- Synthesis and Evaluation of Antimicrobial and Antibiofilm Properties of A-Type Procyanidin Analogues against Resistant Bacteria in Food
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Natural A-type procyanidins have shown very interesting biological activities, such as their proven antiadherence properties against pathogenic bacteria. In order to find the structural features responsible for their activities, we describe herein the design and synthesis of six A-type procyanidin analogues and the evaluation of their antimicrobial and antibiofilm properties against 12 resistant bacteria, both Gram positive and Gram negative, isolated from organic foods. The natural A-type procyanidin A-2, which had known antiadherence activity, was also tested as a reference compound for the comparative studies. Within the series, analogue 4, which had a NO2 group on ring A, showed the highest antimicrobial activity (MIC of 10 μg/mL) and was one of the best molecules at preventing biofilm formation (up to 40% decreases at 100 μg/mL) and disrupting preformed biofilms (up to 40% reductions at 0.1 μg/mL). Structure-activity relationships are also analyzed.
- Alejo-Armijo, Alfonso,Glibota, Nicolás,Frías, María P.,Altarejos, Joaquín,Gálvez, Antonio,Salido, Sofía,Ortega-Morente, Elena
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- Synthesis and equilibrium multistate of new pyrano-3-deoxyanthocyanin-type pigments in aqueous solutions
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Pyrano-flavylium compounds are flavylium derivatives with occurrence in processed foodstuffs such as wine and red fruit juices. In this work, the chemical equilibria of “bio-inspired” pyrano-3-deoxyanthocyanin dyes (4–8), presenting different substituent groups in D ring (10-methyl, 10-catechol, 10-dimethylaminophenyl, 10-carboxy) as well as in B ring (3′,4′-dihydroxy, 4′-carboxy), were studied for the first time in aqueous solutions by UV–Vis spectroscopy. The presence of a methyl group at C-10 (pigment 4) seems to stabilize the flavylium cation (AH+) shifting the deprotonation of 7-OH to a higher pKa1 (pKa1 = 5.0 ± 0.1). On the other hand, the quinoidal bases (A, A?) were more stabilized for the pigments which undergo the first acid-base equilibrium at C-10 substituent, as could be observed by the pKa2 constants (pKa2 = 8.4 ± 0.1 and pKa2 = 8.1 ± 0.1, pigments 6 and 8, respectively).
- Sousa, Joana L.C.,Gomes, Vania,Mateus, Nuno,Pina, Fernando,de Freitas, Victor,Cruz, Luís
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- Thermodynamic Stability of Flavylium Salts as a Valuable Tool to Design the Synthesis of A-Type Proanthocyanidin Analogues
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A convenient method to synthesize A-type proanthocyanidin analogues from flavylium salts and ?€-nucleophiles has been developed. It was found that the thermodynamic stability of the starting flavylium salt, assessed by the measurement of the apparent acidity constant (K′a), was the key parameter to design effective one-pot reactions between flavylium salts and nucleophiles such as phloroglucinol and (+)-catechin. When flavylium salts have a pK′a value of 1.7 or lower, the synthesis of the corresponding 2,8-dioxabyciclo[3.3.1]nonane derivative was properly achieved.
- Alejo-Armijo, Alfonso,Jorge Parola,Pina, Fernando,Altarejos, Joaquín,Salido, Sofía
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- Synthesis and structural characterization of novel pyranoluteolinidin dyes
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The synthesis and structural characterization by LC–MS and NMR of novel pyranoluteolinidin derivatives are reported. The compounds result from the reactions between luteolinidin and three different carboxylic acids in wine model-like solutions. The three pigments possess different substituents attached to the D ring (methyl, catechol and dimethylaminophenyl groups) and the same catechol group in the B ring, yielding a wide spectrum of colors from yellow to pink-purple.
- Cruz, Luís,Sousa, Joana L.C.,Marinho, Andreia,Mateus, Nuno,de Freitas, Victor
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- A simple synthesis of 3-deoxyanthocyanidins and their O-glucosides
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This work deals with the chemical synthesis of simple analogs of anthocyanins, the main class of water-soluble natural pigments. Flavylium ions with hydroxyl, methoxyl and β-D-glucopyranosyloxyl substituents at positions 4′ and 7 have been prepared by straightforward chemical procedures. Moreover, the two 3-deoxyanthocyanidins of red sorghum apigeninidin (4′,5,7-trihydroxyflavylium) and luteolinidin (3′,4′,5,7-tetrahydroxyflavylium) were synthesized in a one-step protocol. Attempts to synthesize luteolinidin O-β-D-glucosides resulted in a mixture of the 5-O- and 7-O-regioisomers in low yield. A preliminary study of the 4′-β-D-glucopyranosyloxy-7-hydroxyflavylium and 7-β-D-glucopyranosyloxy-4′-hydroxy-flavylium ions shows that simply changing the glucosidation site can profoundly affect the color intensity and stability.
- Al Bittar, Sheiraz,Mora, Nathalie,Loonis, Michèle,Dangles, Olivier
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p. 4294 - 4302
(2016/07/06)
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- (±)-Diinsininone: made nature's way
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We report the synthesis of diinsininone (33), the aglycone of (±)-diinsinin (2). Thereby, we complete the first construction of a proanthocyanidin (PA) type-A compound incorporating a [3.3.1]-bicyclic ketal as its characteristic core. Our strategy utilizes a coupling between a benzopyrilium salt and a flavanone that proves applicable to other PA type-A compounds. During this undertaking, treatment of naringenin (9) with 2-iodoxybenzoic acid (IBX) followed by reductive work-up affords eriodictyol (10). This reactivity mirrors that of catechol hydroxylase (F3H) found in the flavonoid pathway. Other interesting transformations include the formation of flavonoids through an ortho-quinone methide (o-QM) cycloaddition-oxidation sequence and regioselective β-glycosidations of several unprotected flavanones suggesting a likely synthesis of 2 from the aglycone 33.
- Selenski, Carolyn,Pettus, Thomas R.R.
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p. 5298 - 5307
(2007/10/03)
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- A new and convenient one-step synthesis of the natural 3-deoxyanthocyanidins apigeninidin and luteolinidin chlorides from 2,4,6-triacetoxybenzaldehyde
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The total synthesis of apigeninidin (1), luteolinidin (2) and 5,7-dihydroxyflavylium (5) chlorides is performed through a one step reaction from an acetylated derivative of a commercial reagent. Condensation reaction between 2,4,6-triacetoxybenzaldehyde and an acetophenone derivative in anhyd methanolic hydrogen chloride provides the 3-deoxyanthocyanidins in high yields.
- Mas, Thierry
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p. 1878 - 1880
(2007/10/03)
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- SYNTHESIS OF ANTHOCYANIDINS-III; TOTAL SYNTHESIS OF APIGENINIDIN AND LUTEOLINIDIN CHLORIDES
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The 3-deoxyanthocyanidins apigeninidin chloride (6a) and luteolinidin chloride (6b) have been synthesized in good yield through the oxidative decarboxylation of the corresponding 4-carboxyflav-2-enes 7a and 7b.
- Sweeny, J.G.,Iacobucci, G.A.
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p. 1481 - 1484
(2007/10/02)
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