Anti-methicillin resistance Staphylococcus aureus and in vitro toxicology evaluation of corilagin-loaded gelatin/agar microspheres with potential biotextile applications.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged since the early 1960s. The increasing resistance of pathogens to currently used antibiotics requires the urgent discovery of new antimicrobials effective in combating drug-resistant bacteria. From past to present, medicinal plants are useful to cure human diseases. Corilagin (ß-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-d-glucose), commonly found in Phyllanthus species, exerts potentiating effect on ß-lactams against MRSA. However, its biological effect may not be fully utilized. Therefore, incorporating microencapsulation technology with the delivery of corilagin would be more effective in utilizing the potential effect on biomedical applications. This work reports the development of a safe micro-particulate system which combined agar with gelatin as wall matrix materials for topical delivery of corilagin in order to eliminate the potential toxicity of the crosslinker formaldehyde. The optimal parameters for microsphere preparation were identified and the particle size of optimal microspheres was 20.11 µm ± 3.58. Antibacterial studies revealed that micro-trapped corilagin (minimum bactericidal concentration, MBC = 0.5 mg/mL) possessed a higher potency against MRSA than free corilagin (MBC = 1 mg/mL). The in vitro skin cytotoxicity showed the safety of the corilagin-loaded microspheres for topical applications, with approximately 90 % of HaCaT cell viability. Our results demonstrated the potential of corilagin-loaded gelatin/agar microspheres for the applicable bio-textile products to treat drug-resistant bacterial infections.

Miconazole and terbinafine induced reactive oxygen species accumulation and topical toxicity in human keratinocytes.

There are an estimated 1 billion cases of superficial fungal infection globally. Fungal pathogens form biofilms within wounds and delay the wound healing process. Miconazole and terbinafine are commonly used to treat fungal infections. They induce the accumulation of reactive oxygen species (ROS) in fungi, resulting in the death of fungal cells. ROS are highly reactive molecules, such as oxygen (O2), superoxide anion (O2•-), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH). Although ROS generation is useful for killing pathogenic fungi, it is cytotoxic to human keratinocytes. To the best of our knowledge, the effect of miconazole and terbinafine on HaCaT cells has not been studied with respect to intracellular ROS stimulation. We hypothesized that miconazole and terbinafine have anti-wound healing effects on skin cells when used in antifungal treatment because they generate ROS in fungal cells. We used sulforhodamine B protein staining to investigate cytotoxicity and 2',7'-dichlorofluorescein diacetate to determine ROS accumulation at the 50% inhibitory concentrations of miconazole and terbinafine in HaCaT cells. Our preliminary results showed that topical treatment with miconazole and terbinafine induced cytotoxic responses, with miconazole showing higher cytotoxicity than terbinafine. Both the treatments stimulated ROS in keratinocytes, which may induce oxidative stress and cell death. This suggests a negative correlation between intracellular ROS accumulation in keratinocytes treated with miconazole or terbinafine and the healing of fungi-infected skin wounds.

The role of reactive oxygen species in the biological activity of antimicrobial agents: An updated mini review.

Antimicrobial resistance remains a serious problem that results in high mortality and increased healthcare costs globally. One of the major issues is that resistant pathogens decrease the efficacy of conventional antimicrobials. Accordingly, development of novel antimicrobial agents and therapeutic strategies is urgently needed to overcome the challenge of antimicrobial resistance. A potential strategy is to kill pathogenic microorganisms via the formation of reactive oxygen species (ROS). ROS are defined as a number of highly reactive molecules that comprise molecular oxygen (O2), superoxide anion (O2•-), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH). ROS exhibit antimicrobial actions against a broad range of pathogens through the induction of oxidative stress, which is an imbalance between ROS and the ability of the antioxidant defence system to detoxify ROS. ROS-dependent oxidative stress can damage cellular macromolecules, including DNA, lipids and proteins. This article reviews the antimicrobial action of ROS, challenges to ROS hypothesis, work to solidify ROS-mediated antimicrobial lethality hypothesis, recent developments in antimicrobial agents using ROS as an antimicrobial strategy, safety concerns related to ROS, and future directions in ROS research.

Recent advances on topical antimicrobials for skin and soft tissue infections and their safety concerns.

