M. Helena Amaral

Effect of hydroxypropyl methylcellulose and hydrogenated castor oil on naproxen release from sustained-release tablets

The effect of the concentration of hydrophilic (hydroxypropyl methylcellulose [HPMC]) and hydrophobic (hydrogenated castor oil [HCO]) products, fillers (lactose and dibasic calcium phosphate), and buffers (sodium bicarbonate, calcium carbonate, and sodium citrate) on naproxen release rate was studied. Matrix tablets were prepared by double compression, andIn vitro dissolution tests were performed. The dissolution results showed that an increased amount of HPMC or hydrogenated castor oil resulted in reduced drug release. The inclusion of buffers in the HPMC matrix tablets enhanced naproxen release. For HCO tablets, only sodium bicarbonate enhanced naproxen release. The presence of lactose on HPMC matrix tablets did not show a significantly different result from that obtained with the formulation containing dibasic calcium phosphate as a filler. However, for the tablets containing HCO, the presence of lactose significantly enhanced the naproxen release rate. The matrix-forming materials in this study were suitable for use in sustained-release tablets containing naproxen. The drug release can be modulated by adding suitable amounts of diluents and buffers.

In vivo Skin Irritation Potential of a Castanea sativa (Chestnut) Leaf Extract, a Putative Natural Antioxidant for Topical Application

Topical application of natural antioxidants has proven to be effective in protecting the skin against ultraviolet-mediated oxidative damage and provides a straightforward way to strengthen the endogenous protection system. However, natural products can provoke skin adverse effects, such as allergic and irritant contact dermatitis. Skin irritation potential of Castanea sativa leaf ethanol:water (7:3) extract was investigated by performing an in vivo patch test in 20 volunteers. Before performing the irritation test, the selection of the solvent and extraction method was guided by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging test and polyphenols extraction (measured by the Folin Ciocalteu assay). Iron-chelating activity and the phenolic composition (high performance liquid chromatography/diode array detection) were evaluated for the extract obtained under optimized conditions. The extraction method adopted consisted in 5 short extractions (10 min.) with ethanol:water (7:3), performed at 40 degrees. The IC(50) found for the iron chelation and DPPH scavenging assays were 132.94 +/- 9.72 and 12.58 +/- 0.54 microg/ml (mean +/- S.E.M.), respectively. The total phenolic content was found to be 283.8 +/- 8.74 mg GAE/g extract (mean +/- S.E.M.). Five phenolic compounds were identified in the extract, namely, chlorogenic acid, ellagic acid, rutin, isoquercitrin and hyperoside. The patch test carried out showed that, with respect to irritant effects, this extract can be regarded as safe for topical application.

Coffee silverskin: A possible valuable cosmetic ingredient

Abstract Context: Currently, there is a great tendency in cosmetic area to use natural extracts. Coffee silverskin (CS) is the most abundant solid by-product generated during roasting of coffee processing. Objectives: To evaluate different CS extracts as promising cosmetic ingredients, regarding antioxidant, antimicrobial, and cytotoxic properties. Materials and methods: Aqueous, hydroalcoholic and ethanolic CS extracts were obtained by an environmentally friendly procedure considering costs and pollution. Extracts were characterized for total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), antimicrobial activity expressed as minimal inhibitory concentration (MIC) and cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and lactate dehydrogenase (LDH) assays in two skin cell lines (fibroblasts and keratinocytes). Results: The TPC of extracts was 18.33–35.25 mg of gallic acid equivalents per g of material on a dry basis (mg GAE/g db). The TFC of extracts was 1.08–2.47 µg cathechin equivalents per g dry material (µg CE/g db). The antioxidant activity was high, with values ranging between 95.95 and 216.40 µmol Fe2+/g for aqueous and alcoholic samples, respectively. Preliminary assays for antimicrobial potential showed that extracts display antibacterial activity. The MIC varied from 31.3 to 250 µg/mL for Gram-positive, and from 31.3 to 1000 µg/mL for Gram-negative. Extracts did not affect in vitro cell viability, with values near 100% in all concentrations tested. Conclusion: Results seem show that CS is a safe source of natural antioxidants with antifungal and antibacterial activity and no cytotoxicity, with potential usefulness for cosmetic applications.

Application of Coffee Silverskin in cosmetic formulations: physical/antioxidant stability studies and cytotoxicity effects.

