Electrochemical Quantification of the Antioxidant Capacity of Medicinal Plants Using Biosensors
Erika Rodríguez-Sevilla,
María-Teresa Ramírez-Silva,
Mario Romero-Romo,
Pedro Ibarra-Escutia,
Manuel Palomar-Pardavé
Affiliations
Erika Rodríguez-Sevilla
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
María-Teresa Ramírez-Silva
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
Mario Romero-Romo
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
Pedro Ibarra-Escutia
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
Manuel Palomar-Pardavé
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
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.
