Abstract
Quercetin (Q) was used as substrate for regioselective glycosylation at the C-7 position catalyzed by Beauveria bassiana AM278 strain. As a result the glycoside quercetin 7-O-β-d-(4″-O-methyl)glucopyranoside (Q 7-MeGlu) was formed. The goal of the studies was to determine the anti-oxidative (liposome membrane protection against free radicals IC50Q 7-MeGlu = 5.47 and IC50Q = 4.49 µM) and anti-inflammatory (COX-1 and COX-2 enzymes activity inhibition) properties of Q 7-MeGlu as compared to Q. Every attempt was made to clarify the antioxidant activity of these molecules, which are able to interact with egg phosphatidylcholine liposomes, using a fluorometric method (by applying the probes MC540, TMA-DPH and DPH). The results indicated that Q 7-MeGlu and Q are responsible for increasing the packing order, mainly in the hydrophilic but also in hydrophobic regions of the membrane (Q > Q 7-MeGlu). These observations, confirmed by a 1H-NMR method, are key to understanding their antioxidant activity which is probably caused by the stabilizing effect on the lipid membranes. The results showed that Q 7-MeGlu and Q have ability to quench the human serum albumin (HSA) intrinsic fluorescence through a static quenching mechanism. The results of thermodynamic parameters indicated that the process of formation complexes between studied molecules and HSA was spontaneous and caused through Van der Waals interactions and hydrogen bonding.
Highlights
Quercetin (3,30,40,5,7-pentahydroxyflavone), a major bioflavonoid found in fruits and vegetables, exhibits unique biological properties [1]
The fungus Beauveria bassiana is known for its ability to modify dozens of different chemical
Beauveria bassianathe is most known for its ability modify of different compounds, it is among frequently usedtowhole celldozens biocatalysts
Summary
Quercetin (3,30 ,40 ,5,7-pentahydroxyflavone), a major bioflavonoid found in fruits and vegetables, exhibits unique biological properties [1]. A broad spectrum of beneficial quercetin properties, including antimutagenic, antifibrotic, antiinflammatory, antiatherogenic, and antibacterial effects, as well as its strong antioxidative capacity, is described. Quercetin is responsible for reducing viability and inducing apoptosis of numerous cancer cells lines, including those from breast, hepatic, colon, lung, ovary, endometrial cancers and prostate cancers. Quercetin can control cancer cell growth by the regulation of specific signaling pathways, e.g., decreasing oncogene expression, inducing malignant cell apoptosis and inhibiting angiogenesis [5,6]. Due to its antiproliferative and proapoptotic properties quercetin is a promising, natural compound which can be used supportively in chemotherapy. Quercetin proves to be an excellent in vitro antioxidant. Considering the whole family of flavonids, it seems to be the most potent
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