Perfil fitoquímico, actividad antimicrobiana y antioxidante de extractos de Gnaphalium oxyphyllum y Euphorbia maculata nativas de Sonora, México

The use of synthetic chemical compounds to preserve foods or treat diseases of bacterial origin is limited because they can cause health damage. Therefore, the food and livestock industries seek natural strategies to preserve foods and preserve the health of animals intended for human consumption. In this sense, some extracts of plant from Sonora, Mexico could be an alternative due to the great diversity of plants and the fact that some of them are traditionally used to treat diseases. On the other hand, there are few studies that support the biological activity of ethanolic extracts of Gnaphalium oxyphyllum (E1) and Euphorbia maculata (E2). In this study, phytochemical content was determined by spectrophotometry, antimicrobial activity was determined by agar diffusion and antioxidant activity was evaluated by ABTS, DPPH and FRAP. The results showed that the E1 and E2 extracts had total phenols, total flavonoids, flavones and flavonols, total flavanones and dihydroflavonols, as well as total tannins, total chlorogenic acid and total polysaccharides. In addition, both extracts showed higher antimicrobial activity against Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Salmonella enterica serovar Typhimurium ATCC 14028 when 1 mg ml-1 was used (P<0.05). In addition, they presented antioxidant activity by the methods of ABTS, DPPH and FRAP. Therefore, the antimicrobial and antioxidant potential of these plants represents a natural alternative to control some Gram-positive and Gram-negative bacteria in the livestock industry, as well as for food preservation.El uso de compuestos químicos sintéticos para conservar alimentos o tratar enfermedades de origen bacteriano está limitado debido a que pueden ocasionar daños en la salud. Por ello, las industrias alimentaria y pecuaria buscan estrategias naturales para conservar alimentos y mantener la salud de los animales destinados a consumo humano. En este sentido, algunos extractos de plantas provenientes de Sonora, México podrían ser una alternativa debido a la gran diversidad de plantas y que algunas de ellas se utilizan tradicionalmente para tratar enfermedades. Por otro lado, son pocos los estudios que sustentan la actividad biológica de los extractos etanólicos de Gnaphalium oxyphyllum (E1) y Euphorbia maculata (E2). En este estudio, el contenido de fitoquímicos se determinó por espectrofotometría, la actividad antimicrobiana se determinó por difusión en agar y la actividad antioxidante se evaluó por ABTS, DPPH y FRAP. Los resultados mostraron que los extractos E1 y E2 presentaron fenoles totales, flavonoides totales, flavonas y flavonoles, flavanonas y dihidroflavonoles totales, así como, taninos totales, ácido clorogénico total y polisacáridos totales. Además, ambos extractos mostraron mayor actividad antimicrobiana contra Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 y Salmonella entérica serovar Typhimurium ATCC 14028 cuando se utilizó 1 mg ml-1 (P<0.05). Además, presentaron actividad antioxidante por los métodos de ABTS, DPPH y FRAP. Por lo anterior, el potencial antimicrobiano y antioxidante de estas plantas representa una alternativa natural para controlar algunas bacterias Gram positivas y Gram negativas en la industria pecuaria, así como para la conservación de alimentos

Effects of Different Irrigation Regimes and Nitrogen Fertilization on the Physicochemical and Bioactive Characteristics of onion (Allium cepa L.)

The availability of water and nitrogen in the soil affect the metabolism of onion bulbs. The synthesis of metabolites and bioactive compounds are the most affected, along with the quality of the onion bulbs However, it is necessary to know the effects of different water levels and nitrogen fertilization to optimize the quality of the onion. The objective of this research was to study the effects of the different conditions of hydric stress and nitrogen fertilization during the development of onion (Allium cepa L.) crop, regarding its physicochemical and bioactive properties. Onions were grown using four available irrigation regimes (25, 50, 75 and 100%) and four doses of nitrogen fertilization (100, 150, 200 and 250 kg N ha&minus;1). Onion without any treatment was considered as a control. The treatments low in irrigation and nitrogen fertilization increased the pH level (5.7 to 5.9) and bulb coloration in bright white/yellowish tones. An increase was observed compared to control in titratable acidity (0.13%) just in the nitrogen content, ascorbic acid (46%) and antioxidant capacity with DPPH (12.3%) and ABTS (93.7%). A decrease was shown in soluble solids (14.6%), firmness (3.5 kg cm&minus;2), dry matter (6.6%), total phenols (50%) and FRAP (33.2%) values. Pyruvic acid remained constant (1.5 &micro;mol g&minus;1 FW). The onion bulb extracts showed an erythroprotective effect with a hemolysis inhibition percentage higher than 95%. Finally, the onions had low pungency, and were soft and extra sweet. The treatments with 25% usable humidity and nitrogen fertilization of 150 and 250 kg ha&minus;1, favored the physical, chemical and bioactive quality of the onion bulb