Ciencia y Tecnología Alimentaria ISSN: Sociedad Mexicana de Nutrición y Tecnología de Alimentos.

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1 Ciencia y Tecnología Alimentaria ISSN: somenta@gmail.com Sociedad Mexicana de Nutrición y Tecnología de Alimentos México Alvarez Parrilla, E.; de la Rosa, L. A.; Martínez, N. R.; González Aguilar, G. A. Total phenols and antioxidant activity of commercial and wild mushrooms from Chihuahua, Mexico Ciencia y Tecnología Alimentaria, vol. 5, núm. 5, 27, pp Sociedad Mexicana de Nutrición y Tecnología de Alimentos Reynosa, México Available in: How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative

2 SOMENTA Sociedad Mexicana de Nutrición y Tecnología de los Alimentos Cienc. Tecnol. Aliment. 5(5) (27) ISSN CIENCIA Y TECNOLOGÍA ALIMENTARIA TOTAL PHENOLS AND ANTIOXIDANT ACTIVITY OF COMMERCIAL AND WILD MUSHROOMS FROM CHIHUAHUA, MEXICO FENOLES TOTALES Y CAPACIDAD ANTIOXIDANTE DE HONGOS COMERCIALES Y SILVESTRES DE CHIHUAHUA, MÉXICO Alvarez-Parrilla, E. 1* ; de la Rosa, L. A. 1 ; Martínez, N. R. 1 ; González Aguilar, G. A. 2 1 Departamento de Ciencias Básicas, Universidad Autónoma de Ciudad Juárez (UACJ), Instituto de Ciencias Biomédicas, Anillo Envolvente del PRONAF y Estocolmo s/n, Ciudad Juárez, Chihuahua, CP 3231, México. 2 Centro de Investigación en Alimentación y Desarrollo, A. C. (CIAD, A. C.), Dirección de Tecnología de Alimentos de Origen Vegetal, Carretera a la Victoria Km.6, La Victoria, Hermosillo, Sonora, CP 83, México Recibido/Received ; aceptado/accepted *Autor para la correspondencia/corresponding author. ealvarez@uacj.mx Abstract Three wild edible mushrooms (Agaricus sp., Boletus sp., and Macrolepiota sp.) from the North of Mexico (Chihuahua state) and two commercial species (Agaricus bisporus white strain and Portabella: Agaricus bisporus brown strain) were analyzed to determine their proximate composition, total phenols and antioxidant activity. Wild mushrooms presented lower humidity values with respect to commercial species. Other proximate parameters such as total protein, lipids, ashes and carbohydrates were similar to those reported for edible mushrooms. Total phenols and antioxidant activity (Ferric Reducing/ Antioxidant Power assay, FRAP) were determined from 8 % methanol extracts. Wild Mushrooms had higher phenol content and antioxidant capacity than commercial mushrooms. A direct correlation between phenols and antioxidant activity (r 2 =.986) was observed. Due to these characteristics, wild mushrooms could be considered as a complement in the diet for the health benefits they present. Resumen Se analizó la composición proximal, fenoles totales y capacidad antioxidante, de tres hongos silvestres (Agaricus sp., Boletus sp., and Macrolepiota sp.) del norte de México (Chihuahua) y dos comerciales (Agaricus bisporus cepa blanca and Portalella: Agaricus bisporus cepa café). Los hongos silvestres presentaron valores menores de humedad que los comerciales. Los demás parámetros proximales (proteínas, lípidos, cenizas y carbohidratos totales) fueron similares a los reportados para hongos silvestres. La concentración de fenoles totales y actividad antioxidante (Ferric Reducing/Antioxidant Power assay, FRAP) se determinaron a partir de extractos con metanol al 8 %. Los hongos silvestres presentaron valores más altos en fenoles totales y actividad antioxidante, frente a los hongos comerciales. Se observó una correlación directa (r 2 =,986) entre fenoles totales y actividad antioxidante. Estas características de los hogos silvestres hacen que puedan ser considerados, como complemento de la dieta ya que puede presentar buenos beneficios en la salud. Keywords: Edible mushrooms, proximate composition, polyphenols, antioxidant activity, FRAP Palabras clave: Hongos comestibles, análisis proximal, polifenoles, actividad antioxidante, FRAP INTRODUCTION Reactive oxygen species (ROS) are formed during the normal cellular metabolism, however, when the concentration increase, they overcome the physiologic antioxidant mechanisms and become toxic. Epidemiological