The Prohost Effect of Antimicrobial Agents as a Predictor of Clinical Outcome

Deciphering the Antimicrobial Potential of Taxus wallichiana Zucc: Identification and Characterization Using Bioassay-Guided Fractionation

Taxus wallichiana Zucc. is a high valued medicinal plant and has been mainly studied for its anti-cancer properties. However, research on its other important biological activities, such as its antimicrobial potential, still needs attention. The focus of the present study is to investigate the antimicrobial activity of secondary metabolites of T. wallichiana needles against 3 different groups of microorganisms, i. e., bacteria, actinobacteria, and fungi. Bioactive compounds from T. wallichiana needles were separated through column chromatography, and, TLC-bioautography. Mobile phases were optimized using Snyder's selectivity triangle. Antimicrobial spots were fractionated and compounds were identified by gas chromatography-mass spectroscopy (GC/MS) and liquid chromatography-mass spectrometry (LC/MS). Functional groups were characterized using Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (NMR) was used to identify the molecular structures. GC/MS and LC/MS data analysis confirm the presence of fatty acids (arachidic acid, behenic acid, palmitic acid, and stearic acid), vitamins (nicotinamide), and alkaloids (cinchonine, timolol), aminobenzamides (procainamide), carbocyclic sugar (myoinositol), and alkane hydrocarbon (hexadecane), having antimicrobial activity in the needles of T. wallichiana. To the best of our knowledge, this is the first report on the isolation and characterization of antimicrobial compounds from the needles of Taxus wallichiana (Himalayan yew). The data obtained from the present study will be supportive to the new drug discoveries in modern medicine with various combinations of medicinal plant's active constituents that can be used for curing many diseases.

Jellyfish Bioprospecting in the Mediterranean Sea: Antioxidant and Lysozyme-Like Activities from Aurelia coerulea (Cnidaria, Scyphozoa) Extracts

Marine invertebrates represent a vast, untapped source of bioactive compounds. Cnidarians are represented by nearly 10,000 species that contain a complex mixture of venoms, collagen, and other bioactive compounds, including enzymes, oligosaccharides, fatty acids, and lipophilic molecules. Due to their high abundance in coastal waters, several jellyfish taxa may be regarded as candidate targets for the discovery of novel lead molecules and biomaterials and as a potential source of food/feed ingredients. The moon jellyfish Aurelia coerulea is one of the most common jellyfish worldwide and is particularly abundant in sheltered coastal lagoons and marinas of the Mediterranean Sea, where it first appeared—as an alien species—in the last century, when Pacific oyster cultivation began. In the present study, the antioxidant and lysozyme antibacterial activities associated with extracts from different medusa compartments—namely the umbrella, oral arms, and secreted mucus—were investigated. Extracts from the oral arms of A. coerulea displayed significant antioxidant activity. Similarly, lysozyme-like activity was the highest in extracts from oral arms. These findings suggest that A. coerulea outbreaks may be used in the search for novel cytolytic and cytotoxic products against marine bacteria. The geographically wide occurrence and the seasonally high abundance of A. coerulea populations in coastal waters envisage and stimulate the search for biotechnological applications of jellyfish biomasses in the pharmaceutical, nutritional, and nutraceutical sectors.

The Jellyfish Rhizostoma pulmo (Cnidaria): Biochemical Composition of Ovaries and Antibacterial Lysozyme-like Activity of the Oocyte Lysate

Jellyfish outbreaks in marine coastal areas represent an emergent problem worldwide, with negative consequences on human activities and ecosystem functioning. However, potential positive effects of jellyfish biomass proliferation may be envisaged as a natural source of bioactive compounds of pharmaceutical interest. We investigated the biochemical composition of mature female gonads and lysozyme antibacterial activity of oocytes in the Mediterranean barrel jellyfish Rhizostoma pulmo. Chemical characterization was performed by means of multinuclear and multidimensional NMR spectroscopy. The ovaries of R. pulmo were mainly composed of water (93.7 ± 1.9% of wet weight), with organic matter (OM) and dry weight made respectively of proteins (761.76 ± 25.11 µg mg-1 and 45.7 ± 1.5%), lipids (192.17 ± 10.56 µg mg-1 and 9.6 ± 0.6%), and carbohydrates (59.66 ± 2.72 µg mg-1 and 3.7 ± 0.3%). The aqueous extract of R. pulmo gonads contained free amino acids, organic acids, and derivatives; the lipid extract was composed of triglycerides (TG), polyunsaturated fatty acids (PUFAs), diunsaturated fatty acids (DUFAs), monounsaturated fatty acids (MUFAs), saturated fatty acids (SFAs), and minor components such as sterols and phospholipids. The R. pulmo oocyte lysate exhibited an antibacterial lysozyme-like activity (mean diameter of lysis of 9.33 ± 0.32 mm corresponding to 1.21 mg/mL of hen egg-white lysozyme). The occurrence of defense molecules is a crucial mechanism to grant healthy development of mature eggs and fertilized embryos (and the reproductive success of the species) by preventing marine bacterial overgrowth. As a corollary, these results call for future investigations for an exploitation of R. pulmo biomasses as a resource of bioactive metabolites of biotechnological importance including pharmaceuticals and nutrition.

