Aspergillus niger catalyzes the synthesis of flavonoids from chalcones

Alarcón, Julio; Alderete, Joel B.; Escobar, Carlos A.; Araya, Ramiro Bustamante; Cespedes‐Acuña, Carlos L.

doi:10.3109/10242422.2013.813489

Cited by 20 publications

(9 citation statements)

References 14 publications

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“…Studies on the interactions of microorganisms with chalcones published thus far show that the transformation of these compounds can only be done by heterotrophic microorganisms, such as bacteria, filamentous fungi and yeast. Biotransformations of chalcones by whole cells of these microorganisms are similar to the metabolic conversion pathways of these compounds in plants and include hydroxylation [ 16 – 21 ], cyclization [ 16 , 17 , 19 – 22 ], O-demethylation [ 16 , 17 , 19 ], O-dealkylation [ 18 ], epoxidation [ 22 ], glycosylation [ 23 – 25 ], and hydrogenation [ 19 , 20 , 26 – 30 ]. The reduction of a dihydrochalcone to the respective alcohol has been rarely reported [ 27 – 30 ].…”

Section: Introductionmentioning

confidence: 99%

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

2017

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BackgroundChalcones are the biogenetic precursors of all known flavonoids, which play an essential role in various metabolic processes in photosynthesizing organisms. The use of whole cyanobacteria cells in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone, is reported. The prokaryotic microalgae cyanobacteria are known to produce phenolic compounds, including flavonoids, as natural components of cells. It seems logical that organisms producing such compounds possess a suitable “enzymatic apparatus” to carry out their biotransformation. Therefore, determination of the ability of whole cells of selected cyanobacteria to carry out biocatalytic transformations of chalcone, the biogenetic precursor of all known flavonoids, was the aim of our study.ResultsChalcone was found to be converted to dihydrochalcone by all examined cyanobacterial strains; however, the effectiveness of this process depends on the strain with biotransformation yields ranging from 3% to >99%. The most effective biocatalysts are Anabaena laxa, Aphanizomenon klebahnii, Nodularia moravica, Synechocystis aquatilis (>99% yield) and Merismopedia glauca (92% yield). The strains Anabaena sp. and Chroococcus minutus transformed chalcone in more than one way, forming a few products; however, dihydrochalcone was the dominant product. The course of biotransformation shed light on the pathway of chalcone conversion, indicating that the process proceeds through the intermediate cis-chalcone. The scaled-up process, conducted on a preparative scale and by using a mini-pilot photobioreactor, fully confirmed the high effectiveness of this bioconversion. Moreover, in the case of the mini-pilot photobioreactor batch cultures, the optimization of culturing conditions allowed the shortening of the process conducted by A. klebahnii by 50% (from 8 to 4 days), maintaining its >99% yield.ConclusionsThis is the first report related to the use of whole cells of halophilic and freshwater cyanobacteria strains in a two-step, light-catalysed regioselective bio-reduction of chalcone, leading to the formation of the corresponding dihydrochalcone. The total bioconversion of chalcone in analytical, preparative, and mini-pilot scales of this process creates the possibility of its use in the food industry for the production of natural sweeteners.

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Section: Introductionmentioning

confidence: 99%

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

2017

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“…Aspergillus species have been widely established as cell factories for the synthesis of enzymes and metabolites. This species is considered an industrial superstar due to the critical role is has in the fermentation process for the production of biofuels, bioactive compounds, and functional foods for human health [17]. In this study, we report the bioconversion of rutin to quercetin by Aspergillus niger.…”

Section: Resultsmentioning

confidence: 99%

Targeting biofilm inhibition using Quercetin – Interaction with bacterial cell membrane and ROS mediated biofilm control

