Sulfated quercetin derivatives are important authentic standards for metabolic studies. Quercetin-3'-O-sulfate, quercetin-4'-O-sulfate, and quercetin-3-O-sulfate as well as quercetin-di-O-sulfate mixture (quercetin-7,3'-di-O-sulfate, quercetin-7,4'-di-O-sulfate, and quercetin-3',4'-di-O-sulfate) were synthetized by arylsulfotransferase from Desulfitobacterium hafniense. Purified monosulfates and disulfates were fully characterized using MS and NMR and tested for their 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺) and N,N-dimethyl-p-phenylenediamine (DMPD) radical scavenging, Folin-Ciocalteau reduction (FCR), ferric reducing antioxidant power (FRAP), and anti-lipoperoxidant activities in rat liver microsomes damaged by tert-butylhydroperoxide. Although, as expected, the sulfated metabolites were usually less active than quercetin, they remained still effective antiradical and reducing agents. Quercetin-3'-O-sulfate was more efficient than quercetin-4'-O-sulfate in DPPH and FCR assays. In contrast, quercetin-4'-O-sulfate was the best ferric reductant and lipoperoxidation inhibitor. The capacity to scavenge ABTS+• and DMPD was comparable for all substances, except for disulfates, which were the most efficient. Quantum calculations and molecular dynamics simulations on membrane models supported rationalization of free radical scavenging and lipid peroxidation inhibition. These results clearly showed that individual metabolites of food bioactives can markedly differ in their biological activity. Therefore, a systematic and thorough investigation of all bioavailable metabolites with respect to native compounds is needed when evaluating food health benefits.
The extract from milk thistle (Silybum marianum (L.) Gaertn. (Asteraceae)), known as silymarin, contains a variety of flavonolignans and displays antioxidant, anti-inflammatory, immunomodulatory and hepatoprotective properties. As silybin is the main component of silymarin, the literature mainly focuses on this compound, ignoring all other components. This leads to problems in reproducibility of scientific results, as the exact composition of silymarin is often unknown and can vary to a certain degree depending on the processing, chemo-variety of the plant used and climatic conditions during the plant growth. There are studies dealing with the analytical separation and quantification of silymarin components as well as studies focused on silymarin content in clinically used drugs, in various plant parts, seasons, geographic locations etc. However, no comparison of detail flavonolignan profiles in various silymarin preparations is available to date. Also, as a result of the focus on the flavonolignans; the oil fraction, which contains linoleic, oleic and palmitic acids, sterols, tocopherol (vitamin E) and phospholipids, has been neglected. Due to all these factors, the whole plant is used e.g. as animal feed, the leaves can be eaten in salads and seed oil, besides culinary uses, can be also utilized for biodiesel or polymer production. Various HPLC separation techniques for the determination of the content of the flavonolignans have been vastly summarized in the present review.
- MeSH
- antiflogistika analýza chemie MeSH
- antioxidancia analýza chemie MeSH
- flavonolignany analýza chemie MeSH
- imunologické faktory analýza chemie MeSH
- rostlinné extrakty analýza chemie MeSH
- semena rostlinná chemie MeSH
- silibinin analýza chemie MeSH
- silymarin analýza chemie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Isoquercitrin, (IQ, quercetin-3-O-β-d-glucopyranoside) is known for strong chemoprotectant activities. Acylation of flavonoid glucosides with carboxylic acids containing an aromatic ring brings entirely new properties to these compounds. Here, we describe the chemical and enzymatic synthesis of a series of IQ derivatives at the C-6″. IQ benzoate, phenylacetate, phenylpropanoate and cinnamate were prepared from respective vinyl esters using Novozym 435 (Lipase B fromCandida antarcticaimmobilized on acrylic resin). The enzymatic procedure gave no products with "hydroxyaromatic" acids, their vinyl esters nor with their benzyl-protected forms. A chemical protection/deprotection method using Steglich reaction yielded IQ 4-hydroxybenzoate, vanillate and gallate. In case ofp-coumaric, caffeic, and ferulic acid, the deprotection lead to the saturation of the double bonds at the phenylpropanoic moiety and yielded 4-hydroxy-, 3,4-dihydroxy- and 3-methoxy-4-hydroxy-phenylpropanoates. Reducing capacity of the cinnamate, gallate and 4-hydroxyphenylpropanoate towards Folin-Ciocalteau reagent was significantly lower than that of IQ, while other derivatives displayed slightly better or comparable capacity. Compared to isoquercitrin, most derivatives were less active in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, but they showed significantly better 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid, ABTS) scavenging activity and were substantially more active in the inhibition oftert-butylhydroperoxide induced lipid peroxidation of rat liver microsomes. The most active compounds were the hydroxyphenylpropanoates.
- MeSH
- estery * chemie MeSH
- hmotnostní spektrometrie MeSH
- molekulární struktura MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- peroxidace lipidů účinky léků MeSH
- quercetin analogy a deriváty analýza chemická syntéza farmakologie MeSH
- scavengery volných radikálů analýza chemická syntéza farmakologie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
