Biodegradation of plastics by white-rot fungi: A review.

Plastic pollution is one of the most environmental problems in the last two centuries, because of their excessive usage and their rapidly increasing production, which overcome the ability of natural degradation. Moreover, this problem become an escalating environmental issue caused by inadequate disposal, ineffective or nonexistent waste collection methods, and a lack of appropriate measures to deal with the problem, such as incineration and landfilling. Consequently, plastic wastes have become so ubiquitous and have accumulated in the environment impacting ecosystems and wildlife. The above, enhances the urgent need to explore alternative approaches that can effectively reduce waste without causing harsh environmental consequences. For example, white-rot fungi are a promising alternative to deal with the problem. These fungi produce ligninolytic enzymes able to break down the molecular structures of plastics, making them more bioavailable and allowing their degradation process, thereby mitigating waste accumulation. Over the years, several research studies have focused on the utilization of white-rot fungi to degrade plastics. This review presents a summary of plastic degradation biochemistry by white-rot fungi and the function of their ligninolytic enzymes. It also includes a collection of different research studies involving white-rot fungi to degrade plastic, their enzymes, the techniques used and the obtained results. Also, this highlights the significance of pre-treatments and the study of plastic blends with natural fibers or metallic ions, which have shown higher levels of degradation. Finally, it raises the limitations of the biotechnological processes and the prospects for future studies.

Submerged cultivation, characterization and in vitro antitumor activity of polysaccharides from Schizophyllum radiatum.

Production of polysaccharides by white-rot-fungi in submerged cultivation has several advantages due to process control. This work deals with the submerged cultivation, extraction and antitumor activity of polysaccharides from a wild strain of Schizophyllum radiatum isolated from a tropical forest of Colombia. The mushroom was cultivated in laboratory conditions, and classified by classical and molecular taxonomy. Submerged cultivation was performed in a bioreactor of 5 L using a ligninolytic residue as substrate. The fermentation conditions were 30 ± 1 °C, pH 4.5, 300 rpm and 1.5 vvm of air for 4 days. The yields were 16.8 g/L (w/v) of biomass, and after extraction, 0.6 g/L of water-soluble exopolysaccharide (SEPS) and 2.01 % (w/w) of water-soluble intrapolysaccharide (SIPS) were obtained. In each extract total carbohydrate, glucans and protein contents were determined. Also, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), high performance liquid chromatography with refraction index detection (HPLC-RI), high performance gel permeation chromatography (HPGPC) and Nuclear Magnetic Resonance (NMR) analysis were performed. Results indicated that SEPS and SIPS are heteropolysaccharides with amorphous structure and high molecular weights. Antitumor and immunostimulant activity was evaluated in different cancer cell lines. The results suggest these polysaccharides have direct and indirect antitumor activity activating immune cells such as macrophages. These findings enhance our knowledge about new sources of fungal metabolites that serve as adjuvant, cheaper and less harmful alternatives to cancer treatment.

Biotechnological production, characterization and in vitro antitumor activity of polysaccharides from a native strain of Lentinus crinitus.

This work deals with the submerged cultivation, extraction and antitumor activity of polysaccharides from Lentinus crinitus. The fungus was isolated from a tropical forest (Antioquia, Colombia), cultivated in laboratory conditions, and classified by classical and molecular taxonomy. Then, it was cultivated in a bioreactor of 5 L using a ligninolytic residue as substrate. The fermentation conditions were 30 ±â€¯1 °C, pH 4.5, 300 rpm and 1.5 vvm for 4 days. The yields of fermentation were 20 g/L of biomass. After extraction, 0.65 g/L of water-soluble exopolysaccharide (LEPS) and 3.3 mg/100 g of water-soluble intrapolysaccharide (LIPS) were obtained. In each extract total carbohydrate, glucans and protein contents were determined. Also, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray diffractometry (XRD), high performance liquid chromatography with refraction index detection (HPLC-RI) and high performance gel permeation chromatography (HPGPC) analysis for characterization were performed. The antitumor activity was evaluated and polysaccharides not only showed anti-proliferative activity in breast cancer cells but also they activate J774 macrophages as evidenced by the increase of nitric oxide and tumor necrosis factor-α (inducers of tumor cell apoptosis). Our findings suggest that polysaccharides can activate macrophages to release nitric oxide (NO) and tumor necrosis factor alpha (TNF-α), which directly blocks cancer cell growth. These findings enhance our knowledge about new sources of fungal metabolites that serve as coadjuvant, cheap and less harmful alternatives to cancer treatment.

