| 词条 | Secondary metabolite |
| 释义 |
Secondary metabolites aid a host in important functions such as protection, competition, and species interactions, but are not necessary for survival. One important defining quality of secondary metabolites is their specificity. Usually, secondary metabolites are specific to an individual species,[2] though there is considerable evidence that horizontal transfer across species or genera of entire pathways plays an important role in bacterial (and, likely, fungal) evolution.[3] Research also shows that secondary metabolic can affect different species in varying ways. In the same forest, four separate species of arboreal marsupial folivores reacted differently to a secondary metabolite in eucalypts.[4] This shows that differing types of secondary metabolites can be the split between two herbivore ecological niches.[4] Additionally, certain species evolve to resist secondary metabolites and even use them for their own benefit. For example, monarch butterflies have evolved to be able to eat milkweed (Asclepias) despite the toxic secondary metabolite it contains.[5] This ability additionally allows the butterfly and caterpillar to be toxic to other predators due to the high concentration of secondary metabolites consumed.[5] Human health implicationsMost polyphenol nutraceuticals from plant origin must undergo intestinal transformations, by microbiota and enterocyte enzymes, in order to be absorbed at enterocyte and colonocyte levels. This gives rise to diverse beneficial effects in the consumer, including a vast array of protective effects against viruses, bacteria, and protozoan parasites.[6] Secondary metabolites also have a strong impact on the food humans eat. Some researchers believe that certain secondary metabolite volatiles are responsible for human food preferences that may be evolutionarily based in nutritional food.[7] This area of interest has not been thoroughly researched, but has interesting implications for human preference. Many secondary metabolites aid the plant in gaining essential nutrients, such as nitrogen. For example, legumes use flavonoids to signal a symbiotic relationship with nitrogen fixing bacteria (rhizobium) to increase their nitrogen uptake.[5] Therefore, many plants that utilize secondary metabolites are high in nutrients and advantageous for human consumption. CategoriesMost of the secondary metabolites of interest to humankind fit into categories which classify secondary metabolites based on their biosynthetic origin. Since secondary metabolites are often created by modified primary metabolite synthases, or "borrow" substrates of primary metabolite origin, these categories should not be interpreted as saying that all molecules in the category are secondary metabolites (for example the steroid category), but rather that there are secondary metabolites in these categories. Small "small molecules"
Big "small molecules", produced by large, modular, "molecular factories"
Non-"small molecules" - DNA, RNA, ribosome, or polysaccharide "classical" biopolymers
See also{{Portal|Metabolism|Molecular and cellular biology}}
References1. ^{{Cite web |url= http://www.biologyreference.com/knowledge/Secondary_metabolites.html |title= Secondary metabolites - Knowledge Encyclopedia |website=www.biologyreference.com |access-date=2016-05-10 }} 2. ^{{cite journal | vauthors = Pichersky E, Gang DR | title = Genetics and biochemistry of secondary metabolites in plants: an evolutionary perspective | journal = Trends in Plant Science | volume = 5 | issue = 10 | pages = 439–45 | date = October 2000 | pmid = 11044721 | doi =10.1016/S1360-1385(00)01741-6 }} 3. ^{{cite journal | vauthors = Juhas M, van der Meer JR, Gaillard M, Harding RM, Hood DW, Crook DW | title = Genomic islands: tools of bacterial horizontal gene transfer and evolution | journal = FEMS Microbiology Reviews | volume = 33 | issue = 2 | pages = 376–93 | date = March 2009 | pmid = 19178566 | pmc = 2704930 | doi = 10.1111/j.1574-6976.2008.00136.x }} 4. ^1 {{cite journal | vauthors = Jensen LM, Wallis IR, Marsh KJ, Moore BD, Wiggins NL, Foley WJ | title = Four species of arboreal folivore show differential tolerance to a secondary metabolite | journal = Oecologia | volume = 176 | issue = 1 | pages = 251–8 | date = September 2014 | pmid = 24974269 | doi = 10.1007/s00442-014-2997-4 }} 5. ^1 2 {{cite book | vauthors = Croteau R, Kutchan TM, Lewis NG | chapter = Chapter 24: Natural products (secondary metabolites) | pages = 1250–1319 | veditors = Civjan N |title=Natural products in chemical biology | location = Hoboken, New Jersey |publisher=Wiley |isbn=978-1-118-10117-9| date = 2012-07-03 }} 6. ^{{cite journal | vauthors = Marín L, Miguélez EM, Villar CJ, Lombó F | title = Bioavailability of dietary polyphenols and gut microbiota metabolism: antimicrobial properties | journal = BioMed Research International | volume = 2015 | pages = 905215 | date = 6 April 2018 | pmid = 25802870 | pmc = 4352739 | doi = 10.1155/2015/905215 }} 7. ^{{cite journal | vauthors = Goff SA, Klee HJ | title = Plant volatile compounds: sensory cues for health and nutritional value? | journal = Science | volume = 311 | issue = 5762 | pages = 815–9 | date = February 2006 | pmid = 16469919 | doi = 10.1126/science.1112614 }} 8. ^{{cite journal | vauthors = Chizzali C, Beerhues L | title = Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans | journal = Beilstein Journal of Organic Chemistry | volume = 8 | pages = 613–20 | year = 2012 | pmid = 22563359 | pmc = 3343287 | doi = 10.3762/bjoc.8.68 }} External links
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