Hypericin (4,5,7,4',5',7'-hexahydroxy-2,2'-dimethylnaphtodianthrone) is a naturally occurring chromophore found in some species of the genus Hypericum, especially Hypericum perforatum L. (St. John's wort), and in some basidiomycetes (Dermocybe spp.) or endophytic fungi (Thielavia subthermophila). In recent decades, hypericin has been intensively studied for its broad pharmacological spectrum. A...

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, whe...

The photophysics of hypericin have been studied in its complex with two different isoforms, A1-1 and P1-1, of the protein glutathione S-transferase (GST). One molecule of hypericin binds to each of the two GST subunits. Comparisons are made with our previous results for the hypericin/human serum albumin complex (Photochem. Photobiol. 1999, 69, 633-645). Hypericin binds with high affinity to the...

Hypericum perforatum is well known for its antidepressant and anti-inflammatory activities, for which hypericin and its derivatives are indicated to be the most active compounds. Hypericin synthase (Hyp-1) is the only protein proven to catalyze the synthesis of hypericin. In this study, the full-length cDNA of Hyp-1 was chemically synthesized according to the Hyp-1 sequence in GenBank (accessio...

Methylglyoxal (MGO) is a highly reactive metabolite of glucose which is known to cause damage and induce apoptosis in endothelial cells. Endothelial cell damage is implicated in the progression of diabetes-associated complications and atherosclerosis. Hypericin, a naphthodianthrone isolated from Hypericum perforatum L. (St. John's Wort), is a potent and selective inhibitor of protein kinase C a...

Fungal elicitor prepared from the cell walls of Aspergillum niger induces multiple responses of Hypericum perforatum cells, including nitric oxide (NO) generation, jasmonic acid (JA) biosynthesis, and hypericin production. To determine the role of NO and JA in elicitor-induced hypericin production, we study the effects of NO scavenger 2- to 4-carboxyphenyl-4,4, 5,5-tetramethylimidazoline-1-oxyl...

Hypericin, Cyanobacteria, Photosynthesis, Photodynamic Action The photodynamic action of hypericin on photosynthesis and respiration were monitored in Synechocystis sp PCC 6803 and Synechoccus ATCC 6311 (Anacystis nidulans). An oxygen electrode was used to measure net oxygen evolution or consumption. The amount of hyperi­ cin required to inhibit photosynthesis was quantitively determined. Photo...

Hypocrellin and its analog, hypericin (Figure 1), are naturally occurring quinones that have been used for centuries as folk medicines in the orient and the occident and that have attracted much interest because of their light-induced toxicity toward the human immunodeficiency virus (HIV).1The structural similarities of hypocrellin and hypericin would seem to suggest that hypocrellin exhibits e...

St. John's wort (SJW), an over-the-counter antidepressant, contains hypericin, which absorbs light in the UV and visible ranges. In vivo studies have determined that hypericin is phototoxic to skin and our previous in vitro studies with lens tissues have determined that it is potentially phototoxic to the human lens. To determine if hypericin might also be phototoxic to the human retina, we exp...

The virucidal and antiviral photoactivities of three compounds, hypericin, tetrabromohypericin and gymnochrome B, were evaluated against dengue viruses. All the three products were active, and both the virucidal and antiviral activities were enhanced by light. Gymnochrome B was more potent than hypericin and tetrabromohypericin. The presence of the side chains on the hypericin core of gymnochro...