Antimicrobial resistance of disease-related microorganisms is considered a worldwide prevalent and serious issue which increases the failure of treatment outcomes and leads to high mortality. Considering that the increased resistance to systemic antimicrobial therapy often needs of the use of more toxic agents, topical antimicrobial therapy emerges as an attractive route for the treatment of infectious diseases. The topical antimicrobial therapy is based on the absorption of high drug doses in a readily accessible skin surface, resulting in a reduction of microbial proliferation at infected skin sites. Topical antimicrobials retain the following features: (a) they are able to escape the enzymatic degradation and rapid clearance in the gastrointestinal tract or the first-pass metabolism during oral administration; (b) alleviate the physical discomfort related to intravenous injection; (c) reduce possible adverse effects and drug interactions of systemic administrations; (d) increase patient compliance and convenience; and (e) reduce the treatment costs. Novel antimicrobials for topical application have been widely exploited to control the emergence of drug-resistant microorganisms. This review provides a description of antimicrobial resistance, common microorganisms causing skin and soft tissue infections, topical delivery route of antimicrobials, safety concerns of topical antimicrobials, recent advances, challenges and future prospective in topical antimicrobial development.

Synthesis of platinum(II) and palladium(II) complexes with 9,9-dihexyl-4,5-diazafluorene and their in vivo antitumour activity against Hep3B xenografted mice.

Two complexes dichloro(9,9-dihexyl-4,5-diazafluorene)platinum(II) (Pt-DHF) and dichloro(9,9-dihexyl-4,5-diazafluorene)palladium(II) (Pd-DHF) were synthesized and their in vivo antitumour activity was investigated using an athymic nude mice model xenografted with human Hep3B carcinoma cells. Pt-DHF- and Pd-DHF-treated groups showed significant tumour growth inhibition (with about 9-fold and 3-fold tumour growth retardation) when compared with the vehicle control group. The liver toxicology effects on the animals of the two compounds were investigated. Pt-DHF and Pd-DHF-treated groups had a lower alanine transaminase and aspartate transaminase values than those of the vehicle treated group as the animals from the vehicle control group had very heavy hepatoma burden. We assume that both complexes could be further investigated as effective antitumour agents and it is worthwhile to study their underlying working mechanism.

Non-toxic agarose/gelatin-based microencapsulation system containing gallic acid for antifungal application.

Aspergillus niger (A. niger) is a common species of Aspergillus molds. Cutaneous aspergillosis usually occurs in skin sites near intravenous injection and approximately 6% of cutaneous aspergillosis cases which do not involve burn or HIV-infected patients are caused by A. niger. Biomaterials and biopharmaceuticals produced from microparticle-based drug delivery systems have received much attention as microencapsulated drugs offer an improvement in therapeutic efficacy due to better human absorption. The frequently used crosslinker, glutaraldehyde, in gelatin-based microencapsulation systems is considered harmful to human beings. In order to tackle the potential risks, agarose has become an alternative polymer to be used with gelatin as wall matrix materials of microcapsules. In the present study, we report the eco-friendly use of an agarose/gelatin-based microencapsulation system to enhance the antifungal activity of gallic acid and reduce its potential cytotoxic effects towards human skin keratinocytes. We used optimal parameter combinations, such as an agarose/gelatin ratio of 1:1, a polymer/oil ratio of 1:60, a surfactant volume of 1% w/w and a stirring speed of 900 rpm. The minimum inhibitory concentration of microencapsulated gallic acid (62.5 µg/ml) was significantly improved when compared with that of the original drug (>750 µg/ml). The anti-A. niger activity of gallic acid -containing microcapsules was much stronger than that of the original drug. Following 48 h of treatment, skin cell survival was approximately 90% with agarose/gelatin microcapsules containing gallic acid, whereas cell viability was only 25-35% with free gallic acid. Our results demonstrate that agarose/gelatin-based microcapsules containing gallic acid may prove to be helpful in the treatment of A. niger-induced skin infections near intravenous injection sites.

