“Hypericin”的意思、由来-开放百科全书

Hypericin is a naphthodianthrone, an anthraquinone derivative which, together with hyperforin, is one of the principal active constituents of Hypericum (Saint John's wort).^[2]^[3] Hypericin is believed to act as an antibiotic, antiviral^[2] and non-specific kinase inhibitor. Hypericin may inhibit the action of the enzyme dopamine β-hydroxylase, leading to increased dopamine levels,{{Citation needed|date=October 2018}} although thus possibly decreasing norepinephrine and epinephrine.

It was initially believed{{According to whom|date=October 2018}} that the anti-depressant pharmacological activity of hypericin was due to inhibition of monoamine oxidase enzyme. 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 receptors.{{Citation needed|date=November 2017}} This points in the direction that other constituents are responsible for the MAOI effect. The current belief is that the mechanism of antidepressant activity is due to the inhibition of reuptake of certain neurotransmitters.^[2]

The large chromophore system in the molecule means that it can cause photosensitivity when ingested beyond threshold amounts.{{Citation needed|date=July 2012}} Photosensitivity is often seen in animals that have been allowed to graze on St. John's Wort.{{Citation needed|date=October 2018}} Because hypericin accumulates preferentially in cancerous tissues, it is also used as an indicator of cancerous cells.{{Citation needed|date=October 2018}} 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.{{Citation needed|date=October 2018}} The antibacterial and antiviral effects of hypericin are also believed to arise from its ability for photo-oxidation of cells and viral particles.^[2]

The biosynthesis of hypericins is in the polyketide pathway where an octaketide chain goes through processes of cylizations and decarboxylations form emodin anthrone which are believed to be the precursors of hypericin. Oxidization reactions yield protoforms which then are converted into hypericin and pseudohypericin. These reactions are photosensitive and take place under exposure to light and using the enzyme Hyp-1.^[6]^[7]^[8]^[9]^[10]

References

1. ^Merck Index, 11th Edition, 4799
2. ^¹²³{{cite web|last=Mehta |first=Sweety |url=http://pharmaxchange.info/press/2012/12/pharmacognosy-of-st-johns-wort/ |title=Pharmacognosy of St. John's Wort |publisher=Pharmaxchange.info |date=2012-12-18 |accessdate=2014-02-16}}
3. ^{{cite web| url = http://www.delano.com/ReferenceArticles/Hypericin-Active.html| title = Hypericin: the active ingredient in Saint John’s Wort| accessdate = September 18, 2006| author =| last = Oubre| first = Alondra| authorlink = | coauthors = | date = | year = 1991| month = | work = | publisher = | pages = | language = | archiveurl =https://web.archive.org/web/20070928004046/http://www.delano.com/ReferenceArticles/Hypericin-Active.html | archivedate =September 28, 2007 }}
4. ^{{cite journal | url = http://www.l2w.cc/pages/HYPE/index.htm | title = A Review of the Hypothetical Biogenesis and Regulation of Hypericin synthesis via the Polyketide Pathway in Hypericum perforatum and Experimental Methods Proposed to Evaluate the Hypothesis | author = Loren W. Walker | year = 1999}}
5. ^{{cite journal | title = Polyketide Biosynthesis | author = Christian Hertweck | journal = Angew. Chem. Int. Ed. | year = 2009 | volume = 48 | pages = 4688–4716 | doi = 10.1002/anie.200806121}}
6. ^{{cite journal |vauthors=Karioti A, Bilia AR |title=Hypericins as potential leads for new therapeutics |journal=Int J Mol Sci |volume=11 |issue=2 |pages=562–594 |date=2010 |pmid=20386655 |pmc=2852855 |doi=10.3390/ijms11020562 |url=}}
7. ^{{cite journal |vauthors=Falk H |title=From the Photosensitizer Hypericin to the Photoreceptor Stentorin- The Chemistry of Phenanthroperylene Quinones |journal=Angew. Chem. Int. Ed. Engl. |volume=38 |issue=21 |pages=3116–3136 |date=1999 |pmid=10556884 |doi= |url=}}
8. ^{{cite journal |vauthors=Bais HP, Vepachedu R, Lawrence CB, Stermitz FR, Vivanco JM |title=Molecular and biochemical characterization of an enzyme responsible for the formation of hypericin in St. John's wort (Hypericum perforatum L.) |journal=J. Biol. Chem. |volume=278 |issue=34 |pages=32413–32422 |date=2003 |pmid=12799379 |doi=10.1074/jbc.M301681200 |url=}}
9. ^{{cite journal |vauthors=Michalska K, Fernandes H, Sikorski M, Jaskolski M |title=Crystal structure of Hyp-1, a St. John's wort protein implicated in the biosynthesis of hypericin |journal=J. Struct. Biol. |volume=169 |issue=2 |pages=161–171 |date=2010 |pmid=19853038 |doi=10.1016/j.jsb.2009.10.008 |url=}}
10. ^{{cite journal |vauthors=Murthy HN, Kim YS, Park SY, Paek KY |title=Hypericins: biotechnological production from cell and organ cultures |journal=Appl. Microbiol. Biotechnol. |volume=98 |issue=22 |pages=9187–9198 |date=2014 |pmid=25301586 |doi=10.1007/s00253-014-6119-3 |url=}}