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A tricyclic intermediate for the synthesis of quasimarin has been synthesized in 14 steps.

Hypericin is a naturally occurring photosensitizer that displays potent antiviral activity in the presence of light. The absence of light in many regions of the body may preclude the use of hypericin and other photosensitizers as therapeutic compounds for the treatment of viral infections in vivo. The chemiluminescent oxidation of luciferin by the luciferase from the North American firefly Photinus pyralis was found to generate sufficiently intense and long-lived emission to induce antiviral activity of hypericin. Light-induced virucidal activity of hypericin was demonstrated against equine infectious anemia virus, a lentivirus structurally, genetically, and antigenically related to the human immunodeficiency virus. The implications for exploiting chemiluminescence as a "molecular flashlight" for effecting photodynamic therapy against virus-infected cells and tumor cells are discussed.

Although industrial researchers have been involved in interdisciplinary studies pertaining to virology for several decades, the participation of academic chemists has been significantly increased owing to the importance of HIV (human immunodeficiency virus), the virus which leads to the onset of AIDS (acquired immune deficiency syndrome). The Center for Disease Control estimates that almost 20 million people have been infected by HIV worldwide. The compelling need for effective antiviral therapies for HIVinfected persons, together with rapid advances in understanding the molecular mechanisms of virus replication, has resulted in an explosion of interest in antiviral agents and approaches to antiviral therapies DisciplinesChemistry | Environmental Chemistry | Inorganic Chemistry | Organic Chemistry | Other Chemistry | Polymer Chemistry CommentsReprinted (adapted) with permission from Chemical Reviews, 96(1); 523-536.

The excited-state photophysics of the light induced antiviral agent, hypericin, are compared with those of its methylated analog, hexamethoxyhypericin. This comparison is instructive in understanding both the groundand the excited-state properties of hypericin. That the hexamethoxy analog has no labile protons that can be transferred, that it cannot protonate its own carbonyl groups, that it has a reduced fluorescence quantum yield and lifetime with respect to hypericin, and that it exhibits no stimulated emission or, more specifically, rise time in stimulated emission completely support our emerging model of the hypericin photophysics. The results are consistent with the presence of intramolecular excited-state proton transfer in hypericin but not in its methylated analog. DisciplinesChemistry | Organic Chemistry | Other Chemistry | Polymer Chemistry CommentsReprinted (adapted) with permission from Journal of American Chemical Society, 119 (13) Abstract:The excited-state photophysics of the light induced antiviral agent, hypericin, are compared with those of its methylated analog, hexamethoxyhypericin. This comparison is instructive in understanding both the ground-and the excited-state properties of hypericin. That the hexamethoxy analog has no labile protons that can be transferred, that it cannot protonate its own carbonyl groups, that it has a reduced fluorescence quantum yield and lifetime with respect to hypericin, and that it exhibits no stimulated emission or, more specifically, rise time in stimulated emission completely support our emerging model of the hypericin photophysics. The results are consistent with the presence of intramolecular excited-state proton transfer in hypericin but not in its methylated analog. IntroductionInterest in the polycyclic quinone, hypericin ( Figure 1a) was spawned by the discovery that it possesses extremely high toxicity toward certain viruses, including HIV and that this toxicity absolutely requires light. [1][2][3] Hypericin is also very similar in structure to the stentorin chromophore that confers phototactic and photophobic responses to protozoan ciliates. 4 The interaction of light with hypericin and hypericin-like chromophores is clearly of fundamental biological importance. In order to understand and eventually to exploit these properties of hypericin, it is essential to elucidate its nonradiative excitedstate processes. We have undertaken this task using the tools of ultrafast time-resolved absorption spectroscopy and have presented our results in a series of articles. [5][6][7][8][9][10][11][12][13] The argument for the presence of intramolecular excited-state proton transfer in hypericin is as follows. The hypericin analog