Biological evaluation of 3-hydroxybenzyl alcohol, an extrolite produced by Aspergillus nidulans strain KZR-132

AIMS

The aim of the study was to purify and characterize a bioactive compound from Aspergillus nidulans strain KZR-132 and its biological evaluation.

METHODS AND RESULTS

A bioactive extolite was purified from A. nidulans strain KZR-132, and its chemical structure was elucidated as 3-hydroxylbenzyl alcohol (3-HBA) based on ¹ H and ¹³ C NMR, FT-IR and mass spectroscopic analysis. The antimicrobial efficacy of 3-HBA was established against Gram-positive, Gram-negative bacteria and different Candida strains. It also showed promising antibiofilm activity against various tested microbial strains. Reactive oxygen species induced by 3-HBA treatment on different Candida strains killed most of the cells and showed necrotic effect. It also exhibited dose-dependent antioxidant and anti-inflammatory activities.

CONCLUSIONS

This bioactive extrolite produced by A. nidulans isolated from a niche habitat was demonstrated to possess significant biotechnological and pharmacological potential since it exhibited broad-spectrum antimicrobial and antibiofilm activities which are reported for the first time.

SIGNIFICANCE AND IMPACT OF THE STUDY

The overall study demonstrates that 3-HBA produced by A. nidulansKZR-132 is a promising bioactive metabolite and possibly can function as a pharmacologically suitable broad-spectrum antimicrobial drug candidate against various dreaded human-related bacterial and fungal pathogens.

Effect of moxifloxacin on production of proinflammatory cytokines from human peripheral blood mononuclear cells

The effects of moxifloxacin, a new methoxyfluoroquinolone, on the production of proinflammatory cytokines from human peripheral blood mononuclear cells (PBMCs) were evaluated. Moxifloxacin inhibited the production of tumor necrosis factor alpha (TNF-alpha) and/or interleukin-6 (IL-6) by PBMCs stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), and heat-killed bacteria in a concentration-dependent manner without cytotoxic effects. The addition of moxifloxacin reduced the population of cells positive for CD-14 and TNF-alpha and for CD-14 and IL-6 among the LPS- or LTA-stimulated PBMCs. By Western blot analysis, moxifloxacin pretreatment reduced the degradation of IkappaBalpha in LPS-stimulated PBMCs. In conclusion, moxifloxacin could interfere with NF-kappaB activation by inhibiting the degradation of IkappaBalpha and reduce the levels of production of proinflammatory cytokines.

In vitro effects of ciprofloxacin and roxithromycin on apoptosis of jurkat T lymphocytes

Ciprofloxacin (CPFX) and roxithromycin (RXM) induced apoptosis of activated Jurkat T cells in vitro. CPFX showed concentration-dependent acceleration of apoptosis of activated Jurkat T cells by enhancing the expression of FasL and activities of caspase-3 and -8. RXM accelerated cell death, enhanced expression of FasL and caspase-3 but not caspase-8, and did not show the concentration dependency.

Influence of cefodizime on pulmonary inflammatory response to heat-killed Klebsiella pneumoniae in mice

Encapsulated Klebsiella pneumoniae strains frequently induce fatal nosocomial pneumonia. Cefodizime (CEF) as an antibiotic is suspected to enhance host resistance against various microbial invasions through interactions with bacteria and host cells. To investigate the influence of CEF on the pulmonary response to Klebsiella that does not merely result from direct bacterial clearance by the drug, we inoculated mice with heat-killed fluorescein isothiocyanate-labeled K. pneumoniae. CEF upregulated (P < 0.01) the early Klebsiella-induced secretion of tumor necrosis factor alpha, as well as the number (P < 0.01) and phagocytic efficacy (P < 0.001) of alveolar macrophages. By contrast, the late polymorphonuclear neutrophil recruitment (P < 0.05) and levels of interleukin-1 alpha (IL-1alpha) (P < 0.05) and IL-6 (P < 0.05) were reduced. The stimulation of an early immune response by CEF followed by late reduction in inflammation may be beneficial against bacterial pneumonia.