studies correlate high ROS values with DNA damage, heart diseases, cancer and other chronic and degenerative diseases (Tesoriere et al., 24). There are several cellular defenses against elevated levels of free radicals, such as the enzymes superoxide dismutase, catalase or glutathione peroxidase, which protect the organism against ROS. Ingestion of exogenous antioxidants through fruit and vegetable rich diets can also help neutralize these free radicals, and consequently decrease the prevalence of 329 several diseases (Ferreira et al., 27). For this reason, during the last decade, an increase in the consumption of antioxidants-rich foods such as fruits and vegetables has been observed. Among the antioxidant compounds, polyphenols have gained importance due to their large array of biological actions that include free radical scavenging, metal chelation and enzyme modulation activities, inhibition of LDL oxidation, among others (Rodrigo and Bosco, 26). The term polyphenol refers to a complex group of compounds that includes in their structure an aromatic ring bearing one or more hydroxyl groups. They include simple phenols such as phenolic acids and derivatives, as well as complex structures such as flavones, flavonoids, anthocyanins, among others.

3 Cienc. Tecnol. Aliment. 5(5) (27) ISSN SOMENTA Mushrooms have been used as traditional foods and medicines in different parts of the world, including Asia, Africa and America. In Mexico, wild edible mushrooms have been part of the diet, especially among ethnic groups. They have nutritional relevance due to their high fiber, minerals and protein content, as well as low fat content (León-Guzmán et al., 1997). Moreover, in the last few years, an increasing interest in the consumption of mushrooms has arisen, due to their elevated polyphenol concentration, which correlates with an elevated antioxidant activity. Several studies analyzing the total phenols and antioxidant activity of fresh and cooked wild and commercial mushrooms have been published (Mau et al., 21; Hsu et al., 22; Mau et al., 22; Yang et al., 22; Lakshmi et al., 24; Lo and Cheung, 25; Choi et al., 26; Ferreira et al., 27). However, as far as we know, characterization of species grown in different regions of México has not been reported. The objective of this study was to evaluate the proximate composition, total phenols and antioxidant activity of wild and commercial edible mushrooms from the State of Chihuahua, in the north of Mexico. MATERIALS AND METHODS Samples Wild mushrooms (wild champignon: (Champignon w) Agaricus sp., Boletus sp, and Macrolepiota sp.) were collected at the end of the rain season at a Holm oak forest, near Namiquipa (29 15 latitude, longitude, and 1828 m over sea level), Chihuahua, Mexico, during September 24. Five to ten mushrooms of each species (1 g to 1 kg, depending of the species) were collected and kept on ice 4-6 h for transportation to the laboratory. Mushrooms were classified only to genus, using macroscopic characteristics. Especial care was taken not to collect toxic specimens. We used this classification having in mind that when people from the region collect wild mushrooms, they usually collect different non toxic species of the same genus, assuming that they are the same mushroom. Commercial mushrooms (Champignon (champignon c): Agaricus bisporus white strain and Portabella: Agaricus bisporus brown strain) were purchased at a local supermarket in Ciudad Juarez. Wild and commercial mushrooms were cut, weighted and frozen at -8 C for 1 day, lyophilized for 48 h (Labconco Freeze dry/shell freeze system), milled and stored at -8 C. In order to minimize variability between individuals from the same species, all mushrooms from the same specie were homogenized. Proximate analysis Moisture content was determined by lyophilization (48 h) in order to prevent polyphenol and antioxidant activity losses. Protein, ash and fat were determined according to the AOAC (2) procedures. For protein determination, a conversion factor of 4.38 was used, in accordance with León-Guzmán et