Isoflavone
Isoflavonesare substituted derivatives of isoflavone, a type of naturally occurringisoflavonoids,[1][2]many of which act asphytoestrogensinmammals.[3]Isoflavones occur in many plant species, but are especially high in soybeans.[1]
Although isoflavones and closely-related phytoestrogens are sold asdietary supplements,there is little scientific evidence for either the safety of long-term supplementation or of health benefits from these compounds.[1]Some studies indicate that isoflavone supplementation may help lower the risk of hormone-related cancers.[1][4]
Organic chemistry and biosynthesis
[edit]Isoflavone is an isomer offlavone,which ischromonesubstituted with a phenyl group in the 2-position.[1]In isoflavone, the phenyl group is in the 3-position.[1][5]
Substituted isoflavone derivatives are related to the parent by the replacement of two or three hydrogen atoms with hydroxyl groups.[1]
Isoflavone differs fromflavone(2-phenyl-4H-1-benzopyr-4-one) in location of thephenyl group.
Isoflavones are produced via a branch of the generalphenylpropanoidpathway that producesflavonoidcompounds in higher plants.Soybeansare the most common source of isoflavones in human food; the major isoflavones insoybeanaregenisteinanddaidzein.[1]The phenylpropanoid pathway begins from theamino acidphenylalanine,and an intermediate of the pathway,naringenin,is sequentially converted into the isoflavone genistein by two legume-specificenzymes,isoflavone synthase, and adehydratase.Similarly, another intermediatenaringenin chalconeis converted to the isoflavone daidzein by sequential action of three legume-specific enzymes: chalcone reductase, type II chalcone isomerase, and isoflavone synthase. Plants use isoflavones and their derivatives asphytoalexincompounds to ward off disease-causingpathogenicfungiand othermicrobes.In addition, soybean uses isoflavones to stimulatesoil-microberhizobiumto form nitrogen-fixingroot nodules.
Occurrence
[edit]Most members of the familyFabaceaecontain significant quantities of isoflavones.[1]Analysis of levels in various species has found the highest levels of genistein and daidzein inpsoralea(Psoralea corylifolia). Various legumes includingsoybean(Glycine maxL.),[6]green bean(Phaseolus vulgarisL.), alfalfa sprout (Medicago sativaL.),mung beansprout (Vigna radiataL.),cowpea(Vigna unguiculataL.),kudzuroot (Pueraria lobataL.), and red clover blossom and red clover sprout (Trifolium pratenseL.) have been studied for their estrogenic activity.[7]Highly processed foods made from legumes, such astofu,retain most of their isoflavone content, and fermentedmiso,which has increased levels.[1]
Soy milk has a much higher concentration of isoflavones than soy sauce, but fermented soybeans show considerably higher concentrations, withtempehhaving the highest isoflavone content.[1][8]
Other dietary sources of isoflavones includechick pea(biochanin A),alfalfa(formononetin), andpeanut(genistein). Isoflavones are also found in foods of animal origin such as dairy products,[9]meat, eggs and seafood,[10]but the overall contribution to total intake is low. In countries using thechorleywood bread process,such as in the UK, bread is a source of isoflavones from soy.[11]
Inplant tissue,they most often occur asglycosidesor their respectivemalonatesor acetyl conjugates,[6]rendering them even more water-soluble (seeisoflavone-7-O-beta-glucoside 6 "-O-malonyltransferase). The latter forms are unstable and are transformed, e.g. bydecarboxylation.Often when leguminose plants are challenged with viral or fungal infections, the water-soluble transport forms arehydrolyzedto the respectiveaglyconesat the target site.[12]
Research
[edit]The consumption of isoflavones-rich food ordietary supplementsis under preliminary research for its potential association with lower rates ofpostmenopausalcancer andosteoporosisin women.[1][4][13]Use of soy isoflavonedietary supplementsmay be associated with reduction ofhot flashesin postmenopausal women.[1][4]Soy isoflavones can act assubstratesforthyroid peroxidase,therebycompetitively inhibitingthyroid hormoneproduction.[14]
Despite the frequent use of isoflavone supplements, there are insufficient data on safety and adverse effects.[1]Isoflavones haveGRASstatus in the United States.[15]In a risk assessment of isoflavone supplements for post-menopausal women, theEuropean Food Safety Authorityfound noadverse effectswith intakes up to 150 mg/d, although it criticized the lack of data.[16]
See also
[edit]References
[edit]- ^abcdefghijklmn"Soy isoflavones".Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis. 2024.Retrieved28 May2024.
- ^Kaufman PB, Duke JA, Brielmann H, Boik J, Hoyt JE (1997). "A comparative survey of leguminous plants as sources of the isoflavones, genistein and daidzein: implications for human nutrition and health".J Altern Complement Med.3(1): 7–12.CiteSeerX10.1.1.320.9747.doi:10.1089/acm.1997.3.7.PMID9395689.
