Conjugation of (–)‐epigallocatechin‐3‐gallate and protein isolate from large yellow croaker (Pseudosciaena crocea) roe: improvement of antioxidant activity and structural characteristics

Abstract

BACKGROUND: Large yellow croaker (Pseudosciaena crocea) roe is the main by-product in the processing of large yellow croaker. Previous studies have found that its protein isolates are composed of vitellogenin, as well as vitellogenin B and C, having good functional properties. (-)-Epigallocatechin-3-gallate (EGCG) is a natural antioxidant component that can be combined with protein to improve antioxidant activity and structural characteristics of protein.RESULTS: EGCG was bound with the P. crocea roe protein isolate (pcRPI) by the free radical method to prepare the conjugate. The formation of pcRPI-EGCG conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel permeation chromatography, which showed that the calculated weight-average molar masses of native-pcRPI and pcRPI-EGCG conjugates were 86.9 and 215.3 kDa, respectively. The results of fluorescence, ultraviolet, circular and infrared spectra indicated that the conjugation of EGCG with native-pcRPI changed the secondary and tertiary structure of native-pcRPI. The pcRPI-EGCG conjugates exhibited higher thermal stability than native-pcRPI. The radical scavenging and reducing power of native-pcRPI were increased by 2.0-2.5-and 1.4-fold, respectively, after the EGCG-grafting reaction.CONCLUSION: These results indicate that the binding of pcRPI and EGCG effectively improved the antioxidant properties and structural characteristics of the pcRPI.

Improving the texture properties and protein thermal stability of Antarctic krill (Euphausia superba) by L‐lysinemarination

“…The secondary structures of krill protein were determined according to a previously reported method 20 . The spectra were recorded by utilizing an infrared spectrophotometer (Perkin Elmer, Salem, MA, USA) from 4000 to 400 cm −1 at a resolution of 4 cm −1 .…”

“…The secondary structures of krill protein were determined according to a previously reported method. 20 The spectra were recorded by utilizing an infrared spectrophotometer (Perkin Elmer, Salem, MA, USA) from 4000 to 400 cm −1 at a resolution of 4 cm −1 . OMNIC Spectra v. 8.2 (Thermo Fisher Scientific, Waltham, MA, USA) was used to fit the amide I band (1700-1600 cm −1 ) and to calculate the relative amount of the secondary structure of krill protein.…”

Current Research on the Extraction, Functional Properties, Interaction with Polyphenols, and Application Evaluation in Delivery Systems of Aquatic-Based Proteins

“…Du et al demonstrated that the EGCG–large yellow croaker ( Pseudosciaena crocea ) roe protein isolate (pcRPI) conjugate prepared by free-radical method exhibited higher weight-average molar mass, thermal stability, and antioxidant activity than the native pcRPI. However, the exact site of interaction between EGCG and pcRPI remained unclear …”

“…Among them, the antioxidant capacity of polyphenol–protein conjugates was closely related to the preparation approach and the type of phenolic compounds used. For example, the radical scavenging and reducing power of large yellow croaker roe protein isolates were remarkably increased by 2.5- and 1.4-fold, respectively, after grafting with EGCG . The conjugates of EGCG and scallop gonad protein showed 4.9 times and 7.4 times higher 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and oxygen radical absorbance capacity (ORAC) than that of native scallop protein, and the covalent complexes of EGCG and scallop proteins had higher antioxidant activity than noncovalent mixtures .…”

Network pharmacology, molecular docking and in vivo and in vitro experiments to explore the molecular mechanism of licorice green tea beverage to scavenge oxygen free radicals

“…With the rapid development of new drugs and treatment technologies, the use of natural substances, especially Chinese herbal medicines (unit herbal medicines, compound formulations, etc.) in the treatment of antioxidant-related diseases has attracted much attention (Du et al, 2021;Hassan et al, 2014Hassan et al, , 2017Hassan & Al-Rawi, 2013;Zou et al, 2021).…”