Microencapsulation-protected l-ascorbic acid for the application of human epithelial HaCaT cell proliferation.

l-ascorbic acid is an abundant water-soluble nutrient found in vegetables and fruits. It enhances the cell proliferation, which is helpful in wound healing process. However, it is relatively unstable and easily degraded under external environments including acidity, alkalinity, evaporation, heat, oxidization, light or moisture. Its storage remains challenged. This study reported the development of l-ascorbic acid microcapsules using the natural protein, gelatin, and the natural polysaccharide, agar, as the wall protection carrier. The physical properties including entrapment efficiency, particle size, surface morphology, chemical compositions and release profile were identified. The cell proliferation of l-ascorbic acid microcapsules was stronger than the free drug. Significant cell growth in microencapsulated l-ascorbic acid-treated human epithelial HaCaT cells was observed when compared with untreated control. Since cell proliferation and wound repair are closely related, it is believed that l-ascorbic acid microcapsules would effectively increase the potential effect of wound healing activity in human skin.

D-Glucose as a modifying agent in gelatin/collagen matrix and reservoir nanoparticles for Calendula officinalis delivery.

Gelatin/Collagen-based matrix and reservoir nanoparticles require crosslinkers to stabilize the formed nanosuspensions, considering that physical instability is the main challenge of nanoparticulate systems. The use of crosslinkers improves the physical integrity of nanoformulations under the-host environment. Aldehyde-based fixatives, such as formaldehyde and glutaraldehyde, have been widely applied to the crosslinking process of polymeric nanoparticles. However, their potential toxicity towards human beings has been demonstrated in many previous studies. In order to tackle this problem, D-glucose was used during nanoparticle formation to stabilize the gelatin/collagen-based matrix wall and reservoir wall for the deliveries of Calendula officinalis powder and oil, respectively. In addition, therapeutic selectivity between malignant and normal cells could be observed. The C. officinalis powder loaded nanoparticles significantly strengthened the anti-cancer effect towards human breast adenocarcinoma MCF7 cells and human hepatoma SKHep1 cells when compared with the free powder. On the contrary, the nanoparticles did not show significant cytotoxicity towards normal esophageal epithelial NE3 cells and human skin keratinocyte HaCaT cells. On the basis of these evidences, D-glucose modified gelatin/collagen matrix nanoparticles containing C. officinalis powder might be proposed as a safer alternative vehicle for anti-cancer treatments.

Development of ruthenium(II) complexes as topical antibiotics against methicillin resistant Staphylococcus aureus.

A series of ruthenium(II) bis(2,2'-bipyridyl) complexes containing N-phenyl-substituted diazafluorenes (Ru-C1, Ru-C6, Ru-C7 and Ru-F) was synthesized and their potential antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) was investigated. The Ru-C7 complex showed significant improvement in both minimum inhibitory concentration (MIC, 6.25 µg mL(-1)) and minimum bactericidal concentration (MBC, 25 µg mL(-1)) towards MRSA when compared with those of methicillin (positive control) (MIC = 25 µg mL(-1) and MBC = 100 µg mL(-1)). The Ru-C7 complex possessed much stronger antibacterial effects than the Ru-C6 complex (MIC, 25 µg mL(-1), MBC, >100 µg mL(-1)). Both Ru-C6 and Ru-C7 complexes were also demonstrated to be biologically safe when tested on normal human skin keratinocytes.

Advanced progress of microencapsulation technologies: in vivo and in vitro models for studying oral and transdermal drug deliveries.

This review provides an overall discussion of microencapsulation systems for both oral and transdermal drug deliveries. Clinically, many drugs, especially proteins and peptides, are susceptible to the gastrointestinal tract and the first-pass metabolism after oral administration while some drugs exhibit low skin permeability through transdermal delivery route. Medicated microcapsules as oral and transdermal drug delivery vehicles are believed to offer an extended drug effect at a relatively low dose and provide a better patient compliance. The polymeric microcapsules can be produced by different microencapsulation methods and the drug microencapsulation technology provides the quality preservation for drug stabilization. The release of the entrapped drug is controlled and prolonged for specific usages. Some recent studies have focused on the evaluation of drug containing microcapsules on potential biological and therapeutic applications. For the oral delivery, in vivo animal models were used for evaluating possible treatment effects of drug containing microcapsules. For the transdermal drug delivery, skin delivery models were introduced to investigate the potential skin delivery of medicated microcapsules. Finally, the challenges and limitations of drug microencapsulation in real life are discussed and the commercially available drug formulations using microencapsulation technology for oral and transdermal applications are shown.

Effects of multiple washing on cotton fabrics containing berberine microcapsules with anti-Staphylococcus aureus activity.

