Leucinostatin-A loaded nanospheres: characterization and in vivo toxicity and efficacy evaluation

Secondary Metabolites of Purpureocilliumlilacinum

Fungi can synthesize a wealth of secondary metabolites, which are widely used in the exploration of lead compounds of pharmaceutical or agricultural importance. Beauveria, Metarhizium, and Cordyceps are the most extensively studied fungi in which a large number of biologically active metabolites have been identified. However, relatively little attention has been paid to Purpureocillium lilacinum. P. lilacinum are soil-habituated fungi that are widely distributed in nature and are very important biocontrol fungi in agriculture, providing good biological control of plant parasitic nematodes and having a significant effect on Aphidoidea, Tetranychus cinnbarinus, and Aleyrodidae. At the same time, it produces secondary metabolites with various biological activities such as anticancer, antimicrobial, and insecticidal. This review attempts to provide a comprehensive overview of the secondary metabolites of P. lilacinum, with emphasis on the chemical diversity and biological activity of these secondary metabolites and the biosynthetic pathways, and gives new insight into the secondary metabolites of medical and entomogenous fungi, which is expected to provide a reference for the development of medicine and agrochemicals in the future.

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

Fighting tuberculosis: old drugs, new formulations

This review reports the state of the art on innovative drug delivery strategies designed for antitubercular chemotherapeutics. The introduction contains the fundamental biological background concerning tuberculosis and a review of the current antitubercular therapy, and is followed by a critical report of the micrometric and nanometric particulate systems designed and investigated to improve tuberculosis chemotherapy.

In vitro and in vivo antitrypanosomal activities of three peptide antibiotics: leucinostatin A and B, alamethicin I and tsushimycin

In the course of our screening for antitrypanosomal compounds from soil microorganisms, as well as from the antibiotics library of the Kitasato Institute for Life Sciences, we found three peptide antibiotics, leucinostatin (A and B), alamethicin I and tsushimycin, which exhibited potent or moderate antitrypanosomal activity. We report here the in vitro and in vivo antitrypanosomal properties and cytotoxicities of leucinostatin A and B, alamethicin I and tsushimycin compared with suramin. We also discuss their possible mode of action. This is the first report of in vitro and in vivo trypanocidal activity of leucinostatin A and B, alamethicin I and tsushimycin.

Delivery systems: a vaccine strategy for overcoming mucosal tolerance?

Antigens administered via the oral and, to a lesser extent, the nasal route are potentially able to invoke tolerance, resulting in a nonreactive immune response. This has been a hurdle for mucosal vaccine development and yet the desire to induce protective local and systemic responses, with pain-free and more convenient products, has been the impetus driving mucosal vaccine R&D. Nevertheless, few mucosal vaccines have reached the marketplace and products are still treated with caution, particularly where live organisms are utilized. In this review, we examine the use of delivery systems with adjuvant properties as key components in a vaccine strategy that does not require the use of live vectors to overcome tolerance and have exemplified their success in mucosal vaccines, concentrating on the nasal and oral routes of administration.

Ketoprofen poly(lactide-co-glycolide) physical interaction

The aim of this work was to provide an understanding of the interaction occurring between ketoprofen and poly(lactic-co-glycolic acid) (PLGA) that leads to polymer plasticization. Experimental glass transition temperature (Tg) values were fitted with the theoretical ones predicted by the Fox and Gordon-Taylor/Kelley-Bueche equations. PLGA films containing different amounts of ketoprofen (KET) were prepared by solvent casting and characterized by scanning electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry evidenced that KET acted as a plasticizer in a similar biphasic way in both end-capped and uncapped PLGA. At KET contents of 20% to 35%, depending on the investigated polymer, the Tg was around 23 degrees C. Higher KET amounts did not lower further the Tg, and the excess of drug was found to crystallize into the polymeric matrix. Experimental Tg's deviated negatively from the predicted ones probably because of hydrogen bonding. The FTIR spectra of the films, loaded with different amounts of KET, showed a shift to higher wavenumbers for the peaks at 1697 and 1655 cm(-1) confirming the presence of some interactions, probably hydrogen bonds between the ketoprofen carboxylic group and the PLGA carbonyl groups along the polymer backbone. The hydrogen bonding between KET and PLGA is probably responsible for KET plasticizing effect. KET behaving as a lubricant may disrupt polymer chain-chain interactions, removing additional barriers to bond rotation and chain mobility.

