Molecular fluorescence in silica particles doped with quercetin-Al3+ complexes

Frederice, Rafael; Ferreira, Ana Paula Garcia; Gehlen, Marcelo Henrique

doi:10.1590/s0103-50532010000700008

Cited by 10 publications

(6 citation statements)

References 5 publications

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“…The microscopic images of the samples containing quercetin are not shown because this compound is not fluorescent. According to Frederice et al ., quercetin exhibits low fluorescence due to a lack of significant emission at room temperature. Furthermore, quercetin only absorbs light in the 400 − 500 nm range when aluminum cations are added to the solution.…”

Section: Resultsmentioning

confidence: 99%

Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity

Uebel

Schmatz

Kuntzler

et al. 2016

J of Applied Polymer Sci

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Polymeric nanofibers are materials that can be used as scaffolds in tissue engineering. Quercetin and curcumin are antioxidants because of scavenge free radicals and chelate metal ions properties, protecting tissues of lipid peroxidation. The objective of this study was to develop a scaffold with potential antioxidant activity that was produced from nanofibers consisting of polycaprolactone (PCL) and a blend of PCL/poly(hydroxybutyrate-co-hydroxyvalerate) (PHB-HV) with the addition of quercetin or curcumin as the bioactive compound. Curcumin and quercetin were integrated into the solution at a concentration of 3%. The electrospun nanofibers were characterized using calorimetry and thermogravimetric analysis, and the addition of bioactive compounds did not alter the thermal properties of the biomaterial. The antioxidant activity of scaffolds with the active compounds was evaluated by hydrate 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2 0 -azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) methods. The scaffolds with PCL and PCL/PHB-HV blend with quercetin exhibited higher antioxidant activity than curcumin with both methods.

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Section: Resultsmentioning

confidence: 99%

Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity

Uebel

Schmatz

Kuntzler

et al. 2016

J of Applied Polymer Sci

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“…Quercetin is a natural polyphenolic antioxidant, which is present in vegetables, fruits and juices. It is a strong antioxidant because it can chelate metal ions such as Pd(II) [4], Cu(II) [5,6], Co(II) [7], Al(III) [8], scavenge oxygen free radicals [9,10] and prevent the oxidation of low density lipoprotein (LDL) in vitro [11]. Oxidized LDL is hypothesized to be an intermediate in the formation of atherosclerotic plaques [12].…”

Section: Introductionmentioning

confidence: 99%

Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms

Pavun

Đurđević

Jelikić-Stankov

et al. 2014

Maced. J. Chem. Chem. Eng.

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A simple, accurate and precise method based on the fluorescence properties of the aluminum(III)-quercetin complex, for the determination of quercetin, has been developed and validated. The complex has strong emission at pH 3.30,  em = 480 nm, with  ex = 420 nm. The linearity range of quercetin determination was 1.5-60.5 ng ml -1 with LOD 0.09 ng ml -1 and LOQ 0.27 ng ml -1. Recovery values in the range of 99.9-100.2% indicate a good accuracy of the method. The established method was applied for the determination of quercetin in capsules, with a recovery value of 98.3%, standard deviation of 0.22% and coefficient of variation of 0.09%.The reliability of the method was checked by the newly developed RP-HPLC/UV method for capsules with the direct determination of quercetin after separation. The good agreement between the two methods indicates the applicability of the proposed spectrofluorimetric method for quercetin determination in pharmaceutical dosage forms, with high reproducibility, and enables the direct and simple determination without its prior extraction from samples.The proposed spectrofluorimetric method has much better sensitivity and LOD and LOQ values that are about 1000 times lower than data reported in the literature.Keywords: quercetin; flavonoids; spectrofluorimetric determination; RP-HPLC; capsules СПЕКТРОФЛУОРОМЕТРИСКО ОПРЕДЕЛУВАЊЕ НА КВЕРЦЕТИН ВО ФАРМАЦЕВТСКИ ДОЗИРАНИ ФОРМИРазвиен и валидиран е едноставен, точен и прецизен метод за определување на кверцетин заснован на флуоресцентните својства на комплексот кверцетин-алуминиум(III). Комплексот покажува силна емисија при pH 3,30,  em = 480 nm и  ex = 420 nm. Линеарниот опсег за определување на кверцетин е 1,5-60,5 ng ml -1 со LOD 0,09 ng ml -1 и LOQ 0,27 ng ml -1. Вредностите на аналитичкиот принос од 99,9-100,2% покажуваат добра точност на методот. Воспоставениот метод е применет за определување на кверцетин во капсули со вредност на аналитичкиот принос од 98.3%, стандардна девијација од 0,22% и коефициент на варијација од 0,09%.Веродостојноста на методот е проверена со новововедениот RP-HPLC/UV метод за капсули со директно определување на кверцетин по негова сепарација. Доброто согласување на двата метода укажува на применливост на предложениот спектрофлуорометриски метод за опреде-лување на кверцетин во фармацевтски дозирани форми со висока репродуцибилност и овозможува директно и едноставно определување без претходна екстракција од примероците.Предложениот спектрофлуорометриски метод има многу подобра осетливост и вредностите LOD и LOQ се за околу 1000 пати пониски од оние дадени во литературата.

