title: Characterization of an antioxidant surfactant-free topical formulation containing Castanea sativa leaf extract.
abstract: BACKGROUND
  Inclusion of antioxidants in topical formulations can contribute to minimize oxidative stress in the skin, which has been associated with photoaging, several dermatosis and cancer.
  
  
  OBJECTIVE
  A Castanea sativa leaf extract with established antioxidant activity was incorporated into a semisolid surfactant-free formulation. The objective of this study was to perform a comprehensive characterization of this formulation.
  
  
  METHODS
  Physical, microbiological and functional stability were evaluated during 6 months storage at 20 °C and 40 °C. Microstructure elucidation (cryo-SEM), in vitro release and in vivo moisturizing effect (Corneometer® CM 825) were also assessed.
  
  
  CONCLUSIONS
  Minor changes were observed in the textural and rheological properties of the formulation when stored at 20 °C for 6 months and the antioxidant activity of the plant extract remained constant throughout the storage period. Microbiological quality was confirmed at the end of the study. Under accelerated conditions, higher modifications of the evaluated parameters were observed. Cryo-SEM analysis revealed the presence of oil droplets dispersed into a gelified external phase. The release rate of the antioxidant compounds (610 ± 70 µgh(-0.5)) followed Higuchi model. A significant in vivo moisturizing effect was demonstrated, that lasted at least 4 h after product's application.
  
  
  CONCLUSIONS
  The physical, functional and microbiological stability of the antioxidant formulation was established. Specific storage conditions should be recommended considering the influence of temperature on the stability. A skin hydration effect and good skin tolerance were also found which suggests that this preparation can be useful in the prevention or treatment of oxidative stress-mediated dysfunctions.
authors.affiliation: Laboratório de Tecnologia Farmacêutica, Departamento de Ciências do Medicamento, Faculdade de Farmácia, Universidade do Porto , Porto , Portugal .
authors.forename: Isabel F
authors.initials: IF
authors.lastname: Almeida
authors.forename: Jitka
authors.initials: J
authors.lastname: Maleckova
authors.forename: Raquel
authors.initials: R
authors.lastname: Saffi
authors.forename: Helena
authors.initials: H
authors.lastname: Monteiro
authors.forename: Filipa
authors.initials: F
authors.lastname: Góios
authors.forename: Maria Helena
authors.initials: MH
authors.lastname: Amaral
authors.forename: Paulo Cardoso
authors.initials: PC
authors.lastname: Costa
authors.forename: Jorge
authors.initials: J
authors.lastname: Garrido
authors.forename: Paulo
authors.initials: P
authors.lastname: Silva
authors.forename: Nazaré
authors.initials: N
authors.lastname: Pestana
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Bahia
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry* / Q000302:isolation & purification; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D029962:Fagaceae; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry* / Q000302:isolation & purification; D018515:Plant Leaves; D012869:Skin Absorption / Q000187:drug effects / Q000502:physiology; D013501:Surface-Active Agents; D055815:Young Adult
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D013501:Surface-Active Agents
keywords: Antioxidant; Castanea sativa; skin moisturization; stability; surfactant-free formulation