The therapeutic efficiency and topical performance of drug-containing microcapsules varied when the drugs existed in an internal oil phase or an internal aqueous phase within the wall shell or wall matrix of microcapsules. In this study, chitosan-based (oil-in-water) and agar-gelatin-based (water-in-oil) microencapsulation systems containing berberine were applied to cotton fabrics to provide an anti-Staphylococcus aureus activity for textile materials. The berberine microcapsule-treated cotton samples were subjected to various washing cycles and their surface morphology, chemical compositions and antibacterial property were investigated after washing. The SEM images and Fourier transform infrared analysis showed that the amount of microcapsules on cotton samples decreased gradually with an increase in washing cycles. After 20 washing cycles, the cotton fabrics with agar-gelatin (water-in-oil) microcapsules containing berberine still exhibited the anti-S. aureus activity. However, the chitosan-based (oil-in-water) system did not show any growth inhibition towards S. aureus but only in the contact areas.

Development of miconazole nitrate containing chitosan microcapsules and their anti-Aspergillus niger activity.

In this article, we report the development of chitosan/miconazole nitrate microcapsules. Four miconazole nitrate ratios including 12.5, 25, 50 and 100 mg were performed in the chitosan-based microencapsulation system. Chitosan microcapsules with the drug input of 25 mg showed the highest encapsulation efficiency (52.47%) and acceptable mean particle size (5.65 µm) when compared with those of 12.5, 50 and 100 mg. Fourier transform infrared spectroscopic spectrum proved the entrapment of miconazole nitrate into chitosan microcapsules. The antifungal result demonstrated that microcapsules containing 75 µg miconazole nitrate possessed comparable anti-Aspergillus niger activity as the commercial ointment. The growth inhibition of miconazole nitrate containing chitosan microcapsules towards human skin keratinocytes was found to be dose dependent. A total of 75 µg of miconazole nitrate containing microcapsules revealed about 25% of growth inhibition while that of 150 µg showed approximately 70% of growth inhibition. Special monitoring should be taken if a higher dose of miconazole nitrate was used to develop the microcapsules.

Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain.

OBJECTIVE: We measured the surface electromyographic activities of vastus medialis obliquus and vastus lateralis in 16 subjects with patellofemoral joint pain syndrome. DESIGN: Each subject performed bilateral static knee extension exercises at 60% of his or her maximal voluntary effort under different combinations of hip rotation (30 degrees of medial rotation, neutral, 45 degrees of lateral rotation) and knee flexion (20 and 40 degrees) in a standing position. The ratio of surface-integrated electromyographic signals of vastus medialis obliquus over vastus lateralis was calculated for each of the six conditions. Because of significant interaction of hip rotation and knee flexion in the two-way analysis of variance, data were analyzed separately with paired t tests for the effect of knee positions and one-way repeated measures analysis of variance for hip positions. RESULTS: At 20 degrees of knee flexion, there was no significant difference among the three hip positions, whereas at 40 degrees of knee flexion, medial rotation of the hip resulted in significantly higher vastus medialis obliquus over vastus lateralis activity ratio than lateral rotation (P < 0.05). CONCLUSIONS: There was relatively more activation of vastus medialis obliquus than vastus lateralis at 40 degrees of semisquat with the hip medially rotated by 30 degrees. This finding has clinical implications for training the vastus medialis obliquus in patients with patellofemoral joint pain syndrome.

ELISA seropositivity for Toxocara canis antibodies in Malaysia, 1989-1991.

The laboratory test results for visceral larva migrans (VLM) using ELISA for Toxocara canis antibodies employed by the Institute for Medical Research, Kuala Lumpur, is described. A total of 331 serum samples received from hospitals and general practitioners all over Malaysia were tested. The test utilises excretory-secretory antigens obtained from in vitro culture of second stage T. canis larvae. The overall seropositivity rate was 19.6%, the highest positive rate being in Indians (35.5%), followed by the Malays (14.8%), Chinese (10.9%) and others (29.4%). Seropositivity rate was highest in children below the age of 10; 89% of patients presented with eosinophilia and 93% with VLM syndrome were children.

Seroprevalence of Toxocara canis antibodies among Orang Asli (aborigines) in Peninsular Malaysia.

