Irene Satiko Kikuchi

Sterilization by pure oxygen plasma and by oxygen-hydrogen peroxide plasma: an efficacy study.

Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 400 W) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods.

About the Sterilization of Chitosan Hydrogel Nanoparticles

In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

Effect of bixin and norbixin on the expression of cytochrome P450 in HepG2 cell line

Bixin and norbixin are the main components of annatto, which is extracted from Bixa orellana and largely used as natural colorant in the food and pharmaceutical industries. Annatto can enhance CYP1A and CYP2B activity in rats; however, the inducer effect has not been investigated in human cell lines. In this study, the ability of bixin and norbixin to induce the cytochrome P450 (CYP) enzymes was assessed in HepG2 human hepatoma cell line. HepG2 cells were treated with bixin and norbixin, and the expression of the CYP genes quantified by real‐time reverse transcription polymerase chain reaction (RT‐PCR). Expression of CYP1A1 and CYP1A2 was significantly increased by bixin treatment, while CYP2B6, 2C9, 2E1 and 3A4 were unaffected. Cells were treated with norbixin showed no inducer effect. The results suggest that the inducer potential of annatto is attributed to bixin, but not to norbixin, despite their similarities in molecular structure.

The Microbial Quality Aspects and Decontamination Approaches for the Herbal Medicinal Plants and Products: An in-Depth Review.

BACKGROUND The present review article provides an overview of the published literature concerning microbial quality of medicinal plants and products and their decontamination methods. It is important to analyze different aspects regarding the cultivation, growing, harvesting, storage, manufacturing, and decontamination of medicinal plant products. Herbal medicinal plants bear a massive microbial load leading to contamination and mycotoxin, which needs to be considered, and properly controlled using suitable sterilization and decontamination methods. METHODS The main focus of this review is on the definition, advantages, disadvantages and applications of decontamination methods, particularly to show that one must consider the characteristics of the initial sample to be decontaminated. RESULTS The effects of various methods (ozone, plasma, irradiation) on medicinal herbs and products treated for microbiological decontamination are dependent on factors related to microbial load (i.e., nature and amount of initial contamination), herb/product matrix (i.e., complexity of chemical composition, physical state - solid or liquid) and treatment conditions (i.e., time, irradiation dose, absence or presence of oxygen). In addition, it is important to accept some loss of the chemical compounds, while decreasing microbial load to acceptable limits according to official herbal pharmacopoeias and literature, thus ensuring a final product with quality, safety and therapeutic efficacy. CONCLUSION The conclusion, which comes from this contribution, is that herbal medicine has more contaminants than a chemically welldefined drug, thus, good manufacturing practices should be followed.

Hydrogel based Drug Delivery Systems: A Review with Special Emphasis on Challenges Associated with Decontamination of Hydrogels and Biomaterials

BACKGROUND Many researches involving the development of new techniques and biomaterials to formulate a suitable drug delivery system and tissue engineering have been conducted. The majority of published literature from these researches emphasizes the production and materials characterization. The safety aspect of hydrogels and biomaterials is a major constraint in their biological applications. OBJECTIVE The present review article aimed to summarize various literatures that encompass the difficulties encountered with decontamination and sterilization methods in the preparations of biomaterials and especially hydrogels for biological applications. METHOD We searched for original and review articles from various indexed journals reporting applications of hydrogels and biomaterials in drug delivery systems and the importance of decontamination process for hydrogel containing preparations based on various patents evidences. RESULTS Despite the vast literature available, limited information regarding the decontamination and sterilization processes related to hydrogels and biomaterials is reported. Sterilization processes to hydrogels are not yet fully explored. Researchers working on hydrogel based systems can consider decontamination of such biomaterial as an important tool to allow for commercialization within the chemical, herbal or pharmaceutical industries. CONCLUSION Unfortunately, till date, limited papers are available which reported the challenges associated with decontamination methods to prepare hydrogels and biomaterials for biological applications. In conclusion, each case of biomaterial requires individual consideration to decontamination and/or sterilization. This must be submitted to a specific method, but more than one technique can be involved. Physicochemical and biological alterations must be avoided and evaluated by the appropriate assays method. Furthermore, it is also important to consider that each method must be validated depending upon the process variables.