al., (1997). Total fat was determined by Soxhlet extraction with hexane and total carbohydrates were calculated by difference. Total energy was calculated according to equation 1 (Manzi et al., 24): Energy (kcal) = 4(g protein + g carbohydrate) + 9(g fat) (1) Total phenols determination Mushroom extracts were obtained according to the methodology proposed by Kähkönen et al. (1999). Briefly,.1 g of powdered dried mushrooms was weighted into a test tube. 5 ml of 8 % methanolic solution was added, stirred and sonicated for 15 min in the dark. Then extract was centrifuged (3 g) for 1 min at 4 C, and the supernatant was collected. Extraction was repeated and a total volume of 1 ml was obtained. This extract was used for determination of total phenols and antioxidant activity. Total phenols were determined according to the method Table 1. Proximate composition (%, fresh weight) of commercial and wild mushrooms. Means with different letters in the same row are significantly different (LSD test, P <.5). Tabla 1. Análisis proximal (% peso fresco) de los hongos comerciales y silvestres. Valores promedio con letras diferentes indican diferencia significativa (prueba DMS, P<,5). Portabella Commercial champignon Macrolepiota Boletus Wild champignon Moisture ±.2 a 9.63 ±2.4 a 86.8 ±.61 b 84.2 ± 2.96 b ±.68 c Ash.13 ±.2 a.96 ±.3 b.5 ±.2 c.22 ±.3 d 1.17 ±.5 e Total fat.7 ±.9 a.29 ±.4 b.76 ±.11 a.62 ±.4 a 1.31 ±.6 c Protein 2.32 ±.16 a 3.16 ±.1 b 1.8 ±.2 c 2.62 ±.15 a 4.42 ±.16 d Total carbohydrates Energy (Kcal/1g FW)

4 SOMENTA 27 Alvarez-Parrilla et al.: Total phenols and antioxidant activity of reported by Georgé et al. (25), with the Folin-Ciocalteu reagent, using caffeic acid in methanol (8 %) as standard. Absorbance at 76 nm was determined by using a BioRad Benchmark Plus microplate reader, and results were expressed as mg of caffeic Acid (CAE)/ 1 g fresh weight. Antioxidant capacity Antioxidant capacity was determined by the ferric reducing/antioxidant power assay (FRAP) according to Benzie and Strain (1996) and modified by Alvarez-Parrilla et al. (25), with slight modifications. FRAP reagent was daily prepared and kept at 37 C, by mixing.3 M acetate buffer, ph 3.6 with 1 mm 2,4,6-tripyridyl-s-triazine (TPTZ, Acrôs Organics, USA) solution in 4 mm HCl plus 2 mm FeCl 3 6H 2 O, at a 1:1:1 ratio. Assay solutions were prepared by mixing 18 µl of FRAP reagent with 24 µl of 3: 1 water: sample mixture, standard or 8% methanol (blank). Methanolic solutions of Fe 2+ (8%) in the range of 1-3 µm were prepared from a 3 µm FeSO 4 7H 2 O stock solution to obtain the calibration curves. All measurements were carried out at 37 C. Absorbance was measured at 595 nm, every 3 s, during 6 min, using a BioRad Benchmark Plus microplate reader. Results are reported as mm Fe 2+ /1 g fresh mushroom. Statistical analysis Values are presented as the mean ± SD of four replicates. ANOVA and LSD analyses were performed in order to determine differences between mushrooms, using the commercial software SPSS 13. (SPSS Inc. Headquarters Chicago, Illinois, USA). RESULTS AND DISCUSSION Proximate composition Moisture was determined by lyophilization to prevent polyphenol degradation and minimize antioxidant activity loss. Table 1 shows the proximate composition of wild and commercial mushrooms. Moisture values ranged from to %. Commercial samples presented statistically higher moisture values than wild samples. The moisture values varied in the order Portabela > commercial champignon > Macrolepiota > Boletus > wild champignon. This may be explained by considering that wild mushrooms were collected at the end of the raining season, when some dehydration may have occurred. Exposure to different ambient conditions of wild mushrooms affected considerably moisture content. Meanwhile the growth of commercial mushrooms is carried out at controlled atmospheres and humidity. The higher moisture of Portabella as compared to commercial champignon may be explained considering that the former mushrooms are sold in plastic packages, with moisture controlled