title: Topical 'Sydney' propolis protects against UV-radiation-induced inflammation, lipid peroxidation and immune suppression in mouse skin.
abstract: BACKGROUND
  Propolis is a honeybee product that has been used in traditional medicine for antioxidant, immune-stimulating, anti-inflammatory and anti-cancer effects. Here, the potential of the topical application of a crude ethanolic extract of Sydney propolis to protect against UV-radiation-induced impairments associated with an increased risk of photocarcinogenesis has been tested in the hairless mouse.
  
  
  METHODS
  Solutions providing between 10 and 200 mg/kg propolis were applied to the skin following UV irradiation. The inflammation from exposure to UV (290-400 nm) was quantitated by measurement of increased skinfold thickness; lipid peroxidation was assayed by the induction of thiobarbituric acid reactive species in the skin; immune function was measured by the contact hypersensitivity (CHS) reaction and supported by the changes in epidermal cytokine expression.
  
  
  RESULTS
  Propolis protected significantly and dose-dependently against both sunburn oedema and the suppression of CHS, and (at 100 mg/kg) against lipid peroxidation. The overexpression of IL-10 and the depletion of IL-12 characteristic of photoimmune suppression were markedly reduced by propolis. Further, the upregulation of IL-6 was decreased, and the associated induction of haem oxygenase was shown to play a role in propolis skin protection.
  
  
  CONCLUSIONS
  Sydney propolis was able to effectively reduce cutaneous inflammation, immunosuppression and lipid peroxidation induced by UV exposure. It is concluded that Sydney propolis might have strong beneficial protective effects against photodamage and skin cancer development in humans.
authors.affiliation: Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia. n.cole@ier.org.au
authors.forename: Nerida
authors.initials: N
authors.lastname: Cole
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sou
authors.forename: Alanna
authors.initials: A
authors.lastname: Ngo
authors.forename: Karen H
authors.initials: KH
authors.lastname: Tsang
authors.forename: Joseph A J
authors.initials: JA
authors.lastname: Severino
authors.forename: Sondur J
authors.initials: SJ
authors.lastname: Arun
authors.forename: Colin C
authors.initials: CC
authors.lastname: Duke
authors.forename: Vivienne E
authors.initials: VE
authors.lastname: Reeve
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism; D003877:Dermatitis, Contact / Q000209:etiology / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000032:analysis; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007165:Immunosuppression Therapy; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000528:radiation effects*; D008665:Metalloporphyrins / Q000493:pharmacokinetics; D051379:Mice; D008812:Mice, Hairless; D010081:Oxazolone / Q000494:pharmacology; D011429:Propolis / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D011524:Protoporphyrins / Q000493:pharmacokinetics; D011855:Radiodermatitis / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D012867:Skin / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D012885:Skinfold Thickness; D013471:Sunburn / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D013729:Terpenes / Q000032:analysis; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D016207:Cytokines; D004791:Enzyme Inhibitors; D005419:Flavonoids; D008665:Metalloporphyrins; D011524:Protoporphyrins; D013729:Terpenes; D017392:Thiobarbituric Acid Reactive Substances; D010081:Oxazolone; D011429:Propolis; C032628:tin protoporphyrin IX; D051547:Heme Oxygenase-1