RESUMEN
In this study, crude polysaccharides of culinary-medicinal mushroom Auricularia auricular-judae were extracted by hot water extraction and alcohol precipitation, and their antimicrobial and antioxidant activities were investigated. An optimum extraction condition was obtained at a ratio of liquid to solid 70 mL/g, temperature 90°C, time 4 h and extraction number 4. Accordingly, the best yield of crude polysaccharides was 6.89% with 76.12% in purity. Some bacteria and fungi were used for antimicrobial studies. It was found that crude A. auricula-judae had great antimicrobial activities against Escherichia coli and Staphylococcus aureus, but no activities on the others. The inhibitory diameters of antimicrobial zones for the two were 5.55 ± 0.182 and 9.84 ± 0.076 mm, respectively. Moreover, crude A. auricula-judae had significant antioxidant activities in scavenging free radicals, reducing power assays, and Fe2+ chelating ability assay. Results revealed that crude A. auricula-judae has a great potential as antimicrobial and antioxidant, and it can be a supplementary food for human health.
Asunto(s)
Agaricales/química , Antiinfecciosos/farmacología , Antioxidantes/farmacología , Polisacáridos/farmacología , Antiinfecciosos/aislamiento & purificación , Antioxidantes/aislamiento & purificación , Quelantes/aislamiento & purificación , Quelantes/farmacología , Pruebas Antimicrobianas de Difusión por Disco , Escherichia coli/efectos de los fármacos , Depuradores de Radicales Libres/aislamiento & purificación , Depuradores de Radicales Libres/farmacología , Radicales Libres/metabolismo , Polisacáridos/aislamiento & purificación , Staphylococcus aureus/efectos de los fármacosRESUMEN
The inhibitory activities, sulfhydryl bonds and far-UV circular dichroism (CD) spectra of Kunitz and Bowman-Birk soybean trypsin inhibitors (KTI and BBTI) were measured before and after ultrasound treatments. The differences between KTI and BBTI in conformation changes and resistance to ultrasound were observed. The secondary structures of KTI were found to be composed of beta-sheet (22.5%), beta-turn (16.2%) and random coils (61.4%) while that of BBTI composed of only beta-sheet (52.6%) and random coils (47.4%). KTI lost its inhibitory activity more quickly than BBTI, proportionally to the ultrasound amplitudes and sonication durations used. Relevant synchronous phenomena observed included the inactivation of KTI, significant rise in sulfhydryl content and corresponding conformation changes, in which there were dramatic decreases in both beta-turn and random coil contents and increase in the beta-sheet structure over the entire sonication duration and ultrasonic amplitude scale used by the study. Ultrasound affected the activities and conformations of KTI and BBTI by exerting an influence on their disulfide bonds. For KTI, up to 55% of inhibitory activity could be inactivated, at which about 71.5% of disulfide bonds were altered and the [theta]200nm value was changed from native -2545deg cm2 dmol(-1) to -1827 deg cm2 dmol(-1). Whereas for BBTI, far-UV CD spectra, beta-sheet and random structures were barely affected, only about 5.29% of disulfide bonds were found altered and the [theta]200nm value was changed only from native -797 deg cm2 dmol(-1) to -700 deg cm2 dmol(-1). It is concluded that ultrasound inactivates KTI by inducing a reduction in the disulfide bonds and then changes the conformations.
Asunto(s)
Inhibidor de la Tripsina de Soja de Bowman-Birk/química , Inhibidor de la Tripsina de Soja de Bowman-Birk/farmacología , Inhibidor de la Tripsina de Soja de Kunitz/química , Inhibidor de la Tripsina de Soja de Kunitz/farmacología , Ultrasonido , Dicroismo Circular , Conformación Molecular , Compuestos de Sulfhidrilo/análisisRESUMEN
Mathematical and kinetic models were set up for heat-induced quality changes in soy milk, including inactivation of trypsin inhibitor activity (TIA) and degradation of thiamin, riboflavin, color, and flavor over a wide range of time-temperature combinations with particular interest in the ultrahigh-temperature (UHT) range. On the basis of these models, multiresponse optimization of the thermal processes for soy milk was carried out to obtain the following effects simultaneously: (1) maximum destruction of bacterial spores, (2) maximum inactivation of TIA, and (3) minimum degradation of sensory and nutritional qualities. By a suitable selection of high temperatures and extended heating times, for example, 143 degrees C/60 s, it is possible to use a single-step UHT process to produce a commercially sterile soy milk with satisfactory TIA inactivation, highly acceptable color and flavor, and thiamin retention between 90 and 93%.