atmosphere, meanwhile, the later is sold in bulk, and consequently some dehydration occurs. All mushrooms, except wild champignon, which showed clear signs of dehydration, had moisture values in the % range. These results are similar to those reported by other authors for fresh mushrooms (León-Guzmán et al., 1997; Choi et al., 26). As expected, fat levels were low (.29 to 1.13 % fresh weight, FW; % dried weight, DW), and similar to those reported for several species of commercial and wild mushrooms studied elsewhere (León-Guzmán et al., 1997; Manzi et al., 21; Manzi et al., 24). Commercial and wild champignon presented the lowest and highest fat levels, respectively. Commercial champignon showed fat content similar to those reported by Manzi et al. (21) for raw and canned champignon. Protein content in the analyzed mushrooms ranged from 1.8 to 4.42 % FW ( % DW). These values are higher to those reported by León-Guzman et al. (1997) for wild mushrooms collected in Queretaro, Mexico ( % DW), but in the range of the commercial Italian fresh mushrooms reported by Manzi et al. (21, 24). Portabella (26.2 % DW) and commercial champignon (33.73% DW) showed lower protein content than those reported by Dikeman et al. (25) for the same mushrooms (42.4 and 37.5 %, respectively). However, the mushrooms studied by Dikeman et al. (25) presented lower moisture content which affects directly protein content. Total carbohydrate content, calculated by difference, varied from to 4.96 % FW ( % DW). These values are in the range of the commercial Italian fresh mushrooms reported by Manzi et al. (21; 24). From the proximate composition, the energy provided by 1 g of fresh samples was calculated and ranged from 38.4 and 91.6 Kcal for Portabella and wild champignon, respectively. These values are similar to those reported by Manzi, et al. (21, 24) for Italian commercial mushrooms. As already discussed, the higher energy value of the champignon samples is due to the low water content of this mushroom. From the low fat content and energy value, it can be concluded that wild and commercial mushrooms can be considered good alternatives for low fat/energy diets. Antioxidant activity It is well known that polyphenols are one of the major contributors to the antioxidant activity of fruits, vegetables and mushrooms (Ferreira et al., 27). For this reason, in this study, total phenols concentration, and antioxidant activity of commercial and wild mushrooms were determined, from methanol:water (8:2) extracts. In the literature, total phenolics of different plant tissues have been reported either as Gallic Acid Equivalent (GAE) or as pyrochatecol equivalent. In the present study, caffeic acid was used as standard, since it has been reported as one of the major phenolic compounds present in some wild and commercial mushrooms (Valentão et al., 25). Figure 1 shows the total phenol concentration of mushrooms, expressed as mg of caffeic acid equivalents 331

5 Cienc. Tecnol. Aliment. 5(5) (27) ISSN SOMENTA mg CAE/1 g FW a b Portabella Macrolepiota Champignon (w) Figure 1. Total phenolic content (expressed as caffeic acid equivalents, CAE/ 1 g FW) of 8% methanolic extracts from wild and commercial mushrooms. Values are mean ± SD from four determinations. Different letters in the bars indicate statistically significant differences (LSD test, P <.5). Figura 1. Concentración fenoles totales (expresado como equivalentes de ácido caféico, CAE/ 1 g peso fresco) del extracto metanol:agua 8:2 de los hongos comerciales y silvestres. Los valores se reportan como media ± DS de cuatro repeticiones. Letras diferentes en las barras indican diferencia significativa (prueba DMS, P <,5). (CAE)/ 1 g of fresh weight. Phenolic concentration ranged from 45.6 mg CAE/ 1 g FW for commercial champignon to 38.3 mg CAE/ 1 g FW for wild champignon. Figure 1 shows that both commercial species presented statistically the same phenolic concentration, and slightly lower than that for Macrolepiota. Boletus presented a total phenol concentration of ± 26.7 mg CAE/1 g FW. The higher phenolic