Supason Wanichwecharungruang

Mucoadhesive curcumin nanospheres: Biological activity, adhesion to stomach mucosa and release of curcumin into the circulation

Although mucoadhesive drug carriers for the gastro-intestinal tract (GIT) have been reported, the mucoadhesive property and drug release characteristics have never been evaluated separately, whilst the adherence of the carriers to the surface of GIT has not been directly visualized. Here, a monopolymeric carrier made from ethylcellulose (EC) and a dipolymeric carrier made from a blend of methylcellulose (MC) and EC (ECMC) were easily fabricated through a self-assembling process and yielded the highest reported curcumin loading of ~48-49%. Both curcumin loaded ECMC (C-ECMC) and curcumin loaded EC (C-EC) particles showed an in vitro free radical scavenging activity and a dose-dependent in vitro cytotoxic effect towards MCF-7 human breast adenocarcinoma and HepG2 hepatoblastoma cells in tissue culture. The in vivo evaluation of their adherence to stomach mucosa and their ability to release curcumin into the circulation were carried out through quantification of curcumin levels in the stomach tissue and in blood of mice orally administered with the two spheres. Direct evidence of the adherence of the C-EC and C-ECMC particles along the mucosal epithelia of the stomach is also presented for the first time through SEM images. The mucoadhesive property of self-assembled C-EC nanoparticles is discussed.

Thymol nanospheres as an effective anti-bacterial agent.

Among thymol, carvacrol, citronellal, eugenol and terpinen-4-ol, thymol showed the highest antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Thymol was then encapsulated into water dispersible submicron sized ethylcellulose/methylcellulose spheres, attaining the relatively high thymol loading level of 43.53% (weight of encapsulated thymol to weight of the thymol-loaded spheres). When tested against the same three bacterial strains, the encapsulated thymol gave comparable minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) values to the unencapsulated compound while mostly showing lower MIC and MBC values than the conventionally used preservative, methyl-p-hydroxybenzoate (methylparaben). The use of encapsulated thymol at 0.078, 0.156 and 0.625 mg ml(-1) (0.52, 1.04 and 4.16 mmol(-1), respectively) in cosmetic lotion formulations provided total suppression of viable E. coli, S. aureus and P. aeruginosa growth (all initially seeded at 10(5) cfu ml(-1)), respectively, over the three month test period, whereas unencapsulated thymol showed effective suppression for only 2-4 weeks. Effective bacterial suppression by encapsulated thymol was also observed when used in cream and aqueous gel cosmetic formulations.

High loading fragrance encapsulation based on a polymer-blend: preparation and release behavior.

The six fragrances, camphor, citronellal, eucalyptol, limonene, menthol and 4-tert-butylcyclohexyl acetate, which represent different chemical functionalities, were encapsulated with a polymer-blend of ethylcellulose (EC), hydroxypropyl methylcellulose (HPMC) and poly(vinyl alcohol) (PV(OH)) using solvent displacement (ethanol displaced by water). The process gave >or=40% fragrance loading capacity with >or=80% encapsulation efficiency at the fragrance to polymer weight ratio of 1:1 and at initial polymer concentrations of 2000-16,000 ppm and the obtained fragrance-encapsulated spheres showed hydrodynamic diameters of less than 450 nm. The release profile of the encapsulated fragrances, evaluated by both thermal gravimetric and electronic nose techniques, indicated different release characteristics amongst the six encapsulated fragrances. Limonene showed the fastest release with essentially no retention by the nanoparticles, while eucalyptol and menthol showed the slowest release.

Preventing the thermal degradation of astaxanthin through nanoencapsulation.

The encapsulation of astaxanthin into polymeric nanospheres by solvent displacement was compared for three chemically diverse polymers, namely; poly(ethylene oxide)-4-methoxycinnamoylphthaloylchitosan (PCPLC), poly(vinylalcohol-co-vinyl-4-methoxycinnamate) (PB4) and ethylcellulose (EC). Although capable of forming nanospheres themselves, EC could not encapsulate astaxanthin at all, whilst PB4 yielded a poor encapsulation efficiency. In contrast, PCPLC yielded reasonably good encapsulation efficiency (98%) at a loading of 40% (w/w). Moreover, the freeze-dried astaxanthin-encapsulated PCPLC nanospheres showed good dispersibility in water yielding stable aqueous suspensions of 300-320 nm nanoparticles. A steady release of astaxanthin from the nanospheres up to a maximum of approximately 85% payload over 60 min was also demonstrated, at least in acetone. NMR analysis indicated that after a two-hour-heating at 70 degrees C in an aqueous environment, PCPLC nanoencapsulated astaxanthin showed minimal heat degradation of olefinic functionality in contrast to that of the unencapsulated pigment molecules which were almost completely destroyed.

