Hypericin structure

Another interesting development is the use of the naturally occurring herbal extract hypericin (4.35), which has the extended quinone structure (4.35), in both photodiagnosis and therapy. This is given to the patient, either orally or topically, who is then illuminated with blue hght. The cancer tumours show up as red spots, the hght from which can be recorded on a red sensitive camera, subjected to computational analysis and then converted into an image on the computer. 

St. John s wort and some individual constituents of the preparations have been administered orally, topically, and intravenously in various pharmaceutical formulations, including tinctures, teas, capsules, purified components, and tablets. These botanical preparations of St. John s wort are prepared from plant components (i.e., flowers, buds, and stalk) whose content of the wide array of structurally diverse bioactive constituents may differ (Table 1 and Fig. 2). Many commercial tablet and capsule formulations of St. John s wort are standardized using the ultraviolet absorbance of the naphtho-dianthrones, hypericin, and pseudohypericin, to contain 0.3% hypericin content. Thus, a 300 mg dose of St. John s wort contains approximately 900 pg hypericin per dose. Despite the standardization of dosage forms... 

Figure 3 Structures of (A) hypericin (B) pseudohypericin (C) hyperforin (D) flavo-noids (R=H quercetin R=a-L-rhamnosyl quercitrine R=P-D-glucosyl isoquerci-trine R=P-D-galactosyl hyperoside R=P-D-rutinosyl rutin R=P-o-glucuronide miquelianin) and (E) procyandin B2.

HYPERICIN AND ITS PERYLENE QUINONE ANALOGS PROBING STRUCTURE, DYNAMICS, AND INTERACTIONS WITH THE ENVIRONMENT... 

Figure 1.7. Structure of hypericin in the normal form (7,14-dioxo tautomer). See the text for details.

As we have discussed in depth elsewhere, despite the similarities in the structures of hypericin and hypocrellin, which are centered about the perylene quinone nucleus, their excited-state photophysics exhibit rich and varied behavior. The H-atom transfer is characterized by a wide range of time constants, which in certain cases exhibit deuterium isotope effects and solvent dependence. Of particular interest is that the shortest time constant we have observed for the H-atom transfer is 10 ps. This is exceptionally long for such a process, 100 fs being expected when the solute H atom does not hydrogen bond to the solvent [62]. That the transfer time is so long in the perylene quinones has been attributed to the identification of the reaction coordinate with skeletal motions of the molecule [48, 50]. 

Hypericin and Its Perylene Quinone Analogs Probing Structure,... 

Neither hypericin, pseudohypericin, their glucuronic acid conjugates, nor their sulfate conjugates were detected in the urine (42). The chemical structure and molecular size (>500 Da) of hypericin and pseudohypericin suggest metabolism via hepatic glucuronidization followed by biliary excretion (42). 

Isolation of hypericin, first named hypericum red , dates back to the beginning of 1800 however, its correct structure and total synthesis was accomplished about one century later [10,31-33], Hypericin, with inorganic... 

Hypericin 1 is present in plants, insects and protozoa. In plants, apart from H. perforatum, it occurs in a number of other species of Hypericum, namely H. hirsutum, H. maculatum, H. nummularium and H. triquetrifolium [17]. It is located in minute glands on different parts of the plants such as young stems, leaves and flowers. Interestingly, hypericin 1 is found in the integument of Australian Lac insects of the Coccoidea family, and appears with a number of structurally-related compounds [18, 19]. In protozoa, the blue-green ciliate, Stentor coerulus possesses a photoreceptor, stentorin, which consists of proteins bound to hypericin 1 [20]. 

Hypericin, the dark-red pigment from Hypericum perforatum, is a dehydrodianthrone, structurally an anthraquinone. However, it does not break down to anthrone in the bowel and is without laxative action. Hypericin has been thoroughly investigated and used (generally in Hypericum extracts standardised to hypericin content) for antidepressant and antiviral activities (Bombardelli and Morazzoni 1995). 

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