Tumor Cell Toxicity of Hypericin and Related Analogs¶

Wills, Nick J.; Park, Jaehun; Wen, Jin; Kesavan, Sarathy; Kraus, George A.; Petrich, Jacob W.; Carpenter, Susan

doi:10.1562/0031-8655(2001)074<0216:tctoha>2.0.co;2

Cited by 20 publications

(5 citation statements)

References 22 publications

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“…This uncertainty is based on data that, for example, indicate a poor correlation between the cytotoxic effect and the singlet oxygen yield (type-II) when Hyp and several analogs were compared [54]. Furthermore, the addition of known quenchers of both, type-I or type-IIgenerated ROS (1,4-diazabicyclo [2,2,2]octane (DABCO) and histidine or desferrioxamine, catalase or superoxide dismutase (SOD) for type-II and type-I, respectively) had a significant inhibitory effect on cell killing observed in a human fibroblast cell line (MRC5) [63].…”

Section: Natural Occurrence Discovery and Usagementioning

confidence: 99%

Cellular Mechanisms and Prospective Applications of Hypericin in Photodynamic Therapy

Kiesslich¹,

Krammer²,

Plaetzer

2006

CMC

111

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During the last decades, Photodynamic Therapy (PDT) has been established as a powerful alternative approved by health agencies of several countries for treatment of various malignant and some non-malignant diseases. PDT makes use of the light-induced destruction of target cells by formation of cytotoxic products in the presence of a photosensitizing agent and oxygen. The light-dependent tumor destructive properties of Hypericin have drawn attention to its promising application as a photosensitizer in the frame of PDT. Hypericin is a naturally occurring secondary metabolite in plants of the Hypericum genus, with Hypericum perforatum (St. John's wort) as it is a commonly known representative. This review focuses on the cellular mechanisms of Hypericin-based phototoxicity and provides an outlook for future application of Hypericin as a fluorescing and photosensitizing agent for diagnosis and treatment of cancerous diseases, respectively.

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Section: Natural Occurrence Discovery and Usagementioning

confidence: 99%

Cellular Mechanisms and Prospective Applications of Hypericin in Photodynamic Therapy

Kiesslich¹,

Krammer²,

Plaetzer

2006

CMC

111

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“…Hypericin in the excited state can also react with molecular oxygen to generate superoxide radicals in a photosensitization reaction called type I, but this seems less significant (53). If hypericin is imbedded in a cell either mechanism can be toxic, because the reactive forms of oxygen can oxidize lipids and damage cell membranes (53,54). Cell damage may also occur from a significant decrease of pH that occurs after irradiation of cells containing hypericin (55).…”

Section: Cancer Treatment Activitymentioning

confidence: 99%

“…Cell damage may also occur from a significant decrease of pH that occurs after irradiation of cells containing hypericin (55). Other factors may also be involved, for example there could be interference in signaling within the cell (53,54).…”

Section: Cancer Treatment Activitymentioning

confidence: 99%

Chemistry of St. John's Wort: Hypericin and Hyperforin

Vollmer¹,

Rosenson²

2004

J. Chem. Educ.

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St. John's wort is a common plant that has been used medicinally for over 20 centuries. This herb is currently used by millions of people, primarily as natural antidepressant; yet, its efficacy is still under constant debate. St. John's wort contains a large aromatic molecule, hypericin, twisted by steric interactions into the shape of a propeller. For use as antidepressant, St. John's wort is standardized to the content of hypericin, but this molecule was recently found not to be the active ingredient. A totally different bicyclic molecule with complex substitution pattern, hyperforin, was then studied as the causative agent. Both molecules are strongly active in biological systems. Hypericin has shown antiviral activity and is a potent natural photosensitizer that has been used in photodynamic therapy against cancer and against HIV in stored blood. Hyperforin was found to activate a particular receptor in the liver that induces the production of an enzyme used for the metabolism of medications. This effect causes more rapid breakdown of many prescription medications and can interfere with their effectiveness. This finding should prompt a reevaluation of regular use of St. John's wort.

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“…This dye is an effective antidepressant and anxyolitic [1][2][3], an antiretroviral agent [1,4], and a potent photosensitizer suggested for use in photodynamic therapy (PDT) of cancer [1,[5][6][7][8][9][10]. It has several desirable properties including a high quantum yield of singlet oxygen generation, a high extinction coefficient near 600 nm, preferential localization in tumor cells and a relatively low dark toxicity [1,2].…”

Section: Introductionmentioning

confidence: 99%