Hizikia fusiforme has a long history of consumption and medicinal use in China. It has been found that natural plants containing polyphenol–polysaccharide complexes have better activity compared with polyphenols and polysaccharides. Therefore, in this study on enzymatic hydrolysis and fractional alcohol precipitation, two kinds of polyphenol–polysaccharide complexes (PPC), PPC1 and PPC2, were initially obtained from Hizikia fusiforme, while the dephenolization of PPC1 and PPC2 produced PPC3 and PPC4. Through in vitro assays, PPC2 and PPC4 were found to have higher antioxidant activity, and thus were selected for testing the PPCs’ anti-aging activity in a subsequent in vivo experiment with D-gal-induced aging in mice. The results indicated that PPCs could regulate the expressions of antioxidant enzymes and products of oxidation, elevate the expressions of genes and proteins related to the Nrf2 pathway in the mouse brain, enrich the gut microbiota species and increase the Bacteroidota–Firmicute (B/F) ratio. Above all, the Hizikia fusiforme polyphenol–polysaccharide complex has potential in the development of natural anti-aging drugs.

Ascophyllum nodosum, a brown algae abundantly found along the North Atlantic coast, is recognized for its high polysaccharide content. In this study, we investigated the anti-hyperlipidemic effect of fucoidans derived from A. nodosum, aiming to provide information for their potential application in anti-hyperlipidemic therapies and to explore comprehensive utilization of this Iceland brown seaweed. The crude fucoidan prepared from A. nodosum was separated using a diethylethanolamine column, resulting in two fucoidan fractions, AFC-1 and AFC-2. Both fractions were predominantly composed of fucose and xylose. AFC-1 exhibited a higher sulfate content of 27.8% compared to AFC-2 with 17.0%. AFC-2 was primarily sulfated at the hydroxy group of C2, whereas AFC-1 was sulfated at both the hydroxy groups of C2 and C4. To evaluate the anti-hyperlipidemic effect, a hyperlipidemia mouse model was established by feeding mice a high-fat diet. The effects of AFC-1, AFC-2, and the crude extract were investigated, with the drug atorvastatin used as a positive comparison. Among the different fucoidan fractions and doses, the high dose of AFC-2 administration demonstrated the most significant anti-hyperlipidemic effect across various aspects, including physiological parameters, blood glucose levels, lipid profile, histological analysis, and the activities of oxidative stress-related enzymes and lipoprotein-metabolism-related enzymes (p < 0.05 for the final body weight and p < 0.01 for the rest indicators, compared with the model group), and its effect is comparable to the atorvastatin administration. Furthermore, fucoidan administration resulted in a lower degree of loss in gut flora diversity compared to atorvastatin administration. These findings highlight the significant biomedical potential of fucoidans derived from A. nodosum as a promising therapeutic solution for hypolipidemia.

In this study, a quantitative method based on fluorescein isothiocyanate (FITC)-labelled Hizikia fusiforme polyphenol–polysaccharide complex (HPC) and its purified fractions (PC1, PC4) was used, and its pharmacokinetics and tissue distribution were investigated in mice. The results showed that the FITC-labelled method had good linearity (R² > 0.99), intra-day and inter-day precision (RSD, %) consistently lower than 15%, recovery (93.19–106.54%), and stability (RSD < 15%), which met the basic criteria for pharmacokinetic studies. The pharmacokinetic and tissue distribution results in mice after administration showed that all three sample groups could enter the blood circulation. and HPC-FITC had a longer half-life (T_1/2: 26.92 ± 0.76 h) and mean retention time (MRT_0–∞: 36.48 h) due to its larger molecular weight. The three groups of samples could be absorbed by the organism in a short time (0.5 h) mainly in the stomach and intestine; the samples could be detected in the urine after 2 h of administration indicating strong renal uptake, and faecal excretion reached its maximum at 12 h. The samples were also detected in the urine after 2 h of administration. This study provides some theoretical basis for the tissue distribution pattern of polyphenol–polysaccharide complex.

Pearl mussel (Hyriopsis cumingii) meat is an underutilized byproduct. In this study, the effects of ultrasonic pretreatment (0–600 W) and protease type (flavorzyme, alcalase, bromelain, and trypsin) on the physicochemical, bioactivity, and functional properties of pearl mussel hydrolysates were systematically investigated. The results demonstrated that ultrasonic pretreatment increased the degree of hydrolysis (DH), with alcalase hydrolysates exhibiting the highest DH value (37.94%). Glutamic acid, aspartic acid, and leucine were identified as the predominant components. Specifically, at 300 W, the alcalase hydrolysate (UAH-3) exhibited excellent antioxidant activity. In contrast, at 600 W, the flavorzyme hydrolysate (UFH-6) and bromelain hydrolysate (UBH-6) demonstrated the highest α-glucosidase inhibitory and emulsion activity. Overall, these findings indicate that the combination of ultrasonication and enzymatic hydrolysis is a promising strategy for enhancing the utilization of pearl mussel byproducts and provides a solid theoretical basis for their application in functional foods and nutraceuticals.