Browsing by Author "Henriquez-Aedo, Karem"
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- ItemA high throughput method for detection of cyclooxygenase-2 enzyme inhibitors by effect-directed analysis applying high performance thin layer chromatography-bioassay-mass spectrometry(Elsevier, 2023) Oyarzún, Paulina; Carrasco, Jonathan; Peterssen, Darlene; Tereucan, Gonzalo; Aranda, Mario; Henriquez-Aedo, KaremA high throughput method was developed to detect bioactive molecules with inhibitory activity over cyclo-oxygenase (COX-2) enzyme applying effect-directed analysis and planar chromatography hyphenated with bioassay and mass spectrometry. The assay was based on the indirect measurement of arachidonic acid trans-formation into prostaglandin with the colorimetric co-substrate N,N,N',N'-tetramethyl-p-phenylenediamine. Inhibitory zones were observed as colorless bands over a blue background. Using a central composite design the critical factors like substrate concentration, enzyme: substrate ratio, reaction time, and co-substrate concentra-tion were optimized. Optimal conditions were achieved with 0.03 mg/mL of arachidonic acid, 0.15 U/mL of COX-2, and 8.21 mg/mL of chromogenic reagent. Method usefulness was challenged analyzing fresh Chiloe's giant garlic (Allium ampeloprasum L) ethanol: water (8:2 v/v) extract, finding COX-2 inhibitors that were pre-liminarily identified as the isomers gamma-glutamyl-S-allyl-L-cysteine and gamma-glutamyl-S-(trans-1-propenyl)-L-cysteine.
- ItemChemometric optimisation of pressurised liquid extraction for the determination of alliin and S-allyl-cysteine in giant garlic (Allium ampeloprasum L.) by liquid chromatography tandem mass spectrometry(2021) Peterssen-Fonseca, Darlene; Henriquez-Aedo, Karem; Carrasco-Sandoval, Jonathan; Canumir-Veas, Juan; Herrero, Miguel; Aranda, MarioIntroduction Giant garlic is a functional food that contains different kinds of bioactive molecules with beneficial effects on chronic noncommunicable diseases like diabetes and cardiovascular conditions. Considering biosynthesis pathways, abundance, and biological activity, alliin and S-allyl-cysteine were used as chemical markers of organosulphur compounds present in giant garlic.
- ItemChemometric optimization of trypsin digestion method applying infrared, microwave and ultrasound energies for determination of caseins and ovalbumin in wines(2021) Pavon-Perez, Jessy; Henriquez-Aedo, Karem; Salazar, Ricardo; Herrero, Miguel; Aranda, MarioCaseins and ovalbumin are frequently used as wine fining agents to remove undesirable compounds like polymeric phenols. Their presence in wines is a subject of concern because may cause adverse effects on susceptible consumers, especially when their presence is not labeled. A key step for its determination is trypsin digestion, which is considered the bottleneck ofbottom-upapproach workflow because usually requires several hours. To reduce this time, the objective of this work was to carry out a chemometric optimization of trypsin digestion method applying infrared, microwave and ultrasound energies to determine caseins and ovalbumin in wines. The conditions of each accelerated digestion method were optimized using a Response Surface Methodology based on central composite design. The parameters optimized were digestion time and trypsin: protein ratio. The response variable evaluated was digestion yield, which was determined through the peak area of each protein transition determined by liquid chromatography-mass spectrometry. The most effective technique was microwave followed by ultrasound and infrared. Since optimal values of microwave and ultrasound-assisted digestion were the same, the later was chosen considering sample preparation and cost. Applying the proposed approach, a reduction ofca.140 and 240-fold on digestion time was achieved compared with optimized and non-optimized conventional methods, respectively. With this workflow, both proteins were digested in a single 3 min process allowing its detection by liquid chromatography-mass spectrometry at mu g L(-1)level, which isca.60 times lower than the current limit of 0.25 mg L-1.