An enzyme-linked immunosorbent assay using excretory-secretory antigens of the second stage larvae maintained in vitro was used to determine the seroprevalence of Toxocara antibodies in Orang Asli (aborigines) of Peninsular Malaysia. The mean + 3 SD optical density of 30 healthy subjects was used as the cut-off point. Overall prevalence was found to be 31.9%. No significant relationship was found between positive rates with sex and age groups, though children between 0 to 9 years recorded the highest positive rates. Eosinophil counts were found to be closely related to the proportion of positivity to toxocaral infection and mean optical densities. There was some degree of cross-reaction with Trichuris trichuria positive sera.

Antifilarial activity of intravenous suramin and oral diethylcarbamazine citrate on subperiodic Brugia malayi in the leaf-monkey, Presbytis cristata.

The known filaricides, suramin and diethylcarbamazine citrate, were tested against subperiodic Brugia malayi infection in the leaf-monkey, Presbytis cristata. As expected, intravenous suramin at 10 mg/kg daily x 5 days or 17 mg/kg weekly x 5 weeks, did not show any microfilaricidal activity, but substantially reduced the recovery of live adult worms to 50.6% and 13.6% of controls respectively. Oral diethylcarbamazine citrate at 6 mg/kg daily x 6 or 10 days reduced final microfilarial counts to 30% of initial counts four weeks post-treatment and adult worm recovery was reduced to 4.5% and 0% of controls respectively. Although the antifilarial activity of these drugs against the infection in this non-human primate model appears to be similar to that seen in man, these results have to be confirmed using larger groups of animals.

Experimental infection of the leaf-monkeys, Presbytis cristata and Presbytis melalophos with subperiodic Brugia malayi.

The leaf-monkeys, Presbytis cristata and Presbytis melalophos, experimentally infected with subperiodic Brugia malayi, have been used for studies on the pathoimmunology of the infection and the screening of potential filaricides during the last 6-8 years, and considerable information on the pattern of microfilaraemia and adult worm recoveries have been obtained. The prepatent periods in 97 P. cristata and 45 P. melalophos, each infected with about 200 infective larvae, were similar, these being approximately 70 and 68 days respectively. Although all infected animals became microfilaraemic, the peak geometric mean count was much higher in P. cristata than in P. melalophos, this being 182.0 and 65.8 per ml blood respectively. Mean adult worm recovery expressed as the percentage of the infective dose was 4.7% and 2.5%, respectively. Most worms were recovered from the sacral nodes/thoracic duct or inguinal lymph nodes in these animals. In view of the higher worm recovery and the higher peak microfilaraemia attained, it is concluded that P. cristata is a better model for the infection than P. melalophos.

Antifilarial activity of CGP 20376 against subperiodic Brugia malayi in the leaf-monkey Presbytis cristata.

CGP 20376, a 5-methoxyl-6-dithiocarbamic-S- (2-carboxy-ethyl) ester derivative of benzothiazole was evaluated for its antifilarial properties and shown to be extremely effective against subperiodic Brugia malayi in the leaf-monkey, Presbytis cristata at oral doses of 20-100 mg/kg. The compound and/or its metabolites had complete micro- and microfilaricidal activities even when given at a single dose of 20 mg/kg. Lower doses had incomplete filaricidal action.

Experimental infection of the leaf-monkey, Presbytis cristata, with subperiodic Brugia malayi.

Presbytis cristata monkeys infected through the inoculation of between 200 and 400 subperiodic Brugia malayi infective larvae (L3) in the right thigh, in both thighs or in the dorsum of the right foot were followed up for varying periods of up to about 8 months after infection. All 148 inoculated animals became patent, with mean prepatent periods being between 66 and 76 days. In animals injected in the thigh, the patterns of microfilaraemia were similar, there being a rapid rise in the geometric mean counts (GMCs) of microfilariae during the first 10-12 weeks of patency, which then plateaued at levels of greater than 1000/ml. Adult worm recovery, expressed as the percentage of the infective dose, was significantly higher in animals injected with 100 L3 in each thigh, being 9.4% as compared with 2.8%-4.8% in other groups. It is therefore recommended that animals should be injected with 100 L3 in each thigh and that the testing of potential filaricides in this model be carried out during the phase of rapid increase in microfilaraemia to ensure that any microfilaricidal effect can easily be detected.