title: Electrochemical quantification of the antioxidant capacity of medicinal plants using biosensors.
abstract: The working area of a screen-printed electrode, SPE, was modified with the enzyme tyrosinase (Tyr) using different immobilization methods, namely entrapment with water-soluble polyvinyl alcohol (PVA), cross-linking using glutaraldehyde (GA), and cross-linking using GA and human serum albumin (HSA); the resulting electrodes were termed SPE/Tyr/PVA, SPE/Tyr/GA and SPE/Tyr/HSA/GA, respectively. These biosensors were characterized by means of amperometry and EIS techniques. From amperometric evaluations, the apparent Michaelis-Menten constant, Km', of each biosensor was evaluated while the respective charge transfer resistance, Rct, was assessed from impedance measurements. It was found that the SPE/Tyr/GA had the smallest Km' (57 ± 7) µM and Rct values. This electrode also displayed both the lowest detection and quantification limits for catechol quantification. Using the SPE/Tyr/GA, the Trolox Equivalent Antioxidant Capacity (TEAC) was determined from infusions prepared with "mirto" (Salvia microphylla), "hHierba dulce" (Lippia dulcis) and "salve real" (Lippia alba), medicinal plants commonly used in Mexico.
authors.affiliation: Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Área de Química Analítica, San Rafael Atlixco 186, Col. Vicentina, Del. Iztapalapa, México D.F., C.P. 09340, Mexico. chinita022001@yahoo.com.mx.
authors.forename: Erika
authors.initials: E
authors.lastname: Rodríguez-Sevilla
authors.affiliation: Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Área de Química Analítica, San Rafael Atlixco 186, Col. Vicentina, Del. Iztapalapa, México D.F., C.P. 09340, Mexico. chinita022001@yahoo.com.mx.
authors.forename: María-Teresa
authors.initials: MT
authors.lastname: Ramírez-Silva
authors.affiliation: Departamento de Materiales, Universidad Autónoma Metropolitana-Azcapotzalco, Área Ingeniería de Materiales, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Del. Azcapotzalco, México, D.F., C.P. 02200, Mexico. mmrr@correo.azc.uam.mx.
authors.forename: Mario
authors.initials: M
authors.lastname: Romero-Romo
authors.affiliation: SEP-Instituto Tecnológico de Toluca. Departamento de Ingeniería Química y Bioquímica. Av, Tecnológico S/N. Fraccionamiento La Virgen, Metepec, Edo de México, C.P. 52149, Mexico. pedroibes@hotmail.com.
authors.forename: Pedro
authors.initials: P
authors.lastname: Ibarra-Escutia
authors.affiliation: Departamento de Materiales, Universidad Autónoma Metropolitana-Azcapotzalco, Área Ingeniería de Materiales, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Del. Azcapotzalco, México, D.F., C.P. 02200, Mexico. mepp@correo.azc.uam.mx.
authors.forename: Manuel
authors.initials: M
authors.lastname: Palomar-Pardavé
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002396:Catechols / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D006801:Humans; D008800:Mexico; D014442:Monophenol Monooxygenase / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D002396:Catechols; D004800:Enzymes, Immobilized; D014442:Monophenol Monooxygenase; C034221:catechol
references.citation: Int J Biochem Cell Biol. 2002 Apr;34(4):332-6
references.pmid: 11854032
references.citation: Biosens Bioelectron. 2013 Feb 15;40(1):57-62
references.pmid: 22809524
references.citation: Biosens Bioelectron. 2008 Jun 15;23(11):1624-30
references.pmid: 18339536
references.citation: Bioelectrochemistry. 2004 Aug;64(1):47-52
references.pmid: 15219246
references.citation: Biochem J. 1992 Nov 15;288 ( Pt 1):63-7
references.pmid: 1445282
references.citation: J Pharm Biomed Anal. 2010 Nov 2;53(3):773-6
references.pmid: 20541883
references.citation: Food Chem. 2008 Oct 15;110(4):1019-24
references.pmid: 26047296
references.citation: Biosens Bioelectron. 2005 Jun 15;20(12):2517-54
references.pmid: 15854824
references.citation: Biochem J. 1998 Apr 15;331 ( Pt 2):547-51
references.pmid: 9531496
references.citation: Food Chem. 2013 Dec 15;141(4):4066-72
references.pmid: 23993586
references.citation: Biochemistry. 2011 Oct 4;50(39):8264-9
references.pmid: 21888353
references.citation: Anal Biochem. 1981 Jul 1;114(2):322-9
references.pmid: 7304923
references.citation: Talanta. 2013 Nov 15;116:991-6
references.pmid: 24148506
references.citation: J Agric Food Chem. 2002 Jul 3;50(14):4108-12
references.pmid: 12083892
references.citation: J Hazard Mater. 2013 Jan 15;244-245:528-36
references.pmid: 23245881
references.citation: Talanta. 2010 Jun 15;81(4-5):1636-42
references.pmid: 20441951