2 resultados para thixotropic behavior

em Universidade Federal do Rio Grande do Norte(UFRN)


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Sunscreen use is the most common photoprotection alternative used by the population, and so these products should offer improved protection with broad - spectrum, UVA and UVB protection . Vegetal substances have recently been considered as resources for sunscreen formulations due to their UV spectrum absorption and antioxidant properties. The Euterpe oleracea Mart., popularly known as açai, in its che mical composition contain polyphenols compounds, such as anthocyanins and flavonoids , to which antioxidant properties have been attributed . The aim of this work was to develop O/W sunscreens emulsions con taining açai glycolic extract ( AGE) and to evaluate both their physical stability , safety and photoprotective efficacy. The safety of the extract was evaluated by in vitro phototoxicity and cytotoxicity tests. Emulsions containing AGE and sunscreens were formulated using different types and concentrations o f polymeric surfactant (Acrylates/C 10 - 30 Alkyl Acrylate Crosspolymer and Sodium Polyacrylate). The influence of two rheology modifiers (Polyacrylamide (and) C13 - 14/Isoparaffin (and) Laureth - 7 and Carbomer) on the stability was also investigated. Physical stability was evaluated by preliminary and accelerated studies. The macroscopic analyses, pH value and electrical conductivity determinations and rheological behavior were evaluated at different time intervals . The in vivo Sun Protect Factor ( SPF ) was determined according to the International Sun Protection Factor Test Method – 2006 and UVA Protection Factor (FPUVA), wavelength critical and reason SPF/FPUVA were performed according to the method Colipa 2011. The extract did not present cytotoxic ity and phototoxic ity . The stable emulsion containing 5% glycolic extract of açai and 1.0% of sodium poliyacrylate showed pseudoplastic and thixotropic behavior . The sunscreen emulsion containing açai glycolic extract showed a SPF 25.3 and PF - UVA = 14.97. Whe n açai glycolic extract was added in the emulsion sunscreen, no significant increase in the in vivo SPF and FPUVA values were observed. This emulsion showed 1.69 of the SPF/PF - UVA ratio and a critical wavelength value of 378 nm, so may therefore be conside red a sunscreen with UVA and UVB protection.

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Opuntia fícus - indica (L.) Mill is a cactacea presents in the Caatinga ecosystem and shows in its chemical c omposition flavonoids, galacturonic acid and sugars. Different hydroglicolic (EHG001 and EHG002) and hydroethanolic subsequently lyophilized (EHE001 and EHE002) extracts were developed. The EHE002 had his preliminary phytochemical composition investigated by thin layer chromatography (TLC) and we observed the predominance of flavonoids. Different formulations were prepared as emulsions with Sodium Polyacrylate (and) Hydrogenated Polydecene (and) Trideceth - 6 (Rapithix® A60), and Polyacrylamide (and) C13 - 14 I soparaffin (and) Laureth - 7 (Sepigel® 305), and gel with Sodium Polyacrylate (Rapithix® A100). The sensorial evaluation was conducted by check - all - that - apply method. There were no significant differences between the scores assigned to the formulations, howe ver, we noted a preference for those formulated with 1,5% of Rapithix® A100 and 3,0% of Sepigel® 305. These and the formulation with 3% Rapithix® A60 were tested for preliminary and accelerated stability. In accelerated stability study, samples were stored at different temperatures for 90 days. Organoleptic characteristics, the pH values and rheological behavior were assessed. T he emulsions formulated with 3,0% of Sepigel® 305 and 1,5% of Rapithix® A60 w ere stable with pseudoplastic and thixotropic behavior . The moisturizing clinical efficacy of the emulsions containing 3,0% of Sepigel® 305 containing 1 and 3% of EHG001 was performed using the capacitance method (Corneometer®) and transepidermal water lost – TEWL evaluation ( Tewameter®). The results showed t hat the formulation with 3% of EHG001 increased the skin moisturizing against the vehicle and the extractor solvent formulation after five hours. The formulations containing 1 and 3% of EHG001 increased skin barrier effect by reducing transepidermal water loss up to four hours after application.