Essential oil of the leaves of psychotria asiatica L.: chemical composition, antioxidant, anti-inflammatory, and cytotoxic properties.

This study is focused on investigating the chemical composition and bioactive properties of the essential oil extracted from Psychotria asiatica L., a plant species known for its medicinal properties. Utilising gas chromatography-mass spectrometry (GC-MS) analysis, the essential oil from P. asiatica was found to contain 53 distinct constituents. Major compounds identified include (E)-citral (20.6%), 10-epi-γ-eudesmol (15.9%), (Z)-citral (10.5%), geraniol (7.4%), α-cadinol (6.7%), 7-epi-α-eudesmol (4.4%), linalool (3.7%), and α-muurolol (3.4%). The essential oil did not exhibit antioxidant activity, as indicated by an IC50 value of > 100 µg/mL, whereas the positive control L-Ascorbic acid had an IC50 of 7.37 ± 0.27 µg/mL in the DPPH model. Assessment of its anti-inflammatory potential revealed an inhibitory effect on NO production, with an IC50 value of 29.08 ± 1.54 µg/mL in Lipopolysaccharide-induced RAW264.7 macrophage cells. Furthermore, the essential oil demonstrated significant cytotoxicity against the SK-LU-1 cancer cell line, with an IC50 value of 39.75 ± 1.79 µg/mL according to the sulforhodamine B (SRB) assay.

Polythiophene-wrapped Chitosan Nanofibrils with a Bouligand Structure toward Electrochemical Macroscopic Membranes.

Exploring structural biomimicry is a great opportunity to replicate hierarchical frameworks inspired by nature in advanced functional materials for boosting new applications. In this work, we present the biomimetic integration of polythiophene into chitosan nanofibrils in a twisted Bouligand structure to afford free-standing macroscopic composite membranes with electrochemical functionality. By considering the integrity of the Bouligand structure in crab shells, we can produce large, free-standing chitosan nanofibril membranes with iridescent colors and flexible toughness. These unique structured features lead the chitosan membranes to host functional additives to mimic hierarchically layered composites. We used the iridescent chitosan nanofibrils as a photonic platform to investigate the host-guest combination between thiophene and chitosan through oxidative polymerization to fabricate homogeneous polythiophene-wrapped chitosan composites. This biomimetic incorporation fully retains the twisted Bouligand organization of nanofibrils in the polymerized assemblies, thus giving rise to free-standing macroscopic electrochemical membranes. Our further experiments are the modification of the biomimetic polythiophene-wrapped chitosan composites on a glassy carbon electrode to design a three-electrode system for simultaneous electrochemical detection of uric acid, xanthine, hypoxanthine, and caffeine at trace concentrations.

Water-soluble chitosan-derived sustainable materials: towards filaments, aerogels, microspheres, and plastics.

Bioinspired materials have aroused great interest as their inherent biocompatible and structural characteristics have given rise to sustainable applications. In this work, we have reported the phase and morphology transformation of chitosan from crystalline nanofibrils into amorphous sheets for fabricating sustainable materials. Acetylation-induced aqueous dissolution of native chitosan nanofibrils affords water-soluble chitosan as a biopolymeric liquid. Water-soluble chitosan macromolecules self-aggregate into amorphous sheets on solidification, presenting an interesting way to inspire new structures of chitosan assemblies. Through control over gelation, lyophilization, and self-assembled confinement of water-soluble chitosan, we have fabricated novel chitosan materials including filaments, aerogels, microspheres, and plastics that are promising for sustainable use.