Abstract Context: Currently, there is an increasing interest of cosmetic industry on natural extracts. The inclusion of antioxidants in topical formulations can contribute to minimize oxidative stress in the skin, which has been associated with aging. Also, questions of sustainability are leading to the study of new cosmetic ingredients obtained from food by-products. Coffee Silverskin (CS) is a food by-product with established antioxidant activity that has not yet been incorporated into a topical formulation. Objective: The aim of this study was to evaluate the physical and microbiological stabilities and antioxidant activity of a hand cream formulation containing 2.5% (w/w) of CS extract upon production and after 6 months of shelf-life and in vitro safety/cytotoxicity on skin cell lines after production. Materials and methods: The in vitro cytotoxicity was evaluated with MTS and LDH assays, at different concentrations, in HaCaT and HFF-1 cells. Formulations were stored at 25 °C/65% RH and 40 °C/75% RH. Physical, microbiological, and antioxidant stabilities were evaluated by centrifugation, viscosity, total colony count, DPPH and total phenolic content (TPC). Results: The hand cream containing 2.5% (w/w) of CS extract showed stable physical characteristics independently of the storage conditions. The DPPH activity and TPC of the CS formulation were significantly higher compared with those of the base formulation. However, during storage, the antioxidant activity decreases slightly. Microbiological quality was also confirmed. No cytotoxic effects were observed. Conclusion: It is possible to suggest that this formulation is stable under extreme conditions and safe for topical use.

Permeation of topically applied caffeine from a food by—product in cosmetic formulations: Is nanoscale in vitro approach an option?

The aim of the present work was to develop and evaluate the potential of nanostructured lipid carriers associated with caffeine extracted from Coffee Silverskin (NLC-CS), a food by-product, as a new possible topical therapy of cellulitis. Caffeine gain increasing research interest due to their cosmetic potential, particularly in gynoid lipodystrophy, commonly known as cellulite. NLC-CS were prepared via double emulsion technique using polysorbate 60 as surfactant and characterized for their morphology, particle size, zeta potential, association encapsulation and stability. The in vitro skin permeation studies were performed on Franz diffusion cells using pig skin ear as permeation membrane and the optimized formulation was compared with a hydroalcoholic solution of Coffee silverskin (CS) extract. NLC-CS were within the nanosized range (≈200nm), with a low polydispersity index (<0.25) and zeta potential values around -30Mv, presenting storage stability up to 180days at 25°C/65% relative humidity (RH) and 40°C/75% RH. The association efficiency (AE) of caffeine was about 30% at production time and after storage period. Cryo-SEM images confirmed the spherical shape of NLC-CS. The in vitro skin permeation study demonstrated that NLC-CS had a similar skin permeation profile when compared to caffeine in CS extract.

The role of liposomes and lipid nanoparticles in the skin hydration

Cosmetics are much more than beauty products and the maintenance of skin hydration could be considered the most important step to getting healthy skin. The hydration could be supplied to the skin internally by ingestion of water, or externally, by applying cosmetic formulations containing moisturizing ingredients and/or components that reduce transepidermal water loss (TEWL). In recent years, liposomes and lipid nanoparticles (solid lipid nanoparticles and nanostructured lipid carriers) have received a great deal of attention in the field of pharmaceutical and cosmetic research. These nanosystems have proved to be very advantageous for skin applications and numerous studies were carried out with the aim of encapsulating numerous cosmetic ingredients in liposomes and lipid nanoparticles. Additionally, when applied on the skin, these systems form a transparent film that reduces the TEWL and increases hydration. The main objectives of this chapter include: presenting the importance of skin hydration to maintain health and the mechanisms that could be involved, exemplifying with moisturizing ingredients commonly used in cosmetics; discussing the application of lipid-based nanocarriers, referring to the advantages of these systems and the ingredients commonly used with benefits to skin; showing and discussing examples of some interesting studies performed in this field; and presenting some examples of marketed cosmetic formulations containing liposomes and lipid nanoparticles.

Pyroelectric effect in benzil

Abstract Measurements of the pyroelectric current have been performed in electrically polarized samples of crystalline BENZIL across the 82K structural transition in this material. The results yield a signal which is a few orders of magnitude below the value expected from a theoretical evaluation of the spontaneous polarization Ps.

Ferroelectric phase transition of SbSBr

Abstract Real (e′) and imaginary (e″) parts of electric permi ttivity of SbSBr were measured as a function of temperature at 1 KHz. A saturation of e′−1 occurs about 30K above the Curie temperature and a fitting to the following expression e′−1= A(T-T0)/[(T-T0)+[Ttilde]] gives [Ttilde] = 112K.

Pyroelectric Effect and Ferroelectric Phase Transition in BixSb1-xSI

The measurements of pyroelectric current in needle shaped crystals of Bix Sb1-xSI (x = 0; 0.08; 0.17; 0.25; 0.50) were carried out by measuring the potential difference across a short-circuiting resistance, while heating the samples at uniform rates. Critical temperature Tc follows a rapid linear decrease when x increases up to 0.50, with a slope of 36 K per 0.10 Bi concentration. Critical exponent β of polarization, deduced from measurements of pyroelectric current, were obtained by using a Tc-independant method and generally these values seem consistent with a mean field theory. It is found that a tricritical point, where the phase transition changes from first to second order, occur at a value of X around 0.17. The appearance of a pyroelectric current above Tc, for those crystals which undergo a second order phase transition, can be explained by existence of an internal bias field.