concentration observed for wild champignon can be partially explained considering its low water content due to dehydration. Wild mushrooms presented, in general, statistically higher phenolic concentration than commercial ones. The total phenolic concentration of the samples analyzed in the present study (4.87 to mg CAE/ g DW) were higher than those reported by Mau et al. (22), and Choi et al. (26), but in the range of those reported by Lo and Cheung (25), Cheung et al. (23), Yang et al. (22), and Ferreira et al. (27) for different commercial and wild mushrooms found world widespread. The antioxidant activity of wild and commercial mushrooms has been determined by several methods, such as 2,2-diphenyl-1-pycrilhydracyl radical, DPPH (Mau et al., 21; Mau et al., 22; Cheung et al., 23; Lakshmi et al., 24; Ribeiro et al., 26; Turkoglu et al., 27), TEAC (Lakshmi et al., 24), conjugated diene method (Mau et al., 21; Mau et al., 22), Ferricyanide reducing power (Mau et al., 21; Mau et al., 22), and ferric reducing/ antioxidant power assay, FRAP (Lakshmi et al., 24), among others. In the present work, antioxidant activity was measured by the FRAP method, which measures the capacity of an antioxidant to reduce a Fe 3+ -TPTZ complex c a Champignon (c) d Boletus Abs 595 nm mmol Fe 2+ /1 g FW (A) (B) a,b Time (s) c b Portabella Macrolepiota Champignon (w) Portabella Champignon (c) Boletus Macrolepiota Champignon (w) Figure 2. Antioxidant activity, estimated by the FRAP assay (expressed as mmol Fe 2+ / 1 g FW) of (a) FRAP reaction kinetics of 8 % methanolic extracts from wild and commercial mushrooms, measure at 595 nm and (b) Ferric reducing ability of methanolic extracts determined at 3 min. Values are mean ± SD from four estimations. Different letters in the bars indicate statistically significant differences (LSD test, P <.5). Figura 2. Actividad antioxidante, determinada por el método FRAP (expresado como mmol Fe 2+ / 1 g peso fresco) de (a) cinética de reacción FRAP de los extractos metanol:agua (8:2) de los hongos comerciales y silvestres, determinado a 595 nm y (b) actividad antioxidante de los extractos determinado a los 3 min. Los valores se reportan como media ± DS de cuatro repeticiones. Letras diferentes en las barras indican diferencia significativa (prueba DMS, P <,5). to Fe 2+ -TPTZ. In this way, a higher Fe 3+ -TPTZ reduction means a higher antioxidant activity. The original FRAP methodology proposed by Benzie and Strain (1996) established a 4 min interval before the determination of the FRAP value. However, as shown in Figure 2a, and in agreement with Pulido et al. (2) and Alvarez-Parrilla et al. (25), the reduction of Fe 3+ to Fe 2+ in the presence of the mushroom extract follows a slow kinetic mechanism, and even after 3 min the reaction was not totally completed. For this reason, FRAP values were determined at 3 min, as suggested in the literature (Pulido et al., 2; Alvarez-Parrilla et al., 25). When the FRAP values determined at 4 and 3 min were compared, a % increment was observed. However, the increment in the FRAP values at 6 min was less than 2 % higher compared to those observed at 3 min. Figure 2b shows the FRAP values of the 8 % methanolic mushroom extracts determined at 3 min and expressed as mmol Fe 2+ / 1 g FW. Figure 2b shows that the antioxidant activity varied in a similar pattern than the a Champignon (c) d Boletus 332

6 SOMENTA 27 Alvarez-Parrilla et al.: Total phenols and antioxidant activity of Mmol Fe 2+ /1 g FW mg CAE / 1 g FW Figure 3. Linear correlation between total polyphenols (expressed as caffeic acid equivalents, CAE/ 1 g FW) and antioxidant activity (expressed as mmol Fe 2+ / 1 g FW) of 8% methanol extract from wild and commercial mushrooms. Values are mean ± SD from four estimations. Correlation coefficient =.9721, significance level P <.2. Figura 3. Correlación linear entre los fenoles totales (expresado como equivalentes de ácido caféico, CAE/ 1 g peso fresco) y actividad antioxidante (expresado como mmol Fe 2+ / 1 g peso fresco) de de los extractos metanol:agua 8:2 de los