Dihydromyricetin (DMY) is a kind of flavone. It has a variety of physiological effects, and its content in Ampelopsis grossedentata is as high as 35%. There are two shortcomings in the traditional batch extraction process commonly used in a laboratory: long extraction time and low extraction rate. In this study, a new chelating extraction method was proposed, that is, Zn 2+ was introduced into the extraction and purification process to chelate with DMY, and the yield and purity were taken as evaluation indices for a comparative study with the traditional batch extraction method. In addition, 1 H NMR, single-crystal X-ray diffraction, IR, and UV were used to analyze the product structure; thermogravimetry and differential thermal analysis was utilized to examine the thermal stability of DMY. The results were shown as follows. Compared with the batch extraction method, the chelation extraction method could effectively avoid the oxidation of DMY by air during the extraction and purification process, and the yield of the DMY also increased. Furthermore, this method was time-saving. Through investigating the extraction process and characterizing the structure and thermal stability of DMY, the chelating extraction method could be considered to provide a reference for commercial applications of DMY.

Immunogenic, methionine copper-induced response had proven to be precedent in providing resistance against certain diseases in fish. This study allocates the fitness strategy for Oreochromis niloticus by introducing and incorporating the well-designed, stabilized, and biocompatible N -carbamoyl-methionine copper (NCM-Cu) as a Cu potent source in diet that enhances the bioavailability and fitness. The synchronized NCM-Cu complex was characterized by directing ultraviolet and visible spectrophotometry (UV–vis), Fourier-transform infrared (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction. Results revealed blue columnar crystalline, NCM-Cu complex with an empirical formula as C 12 H 30 CuN 4 O 10 S 2 . Anonymously, the overall growth performance of the fish remained unaltered with NCM-Cu adjunct feed. NCM-Cu significantly raised the Cu accumulation in the fish muscles, liver, gill, and intestine in contrast to the basic Cu-rich feed. The serum antioxidant enzyme activity elevated up to (ceruloplasmin: 19.38 U/L) and the lowest liver malondialdehyde (MDA) content (8.81 nmol/mg prot.) and triglyceride content (0.39 nmol/g prot.) were observed in the NCM-Cu group as compared to the basic Cu and CuSO 4 groups, suggesting that NCM-Cu promoted antioxidative responses and alleviated lipid peroxidation of O. niloticus . Overweening, the synthesized complex, NCM-Cu significantly regulated the expression levels of lysozyme, immunoglobulin M, complement 4, and complement 3 up to 10.93 U/mL, 0.72, 0.77, and 1.18 mg/mL in serum, respectively. Thus, such endorsed results reveal the preeminence of NCM-Cu-supplemented diet for the fitness in O. niloticus .

Zn is one of the essential elements to maintain normal fish metabolic process (including growth, development and reproduction), which have different chemical status in nature including inorganic, organic and nano‐sized. In this work, the efficacy of gluconic acid zinc (Glu‐Zn), nano zinc oxide (Nano ZnO), zinc sulphate (ZnSO4) on the growth performance, tissue mineral elements deposition, antioxidant activity and immune response of the tilapia fish Nile tilapia (Oreochromis niloticus) was evaluated. Three experimental diets were prepared by adding different forms of Zn sources (ZnSO4 as a control group) with same Zn concentration (40 mg/kg) and used to feed fish for 60 days. The biological trial results displayed that the growth performance of Nile tilapia has not obviously affected by different Zn form source supplement. However, Glu‐Zn and Nano ZnO supplements have significantly stimulated the Zn and Cu absorption deposition efficiency in the fish tissues as compared to ZnSO4 group. Besides, there was a significant increase in Cu‐Zn superoxide dismutase (35.03 U/mgprot), alkaline phosphatase (79.34 U/mgprot), aspartate aminotransferase (23.42 U/L), alanine aminotransferase (18.45 U/L), glutathione peroxidase (171.24 U/mgprot) and fatty acid synthase (11.55 ng/mL) content in Glu‐Zn treatment. Additionally, Glu‐Zn supply significantly increased serum lysozyme (9.91 U/mL), immunoglobulin M (0.48 g/L), complement 3 (0.74 g/L) and complement 4 (0.95 g/L) activity of Nile tilapia. Also, compared to ZnSO4 diet, lysozyme (11.44 U/mL) and complement 4 (0.63 g/L) content were obviously higher in fish fed Nano Zn diet. These findings revealed that supplementation with Glu‐Zn as a Zn source in feed is better than ZnSO4 for improving tissue mineralization, antioxidant stress, alleviate lipid peroxidation and immunity response of Nile tilapia. Meantime, Nano ZnO also played a positive role in the tissue mineralization and immunity response of Nile tilapia.

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Both inorganic and organic selenium (Se) can prevent and treat various diseases caused by Se deficiency. However, organic Se has less toxicity and a higher absorption rate than inorganic Se. In this study, inorganic Se (Na2SeO3) was bio-transformed into Se-enriched discarded beer yeast (Se-enriched DB-yeast) through fermentation accumulation by re-using discarded Saccharomyces cerevisiae from the beer industry for Se-enriched fodder application. Through a single-factor experiment and L9(34)-orthogonal test for optimization of fermentation conditions, the Se content and biomass of Se-enriched DB-yeast were calculated as 14.95 mg/L and 7.3 g/L, respectively, under the optimized condition. The total amino-acid content of Se-enriched DB-yeast was increased by 9.9% compared with that from DB yeast. Additionally, alkaline amino-acid content was increased, whereas acidic amino-acid and sulfur-containing amino-acid contents were decreased. Reducing capacity, hydroxyl radical removal capacity, and sulfhydryl content after treatment with H2O2 of the Se-enriched DB-yeast extracted protein were obviously increased compared with those of the DB-yeast extracted protein. Mouse and genetically improved farmed tilapia (Oreochromis niloticus) (GIFT) bioassays showed that the Se sedimentation of organs and serum indexes after feeding Se-enriched DB-yeast-containing fodder were higher than those of DB-yeast-containing fodder. The half lethal dose (LD50) of Se-enriched DB-yeast (9260.0 mg/kg body weight (BW), 18.97 mg/kg of Se content, non-toxic level) was considerably higher than that of Na2SeO3 (20.0 mg/kg BW, 5.08 mg/kg of Se content, highly toxic level) against mouse. Therefore, Se-enriched yeast prepared by re-using discarded S. cerevisiae from beer industry fermentation accumulation has the potential to be a safe and effective Se-enriched fodder additive.