Khác biệt giữa bản sửa đổi của “Carrageenan”
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'''Carrageenan''' hay '''caragenan''' là nhóm các [[polysaccharid]] mạch thẳng sulfat hóa, được chiết từ các loài rong sụn
== Tính chất==
[[
Carrageenan là các polysaccharid tạo bởi các chuỗi lặp lại của các đơn vị galactose và 3,6 anhydrogalactose (3,6-AG), cả dạng sulfat hóa và không sulfat hóa. Các đơn vị này tham gia các liên kết α-1,3 và β-1,4 glycosid.
Dòng 18:
== Production == --->
[[
Although carrageenans were introduced on an industrial scale in the 1930s, they were first used in [[China]] around 600 B.C. (where ''Gigartina'' was used) and in [[Ireland]] around 400 A.D.{{Citation needed|date=July 2009}} Carrageen gelatin can be prepared at home using the traditional recipe found in Diderot's encyclopedie and used for centuries. 5oz rinsed Irish moss is cooked with 8 quarts of water for 10 minutes, stirred as it boils. Hard water should be mixed with 1/2 oz of borax. Two quarts of cold water are rapidly added to the hot brew, and after the mixture has cooled it is strained through a cloth. It is then cooled for 24 hours and becomes gelatinous.{{Citation needed|date = April 2014}}
{{As of|2011}}, global sales of carageenan were estimated at $640 million.<ref name=":0">{{Cite report|accessdate = ngày 6
</ref> while China is the main exporter to global markets in the US and Europe.<ref name=":0" /> The most commonly used sources are ''E. cottonii'' (''Kappaphycus alvarezii, K.striatum'') and ''E. spinosum'' (''Eucheuma denticulatum''), which together provide about three-quarters of the world production. These grow from the sea surface to a depth of about 2 metres. The seaweed is normally grown on nylon lines strung between bamboo floats, and it is harvested after three months or so, when each plant weighs approximately 1 kg.
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===Medical uses=== --><!-- This section is linked from [[Human papillomavirus]] --><!--
[[
A 2006 ''in vitro'' study and a 2007 mouse study at the [[National Cancer Institute]] in the United States suggested that carrageenans might function as a [[Microbicides for sexually transmitted diseases|topical microbicide]].<ref name="Buck 2006">{{cite journal|last1=Buck|first1=Christopher B.|last2=Thompson|first2=Cynthia D.|last3=Roberts|first3=Jeffrey N.|last4=Müller|first4=Martin|last5=Lowy|first5=Douglas R.|last6=Schiller|first6=John T.|date=July 2006|title=Carrageenan is a potent inhibitor of papillomavirus infection|journal=PLoS Pathogens|volume=2|issue=7|pages=671–680|doi=10.1371/journal.ppat.0020069|pmid=16839203|pmc=1500806|quote=Some, but not all, carrageenan-containing over-the-counter sexual lubricant gels we tested were extremely effective for blocking the infectivity of an HPV16 reporter pseudovirus in vitro. These results raise the possibility that use of such lubricant products, or condoms lubricated with carrageenan based gels, could block the sexual transmission of HPV. However, in the absence of clinical efficacy data, it would be inappropriate to recommend currently available products for use as topical microbicides.}}</ref><ref name="Roberts 2007">{{cite journal|last1=Roberts|first1=Jeffrey N.|last2=Buck|first2=Christopher B.|last3=Thompson|first3=Cynthia D.|last4=Kines|first4=Rhonda|last5=Bernardo|first5=Marcelino|last6=Choyke|first6=Peter L.|last7=Lowy|first7=Douglas R.|last8=Schiller|first8=John T.|date=July 2007|title=Genital transmission of HPV in a mouse model is potentiated by nonoxynol-9 and inhibited by carrageenan|journal=Nature Medicine|volume=13|issue=7|pages=857–861|doi=10.1038/nm1598|pmid=17603495}}</ref> A 1987 ''in vitro'' study in Spain revealed a broad spectrum antiviral activity of carrageenan.<ref name="González 1987">{{cite journal|last1=González|first1=María Eugenia|last2=Alarcón|first2=Balbino|last3=Carrasco|first3=Luis|date=September 1987|title=Polysaccharides as antiviral agents: antiviral activity of carrageenan|journal=Antimicrobial Agents and Chemotherapy|volume=31|issue=9|pages=1388–1393|doi=10.1128/AAC.31.9.1388|pmid=2823697|pmc=174948}}</ref>
====HSV====
