A glutinous rice cultivar and its 11 derived amino acid substitution mutants of starch synthase IIIa (SSIIIa) and branching enzyme IIb (BEIIb) were investigated for the contributions of amylopectin chain length distributions (CLDs) to starch physicochemical properties. The CLDs quantified using four commonly adopted classification methods exhibited substantial and fraction-specific variations among the mutants. The partial least squares (PLS) regression models for relationships between CLDs and starch physicochemical properties exhibited satisfactory predictive ability, as indicated by Q2(cum) over 0.5 for the majority (19/24) of models. Regression coefficients and loading plots revealed that short branch-chain fractions were positively correlated with relative crystallinity and lamellar peak intensity, while negatively correlated with lamellar distance, gelatinization temperature, and gelatinization enthalpy. In contrast, average chain length (ACL) and long branch-chain fractions exhibited opposite trends. Very short branch-chain fractions showed positive correlations with high-temperature swelling power and setback viscosity, whereas medium-long branch-chain fractions were negatively correlated with high-temperature swelling power, setback viscosity, and breakdown viscosity, but positively correlated with hot viscosity. Furthermore, longer branch-chain fractions and increased ACL tended to elevate resistant starch while reducing slowly digestible starch. Notably, PLS discriminant analysis based on CLDs effectively distinguished ssIIIa mutants from beIIb mutants within the mutation population.
Agaro-oligosaccharides (AGOS), derived from agar depolymerization, are marine-derived functional carbohydrates with diverse structures and promising bioactivities, including antioxidant, anti-inflammatory, and metabolic regulatory effects. Enzymatic degradation is an attractive strategy for AGOS production due to its mild conditions, high selectivity, and ability to preserve functional groups. However, the rational preparation of structurally defined AGOS remains challenging because product profiles are determined by complex interactions among agarase catalytic architecture, substrate recognition, substrate properties, and reaction conditions. This review summarizes the catalytic characteristics of agarases and their roles in determining AGOS structural diversity. We then discuss the challenges in establishing reliable structure–function relationships, as many reported bioactivities remain based on phenotypic observations and lack direct mechanistic validation. Finally, we highlight key barriers limiting AGOS applications, including scalable production, quality control, gastrointestinal fate, and human validation. An enzyme–structure–function framework is proposed to guide the rational production and application of structurally defined AGOS.
While polysaccharide-based biomaterials show great promise in wound management, endowing them with potent, antibiotic-free antibacterial and immunomodulatory properties remains a profound challenge. Herein, we report the functionalization of aspirin-derived carbon dots with a bioactive carbohydrate derivative, quaternized chitosan, via a one-step hydrothermal synthesis, yielding a novel dual-functional macromolecular conjugate (CS-ACD). Leveraging the strong polycationic properties of the modified carbohydrate, CS-ACD achieves a remarkable 97.3% sterilization rate against E. coli through physical membrane lysis, inherently circumventing drug resistance. Concurrently, the entire macromolecular conjugate acts as a potent immunomodulator, driving macrophage reprogramming from a pro-inflammatory M1 to a reparative M2 phenotype. This shift significantly reduces TNF-α expression (9.85-fold) while elevating M2 markers (13.59-fold). To optimize clinical translation, we integrated this carbohydrate-functionalized conjugate into a sandwich-structured electrospun nanofiber/fibrin gel polymeric composite. This scaffold provides hemostasis, optimal gas exchange, and sustained localized release. In an E. coli-infected murine wound model, the composite drastically reduced bacterial burdens (15.26-fold) and accelerated tissue regeneration, leaving only ~1.0% residual wound area by day 13. By coupling targeted polysaccharide functionalization with an advanced polymeric scaffold, this work presents a highly translatable, carbohydrate-based strategy for treating infected wounds.
A novel polysaccharide AES-S was extracted from safflower post-extraction residues using response surface methodology (RSM) and artificial neural network (ANN) optimization techniques, and was purified to obtain a homogeneous polysaccharide. Structural analysis revealed that AES-S is an RG-I-type pectic polysaccharide with a backbone of →4)-α-GalpA-(1 → 2)-α-Rhap-(1 → and a molecular weight (Mw) of 16.27 kDa. AES-S restored the immune homeostasis of cyclophosphamide (CTX)-induced immunosuppressed mice by promoting cytokine secretion, recovering T cell proliferation, increasing immunoglobulins and maintaining intestinal barrier integrity. Based on a pseudosterility mice model and fecal microbiota transplantation (FMT), a crucial role of the gut microbiome and its associated metabolites in protective effects of AES-S against intestinal injury was confirmed. 16S ribosomal RNA (rRNA) and Internal Transcribed Spacer (ITS) sequencing showed that AES-S remodeled the gut microbiome, enriching beneficial bacteriota (Corynebacterium) and mycobiota (Rhodotorula). Metabolomics further revealed key changes in immunomodulatory metabolites, including 5-methylthio-d-ribose and D-galactose 6-sulfate, as well as a marked increase in short-chain fatty acids (SCFAs). Correlation analyses linked these microbial shifts to metabolic recovery. These findings demonstrate that AES-S exerts immunomodulatory effects via the gut microbiome-metabolism axis, positioning it as a promising natural immunomodulatory agent.
Renatured β-1,3-1,6-glucan nanoparticles (r-glucan NPs) are hydrated polysaccharide nanostructures formed by alkali dissociation and neutralization-induced renaturation of glucan chains. Unlike rigid molecular hosts, their guest-accommodating environments are flexible, heterogeneous, and water-accessible. Here, aromatic guest incorporation into r-glucan NPs was investigated using resveratrol as a model guest for solvent-exchange analysis and 32 stilbene, azobenzene, and cinnamic acid derivatives as molecular probes. Solvent-exchange experiments showed that acetone-dependent loading conditions affected resveratrol retention, the transient colloidal state of r-glucan NPs, the recovered-complex state, and the chiral organization of retained resveratrol. Descriptor-based analysis revealed that guest molar fraction was positively associated with polarity- and hydrogen-bonding-related descriptors, including tPSA, OH count, and dipole moment, whereas logP and hydrophobic surface area showed negative correlations. Pairwise two-descriptor regression identified the logP/OH count model as the most chemically interpretable descriptor combination, highlighting the need to suppress excessive hydrophobic self-association while enabling hydroxy-group-derived stabilization. These results support a model in which aromatic guest incorporation is governed by kinetic selection during solvent exchange followed by stabilization within a hydrated glucan matrix. This study clarifies the inclusion characteristics of flexible hydrated polysaccharide matrices and provides descriptor-guided design principles for aromatic guest incorporation into r-glucan NPs.