- ItemEvaluation of biogenic amines content in chilean reserve varietal wines(2012) Henriquez-Aedo, Karem; Vega, Mario; Prieto-Rodriguez, Sonia; Aranda Bustos, Mario Antonio
- ItemImpact of molecular weight and deacetylation degree of chitosan on the bioaccessibility of quercetin encapsulated in alginate/chitosan-coated zein nanoparticles(2023) Carrasco-Sandoval, Jonathan; Aranda, Mario; Henriquez-Aedo, Karem; Fernandez, Marcos; Lopez-Rubio, Amparo; Fabra, Maria JoseThis work aimed at studying the effect of molecular weight (MW) and deacetylation degree (DD) of chitosan on the quercetin bioaccessibility encapsulated in alginate/chitosan-coated zein nanoparticles (alg/chiZN). The chitosan coating layer produced nanoparticulate systems with good stability parameters, high encapsulation efficiency (EE) and a higher bioaccessibilty of quercetin after in-vitro digestion. By increasing the DD of chitosan, the zeta-potential of the colloidal system significantly increased (>= 27.1 mV), while low and very low MW chitosans generated systems with smaller particle sizes (<= 277.8 nm) and polydispersity index [PDI (0.189)]. The best results, in terms of EE (>= 84.44) and bioaccessibility (>= 76.70), were obtained when the systems were prepared with low MW chitosan and high DD. Thus, the alg/chiZN nanocapsules may be a promising delivery system for improving the quercetin bioaccessibility or other compounds with a similar chemical nature, especially when higher DD and lower MWs are used.
- ItemLC-MS/MS METHOD FOR L-DOPA QUANTIFICATION IN DIFFERENT TISSUES OF VICIA FABA(2019) Pavon-Perez, Jessy; Oviedo, Claudia A.; Elso-Freudenberg, Mhartyn; Henriquez-Aedo, Karem; Aranda, MarioA rapid, sensitive, precise and accurate liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for levo 3,4-dihydroxyphenylalanine (L-DOPA) determination in Vicia faba during different growth stages. The method applied a simple sample preparation step followed by a chromatographic separation on a Kinetex XB Core-Shell C-18 (100 mm x 4.6 mm, 2.6 mu m) column, using a mixture of ultrapure pure water (A) with 0.5 % (v/v) formic acid and methanol (B) as mobile phase. Analysis of L-DOPA was carried out by MS/MS applying a Multiple Reaction Monitoring (MRM) method using the transition m/z 198 -> m/z 152. This LC-MS/MS method allowed a well-resolved detection of L-DOPA in ca. 2 min within 6 min run. Method was validated showing a linear range from 0.05 to 10 mg L-1 (R-2 = 0.99); repeatability showed RSD value of 1.40%. Recoveries ranged from 94.14 to 116.62% with RSD values <= 5.66% and detection and quantification limits were 0.01 and 0.05 mg L-1, respectively. Applying this validated method, L-DOPA was determined in Vicia faba samples to determined its tissue distribution. As expected, a broad range of L-DOPA content finding the lowest content in seeds (4.72 +/- 2.12 mg g(-1)) and the highest in sprouts (133.60 +/- 5.65 mg g(-1)).
- ItemMultivariate optimization of microwave-assisted enzyme digestion of α-casein for generation of bioactive peptides(2023) Lopez, Katherine; Espinoza-Bello, Alejandra; Carrasco, Jonathan; Pena-Farfal, Carlos; Aranda, Mario; Henriquez-Aedo, KaremCaseins are the principal milk proteins and serve as an important source of bioactive peptides with diverse beneficial effects for human health, such as antihypertensive, immunomodulating, anti-inflammatory, and antithrombotic. The objective of this study was to optimize, using the design of the experiment, the production of bioactive peptides from alpha-casein applying microwave -assisted enzyme digestion (MAED). The optimal MAED conditions (time, temperature, and enzyme/protein ratio) were established for pepsin (digestion time 4 min, temperature 41 degrees C, and E:P ratio 1:40) and trypsin (digestion time 10 min, temperature 37 degrees C and E:P ratio 1:200.) enzymes. Digestion yields and the intensity of different bioactivities, i.e., antimicrobial, antioxidant, and acetylcholinesterase and alpha glucosidase inhibitory activities, evaluated by the HPTLC-bioassay technique were used as response variables. Trypsin-formed alpha-casein peptides showed antimicrobial, antioxidant, and acetylcholinesterase inhibition activities, while pepsin -formed showed antimicrobial, antioxidant, and alpha-glucosidase inhibition activities. These results demonstrate that MAED is a fast and effective technique for bioactive peptide production from casein proteins.