A polysaccharide isolated and purified from Platycladus orientalis (L.) Franco leaves, characterization, bioactivity and its regulation on macrophage polarization.

The structure and bioactivity of a novel polysaccharide from Platycladus orientalis (L.) Franco leaves (POP2) were investigated in the present study. Structure characterization demonstrated that the average molecular weight of POP2 was 9.69 kDa and consisted of arabinose (14.39%), mannose (10.24%), glucose (63.95%) and galactose (11.42%). The main linkage types of POP2 consisted of (1→4)-linked α-d-Glc and (1→6)-linked α-d-Glc based on methylation and NMR analysis. Bioactivity evaluation showed that POP2 could effectively promote the secretion of inflammatory cytokines (IL-6 and TNF-α), as well as the anti-inflammatory cytokines (IL-10) in LPS-induced cells. Besides, the secretion of NO was significantly inhibited by POP2 in M1 model. POP2 could enhance the level of inflammatory cytokines (NO, IL-6 and TNF-α), while the secretion of the anti-inflammatory cytokine TGF-ß was markedly suppressed in IL-4 induced cells. Our work attempted to elucidate the regulation of macrophage polarization and support the potential application of POP2 as bioactive ingredient for functional foods.

Anti-hyperuricemic peptides derived from bonito hydrolysates based on in vivo hyperuricemic model and in vitro xanthine oxidase inhibitory activity.

Traditional drugs used to treat hyperuricemia have adverse effects. In this study, to identify safer anti-hyperuricemic bioactive peptides isolated from food-derived protein hydrolysates, a hyperuricemia rat model induced by potassium oxonate (PO) was used to evaluate the activity of bonito hydrolysates (BH), dephenolised walnut hydrolysates (DWH), and soybean hydrolysates (SH). The serum uric acid level of rats in the BH group (95.4 ± 27.4 µM, p < 0.01) was significantly reduced compared to that in the model group (212.00 ± 30.00 µM) to a level even lower than that in allopurinol group (114.3 ± 53.0 µM). Furthermore, BH alleviated renal impairment caused by PO in vivo and exhibited the greatest xanthine oxidase (XOD) inhibitory activity (65.5 ± 8.0%) in vitro compared to the other hydrolysates. Two peptides identified from BH bound the catalytic site of XOD, among which the hydrophobic peptide WML entered the active site of XOD more easily compared to the hydrophilic peptide PGACSN, possibly because of hydrophobic interactions. The chemically synthesized WML demonstrated high XOD inhibitory effect compared to PGACSN and a significant change in the secondary structure of XOD. Therefore, hexapeptide PGACSN and tripeptide WML are partially responsible for the anti-hyperuricemic activity of BH, and hydrophobic amino acids play important roles in the XOD inhibitory activity of peptides.

Moderation of hyperuricemia in rats via consuming walnut protein hydrolysate diet and identification of new antihyperuricemic peptides.

In this study, walnut meal hydrolysates (WMH) and dephenolized walnut meal hydrolysates (DWMH) were found to effectively decrease the serum uric acid level and protect the renal function in potassium oxonate-induced hyperuricemic rats in vivo as well as inhibit xanthine oxidase in vitro. Two novel antihyperuricemic peptides including WPPKN (640.8 Da) and ADIYTE (710.7 Da) were purified from DWMH via Sephadex G-15 gel filtration and reverse-phase high-performance liquid chromatography and identified by LC-ESI-MS/MS. These peptides displayed high in vitro xanthine oxidase inhibition (XOI) activity with IC50 values of 17.75 ± 0.12 mg mL-1 (WPPKN) and 19.01 ± 0.23 mg mL-1 (ADIYTE). Based on the results of molecular simulation, WPPKN entered into the hydrophobic channel and even obstructed the interaction between xanthine and xanthine oxidase (XO), while ADIYTE was positioned on the surface of the B-chain and blocked the entrance of the substrate to the hydrophobic channel. Therefore, the two peptides are partially responsible for the antihyperuricemic properties of DWMH.