Application of Three Compounds Extracted from Cynodon dactylon against Streptococcus mutans Biofilm Formation to Prevent Oral Diseases

Streptococcus mutans bacteria form a biofilm called plaque that causes oral diseases, including tooth decay. Therefore, inhibition of biofilm formation is essential to maintaining good oral health. The health and nutritional benefits of Cynodon dactylon are well documented, but very little is known about its use to treat against oral diseases. The aim of this study was to detect the adhesion strength of the S. mutans bacterial biofilm in 100 cases in the Rajshahi region and evaluate the inhibitory activity of different compound extracts of C. dactylon on the S. mutans bacterial biofilm by determining the composition of isolated compounds using phytochemical analysis. Nuclear magnetic resonance (NMR) spectroscopy confirmed that three specific compounds from C. dactylon were discovered in this study: 3,7,11,15 tetramethyl hexadec-2-4dien 1-o1, compound 3,7,11,15 tetramethylhexadec-2-en-1-o1 from phytol derivatives, and stigmasterol. Results indicated that the compound of 3,7,11,15-tetramethyl-hexadec-2-en-1-ol exhibited higher antibiofilm activities on S. mutans than those of the other compound extracts. A lower level of minimum inhibitory concentration was exposed by 3, 7, 11,15 tetramethyl hexadeca-2-en-1-o1 (T2) on S. mutans at 12.5 mL. In this case, the compound of 3,7,11,15 tetramethyl hexadec 2en-1-o1 was used, and patients showed a mean value and standard error reduced from 3.42 ± 0.21 to 0.33 ± 0.06 nm. The maximum inhibition was (80.10%) in the case of patient no. 17, with a value of p < 0.05 found for S. mutans to which 12.5 μL/mL ethyl acetate extract was applied. From these findings, it may be concluded that C. dactylon extracts can be incorporated into various oral preparations to prevent tooth decay.

Fucoidan-Containing, Low-Adhesive Siloxane Coatings for Medical Applications: Inhibition of Bacterial Growth and Biofilm Development

The deposition of low-adhesive siloxane coatings is a current trend for the non-toxic control of bacterial growth and biofilm formation. Total elimination of biofilm formation has not been reported so far. The aim of this investigation was to study the ability of a non-toxic, natural, biologically active substance, such as fucoidan, to inhibit bacterial growth on similar medical coatings. The fucoidan amount was varied, and its impact on the bioadhesion-influencing surface characteristics, as well as on bacterial cell growth, was investigated. The inclusion of up to 3-4 wt.% brown algae-derived fucoidan in the coatings increases their inhibitory effect, more significantly on the Gram-positive bacterium S. aureus than on the Gram-negative bacterium Escherichia coli. The biological activity of the studied siloxane coatings was ascribed to the formation of a low-adhesive, biologically active surface top layer consisting of siloxane oil and dispersed water-soluble fucoidan particles. This is the first report on the antibacterial activity of fucoidan-containing medical siloxane coatings. The experimental results give reason to expect that relevantly selected, natural biologically active substances can be efficient in the non-toxic control of bacterial growth on medical devices and, as a result, medical device-associated infections.

The critical role of the aldehyde dehydrogenase PauC in spermine, spermidine, and diaminopropane toxicity in Pseudomonas aeruginosa: Its possible use as a drug target

The opportunistic human pathogen Pseudomonas aeruginosa exhibits great resistance to antibiotics; so, new therapeutic agents are urgently needed. Since polyamines levels are incremented in infected tissues, we explored whether the formation of a toxic aldehyde in polyamines degradation can be exploited in combating infection. We cloned the gene encoding the only aminoaldehyde dehydrogenase involved in P. aeruginosa polyamines-degradation routes, PaPauC, overexpressed this enzyme, and found that it oxidizes 3-aminopropionaldehyde (APAL) and 3-glutamyl-3-aminopropionaldehyde (GluAPAL) - produced in spermine (Spm), spermidine (Spd), and diaminopropane (Dap) degradation, as well as 4-aminobutyraldehyde (ABAL) and 4-glutamyl-4-aminobutyraldehyde (GluABAL) - formed in putrescine (Put) degradation. As the catalytic efficiency of PaPauC with APAL was 30-times lower than with GluAPAL, and GluAPAL is predominantly formed, APAL will be poorly oxidized 'in vivo'. We found polyamines-induced increases in the PaPauC activity of cell crude-extracts and in the expression of the PapauC gene that were diminished by glucose. Spm, Spd, or Dap, but not Put, were toxic to P. aeruginosa even in the presence of other carbon and nitrogen sources, particularly to a strain with the PapauC gene disrupted. APAL, but not GluAPAL, was highly toxic even to wild-type cells, suggesting that its accumulation, particularly in the absence of, or low, PaPauC activity is responsible for the toxicity of Spm, Spd, and Dap. Our results shed light on the toxicity mechanism of these three polyamines and strongly support the critical role of PaPauC in this toxicity. Thus, PaPauC emerges as a novel potential drug target whose inhibition might help in combating infection by this important pathogen.

