Hypericin
Encyclopedia
Hypericin is a naphthodianthrone, a red-colored anthraquinone
-derivative, which, together with hyperforin
, is one of the principal active constituents of Hypericum
(Saint John's wort). Hypericin is believed to act as an antibiotic
and non-specific kinase
inhibitor
. Hypericin may inhibit the action of the enzyme dopamine β-hydroxylase
, leading to increased dopamine
levels, although thus possibly decreasing norepinephrine
and epinephrine
.
The crude extract of Hypericum is a weak inhibitor of MAO-A
and MAO-B
. Isolated hypericin does not display this activity, but does have some affinity for NMDA receptor
s. This points in the direction that other constituents are responsible for the MAOI effect.
The large chromophore
system in the molecule means that it can cause photosensitivity
when ingested beyond threshold amounts. Photosensitivity is often seen in animals
that have been allowed to graze on St. John's Wort. Because hypericin accumulates preferentially in cancerous
tissues, it is also used as an indicator of cancerous cells. In addition, hypericin is under research as an agent in photodynamic therapy
, whereby a biochemical is absorbed by an organism to be later activated with spectrum-specific light from specialized lamps or laser
sources, for therapeutic purposes.
Hypericin derives from polyketide
s cyclisation.
Anthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula . Several isomers are possible, each of which can be viewed as a quinone derivative...
-derivative, which, together with hyperforin
Hyperforin
Hyperforin is a phytochemical produced by some of the members of the plant genus Hypericum, notably Hypericum perforatum .- Occurrence :...
, is one of the principal active constituents of Hypericum
Hypericum
Hypericum is a genus of about 400 species of flowering plants in the family Hypericaceae ....
(Saint John's wort). Hypericin is believed to act as an antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
and non-specific kinase
Kinase
In chemistry and biochemistry, a kinase is a type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific substrates, a process referred to as phosphorylation. Kinases are part of the larger family of phosphotransferases...
inhibitor
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
. Hypericin may inhibit the action of the enzyme dopamine β-hydroxylase
Dopamine beta hydroxylase
Dopamine β-hydroxylase is an enzyme that converts dopamine to norepinephrine.DBH is a 290 kDa copper-containing oxygenase consisting of four identical subunits, and its activity requires ascorbate as a cofactor...
, leading to increased dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
levels, although thus possibly decreasing norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
and epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
.
The crude extract of Hypericum is a weak inhibitor of MAO-A
Monoamine Oxidase A
Monoamine oxidase A, also known as MAO-A, is an enzyme that in humans is encoded by the MAO-A gene. Monoamine oxidase A is an isozyme of monoamine oxidase. It preferentially deaminates norepinephrine , epinephrine , serotonin, and dopamine...
and MAO-B
Monoamine oxidase B
Monoamine oxidase B, also known as MAOB, is a protein that in humans is encoded by the MAOB gene.The protein encoded by this gene belongs to the flavin monoamine oxidase family. It is an enzyme located in the mitochondrial outer membrane...
. Isolated hypericin does not display this activity, but does have some affinity for NMDA receptor
NMDA receptor
The NMDA receptor , a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function....
s. This points in the direction that other constituents are responsible for the MAOI effect.
The large chromophore
Chromophore
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls...
system in the molecule means that it can cause photosensitivity
Photosensitivity
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.- Human medicine :Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn...
when ingested beyond threshold amounts. Photosensitivity is often seen in animals
Photosensitivity in animals
Photosensitivity is an abnormal skin reaction to direct sunlight exposure. It is unrelated to a sunburn. These reactions are due to photosensitization, the accumulation of photosensitive compounds beneath the skin. In some cases, the photodynamic substances come from ingested plants or drugs, after...
that have been allowed to graze on St. John's Wort. Because hypericin accumulates preferentially in cancerous
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
tissues, it is also used as an indicator of cancerous cells. In addition, hypericin is under research as an agent in photodynamic therapy
Photodynamic therapy
Photodynamic therapy is used clinically to treat a wide range of medical conditions, including malignant cancers, and is recognised as a treatment strategy which is both minimally invasive and minimally toxic...
, whereby a biochemical is absorbed by an organism to be later activated with spectrum-specific light from specialized lamps or laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
sources, for therapeutic purposes.
Hypericin derives from polyketide
Polyketide
Polyketides are secondary metabolites from bacteria, fungi, plants, and animals. Polyketides are usually biosynthesized through the decarboxylative condensation of malonyl-CoA derived extender units in a similar process to fatty acid synthesis...
s cyclisation.