A series of hypericin analogs were found to differ in their cytotoxic activity induced by ambient light levels. These analogs vary in their ability to partition into cells, to generate singlet oxygen as well as in other photophysical properties. The data suggest that the biological activity of hypericin is due to a combination of factors whose roles may vary under different circumstances.
The synthesis of a molecule containing hypericin and luciferin moieties joined by a tether is reported. The light-induced (in vitro) antiviral activity as well as the photophysical properties of this new compound are measured and compared with those of the parent compounds, hypericin and pseudohypericin. This tethered molecule exhibits excited-state behavior that is very similar to that of its parent compounds and antiviral activity that is identical, within experimental error, to that of its more closely related parent compound, pseudohypericin. The implications for a photodynamic therapy that is independent of external light sources are discussed.
A series of hypericin analogs were found to differ in their cytotoxic activity induced by ambient light levels. These analogs vary in their ability to partition into cells, to generate singlet oxygen as well as in other photophysical properties. The data suggest that the biological activity of hypericin is due to a combination of factors whose roles may vary under different circumstances.
Hydroxy and methoxy perylene quinones are synthesized in an attempt to isolate the essential spectroscopic and biological features of light-induced antiviral agents such as hypericin and hypocrellin. Unlike their naturally occurring counterparts, these synthetic quinones bear the carbonyl, hydroxyl, and methoxy groups in the "bay region." The hydroxy and methoxy compounds have rich absorption spectra with broad features in the visible (approximately 450-800 nm) and relatively more intense and narrow features at wavelengths < or = 350 nm. High-level ab initio quantum mechanical calculations assign the features in the absorption spectra to electronic transitions from S0 to S2 and to higher-lying electronic states. The calculations indicate that in the ground state the trans dihydroxy isomer is 12.5 kcal/mol lower in energy than the cis dihydroxy isomer and is thus the only species present. The lowest-energy trans methoxy ground state isomer and the lowest-energy cis methoxy ground state isomer are found to be degenerate. An additional cis methoxy isomer 6.3 kcal/mol higher in energy than the global minimum is assumed to contribute to the spectrum and is also considered. Finally, the synthetic compounds exhibit similar light-induced antiviral activity to each other, but significantly less than that of hypericin.
The synthesis of a molecule containing hypericin and luciferin moieties joined by a tether is reported. The light‐induced (in vitro) antiviral activity as well as the photophysical properties of this new compound are measured and compared with those of the parent compounds, hypericin and pseudohypericin. This tethered molecule exhibits excited‐state behavior that is very similar to that of its parent compounds and antiviral activity that is identical, within experimental error, to that of its more closely related parent compound, pseudohypericin. The implications for a photodynamic therapy that is independent of external light sources are discussed.
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