retinol-palmitate and oxybenzone

Topics: Benzophenones; Diterpenes; Humans; Nanoparticles; Retinyl Esters; Sunscreening Agents; Titanium; Vitamin A; Zinc Oxide

This study aimed to assess the phototoxic potential of combined UV-filters and retinyl palmitate (RP) in the presence or not of bemotrizinol (BMTZ), employing photostability and in vitro and in vivo phototoxicity assays. The formulations tested contained octocrylene (OCT), octyl methoxycinnamate (OMC), benzophenone-3 (BZP-3) and RP (photostable) or octocrylene (OCT), octyl methoxycinnamate (OMC), avobenzone (AVO) and RP (less photostable). Both formulations were supplemented with bemotrizinol. Photostability was evaluated by exposing, or not, formulations spread on a glass plate to UVA/UVB irradiation. The resulting products were quantified by HPLC analysis. In vitro phototoxicity of UV-filters and combinations were evaluated using 3T3 viable monolayer fibroblast cultures submitted, or not, to irradiation according to OECD TG 432. In vivo photoallergy and photoxicity were assessed by clinical studies (photopatch test). Photostability assays showed that UV-filter bemotrizinol was a better photostabilizer for RP/benzophenone-3 than for RP/avobenzone. The in vitro phototoxicity of the combination RP/avobenzone was reduced by bemotrizinol. Clinical studies did not indicate phototoxic or photoallergenic potentials in all formulations tested. It is concluded that the 3T3 NRU phototoxicity test may be considered a supplementary assay in formulation developments, since it can detect chemically unstable and potentially phototoxic combinations. However, extrapolation of in vitro positive results to human photopatch tests may be performed only to a limited extent.

Topics: 3T3 Cells; Acrylates; Adolescent; Adult; Aged; Animals; Benzophenones; Cinnamates; Dermatitis, Photoallergic; Dermatitis, Phototoxic; Diterpenes; Double-Blind Method; Drug Interactions; Drug Stability; Humans; Mice; Middle Aged; Neutral Red; Phenols; Retinyl Esters; Risk Assessment; Sunscreening Agents; Triazines; Ultraviolet Rays; Vitamin A; Young Adult

Nanocapsules containing poly(d,l-lactide) shell and retinyl palmitate core have been prepared by the pre-formed polymer interfacial deposition method. Dynamic light scattering measurements yielded an average hydrodynamic diameter of ∼220nm and a polydispersity index of ∼0.12. Small-angle neutron scattering experiments revealed the presence of two populations of nanocapsules of core diameters ∼192 and 65nm. Freeze fracture transmission electron microscopy showed a polydisperse population of nanocapsules (NC), with a poly(d,l-lactide) shell thickness between 11 and 3nm. For comparison purposes, nanoemulsions (NE, no polymer) and nanospheres (NS, polymer matrix) were also prepared. Each type of nanoparticles exhibited a different morphology (when examined by electron microscopy), in particular NC showed deformability by capillary adhesion. All three types of nanoparticles successfully encapsulated the poorly water-soluble molecules baicalein and benzophenone-3. The thermal behavior of the various nanoparticles was different to a physical mixture of its individual components. Cytotoxicity and phototoxicity assays, performed in human keratinocytes (HaCaT) and murine fibroblasts (BALB/c 3T3), showed that the NC were only cytotoxic at high concentrations. In vitro release studies of benzophenone-3, by the dialysis bag method using NC and NS, showed a sustained release; however, permeation studies using plastic surgery human abdominal skin in Franz diffusion cells showed that a higher amount of benzophenone-3 from NC penetrated into the skin, most probably due to the deformable nature of these nanoparticles.

Topics: Animals; Antioxidants; BALB 3T3 Cells; Benzophenones; Cell Line; Diterpenes; Flavanones; Humans; Mice; Nanocapsules; Particle Size; Polyesters; Retinyl Esters; Skin; Skin Absorption; Sunscreening Agents; Vitamin A