There are indications a carrageenan-based gel may offer some protection against [[Herpes simplex virus 2|HSV-2]] transmission by binding to the receptors on the herpes virus, thus preventing the virus from binding to cells. Research has shown a carrageenan-based gel effectively prevented HSV-2 infection at a rate of 85% in a mouse model.<ref name="Population Council 2009">{{
====HPV====
Laboratory studies have shown carrageenans inhibit [[HPV]] infection ''in vitro'' and in mouse challenge models.<ref name="Buck 2006"/><ref name="Roberts 2007"/>
A substudy of a South African HIV-prevention clinical trial found a lower prevalence of high risk HPV infection in users of a carrageenan-based vaginal microbicide, ''Carraguard'', versus placebo users at the end of the trial—prevalence of high risk HPV infection at the beginning of the trial was not ascertained.<ref name="Marais 2010">{{
====HIV====
A phase 3 [[clinical trial]] by the [[Population Council]] examined whether a carrageenan-based product was effective as a [[topical microbicide]] for blocking [[HIV]] infection in women.<ref name="Population Council 2009"/> The trial ran from 2004 to 2007, with more than 4,000 [[South Africa]]n women completing the study, but found no statistical difference in infection between those having used the lubricant and those not having used the lubricant.<ref>{{
| title = Trial Shows Anti-HIV Microbicide Is Safe, but does Not Prove it Effective
| work = Population Council
| accessdate = 2008-03-12
| date = ngày 18
| url = http://www.popcouncil.org/mediacenter/newsreleases/Carraguard_Findings.html
}}</ref><ref>
{{
| title = Experimental Microbicide Carraguard Does Not Provide Protection Against HIV, Study Finds
| work = kaisernetwork.org
| accessdate = 2008-03-12
| date = ngày 20
| url = http://www.kaisernetwork.org/Daily_reports/rep_index.cfm?DR_ID=50494
}}</ref> The trial also provided information about usage patterns and showed that the gel does not increase infection any more than the baseline or cause significant side-effects. As such, it is expected to be used as a stable delivery vehicle for experimental [[antiretroviral]]s in future studies.
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===Regulatory status===
In the U.S., carrageenan is allowed under FDA regulations<ref>21 Code of Federal Regulations 172.620</ref> as a direct food additive and is considered safe<ref>Generally Recognized As Safe [[21 CRF §182.7255]] GRAS ID Code 9000-07-1 (1973)</ref> when used in the amount necessary as an emulsifier, stabilizer, or thickener in foods, except those standardized foods that do not provide for such use. FDA also reviewed carrageenan safety for infant formula.<ref>Federal Food, Drug, and Cosmetic Act [[21 U.S.C. 350(a)]] §412</ref> The National Organic Program (NOP) added carrageenan to the National List;<ref>68 FR 61993 (2003)</ref> reviewed and reauthorized in 2008<ref>65 FR 80548</ref> as "critical to organic production and handling operations".<ref>73 FR 59481</ref> The European Food Safety Authority concluded "there is no evidence of any adverse effects in humans from exposure to food-grade carrageenan, or that exposure to degraded carrageenan from use of food-grade carrageenan is occurring",<ref>Opinion of the Scientific Committee on Food on Carrageenan (2003) [http://ec.europa.eu/food/fs/sc/scf/out164_en.pdf] p. 5</ref> however, the Joint [[FAO]]/[[WHO]] expert committee on food additives states that "based on the information available, it is inadvisable to use carrageenan or processed eucheuma seaweed in infant formulas".<ref>[http://web.archive.org/web/20080314152241/http://www.who.int/ipcs/food/jecfa/summaries/summary68.pdf Joint FAO/WHO Expert Committee on Food Additives]. Who.int.
===Effects of radiation===
Environmental advocate Dr. [[Helen Caldicott]] has drawn attention to the effect of [[radiation effects from the Fukushima Daiichi nuclear disaster]] on ocean life, arguing that seaweeds come from the Pacific Ocean must be looked at carefully.<ref>Caldicott, Helen. "The Medical Implications of Fukushima". Invited talk. International House of Japan in Roppongi, Tokyo, on
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