Whey protein and flaxseed gum co-encapsulated fucoxanthin promoted tumor cells apoptosis based on MAPK-PI3K/Akt regulation on Huh-7 cell xenografted nude mice.

Fucoxanthin (FX), a non-provitamin-A carotenoid, is a well-known major xanthophyll contained in edible brown algae. The nanoencapsulation of FX was motivated due to its multiple activities. Here, nano-encapsulated-FX (nano-FX) was prepared according to our early method by using whey protein and flaxseed gum as the biomacromolecule carrier material, then in vivo antitumor effect and mechanism of nano-FX on xenograft mice were investigated. Thirty 4-week-old male BALB/c nude mice were fed adaptively for 7 days to establish xenograft tumor model with Huh-7 cells. The tumor-bearing mice consumed nano-FX (50, 25, and 12.5 mg kg-1) and doxorubicin hydrochloride (DOX, 1 mg kg-1) or did not consume (Control) for 21 days, n = 6. The tumor inhibition rates of nano-FX were as high as 54.67 ± 1.04 %. Nano-FX intervention promoted apoptosis and induced hyperchromatic pyknosis and focal necrosis in tumor tissue by down-regulating the expression of p-JNK, p-ERK, PI3Kp85α, p-AKT, p-p38MAPK, Bcl-2, CyclinD1 and Ki-67, while up-regulating the expression of cleaved caspase-3 and Bax. Nano-FX inhibited tumor growth and protected liver function of tumor bearing mice in a dose-dependent manner, up-regulate the level of apoptosis-related proteins, inhibit the MAPK-PI3K/Akt pathways, and promote tumor cell apoptosis.

The influence of drying methods on extract content, tyrosinase activity inhibition, and mechanism in Ascophyllum nodosum: A combined microstructural and kinetic study.

This study evaluates vacuum drying (VD), microwave drying (MD), hot air drying (HAD), and freeze drying (FD), on the color and microstructure changes of Ascophyllum nodosum (A. nodosum), which affect the extraction of polyphenols and flavonoids. During drying, VD and FD show slight color change and looser structure, aiding in active compound preservation and extraction. Polyphenols extracted from A. nodosum (PEAn) using these methods show higher anti-tyrosinase activity, with VD treatment exhibiting the strongest inhibition. Kinetic studies demonstrate competitive inhibition between PEAn and tyrosinase. The binding constant (Ki) values indicate that PEAn treated with VD exhibits the most effective inhibition on tyrosinase, and the Zeta potential suggests the formation of the most stable complex. Circular dichroism (CD) spectroscopy shows significant enzyme rearrangement with VD-treated PEAn. Molecular docking confirms strong binding affinity. This study aims to enhance the utility of A. nodosum and develop novel uses for tyrosinase inhibitors in food.

Polyphenol oxidase mediates (-)-epigallocatechin gallate to inhibit endogenous cathepsin activity in Apostichopus japonicus.

Apostichopus japonicus (A. japonicus) has rich nutritional value and is an important economic crop. Due to its rich endogenous enzyme system, fresh A. japonicus is prone to autolysis during market circulation and storage, resulting in economic losses. In order to alleviate this phenomenon, we investigated the effect of polyphenol oxidase (PPO) mediated (-)-epigallocatechin gallate (EGCG) on the activity and structure of endogenous cathepsin series protein (CEP) from A. japonicus. Research on cathepsin activity showed that PPO mediated EGCG could significantly reduce enzyme activity, resulting in a decrease in enzymatic reaction rate. SDS-PAGE and scanning electron microscopy results showed that PPO mediates EGCG could induce CEP aggregation to form protein aggregates. Various spectral results indicated that EGCG caused changes in the structure of CEP. Meanwhile, the conjugates formed by PPO mediated EGCG had lower thermal stability. In conclusion, PPO mediated EGCG was an effective method to inhibit the endogenous enzyme activity.