Chitosan-Acrylic Polymeric Nanoparticles with Dynamic Covalent Bonds. Synthesis and Stimuli Behavior.

Drug delivery represents one of the most important research fields within the pharmaceutical industry. Different strategies are reported every day in a dynamic search for carriers with the ability to transport drugs across the body, avoiding or decreasing toxic issues and improving therapeutic activity. One of the most interesting strategies currently under research is the development of drug delivery systems sensitive to different stimuli, due to the high potential attributed to the selective delivery of the payload. In this work, a stimuli-sensitive nanocarrier was built with a bifunctional acrylic polymer, linked by imine and disulfide bonds to thiolate chitosan, the latter being a biopolymer widely known in the field of tissue engineering and drug delivery by its biodegradability and biocompatibility. These polymer nanoparticles were exposed to different changes in pH and redox potential, which are environments commonly found inside cancer cells. The results proof the ability of the nanoparticles to keep the original structure when either changes in pH or redox potential were applied individually. However, when both stimuli were applied simultaneously, a disassembly of the nanoparticles was evident. These special characteristics make these nanoparticles suitable nanocarriers with potential for the selective delivery of anticancer drugs.

Producción de polisacáridos a partir de Ganoderma sp., aislado en la región andina / Polysaccharides production by Ganoderma sp., isolated from andina region

Los hongos de la podredumbre blanca de la madera, como Ganoderma sp., han sido utilizados alrededor del mundo por sus propiedades medicinales, ya que poseen compuestos bioactivos como los triterpenos y los polisacáridos. Esta investigación se centra en la producción de polisacáridos a escala de laboratorio y de biorreactor, a partir de Ganoderma sp., aislado en la región andina, utilizando como sustrato un residuo ligninocelulósico de la industria agrícola suplementado con glucosa y lactosa. Se encontró que las condiciones más adecuadas y viables para la producción de biomasa y polisacáridos de Ganoderma sp., son: medio Bio 3%, 10 días de incubación, lactosa 10%, pH= 4,0, T= 30°C, 300 rpm y 1 vvm. Los ensayos espectrofotométricos (fenol ácido sulfúrico y escaneo en UV entre 200 y 400 nm), enzimáticos y de infrarrojo permitieron identificar y cuantificar glucanos y algunas proteínas en los extractos, sugiriendo que los hongos endógenos de la región Andina poseen características propias de metabolitos importantes a nivel medicinal. Adicionalmente se demostró el efecto antiproliferativo en células J774, especialmente del extracto GIPSi (IC50= 86%) similar al efecto generado por estándares comerciales.

The white rot wood fungi like Ganoderma has been used worldwide because it has triterpenoids and polysaccharides with medicinal properties. This research focuses on determining the polysaccharide production conditions and laboratory and bioreactor scale, from the aforementioned fungi, isolated in the Andean region. It was used agricultural lignin-residue supplemented with glucose and lactose. We found that the most appropriate and feasible production conditions for biomass and Ganoderma polysaccharides are: Bio medium 3%, t = 10 days, 10% lactose, pH= 4,0, T= 30°C, 300 rpm and 1 vvm. The spectrophotometric, enzymatic and IR tests; allowed us to identify the presence of polysaccharides and proteins in some extracts, suggesting that the endogenous mushrooms in the Andean region also have characteristics similar to those of metabolites that are important in medicine. Additionally, the antiproliferative effect was observed in J774 sarcoma cells, particularly GIPSi extract (IC50= 86%) similar to the effect generated by commercial standards.

Synthesis and characterization of surface-modified PBLG nanoparticles for bone targeting: in vitro and in vivo evaluations.

In this study, poly(γ-benzyl-l-glutamate) (PBLG) polypeptide derivatives were synthesized by ring-opening polymerization of amino acid N-carboxyanhydride using selected amine-terminated initiators. Alendronate, a targeting moiety that has a strong affinity for bone, was conjugated to PBLG. Monomethoxy polyethylene glycol (PEG) was used for a hydrophilic layer on the surface of the nanoparticles (NPs) to avoid reticuloendothelial system uptake. NPs were prepared by nanoprecipitation technique not only for PBLG or PBLG-PEG but also for composite polymers with different ratios. Fluorescein isothiocyanate would be attached to the NPs as a labeling agent. The size and morphology of NPs were evaluated by dynamic laser light scattering and transmission electron microscopy, and were found to be in a useful range (less than 80 nm) for bone-targeted drug delivery. In addition, the PEGylation of NPs was supported by isothermal titration calorimetry analysis. The bone-targeting potential of NPs was evaluated in vitro by calcium binding and hydroxyapatite affinity assays, and in vivo by fluorescent imaging experiments on rats. The targeted NPs showed bright fluorescent labeling in femur tissue. These results demonstrated the possibility of optimized NPs prepared with new PBLG derivatives to accumulate in bone successfully.