Immunomodulating effects of HMR 3004 on pulmonary inflammation caused by heat-killed Streptococcus pneumoniae in mice

We investigated the influence of HMR 3004, a new ketolide antibiotic, on the pulmonary inflammation induced by heat-killed fluorescein isothiocyanate-labeled Streptococcus pneumoniae. HMR 3004 downregulated (P < 0.05) the pneumococcus-induced release of interleukin-6 (IL-6), IL-1beta, and nitric oxide in bronchoalveolar lavage fluid. The drug limited (P < 0.05) neutrophil recruitment to lung tissues and alveoli but did not interfere with phagocytosis. HMR 3004 totally abrogated lung edema. By reducing inflammation in addition to possessing antimicrobial properties, HMR 3004 may participate in improving the outcome of bacterial pneumonia.

Reduction by cefodizime of the pulmonary inflammatory response induced by heat-killed Streptococcus pneumoniae in mice

It has recently become apparent that overwhelming inflammatory reactions contribute to the high mortality rate associated with pneumococcal infection in immunocompetent hosts. Cefodizime (CEF) is an antibiotic that seems to be endowed with immunomodulating properties. To investigate the influence of CEF on the pulmonary inflammatory response induced by Streptococcus pneumoniae, we infected mice with repeated intranasal inoculations of 10(7) CFU of heat-killed fluorescein isothiocyanate-labeled bacteria, which are insensitive to the killing properties of the drug. CEF downregulated but did not abolish the strong polymorphonuclear leukocyte (PMN) recruitment induced by S. pneumoniae. PMN recruitment was not primarily mediated by leukotriene B4 in this model. The drug did not interfere with intrinsic mechanisms of phagocytosis by PMNs and alveolar macrophages. CEF totally abrogated the pneumococcus-induced tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) secretion in bronchoalveolar lavage fluid. The drug also prevented IL-6 release in lung homogenates and partly inhibited TNF-alpha, but it did not interfere with IL-1alpha secretion in the lungs of infected mice. The fractional and selective downregulation of inflammatory cells and cytokines by CEF suggests cell-specific and intracellular specific mechanisms of interaction of the drug. The immunomodulatory properties of CEF may help restrain excessive inflammatory reactions, thus contributing to the reported good clinical efficacy of the drug against lower respiratory tract infections.

Selecting antibacterial agents for the control of surgical infection: mini-review

An analysis of the recent literature on the control of surgical infections confirms the role of antimicrobial agents which guarantee valid perioperative antisepsis in both clean and clean-contaminated surgery. Current chemotherapy is able to check serious postoperative infectious complications by reducing the risk of septic shock with use of a glycopeptide-aminoglycoside-betalactam combination together with anti-inflammatory drugs.

Antibacterial agents--phagocytes: new concepts for old in immunomodulation

The possibility that antibacterial agents, primarily directed against microorganisms, also modify host functions is widely recognized. While a knowledge of these non-antimicrobial effects of antibiotics, sometimes considered as 'side-effects', is necessary to prevent antibiotic-associated toxicity, the development of drugs derived from antibacterial agents for use in non-infectious diseases (e.g. motilins and antidiabetic drugs) is a new field of therapeutic research. Interactions between antibacterial drugs and the immune system may contribute to therapeutic efficacy in infectious diseases [1,2]. The immune system itself is a complex pyramid of redundant cellular factors/humoral effectors/mediators, whose fine regulation is just beginning to be unraveled. Phagocytes, ubiquitous and multifaceted cells are key components of cellular immunity, being involved both in immediate defences against non-self targets (pathogens, tumour cells, exogenous molecules, etc.) and in the regulation and triggering of specific immune responses. They are thus, prime targets of immune response modifiers. This review reconsiders the widely explored problem of interactions between antibacterial agents and phagocytes, focusing on future prospects in both infectious and non-infectious diseases.