Dual crosslinked pectin–alginate network as sustained release hydrophilic matrix for repaglinide

Repaglinide, an oral antidiabetic agent, has a rapid onset of action and short half-life of approximately 1h. Developing a controlled and prolonged release delivery system is required to maintain its therapeutic plasma concentration and to eliminate its adverse effects particularly hypoglycemia. The present study aimed to develop controlled release repaglinide loaded beads using sodium alginate and pectin with dual cross-linking for effective control of drug release. The prepared beads were characterized for size, percentage drug entrapment efficiency, in vitro drug release and the morphological examination using scanning electron microscope. For the comparative study, the release profile of a marketed conventional tablet of repaglinide (Prandin® tablets 2mg, Novo Nordisk) was determined by the same procedure as followed for beads. The particle size of beads was in the range of 698±2.34-769±1.43μm. The drug entrapment efficiency varied between 55.24±4.61 to 82.29±3.42%. The FTIR results suggest that there was no interaction between repaglinide and excipients. The XRD and DSC results suggest partial molecular dispersion and amorphization of the drug throughout the system. These results suggest that repaglinide did not dissolve completely in the polymer composition and seems not to be involved in the cross-linking reaction. The percent drug release was decreased with higher polymer concentrations. In conclusion, the developed beads could enhance drug entrapment efficiency, prolong the drug release and enhance bioavailability for better control of diabetes.

Nephrotoxicity in Rats Exposed to Paracetamol: The Protective Role of Moralbosteroid, a Steroidal Glycoside

Paracetamol (PCM) has an acceptable safety profile when used at prescribed doses. However, it is now understood that paracetamol can damage the kidneys when administered as an overdose. In addition, oxidative stress can play a major role in causing nephrotoxicity. This investigation studies the efficacy of moralbosteroid isolated from M. alba stem bark. Nephrotoxicity was induced with administration of paracetamol. Nephroprotection was studied using two doses of the extract. The experimental animals were divided into four groups (n = 6). Two groups served as positive and negative controls, respectively, and two received the test substances. All of the contents were orally administered. Significant reductions in nephrotoxicity and oxidative damages were observed in the treatment groups. There was a marked decrease in blood levels of urea, creatinine, and lipid peroxidation. Furthermore, it was found that glutathione levels in the blood increased dramatically after treatment. Histological findings confirmed the potent renoprotective potential of moralbosteroid. This was evidenced by the minimized intensity of nephritic cellular destruction. In animal studies, moralbosteroid exhibited dose-dependent activity, which is thought to be mediated through its antioxidant potential.

Silicone Gel Bleed on Breast Implants

Silicone is a polymer widely used for medical purposes, including breast implants. The aim of this work is to verify the occurrence of silicone gel diffusion through the lining membrane (bleed) of gel breast implants with smooth, textured, and polyurethane foam coated surfaces, sterilized by dry heat and ethylene oxide. The results enable us to conclude that there is significant difference for the bleed results among gel breast implants of smooth, textured, and polyurethane foam coated surfaces in relation to the bleed test. The bleed results for implants sterilized by dry heat and ethylene oxide also show significant difference. These results suggest that the gel diffusion through the lining membrane is related to the type of gel breast implants, as well as to the sterilization method. It means that polyurethane foam coated surface breast implant shows less gel diffusion than textured and smooth breast implants and breast implants sterilized by dry heat show less gel diffusion than those sterilied by ethylene oxide.

Evaluation of cytochrome P-450 concentration in Saccharomyces cerevisiae strains

Saccharomyces cerevisiae has been widely used in mutagenicity tests due to the presence of a cytochrome P-450 system, capable of metabolizing promutagens to active mutagens. There are a large number of S. cerevisiae strains with varying abilities to produce cytochrome P-450. However, strain selection and ideal cultivation conditions are not well defined. We compared cytochrome P-450 levels in four different S. cerevisiae strains and evaluated the cultivation conditions necessary to obtain the highest levels. The amount of cytochrome P-450 produced by each strain varied, as did the incubation time needed to reach the maximum level. The highest cytochrome P-450 concentrations were found in media containing fermentable sugars. The NCYC 240 strain produced the highest level of cytochrome P-450 when grown in the presence of 20 % (w/v) glucose. The addition of ethanol to the media also increased cytochrome P-450 synthesis in this strain. These results indicate cultivation conditions must be specific and well-established for the strain selected in order to assure high cytochrome P-450 levels and reliable mutagenicity results.