Gelatin-based microspheres crosslinked with glutaraldehyde and rutin oriented to cosmetics

ABSTRACT Glutaraldehyde (GTA) has been extensively used as a gelatin crosslinking agent, however, new natural ones have been suggested as more biocompatible. Polyphenols are possible candidates and the flavonols, such as rutin (RUT), also exhibit potential synergism with sunscreens and antioxidant agents used in cosmetics. In this work, gelatin microspheres (M0) were obtained and crosslinked with GTA 10 mM (MG) or RUT 10 mM (MR), dissolved in acetone:NaOH 0,01M (70:30 v/v). MG exhibited crosslinking extent of 54.4%. Gelatin, M0, MG and MR did not elicit any signs of skin damage, regarding the formation of erythema, the barrier function disruption and negative interference in the stratum corneum hydration. Oily dispersions containing M0, MG or MR, isolated or combined with benzophenone-3 or octyl methoxycinnamate, suggested that the microspheres, at a 5.0% w/w, had no additional chemical or physical photoprotective effect in vitro. Crosslinking with RUT had occurred, but in a lower degree than GTA. Microspheres had not improved sun protection parameters, although, non-treated gelatin interfered positively with the SPF for both UV filters. The in vivo studies demonstrated that these materials had very good skin compatibility

Annual cyclicity in high-resolution stable carbon and oxygen isotope ratios in the wood of the mangrove tree Rhizophora mucronata

In the present study, the high-resolution stable carbon (13C/12C) and oxygen (18O/16O) isotope ratio profiles in the wood of the mangrove Rhizophora mucronata Lam., a tropical tree species lacking distinct growth rings, were investigated. Variations of both isotope ratios revealed a remarkable annual cyclicity with lowest values occurring at the latewood/earlywood boundary (April–May) and highest values during the transition from earlywood to latewood (October–November). Based on the current knowledge of the physiology of this mangrove species, as well as on the current literature available on high-resolution profiles of stable isotope ratios in tree rings, possible driving forces responsible for this seasonal pattern are discussed. The annual cyclicity, together with a conspicuous isotope pattern appearing in the El-Niño year 1997, promises great potential for tropical dendrochronology