third species (HRV species C). To investigate their diversity and population turnover, screening for the detection and the genetic characterization of HRV variants in diagnostic respiratory samples was performed by using nested primers for the efficient amplification of the VP4-VP2 region of HRV (and enterovirus) species and serotype identification. HRV species A, B, and C variants were detected in 14%, 1.8%, and 6.8%, respectively, of 456 diagnostic respiratory samples from 345 subjects (6 samples also contained enteroviruses), predominantly among children under age 10 years. HRV species A and B variants were remarkably heterogeneous, with 22 and 6 different serotypes, respectively, detected among 73 positive samples. Similarly, by using a pairwise distance threshold of 0.1, species C variants occurring worldwide were provisionally assigned to 47 different types, of which 15 were present among samples from Edinburgh, United Kingdom. There was a rapid turnover of variants, with only 5 of 43 serotypes detected during both sampling periods. By using divergence thresholds and phylogenetic analysis, several species A and C variants could provisionally be assigned to new types. An initial investigation of the clinical differences between rhinovirus species found HRV species C to be nearly twice as frequently associated with ARTIs than other rhinovirus species, which matches the frequencies of detection of respiratory syncytial virus. The study demonstrates the extraordinary genetic diversity of HRVs, their rapid population turnover, and their extensive involvement in childhood respiratory disease.

A one-year survey of Neisseria gonorrhoeae isolated from patients attending an east London genitourinary medicine clinic: antibiotic susceptibility patterns and patients' characteristics.

OBJECTIVES: To collect epidemiological data on gonococcal infection in an east London genitourinary medicine (GUM) clinic; to perform antibiotic susceptibility testing on Neisseria gonorrhoeae isolates and relate results to patient data; to assess the efficacy of current first-line antibiotic therapy for treating gonorrhoea. METHODS: Gonococcal isolates were collected from 113 patients attending the GUM clinic at Newham General Hospital over a one year period. Isolates (104) were tested for susceptibility to various antibiotics. Plasmid profiles were obtained for penicillinase producing gonococci (PPNG) and isolates exhibiting high-level tetracycline resistance (TRNG). Epidemiological information was collected from clinic attenders by routine note-taking. RESULTS: PPNG (16) accounted for 15% of isolates tested, only three being acquired outside the United Kingdom (U.K.). Plasmid typing showed three types of beta-lactamase-encoding plasmids were represented (2.9 MDa, 3.2 MDa and 4.4 MDa). Amongst the non-PPNG isolates, high-level chromosomal resistance to penicillin (CMRNG) was found in 3.5%, intermediate resistance in 57.5% and full susceptibility in 39%. One isolate showed decreased susceptibility to ciprofloxacin (MIC = 0.06 mg/l). Three PPNG isolates also possessed a 25.2 MDa plasmid and expressed high-level tetracycline resistance encoded by tetM. All isolates were susceptible to cefixime, cefotaxime, azithromycin and spectinomycin. Most gonorrhoea (90%) was seen in local residents. The male:female case ratio was 2:1 with homosexually-acquired gonorrhoea accounting for only 3.5% of the total. Most patients (96%) had acquired gonorrhoea in the U.K.. A past history of gonorrhoea was more frequent in male patients. Concurrent chlamydial infection was seen in 31% females and 16% males. CONCLUSIONS: The high PPNG rate supports a previous decision to change first-line therapy from amoxycillin with probenecid to ciprofloxacin. There was no evidence of clinical treatment failure with ciprofloxacin. Cefixime, cefotaxime, azithromycin and spectinomycin all appear to be suitable alternative therapies. Acquisition of gonorrhoea abroad was associated with isolates exhibiting penicillin resistance but such isolates were also obtained from patients infected locally and without a history of foreign travel.