hongos comerciales y silvestres. Los valores se reportan como media ± DS de cuatro repeticiones. Coeficiente de correlación =,9721, nivel de significancia P <,2. total phenolic concentration in the order: wild champignon> Boletus > Macrolepiota >Portabela H = commercial champignon. FRAP values ranged from.94 mmol Fe 2+ / 1 g FW (1.1 mmol Fe 2+ / 1 g DW) for commercial champignon to 4.49 mmol Fe 2+ / 1 g FW (2.3 mmol Fe 2+ / 1 g DW) for wild champignon. Both commercial mushrooms presented statistically lower FRAP values, compared with wild mushrooms. Even though Lakshmi et al. (24) determined the antioxidant activity of several Indian mushrooms with the FRAP method, observing high FRAP values, however, our results can not be compared with the former study, since they expressed the antioxidant activity as TROLOX or ascorbic acid equivalents. When the antioxidant activity values of the wild and commercial mushrooms determined by the FRAP method where compared with other fruits, it was observed that mushrooms presented higher antioxidant activity than those reported for peaches, which ranged from.84 to 1.2 mmol Fe 2+ / 1 g FW (Rodrigo-García et al., 26), but lower than those for strawberries ( mmol Fe 2+ / 1 g DW) (Böhm et al., 26). It has been reported that polyphenols are the main contributors to the antioxidant activity of fruits and vegetables (Mau et al., 22), therefore a correlation study between total phenols and antioxidant activity of wild and commercial mushrooms was carried out. Figure 3 shows a good correlation (R 2 =.9721, significance level P <.2) between these two parameters. This result indicates that polyphenols may be the main antioxidant compounds found in mushrooms, in agreement with several authors (Lo and Cheung, 25; Choi et al., 26; Ferreira et al., 27). However it is important to evaluate the type of phenol present in mushroom and its individual contribution to the total antioxidant capacity. In this regards, studies are in progress evaluating other phenols and antioxidants present in mushrooms. In conclusion, the results reveal that wild mushrooms could be an important source for low caloric, low fat functional foods, with high level of polyphenols and antioxidant activity, especially for the ethnic groups (Tarahumaras tribes) living in the North of Mexico. From the wild mushrooms studied, «Boletus» may be an interesting group due to their high nutritional value, total phenol concentration and antioxidant activity, as well as its high relative abundance in the region. As far as we know, this is the first study of Mexican wild edible mushrooms were in vitro antioxidant activity analysis was evaluated and compared with commercial species. ACKNOWLEDGEMENTS Financial support from UACJ (internal projects) is gratefully acknowledged. The authors would like to express appreciation to Dr. Marcos Lizarraga for his helpful assistance in collecting and identifying wild mushrooms and to Héctor Osvaldo Sosa for technical assistance. REFERENCES Alvarez-Parrilla, E.; de la Rosa, L. A.; Torres-Rivas, F.; Rodrigo-García, J.; González-Aguilar, G. A. 25. Complexation of apple antioxidants: chlorogenic acid, quercetin and rutin by β-cyclodextrin (β-cd). Journal Inclusion Phenomena Macrocyclic Chemistry 53, AOAC. Official Methods of Analysis of the Association of Official Analytical Chemistry, 17 th edition Maryland, USA, 2. Benzie, I. F. F.; Strain, J. J The ferric reducing ability of plasma (FRAP) as a measure of «antioxidant power»: The FRAP assay. Analytical Biochemistry 239, Böhm, V.; Kühnert, S.; Rohm, H.; Scholza, G. 26. Improving the nutritional quality of microwavevacuum dried strawberries: A preliminary study. Food Science and Technology International 12, Cheung, L. M.; Cheung, P. C. K.; Ooi, V. E. C. 23. Antioxidant activity and total phenolics of edible mushroom extracts. Food Chemistry 81, Choi, Y.; Lee, S. M.; Chun, J.; Lee, H. B.; Lee, J. 26. Influence of heat treatment on the antioxidant activities and polyphenolic compounds of Shiitake 333

