Aldehyde group pendant-grafted pectin-based injectable hydrogel.

Periodate oxidation has been the widely accepted route for obtaining aldehyde group-functionalized polysaccharides but significantly influenced the various physicochemical properties due to the ring opening of the backbone of polysaccharides. The present study, for the first time, presents a novel method for the preparation of aldehyde group-functionalized polysaccharides that could retain the ring structure and the consequent rigidity of the backbone. Pectin was collected as the representative of polysaccharides and modified with cyclopropyl formaldehyde to obtain pectin aldehyde (AP), which was further crosslinked by DL-lysine (LYS) via the Schiff base reaction to prepare injectable hydrogel. The feasibility of the functionalization was proved by FT-IR and 1H NMR techniques. The obtained hydrogel showed acceptable mechanical properties, self-healing ability, syringeability, and sustained-release performance. Also, as-prepared injectable hydrogel presented great biocompatibility with a cell proliferation rate of 96 %, and the drug-loaded hydrogel exhibited clear inhibition of cancer cell proliferation. Overall, the present study showed a new method for the preparation of aldehyde group-functionalized polysaccharides, and the drug-loaded hydrogel has potential in drug release applications.

Quassinoids from Brucea javanica and attenuates lipopolysaccharide-induced acute lung injury by inhibiting PI3K/Akt/NF-κB pathways.

Four new quassinoids (1-4) and twenty known analogues (5-24) were isolated from the seeds of Brucea javanica. All the compounds belong to tetracyclic quassinoids. The structures of the new compounds were elucidated by comprehensive spectroscopic analysis, including HRESIMS and 1D, 2D NMR. In in vitro bioassays, (5-9, 17-19 and 23) showed inhibitory activities for nitric oxide (NO) release in LPS-activated MH-S macrophages and IC50 values of 0.11-45.56 µM. Among them, bruceoside B significantly decreased LPS-induced NO, secretion of inflammatory factor cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß). Western Blot was used to verify the expression of p-IκB-α, IκB-α, p-NF-κB, NF-κB, Bax, Bcl-2, Caspase-3, p-PI3K, PI3K, p-Akt, and Akt proteins in PI3K/Akt/NF-κB signal pathway. Bruceoside B inhibited the activity of Akt and its downstream pathways and reduced the activation of apoptotic. In vivo, it was found that bruceoside B had obvious therapeutic effect on LPS-induced acute lung injury (ALI) in mice, and the effect of tissue section was obvious. The regulatory signal pathway of bruceoside B on inflammation was consistent with the anti-inflammatory pathway in vitro. Therefore, the results implied that bruceoside B has a certain therapeutic effect on inflammation and has a certainly effect on acute lung injury.