Enhancement of immune response to a DNA vaccine against Mycobacterium tuberculosis Ag85B by incorporation of an autophagy inducing system

DNA vaccines are a promising new generation of vaccines that can elicit an immune response using DNA encoding the antigen of interest. The efficacy of these vaccines, however, still needs to be improved. In this study, we investigated the effect of autophagy on increasing the efficacy of a candidate DNA vaccine against Mycobacterium tuberculosis (MTB), a causative agent of tuberculosis. Low molecular weight chitosan was used to encapsulate plasmid DNA containing a gene encoding MTB Antigen 85B (Ag85B), a secreted fibronectin-binding protein. To induce autophagy upon DNA vaccination, the kinase defective mTOR (mTOR-KD) was transfected into cells, and autophagy was detected based on the presence of LC3II. To investigate whether autophagy enhances an immune response upon DNA vaccination, we coencapsualted the Ag85B-containing plasmid with a plasmid encoding mTOR-KD. Plasmids encapsulated by chitosan particles were used for primary subcutaneous immunization and for intranasal boost in mice. After the boost vaccination, sera from the mice were measured for humoral immune response. The DNA vaccine with the autophagy-inducing construct elicited significantly higher Ag85B-specific antibody levels than the control group treated with the Ag85B plasmid alone or with the Ag85B plasmid plus the wild type mTOR construct. Upon in vitro stimulation of splenocytes from mice immunized with recombinant Ag85B, the highest levels of secreted IFN-γ and IL-2 were detected in mice immunized with the autophagy-inducing plasmid, while no differences in IL-4 levels were detected between the groups, suggesting that the DNA vaccine regimen with autophagy induction induced primarily a Th1 immune response. Furthermore, the enhanced proliferation of CD4+ T cells from mice receiving the autophagy-inducing vaccine was observed in vitro. Based on the evidence presented, we conclude that incorporating an autophagy-inducing element into a DNA vaccine may help to improve immune response.

Retinyl acetate-loaded nanoparticles: dermal penetration and release of the retinyl acetate.

Retinyl acetate (RA) loaded polymeric nanoparticle (NP) carriers were prepared using two different single polymers, ethyl cellulose (EC) and poly (ethylene glycol)-4-methoxycinnamoylphthaloylchitosan (PCPLC). The stability of RA to aqueous solution and UVA light was significantly improved when encapsulated with PCPLC, whilst EC encapsulation gave some improved stability in water but showed no improved photostability. Ex vivo application of free RA and the RA-loaded PCPLC NPs onto the surface of the freshly excised skin from a baby mouse indicated a significantly slower skin absorption rate for the encapsulated RA. However, 100% retention of the encapsulated RA in the skin tissue was observed after 24h. Confocal fluorescent analysis of the skin pieces applied with the RA-loaded PCPLC NPs indicated likely entry and accumulation of the PCPLC NPs and RA at the hair follicles. Release of RA from the PCPLC NP carriers was confirmed through the detection of an increasingly higher RA/PCPLC fluorescent signal ratio deeper into the dermis and away from the hair follicles.

Encapsulated curcumin results in prolonged curcumin activity in vitro and radical scavenging activity ex vivo on skin after UVB-irradiation.

The phytochemical curcumin possesses antioxidant activity; however, it becomes unstable after being exposed to light or heat or loses activity during storage. This is especially important when curcumin is applied to the skin within a cosmetic or pharmaceutical formulation, since sun exposure is unavoidable. This drawback can be directly addressed by encapsulation of curcumin in photo-stable nanospheres. Therefore, curcumin was encapsulated into nanoparticles consisting of ethyl cellulose and/or methyl cellulose. Nanoparticles were subjected to processing conditions commonly used in industry, for example, temperature and pressure and thus retained their morphology. Furthermore, sun exposure resulted in the protection of curcumin by nanoparticles, whereas non-encapsulated curcumin degraded completely. Determination of the radical protection factor resulted in similar antioxidant activity of encapsulated and non-encapsulated curcumin indicating that curcumin maintains its antioxidant activity. Application of lotions containing curcumin or curcumin nanoparticles to the skin and subsequent UVB-irradiation resulted in less radical formation compared to lotion application only. Moreover, radical formation was even less after nanoparticle application compared to free curcumin. Nanoencapsulation protects curcumin from photo degradation and can therefore prolong the antioxidant activity of curcumin.

