title: UVB photolysis of hydrocortisone 21-acetate.
abstract: Hydrocortisone 21-acetate (HCA) in methanol solution undergoes photodegradation under UVB light, as monitored by HPLC. Five main photoproducts have been isolated and characterized by means of NMR and mass spectroscopy. One of them derives from a Norrish I photoreaction which cleaves the C17-C20 bond of the steroid yielding the andro-derivative, a second product comes from a Yang-type photorearrangement which links C18 to C20 yielding a cyclobutane adduct. The former photoproduct, in turn, undergoes further photolysis giving rise to various photoproducts, of which three have been characterized. The first is a stereoisomer of the andro-derivative, the others arise from the opening of the five-membered ring. HCA also proved photounstable in the solid state and in a commercial formulation for topical use, thus confirming the requirements of the Pharmacopeias for light protection of this drug. Indeed, experiments on LPS-stimulated THP-1 cells demonstrated the loss of anti-inflammatory activity when HCA was UVB-photodegraded. The radical mechanism involved in HCA photolysis seems also responsible for the in vitro photohemolytic effect and lipid peroxidation induced by HCA in combination with UVB light.
authors.affiliation: Department of Pharmaceutical Sciences, University of Padova, Via F. Marzolo 5, I-35131 Padova, Italy. sergio.caffieri@unipd.it
authors.forename: Sergio
authors.initials: S
authors.lastname: Caffieri
authors.forename: Stefano
authors.initials: S
authors.lastname: Dall'Acqua
authors.forename: Ignazio
authors.initials: I
authors.lastname: Castagliuolo
authors.forename: Paola
authors.initials: P
authors.lastname: Brun
authors.forename: Giorgia
authors.initials: G
authors.lastname: Miolo
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D017077:Culture Media, Conditioned / Q000032:analysis / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004912:Erythrocytes / Q000528:radiation effects; D006461:Hemolysis / Q000528:radiation effects; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects; D053583:Interleukin-1beta / Q000032:analysis; D007948:Leukemia, Monocytic, Acute / Q000473:pathology; D019787:Linoleic Acid / Q000528:radiation effects; D015227:Lipid Peroxidation / Q000528:radiation effects; D008264:Macrophages / Q000187:drug effects; D013058:Mass Spectrometry; D051379:Mice; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018462:Photobiology; D010782:Photolysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D000893:Anti-Inflammatory Agents; D017077:Culture Media, Conditioned; D053583:Interleukin-1beta; C021650:hydrocortisone acetate; D019787:Linoleic Acid; D013755:Tetradecanoylphorbol Acetate; D006854:Hydrocortisone