Sarangapani¹,

Jayachitra²

2018

FFHD

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Citation: Sreelatha S., Jayachitra A., Targeting biofilm inhibition using Quercetin -Interaction with bacterial cell membrane and ROS mediated biofilm control. Functional Foods in Health and Disease 2018; 8(6): 292-306 ABSTRACT Background: Quercetin is an active nutraceutical ingredient widely distributed in foods, vegetables, fruits, and more. Quercetin is a versatile functional food with extensive protective effects against many infectious and degenerative diseases due to their antioxidant activities. Apsergillus niger is a filamentous fungus and the most abundant mold found in the environment. This fungus has been the source of several bioactive compounds and industrial enzymes through biotransformation. Aim:In this report we emphasized the potential of Aspergillus species for the selective conversion of rutin to quercetin, which involved stereoselective and regiospecific reactions with enhanced production and minimization of the formation of toxic wastes. This fungal microbe was able to transform the complex structure of rutin to quercetin with remarkable catalytic activity for the reaction with high product yield. The quercetin produced demonstrated the ability to inhibit biofilm formation and eradicate established biofilm involving the production of reactive oxygen species (ROS) indicative of membrane activity. These results suggest quercetin may have implications in biofilm control targeting reactive oxygen species as a novel therapeutic strategy. Methods: Quercetin was synthesized by microbial biotransformation recruiting Aspergillus niger.The synthesis of quercetin was compared with the chemical process. Furthermore, the quercetin produced by the biotransformation process was characterized by high performance thin layer liquid chromatography. The quercetin produced was assessed for biological activities. The antimicrobial activity, hemolytic activity, inhibition of biofilm by crystal violet staining, and cell viability by confocal laser scanning microscope was assessed. The membrane interaction effect and oxidant scavenging effect by DPPH, Intracellular ROS release, and lipid peroxidation was measured. Results:Quercetin produced by microbial transformation demonstrated antimicrobial activity against S. aureus by effectively inhibiting the growth and dispersion of preformed biofilms. Quercetin demonstrated a significant free radical scavenging activity and significant inhibition of lipid peroxidation. Significant release of reactive oxygen species was observed in bacterial cells.

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“…The potential cytotoxic effect of the compounds CH1 and CH2 ( Figure 2 a) [ 26 , 27 ] were measured in HepG2, HuH-7 and HepM cells. As shown in Figure 2 b–d, both chalcones had a cytotoxic effect only in HCC (HuH-7 and HepG2) cells, whereas cytotoxic effects were not observed in mouse hepatocytes ( Figure 2 e).…”

Section: Resultsmentioning

confidence: 99%

Chalcone-Induced Apoptosis through Caspase-Dependent Intrinsic Pathways in Human Hepatocellular Carcinoma Cells

Ramírez-Tagle

Escobar

Romero

et al. 2016

IJMS

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Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed cancers worldwide. Chemoprevention of HCC can be achieved through the use of natural or synthetic compounds that reverse, suppress or prevent the development of cancer progression. In this study, we investigated the antiproliferative effects and the mechanism of action of two compounds, 2,3,4′-trimethoxy-2′-hydroxy-chalcone (CH1) and 3′-bromo-3,4-dimethoxy-chalcone (CH2), over human hepatoma cells (HepG2 and Huh-7) and cultured mouse hepatocytes (HepM). Cytotoxic effects were observed over the HepG2 and Huh-7, and no effects were observed over the HepM. For HepG2 cells, treated separately with each chalcone, typical apoptotic laddering and nuclear condensation were observed. Additionally, the caspases and Bcl-2 family proteins activation by using Western blotting and immunocytochemistry were studied. Caspase-8 was not activated, but caspase-3 and -9 were both activated by chalcones in HepG2 cells. Chalcones also induced reactive oxygen species (ROS) accumulation after 4, 8 and 24 h of treatment in HepG2 cells. These results suggest that apoptosis in HepG2 was induced through: (i) a caspase-dependent intrinsic pathway; and (ii) by alterations in the cellular levels of Bcl-2 family proteins, and also, that the chalcone moiety could be a potent candidate as novel anticancer agents acting on human hepatomas.

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Aspergillus niger catalyzes the synthesis of flavonoids from chalcones

Cited by 20 publications

References 14 publications

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

Highly effective, regiospecific reduction of chalcone by cyanobacteria leads to the formation of dihydrochalcone: two steps towards natural sweetness

Targeting biofilm inhibition using Quercetin – Interaction with bacterial cell membrane and ROS mediated biofilm control

Chalcone-Induced Apoptosis through Caspase-Dependent Intrinsic Pathways in Human Hepatocellular Carcinoma Cells

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