Preparation and antibacterial activity evaluation of rifampicin-loaded poly lactide-co-glycolide nanoparticles

Biodegradable polymers such as poly lactide-co-glycolides (PLGA) have been considered for the preparation of nanoparticles (NPs). In this study, rifampicin (RIF)-loaded PLGA NPs were fabricated by an emulsification/solvent diffusion method. The effect of several variables on the NPs' characteristics were evaluated, including the amount of RIF, amount of the poly vinyl alcohol as surfactant, and internal-phase volume and composition. The RIF encapsulation efficacy and the particle size distribution were optimized by varying these parameters. NPs were spherical with a relatively monodispersed size distribution. The effect of nanoencapsulation of RIF on the antibacterial activity of RIF against gram-positive and gram-negative bacteria was evaluated. It was shown that RIF NPs could considerably improve the RIF antibacterial efficacy.

Probing the initial events in the spontaneous emulsification of trans-anethole using dynamic NMR spectroscopy

The spontaneous emulsification of alcoholic solutions of trans-anethole (t-A) in water is investigated using EXSY and DOSY NMR techniques. The system investigated (5-10 mM t-A in 5% EtOH/H2O solution) is exceptional in providing sharp, clearly resolved signals for both t-A that is dissolved in the aqueous phase (free t-A) and t-A that is incorporated in aggregates (3-6 nm diameter) thus allowing both fractions to be probed simultaneously. This feature is utilized to explore the initial events that occur during the spontaneous emulsification process. Upon mixing, the majority of the t-A (ca. 75%) undergoes nucleation to form small aggregates (ca. 10 nm diameter), while 15% (corresponding to [t-A] = 7.5 x 10(-4) M) is dissolved in the aqueous phase. The kinetic rates governing the exchange process between aggregated and free t-A are found to be time-dependent and slow on the NMR time scale (k = 0.8-2 s(-1)). DOSY experiments indicate that the initially formed small aggregates undergo rapid coalescence to form larger droplets. Ostwald ripening of these droplets at the expense of the remaining small aggregates is responsible for the subsequent, slower time-evolution of the system.

Novel functionalized biodegradable polymers for nanoparticle drug delivery systems

We have prepared and screened a library of novel functionalized polymers for development of nanoparticle drug delivery systems. The polymer backbone consisting of two ester-linked, nontoxic, biological monomers, glycerol and adipic acid, was prepared using a hydrolytic enzyme. The specificity of the chosen enzyme yields a linear polymer with one free pendant hydroxyl group per repeat unit, which can be further functionalized. This protocol gives control over the backbone polymer molecular weight, together with the ability to incorporate various amounts of different fatty acyl substituents. These functionalized polymers are able to self-assemble into well-defined small particles of high homogeneity with a very low toxicity. They are able to incorporate a water soluble drug, dexamethasone phosphate, with a high efficiency and drug loading which varies with the polymer specification. The above characteristics strongly suggest that these polymers could be developed into useful nanoparticulate drug delivery systems.

Particle size and temperature effect on the physical stability of PLGA nanospheres and microspheres containing Bodipy

The purpose of this study was to investigate the effect of particle size, storage temperature, and duration of storage on the physical stability and morphology of polylactic-co-glycolic acid (PLGA) nanospheres and microspheres. PLGA nanospheres and microspheres containing the fluorescent dye, Bodipy, were prepared in varying sizes by controlling the method and degree of agitation during the emulsification phase of preparation. Mean diameters of the particles were measured by dynamic light scattering. To evaluate the effect of storage temperature and duration of storage on the extent of aggregation, nanospheres and microspheres were stored at 4 degrees C, 25 degrees C, 37 degrees C, and 50 degrees C for 6 days and then monitored using both confocal and scanning electron microscopy. The mean +/- SD diameters of PLGA particles containing Bodipy were: 266.9 +/- 2.8, 351.6 +/- 1.8, 988.8 +/- 14.1, and 1865.9 +/- 67.0 nm. The extent of aggregation of the particulate delivery system decreased as the mean diameter increased, and increased as the storage temperature increased. The maximum extent of aggregation was observed with the smallest (266 nm) nanospheres. Microspheres did not aggregate. The aggregation of nanospheres was significantly reduced by introducing an additional evaporation step during preparation, suggesting that migration of residual dichloromethane from within the nanospheres may have dissolved the PLGA on the surface. The extent of aggregation of nanospheres increased as the temperature was increased from 4 degrees C to 50 degrees C, and decreased as particle size increased. To avoid aggregation, PLGA nanospheres should be stored at 4 degrees C.