7 Cienc. Tecnol. Aliment. 5(5) (27) ISSN SOMENTA (Lentinus edodes) mushroom. Food Chemistry 99, Dikeman, C. L.; Bauer, L. L.; Flickinger, E. A.; Fahey, G. C. 25. Effects of stage of maturity and cooking on the chemical composition of selected mushroom varieties. Journal of Agricultural and Food Chemistry 53, Ferreira, I. C. F. R.; Baptista, P.; Vilas-Boas, M.; Barros, L. 27. Free-radical scavenging capacity and reducing power of wild edible mushrooms from northeast Portugal: Individual cap and stipe activity. Food Chemistry 1, Georgé, S.; Brat, P.; Alter, P.; Amiot, M. J. 25. Rapid determination of polyphenols and vitamin C in plant-derived products. Journal of Agricultural and Food Chemistry 53, Hsu, T.H.; Shiao, L.H.; Hsieh, C.; Chang, D. M. 22. A comparison of the chemical composition and bioactive ingredients of the Chinese medicinal mushroom Dong Chong Xia Cao, its counterfeit and mimic, and fermented mycelium of Cordyceps sinensis. Food Chemistry 78, Kähkönen, M. P.; Hopia, A. I.; Heikki, J. V.; Jussi-Pekka, R.; Pihlaja, K.; Kujala, T. S.; Heinonene, M Antioxidant activity of plant extracts containing phenolic compounds. Journal of Agricultural and Food Chemistry 47, Lakshmi, B.; Tilak, J. C.; Adhikari, S.; Decasagayam, T. P. A.; Janardhanan, K. K. 24. Avaluation of antioxidant activity of selected indian mushrooms. Pharmaceutical Biology 42, León-Guzmán, M. F.; Silva, I.; López, M. G Proximate chemical composition, free amino acid contents, and free fatty acids contents of some wild edible mushrooms from Queretaro, México. Journal of Agricultural and Food Chemistry 45, Lo, K. M.; Cheung, P. C. K. 25. Antioxidant activity of extracts from the fruiting bodies of Agrocybe aegerita var. Alba. Food Chemistry 89, Manzi, P.; Aguzzi, A.; Pizzoferrato, L. 21. Nutritional value of mushrooms widely consumed in Italy. Food Chemistry 73, Manzi, P.; Marconi, S.; Aguzzi, A.; Pizzoferrato, L. 24. Commercial mushrooms: nutritional quality and effect of cooking. Food Chemistry 84, Mau, J. L.; Chao, G. R.; Wu, K. T. 21. Antioxidant properties of methanolic extracts from several ear mushrooms. Journal of Agricultural and Food Chemistry 49, Mau, J. L.; Lin, H. C.; Song, S. F. 22. Antioxidant properties of several specialty mushrooms. Food Research International 35, Pulido, R.; Bravo, L.; Saura-Calixto, F. 2. Antioxidant activity of dietary polyphenols as determined by a modified ferric reducing/antioxidant power assay. Journal of Agricultural and Food Chemistry 48, Ribeiro, B.; Rangel, J.; Valentão, P.; Baptista, P.; Reabra, R. M.; Andrade, P. B. 26. Contents of carboxylic acids and two phenolics and antioxidant activity of dried Portuguese wild edible mushrooms. Journal of Agricultural and Food Chemistry 54, Rodrigo-García, J.; Alvarez-Parrilla, E.; de la Rosa, L. A.; Mercado-Mercado, G.; Herrera-Dunez, B. 26. Valoración de la capacidad antioxidante y actividad polifenoloxidasa en duraznos de diferentes áreas de producción. pp In González-Aguilar, G. A (Ed.).I Simposio Iberoamericano de Vegetales Frescos Cortados: Aseguramiento de la calidad microbiológica, CIAD, Mexico. Rodrigo, R.; Bosco, C. 26. Oxidative stress and protective effects of polyphenols: comparative studies in human and rodent kidney. A review. Comprehensive Biochemistry and Physiology Part C 142, Tesoriere, L.; Butera, D.; Pintaudi, A. M.; Allegra, M.; Livrea, M. 24. Supplementation with cactus pear (Opuntia ficus-indica) fruit decreases oxidative stress in healthy humans: a comparative study with vitamin C. American Journal of Clinical Nutrition 8, Turkoglu, A.; Duru, M. E.; Mercan, N.; Kivrak, I.; Gezer, K. 27. Antioxidant and antimicrobial activities of Laetiporus sulphureus (Bull.) Murril. Food Chemistry 11, Valentão, P.; Andrade, P. B.; Rangel, J.; Ribeiro, B.; Silva, B. M.; Baptista, P.; Seabra, R. M. 25. Effect of the conservation procedure on the contents of phenolic compounds and organic acids in chanderelle (Cantharellus cibarius) mushroom. Journal of Agriculture and Food Chemistry 53, Yang, J. H.; Lin, H. C.; Mau, J. L. 22. Antioxidant properties of several commercial mushrooms. Food Chemistry 77,