Biological activities and safety of Thanaka (Hesperethusa crenulata) stem bark.

ETHNOPHARMACOLOGICAL RELEVANCE The stem bark powder of Hesperethusa crenulata or Thanaka has been used on the face by Myanmar women for more than a thousand years as a skin care regiment. AIM OF THE STUDY The aim of the current study was to both verify the safety and evaluate some biological activities of the Thanaka bark. MATERIALS AND METHODS Maceration of the Thanaka bark powder resulted in hexane, dichloromethane, ethyl acetate, methanol, 85% ethanol and water extracts. For the safety evaluation, cytotoxicity and genotoxicity of each extract were tested. Antibacterial, tyrosinase inhibition, antioxidant and anti-inflammatory activities were evaluated for each extract. RESULTS AND CONCLUSIONS Extracts from Thanaka bark showed strong anti-inflammatory, significant antioxidation, mild tyrosinase inhibition and slight antibacterial activities. All extracts and the original bark powder showed no detectable genotoxicity while very low cytotoxicity with IC(50) value of more than 12 mg/ml was detected in the water extract. Thus, the use of the Thanaka bark in the form of a watery paste as a skin care regiment is not only safe but also beneficial to skin.

2-Ethylhexyl-2,4,5-trimethoxycinnamate and di-(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate as novel UVA filters.

A series of 2‐ethylhexylmethoxy substituted cinnamates and benzalmalonates have been synthesized and characterized. 2‐Ethylhexyl‐2,4,5‐trimethoxycinnamate (E8) and di‐(2‐ethylhexyl)‐2,4,5‐trimethoxybenzalmalonate (B8) show UVA absorption with high molar absorption coefficients (12000‐14000 cm−1 M−1 at 350 nm). E8 undergoes trans to cis photoisomerization under UVA exposure causing the decrease in UV absorption efficiency. E8 is more photostable than butyl methoxydibenzoylmethane (BMDBM). For example, 41.64 J cm−2 UVA irradiation produces 20 ± 2% and 25 ± 2% loss in UV absorption for E8 and BMDBM, respectively. Similar irradiation produces no change in the UV absorption of B8. Both the oily liquid E8 and the yellow solid B8 can be dissolved in various organic solvents, ranging from methanol to hexane, various silicone fluids and 2‐ethylhexyl‐4‐trimethoxycinnamate (EHMC, a widely used UVB filter). A liquid broadband filter comprising B8 and EHMC shows excellent photostability in both UVB and UVA regions.

Shape Effect on Particle-Lipid Bilayer Membrane Association, Cellular Uptake, and Cytotoxicity.

Although computer simulation and cell culture experiments have shown that elongated spherical particles can be taken up into cells more efficiently than spherical particles, experimental investigation on effects of these different shapes over the particle-membrane association has never been reported. Therefore, whether the higher cellular uptake of an elongated spherical particles is a result of a better particle-membrane association as suggested by some calculation works or a consequence of its influence on other cellular trans-membrane components involved in particle translocation process, cannot be concluded. Here, we study the effect of particle shape on the particle-membrane interaction by monitoring the association between particles of various shapes and lipid bilayer membrane of artificial cell-sized liposomes. Among the three shaped lanthanide-doped NaYF4 particles, all with high shape purity and uniformity, similar crystal phase, and surface chemistry, the elongated spherical particle shows the highest level of membrane association, followed by the spherical particle with a similar radius, and the hexagonal prism-shaped particle, respectively. The free energy of membrane curvature calculated based on a membrane indentation induced by a particle association indicates that among the three particle shapes, the elongated spherical particle give the most stable membrane curvature. The elongated spherical particles show the highest cellular uptake into cytosol of human melanoma (A-375) and human liver carcinoma (HepG2) cells when observed through a confocal laser scanning fluorescence microscope. Quantitative study using flow cytometry also gives the same result. The elongated spherical particles also possess the highest cytotoxicity in A-375 and normal skin (WI-38) cell lines, comparing to the other two shaped particles.