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Efficacy of quercetin on α-amylase, lipase and protease activities via crustacean cardioactive peptide (CCAP) content of the midgut of the diamondback moth, Plutella xylostella (L.) was investigated. Fresh cabbage leaf discs were dipped in quercetin solution at different concentrations (100, 500 and 1000ppm) for 10 seconds. Third instar larvae of P. xylostella were fed on leaf dipped in quercetin solutions for 5 days. α-Amylase, lipase and protease activities were evaluated for 5 days. Quercetin significantly decreased lipase, protease and α-amylase activities in the midgut. The results of competitive ELISA showed that different concentration of quercetin had no effect on short neuropeptide F, tachykinin-4 and allatostatin content of the midgut, but it was shown that quercetin (500 and 1000ppm) decreased CCAP content of the midgut. Moreover, incubation of dissected midgut with CCAP increased α-amylase, lipase and protease activities. The injection of CCAP into the hemocoel clearly increased α-amylase, lipase and protease activities. Here, for the first time, it was confirmed that feeding on leaf dipped in quercetin, decreases CCAP content in the midgut of P. xylostella, that itself led to decrease of α-amylase, protease and lipase activities.
 
 

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Quercetin is a flavonoid, abundantly present in plants and has gained considerable interest for its antioxidant properties.  The present study was designed to assess and compare the influence of both free and nano-encapsulated quercetin on growth indices and survival in Penaeus vannamei. The ionic gelation method was used to prepare quercetin loaded nanoparticles (Qu-ChiNPs), and their characteristics were determined using DLS method. The finding related to the characterization of Qu-ChiNPs demonstrated that hydrodynamic size and Zeta potential were 160/1 nm and 33/8 mV, respectively, and in vitro release of drug from Qu ChiNPs illustrated burst release in the initial period. For feeding trial, shrimps with an average weight of 2/27 ± 0/18 g with 5 diets including: basic diet without Qu, Qu-Chi and Chitosan nanoparticles supplement (control), supplement with 0.5 g Querectin, 0.25 g Qu-Chi, 0.5 g Qu-Chi and 0.5 g Chitosan nanoparticles per kg of diet were fed. Shrimp were randomly divided into 5 groups, with 3 replicates in each group and 50 shrimp in each replicate. After a 2-month feeding period, results showed that final weight (Wf), weight gain (WG) and mean daily weight gain (ADG) of shrimp fed Qu-Chi 0.5 g were higher than the other treatments (P˂ 0.05). However, there was no significant difference in survival rate (SR) between treatments. The results showed that the use of Qu-Chi 0.5 g in the diet can have a positive effect on growth performance and survival of Penaeus vannamei.

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The purpose of this research was to prepare nanocomposite film based on wheat gluten containing quercetin nanoliposome and zinc oxide nanoparticles and use it to package rainbow salmon; For this purpose, in this research, the effect of quercetin nanoliposome at the levels (0, 5, 10% by volume) and zinc oxide nanoparticles at the levels (0, 3, 6% by weight) using the response surface method in The central composite design template was investigated on the physicochemical properties of the nanocomposite film, and finally, the optimal sample was used in the packaging of rainbow salmon meat to check its properties during the storage period (0, 3 and 6 days). Also, the results of the research on packaged fish meat showed that the use of wheat gluten nanocomposite film containing 10% quercetin nanoliposomes and 6% zinc oxide nanoparticles led to a decrease in peroxide index, volatile nitrogen compounds index, thiobarbituric acid index and total microbial count during the storage period. Became. Also, no significant difference was observed in the fat of the examined samples, and the color of the packaged fish meat was duller than the control sample. Finally, according to the obtained results and investigations, the addition of 10% quercetin nanoliposome and 6% zinc oxide nanoparticles in the wheat gluten nanocomposite film formulation led to the improvement of the properties of the produced film and the properties of the packaged fish during the storage period.