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“…The content of total flavonoids was estimated spectrophotometrically by reaction with AlCl3, using quercetin as a standard (DOWLD, 1959;WOISKY and SALATINO, 1998;FREDERICE et al, 2010). The essential oils were diluted in ethanol to obtain solutions with a concentration of 10 mg mL -1 .…”

Section: Total Flavonoidsmentioning

confidence: 99%

Chemical profile, stability and fungicide activity of oil-in-water nanoemulsion (O / A) incorporated with Ba-har essential oil

Felizardo¹,

Pereira²,

Lima³

et al. 2021

CeN

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The increase in strains resistant to conventional antifungals means that there is a need for studies related to alternative therapeutic practices, such as medicinal plants. This study aims to evaluate the chemical profile and fungicidal activity of the nanoemulsion of the essential oil obtained from Ba-har (Syrian pepper). The phytochemical profile of the plant material was performed based on the methodology of Matos (2009). For extraction of essential oil, 100g of plant material was used, with the isolation of essential oil by the hydrodistillation technique conducted at 100 °C / 3h. To quantify the total phenolics present in the OE, the Folin-Ciocalteu method was used. For the total flavonoids, the AlCl3 complexation method was used. The oil-in-water nanoemulsion was formulated by the low-energy method of phase inversion using essential oil, non-ionic surfactant and water, and the obtained nanoemulsion was subjected to thermodynamic stability tests. The essential oils and stable nanoemulsions were subjected to evaluation of the fungicidal action against strains of Aspergillus niger (ATCC 6275), Colletotrichum gloeosporioides (ATCC 96723) and Penicilium chrysogenum (ATCC 10106). The fungicidal activity was performed according to CLSI (2020) using the Broth Dilution method to obtain the Minimum Inhibitory Concentration (MIC) and sowing on agar for Minimum Fungicidal Concentration (CFM). The results obtained for the total phenolic content were quantified at 348.3 mg EAT g-1 and 346.21 mg EQ g-1 for flavonoids. Ba-har essential oil was more efficient in inhibiting A. niger, as it presented the lowest MIC (200 µg mL-1), followed by P. chrysogenum (250 µg mL-1) and later by C. gloeosporioides (300 µg mL-1). The identification of the secondary metabolites present in Ba-har was quite considerable, since they are responsible for the biological properties, thus inspiring the continuity of studies related to its biological activities. As for the total phenolic content and flavonoids present in the essential oil, they indicated the important antioxidant potential. The fungicidal potential of Ba-har oil showed strong inhibition and mortality, however the nanoemulsion product with the essential oil incorporated showed a more efficient action against the pathogenic fungi tested,

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Molecular fluorescence in silica particles doped with quercetin-Al3+ complexes

Cited by 10 publications

References 5 publications

Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity

Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity

Spectrofluorimetric determination of quercetin in pharmaceutical dosage forms

Chemical profile, stability and fungicide activity of oil-in-water nanoemulsion (O / A) incorporated with Ba-har essential oil

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