Tailoring Nano-Porous Surface of Aligned Electrospun Poly (L-Lactic Acid) Fibers for Nerve Tissue Engineering

Despite the existence of many attempts at nerve tissue engineering, there is no ideal strategy to date for effectively treating defective peripheral nerve tissue. In the present study, well-aligned poly (L-lactic acid) (PLLA) nanofibers with varied nano-porous surface structures were designed within different ambient humidity levels using the stable jet electrospinning (SJES) technique. Nanofibers have the capacity to inhibit bacterial adhesion, especially with respect to Staphylococcus aureus (S. aureus). It was noteworthy to find that the large nano-porous fibers were less detrimentally affected by S. aureus than smaller fibers. Large nano-pores furthermore proved more conducive to the proliferation and differentiation of neural stem cells (NSCs), while small nano-pores were more beneficial to NSC migration. Thus, this study concluded that well-aligned fibers with varied nano-porous surface structures could reduce bacterial colonization and enhance cellular responses, which could be used as promising material in tissue engineering, especially for neuro-regeneration.

Anti-FIM and Anti-FHA Antibodies Inhibit Bordetella pertussis Growth and Reduce Epithelial Cell Inflammation Through Bacterial Aggregation

The pertussis vaccination is highly recommended for infants, children, and pregnant women. Despite a high coverage of vaccination, pertussis continues to be of public health concern as a re-emerging infectious disease. The mechanism by which vaccine-elicited anti-pertussis antibodies mediate direct bactericidal effects is poorly understood. In this study, we showed that the interaction of B. pertussis with A549 epithelial cells induce release of biological factors which enhance bacteria growth. Complement-depleted antisera from vaccine-immunized guinea pigs or monoclonal antibodies targeting FHA and FIM mediate bacteria aggregation and elicit bactericidal effects. Our in vitro results indicated that aggregation of bacteria through anti-FIM and anti-FHA specific antibodies is one of the major biological mechanisms to clear bacterial infections and restore epithelial cell survival in vitro. Our data also indicates that the anti-pertussis antibodies reduce secretion of proinflammatory chemokines and cytokines by preventing interaction of B. pertussis with host cells. The results of this study not only demonstrate mechanism of action of anti-FIM and anti-FHA antibodies, but also opens translational applications for potential therapeutic approaches or development of analytical assays such as in vitro potency assays.

Assessment of the Antimicrobial Activity of Olive Leaf Extract Against Foodborne Bacterial Pathogens

Olive leaf extract (OLE) has been used traditionally as a herbal supplement since it contains polyphenolic compounds with beneficial properties ranging from increasing energy levels, lowering blood pressure, and supporting the cardiovascular and immune systems. In addition to the beneficial effects on human health, OLE also has antimicrobial properties. The aim of this work was to investigate the antimicrobial effect of OLE against major foodborne pathogens, including Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis. Our results demonstrated that at a concentration of 62.5 mg/ml, OLE almost completely inhibited the growth of these three pathogens. In addition, OLE also reduced cell motility in L. monocytogenes, which correlated with the absence of flagella as shown by scanning electron microscopy. Moreover, OLE inhibited biofilm formation in L. monocytogenes and S. Enteritidis. Taken together, OLE, as a natural product, has the potential to be used as an antimicrobial to control foodborne pathogens.

Structural alteration in the pore motif of the bacterial 20S proteasome homolog HslV leads to uncontrolled protein degradation

In all cells, ATP-dependent proteases play central roles in the controlled degradation of short-lived regulatory or misfolded proteins. A hallmark of these enzymes is that proteolytic active sites are sequestered within a compartmentalized space, which is accessible to substrates only when they are fed into the cavity by protein-unfolding ATPases. HslVU is a prototype of such enzymes, consisting of the hexameric HslU ATPase and the dodecameric HslV protease. HslV forms a barrel-shaped proteolytic chamber with two constricted axial pores. Here, we report that structural alterations of HslV's pore motif dramatically affect the proteolytic activities of both HslV and HslVU complexes. Mutations of a conserved pore residue in HslV (Leu88 to Ala, Gly, or Ser) led to a tighter binding between HslV and HslU and a dramatic stimulation of both the proteolytic and ATPase activities. Furthermore, the HslV mutants alone showed a marked increase of basal hydrolytic activities toward small peptides and unstructured proteins. A synthetic peptide of the HslU C-terminal tail further stimulated the proteolytic activities of these mutants, even allowing degradation of certain folded proteins in the absence of HslU. Moreover, expression of the L88A mutant in Escherichia coli inhibited cell growth, suggesting that HslV pore mutations dysregulate the protease through relaxing the pore constriction, which normally prevents essential cellular proteins from random degradation. Consistent with these observations, an X-ray crystal structure shows that the pore loop of L88A-HslV is largely disordered. Collectively, these results suggest that substrate degradation by HslV is controlled by gating of its pores.