Pegylation of poly(γ-benzyl-L-glutamate) nanoparticles is efficient for avoiding mononuclear phagocyte system capture in rats.

Poly(γ-benzyl-L-glutamate) (PBLG) derivatives are synthetic polypeptides for preparing nanoparticles with well controlled surface properties. The aim of this paper was to investigate the biodistribution of pegylated PBLG in rats. For this purpose, nanoparticles were prepared by a nanoprecipitation method using mixtures of different PBLG derivates, including a pegylated derivate to avoid mononuclear phagocyte system uptake. The morphology, size distribution, and surface charge of the nanoparticles were investigated as a function of the amount of polymer employed for the preparation. Moderately polydispersed nanoparticles (polydispersity index less than 0.2) were obtained. Their size increased with polymer concentration. The zeta potential values were negative whatever the formulations. The availability of polyethylene glycol chains on the nanoparticles' surface was confirmed by measuring the decrease in bovine serum albumin adsorption. For in vivo distribution studies, pegylated and nonpegylated nanoparticles were prepared with polymer mixtures containing PBLG-fluorescein isothiocyanate and imaged by fluorescence microscopy to measure their accumulation in liver and spleen tissues of rats after intravenous administration. Injection of stealth formulations resulted in negligible fluorescence in liver and spleen compared with nonpegylated formulations, which suggests that these nanoparticles are promising candidates as a stealth-type long-circulating drug carrier system and could be useful for active targeting of drugs while reducing systemic side effects.

Synthesis and characterization of functionalized poly(gamma-benzyl-L-glutamate) derivates and corresponding nanoparticles preparation and characterization.

For being fully efficient a targeted delivery system should associate simultaneously multiple functionalities. In this context, the association of several polymeric materials to form composite multifunctional particles can be foreseen. The present work describes the synthesis of different derivates of poly(gamma-benzyl-L-glutamate) and their use for the preparation of nanoparticles exhibiting different properties, including surface hydrophilization by PEG, fluorescence imaging by FITC and target recognition through easy attachment of desired ligands by using the avidin-biotin interaction, after the nanoparticles preparation. Four PBLG derivates were successfully obtained by ring-opening polymerization (ROP) of NCA, using various initiators corresponding to the molecules to be introduced into the copolymers. Further, nanoparticles smaller than 100 nm could be prepared using a nanoprecipitation technique and the presence of the active moieties introduced within the particles as well as their functionality has been checked. Very interestingly, it has been shown that biotin molecules could be efficiently introduced at the surface of the nanoparticles, which (for 75% of the theoretical amount) could be engaged in a complexation with avidin. It is suggested that this strategy offers the possibility to easily decorate these nanoparticles with various recognition ligands for specific targeting applications by using the well known biotin-avidin sandwich technique.

Elucidation of the complexation mechanism between (+)-usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase-solubility diagram experiments.

In the present work the complexation mechanism between (+)-usnic acid (UA) and cyclodextrins (CDs) has been investigated by isothermal titration calorimetry (ITC) and phase-solubility diagrams using pH as a tool for modifying the molecule ionization. ITC experiments have been employed to evaluate the stoichiometry of interaction (N), affinity constants (K), and thermodynamic parameter variation associated with complexation between (+)-UA and alpha-, beta-, HP-beta-, SBE-beta-, and gamma-CD. It was shown that (+)-UA did not interact with alpha-CD and tended to interact more favorably with gamma-CD (K = 1030 M(-1), DeltaG = -17.18 kJ x mol(-1)) than beta-CD (K = 153 M(-1), DeltaG = -12.46 kJ x mol(-1)) forming 1:1 complexes. It was also demonstrated using ITC and solubilization experiments that chemical modifications of the parent beta-CD resulted in stronger and more spontaneous interactions (K = 281 M(-1), DeltaG = -13.97 kJ x mol(-1) for SBE-beta-CD and K = 405 M(-1), DeltaG = -14.87 kJ x mol(-1) for HP-beta-CD). Analysis of the thermodynamic data suggested that van der Waals forces and hydrogen bonds were responsible for the formation of complexes with a predominance of van der Waals forces. Finally, pH induced modifications of (+)-UA ionization provided important informations relative to the topology of the interaction between (+)-UA molecule and the gamma-CD cavity, which were confirmed by molecular modeling.