RESUMEN
Papaya fruits (Carica papaya L. cv 'Sui you 2') harvested with < 5% yellow surface at the blossom end were fumigated with 60 microL/L of nitric oxide for 3 h and then stored at 20 degrees C with 85% relative humility for 20 days. The effects of nitric oxide treatment on ethylene production rate, the activities of cell wall softening related enzymes including polygalacturonase, pectin methyl esterase, pectate lyase and cellulase and the levels of hormones including indole acetic acid, abscisic acid, gibberellin and zeatin riboside were examined. The results showed that papaya fruits treated with nitric oxide had a significantly lower rate of ethylene production and a lesser loss of firmness during storage. A decrease in polygalacturonase, pectin methyl esterase, pectate lyase and cellulase activities was observed in nitric oxide treated fruit. In addition, the contents of indole acetic acid, abscisic acid and zeatin riboside were reduced in nitric oxide treated fruit, but no significant reduction in the level of gibberellin was found. These results indicate that nitric oxide treatment can effectively delay the softening and ripening of papaya fruit, likely via the regulation of cell wall softening related enzymes and certain hormones.
Asunto(s)
Carica/efectos de los fármacos , Carica/enzimología , Pared Celular/efectos de los fármacos , Almacenamiento de Alimentos/métodos , Óxido Nítrico/farmacología , Reguladores del Crecimiento de las Plantas/metabolismo , Ácido Abscísico/análisis , Ácido Abscísico/metabolismo , Hidrolasas de Éster Carboxílico/efectos de los fármacos , Hidrolasas de Éster Carboxílico/metabolismo , Celulasa/efectos de los fármacos , Celulasa/metabolismo , Etilenos/metabolismo , Depuradores de Radicales Libres/farmacología , Giberelinas/análisis , Giberelinas/metabolismo , Ácidos Indolacéticos/análisis , Ácidos Indolacéticos/metabolismo , Isopenteniladenosina/análogos & derivados , Isopenteniladenosina/análisis , Isopenteniladenosina/metabolismo , Reguladores del Crecimiento de las Plantas/análisis , Poligalacturonasa/efectos de los fármacos , Poligalacturonasa/metabolismo , Polisacárido Liasas/efectos de los fármacos , Polisacárido Liasas/metabolismoRESUMEN
The effect of fenugreek seeds on the activities of beta-glucuronidase and mucinase during 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats was studied. Rats were given a weekly subcutaneous injection of DMH at a dose of 20 mg/kg body weight, for 15 weeks. Fenugreek seed powder was weighed depending upon the weight of individual rats and incorporated in the powdered pellet diet at a dose of 2 g/kg body weight. After an experimental period of 30 weeks the activity of beta-glucuronidase significantly increased in the colon, intestine, liver and colon contents in DMH administered rats when compared to an untreated control group. Increase in beta-glucuronidase may increase the hydrolysis of carcinogen-glucuronide conjugate, liberating carcinogen and/or co-carcinogen within the colonic lumen. Inclusion of fenugreek seed powder in the diet significantly decreased the activity of beta-glucuronidase in all the tissues studied. This may prevent the free carcinogens from acting on colonocytes. Mucinase helps in hydrolysing the protective mucin. Mucinase activity was increased in the colon content and fecal content of animals given DMH when compared to control, while the activity was significantly reduced in animals given DMH + fenugreek when compared to animals given DMH only. Our study shows that supplementation of fenugreek seeds in the diet inhibits colon carcinogenesis, by modulating the activities of beta-glucuronidase and mucinase. The beneficial effect may be attributed to the presence of fibre, flavonoids and/or saponins.