- ^Heber, D (2008). "Plant Foods and PhyTOChemicals in Human Health". In Berdanier, C.D; Dwyer, J.T.; Feldman, E.B. (eds.).Handbook of Nutrition and Food, Second Edition.CRC Press. pp. 176–181.doi:10.1201/9781420008890.ch70.ISBN978-0-8493-9218-4.
- ^abc"Soy".MedlinePlus, US National Library of Medicine. 13 April 2023.Retrieved28 May2024.
- ^Gaspar, Alexandra; Matos, Maria João; Garrido, Jorge; Uriarte, Eugenio; Borges, Fernanda (2014)."Chromone: A Valid Scaffold in Medicinal Chemistry".Chemical Reviews.114(9): 4960–4992.doi:10.1021/cr400265z.PMID24555663.
- ^abCotrim, G. S.; Silva, D. M.; Graça, J. P.; Oliveira Junior, A.; Castro, C.; Zocolo, G. J.; Lannes, L. S.; Hoffmann-Campo, C. B. (2023)."Glycine max (L.) Merr. (Soybean) metabolome responses to potassium availability".Phytochemistry.205:113472.doi:10.1016/j.phytochem.2022.113472.ISSN0031-9422.PMID36270412.S2CID253027906.
- ^Boué, Stephen M.; Wiese, Thomas E.; Nehls, Suzanne; Burow, Matthew E.; Elliott, Steven; Carter-Wientjes, Carol H.; Shih, Betty Y.; McLachlan, John A.; Cleveland, Thomas E. (2003). "Evaluation of the Estrogenic Effects of Legume Extracts Containing Phytoestrogens".Journal of Agricultural and Food Chemistry.51(8): 2193–2199.doi:10.1021/jf021114s.ISSN0021-8561.PMID12670155.
- ^Luca SV, Macovei I, Bujor A, Trifan A (2020). "Bioactivity of dietary polyphenols: The role of metabolites".Critical Reviews in Food Science and Nutrition.60(4): 626–659.doi:10.1080/10408398.2018.1546669.PMID30614249.S2CID58651581.
- ^Kasparovska, J; Pecinkova, M; Dadakova, K; Krizova, L; Hadrova, S; Lexa, M; Lochman, J; Kasparovsky, T (2016)."Effects of Isoflavone-Enriched Feed on the Rumen Microbiota in Dairy Cows".PLOS ONE.11(4): e0154642.Bibcode:2016PLoSO..1154642K.doi:10.1371/journal.pone.0154642.PMC4849651.PMID27124615.
- ^Kuhnle, G. G.; Dell'Aquila, C; Aspinall, S. M.; Runswick, S. A.; Mulligan, A. A.; Bingham, S. A. (2008). "Phytoestrogen content of foods of animal origin: Dairy products, eggs, meat, fish, and seafood".Journal of Agricultural and Food Chemistry.56(21): 10099–104.doi:10.1021/jf801344x.PMID18922017.
- ^Mulligan, A. A.; Welch, A. A.; McTaggart, A. A.; Bhaniani, A; Bingham, S. A. (2007)."Intakes and sources of soya foods and isoflavones in a UK population cohort study (EPIC-Norfolk)".European Journal of Clinical Nutrition.61(2): 248–54.doi:10.1038/sj.ejcn.1602509.PMID16943849.
- ^Long-ze Lin; et al. (2000). "LC-ESI-MS Study of the Flavonoid Glycoside Malonates of Red Clover (Trifolium pratense)".Journal of Agricultural and Food Chemistry.2(48): 354–365.doi:10.1021/jf991002.PMID10691640.
- ^Wei, P; Liu, M; Chen, Y; Chen, D. C. (2012)."Systematic review of soy isoflavone supplements on osteoporosis in women".Asian Pacific Journal of Tropical Medicine.5(3): 243–8.doi:10.1016/S1995-7645(12)60033-9.PMID22305793.
- ^Hüser S, Guth S, Joost HG, Soukup ST, Kulling SE (2018)."Effects of isoflavones on breast tissue and the thyroid hormone system in humans: a comprehensive safety evaluation".Archives of Toxicology.92(9): 2703–2748.doi:10.1007/s00204-018-2279-8.PMC6132702.PMID30132047.
- ^Archer Daniels Midland Company (4 February 1998)."GRAS Notification for Isoflavones Derived from Soybeans"(PDF).US Food and Drug Administration.Retrieved25 July2016.
- ^EFSA panel on food additives and nutrient sources added to food (21 October 2015)."Risk assessment for peri- and post-menopausal women taking food supplements containing isolated isoflavones"(PDF).EFSA Journal.13(10): 4246.doi:10.2903/j.efsa.2015.4246.Retrieved25 July2016.