title: Roles of oxygen and photoinduced acidification in the light-dependent antiviral activity of hypocrellin A.
abstract: Hypocrellin A displays photoinduced antiviral activity, in particular against the human immunodeficiency virus (HIV), as does its counterpart, hypericin. Although hypocrellin A, like hypericin, executes an excited-state intramolecular proton transfer, it differs from hypericin in two important ways. Unlike hypericin, hypocrellin A absolutely requires oxygen for its antiviral activity. Also, whereas we have previously demonstrated that hypericin functions as a light-induced proton source, we do not observe that hypocrellin A acidifies its surrounding medium in the presence of light. These results are discussed in the context of the ground- and excited-state photophysics of hypericin and its mechanisms of photoinduced virucidal activity.
mesh_terms: D000873:Anthracenes; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D006678:HIV / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008027:Light; D010100:Oxygen / Q000378:metabolism*; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D019800:Phenol; D010777:Photochemistry; D011809:Quinones / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000873:Anthracenes; D000998:Antiviral Agents; D011809:Quinones; D019800:Phenol; D010569:Perylene; C004965:hypericin; D010100:Oxygen; C048388:hypocrellin A