No abstract

This study tests biodegradation resistance of a custom synthesized novel ethylene glycol ethyl methacrylate (EGEMA) with ester bond linkages that are external to the central polymer backbone when polymerized. Ethylene glycol dimethacrylate (EGDMA) with internal ester bond linkages and EGEMA discs were prepared in a polytetrafluoroethylene (PTFE) mold using 40 μl macromer and photo/co‐initiator mixture cured for 40 s at 1000 mW/cm2. The discs were stored in the constant presence of Streptococcus mutans (S. mutans) in Todd Hewitt Yeast + Glucose (THYE+G) media up to 9 weeks (n = 8 for each macromer type) and physical/mechanical properties were assessed. Initial measurements EGEMA versus EGDMA polymer discs showed equivalent degree of conversion (45.69% ± 2.38 vs. 46.79% ± 4.64), diametral tensile stress (DTS; 8.12± 2.92 MPa vs. 6.02 ± 1.48 MPa), and low subsurface optical defects (0.41% ± 0.254% vs. 0.11% ± 0.074%). The initial surface wettability (contact angle) was slightly higher (p ≤ .012) for EGEMA (62.02° ± 3.56) than EGDMA (53.86° ± 5.61°). EGDMA showed higher initial Vicker's hardness than EGEMA (8.03 ± 0.88 HV vs. 5.93 ± 0.69 HV; p ≤ .001). After 9 weeks of S. mutans exposure, EGEMA (ΔDTS—1.30 MPa) showed higher resistance to biodegradation effects with a superior DTS than EGDMA (ΔDTS—6.39 MPa) (p = .0039). Visible and scanning electron microscopy images of EGEMA show less surface cracking and defects than EGDMA. EGDMA had higher loss of material (18.9% vs. 8.5%, p = .0009), relative changes to fracture toughness (92.5% vs. 49.2%, p = .0022) and increased water sorption (6.1% vs. 1.9%, p = .0022) compared to EGEMA discs. The flipped external ester group linkage design is attributed to EGEMA showing higher resistance to bacterial degradation effects than an internal ester group linkage design methacrylate.

The fragment FOL7185 (compound 17) was found to be a hit against IspD and IspE enzymes isolated from bacteria, and a series of analogs containing the pyrazolopyrimidine core were synthesized. The majority of these compounds inhibited the growth of Burkholderia thailandensis (Bt) and Pseudomonas aeruginosa (Pa) in the Kirby-Bauer disk diffusion susceptibility test. Compound 29 shows inhibitory activity at 0.1 mM (32.2 µg/mL), which is comparable to the control compound kanamycin (48.5 µg/mL). Compound 29 also shows inhibitory activity at 0.5 mM against kanamycin resistant P. aeruginosa. Saturation transfer difference NMR (STD-NMR) screening of these compounds against BtIspD and BtIspE indicated that most of these compounds significantly interact with BtIspE, suggesting that the compounds may inhibit the growth of Bt by disrupting isoprenoid biosynthesis. Ligand epitope mapping of compound 29 with BtIspE indicated that hydrogens on 2,4-dichlorophenyl group have higher proximity to the surface of the enzyme than hydrogens on the pyrazolopyrimidine ring.

No abstract

Infectious diseases are a major cause of morbidity and mortality around the world, accounting for approximately 50% of all deaths in tropical countries. Despite remarkable progress in the field of microbiology, inability to control or mitigate, epidemics caused by drug-resistant microorganisms pose a serious health hazard to the global population. New therapeutic strategies must be developed as a global initiative for the prevention and control of infectious diseases. This study focuses on Kenyan medicinal plants and their activity against bacteria. Plant extracts obtained from seven Kenyan plants used in traditional medicine were screened for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Mycobacterium smegmatis. Extracts from all these plants showed antibacterial activity against at least one of the tested organisms at a concentration of 2 mg/mL. Chemical screening showed the presence of different classes of phytochemicals such as alkaloids, terpenes, tannins, in some active extracts.