Polyphenols and gamma-aminobutyric acid (GABA) are diet-derived bioactive compounds with distinct yet complementary health benefits. Polyphenols exert strong antioxidant and anti-inflammatory effects, whereas GABA serves as an inhibitory neurotransmitter that supports neurological balance. Functional beverages enriched with both compounds based on fruits, vegetables, and herbs, therefore, hold considerable potential for promoting health. However, formulating such products presents substantial challenges. Fruits, vegetables, and herbs are typically rich in polyphenols but low in GABA, while GABA-rich foods often contain minimal polyphenols. Analysis of available data on the polyphenol and GABA content of such beverages revealed substantial variability, underscoring the need for greater standardization. To provide a clearer framework for this review, functional beverages were defined as effective sources of these bioactives if they deliver at least 200 mg of GABA and 500 mg of polyphenols per single daily serving. However, none of the reviewed studies met both criteria, highlighting the need for an integrated approach to develop beverages capable of supplying meaningful amounts of each compound. While fermentation, particularly with lactic acid bacteria, can substantially increase GABA levels, selecting antioxidant-rich fruits and herbs naturally high in polyphenols remains essential. Together, these approaches offer a viable pathway for creating multifunctional beverages with enhanced health value and may help meet the growing demand for natural, functional, health-promoting products.

In the present study, for the first time, a biodegradable and non-toxic polyphosphoramidate glycohydrogel (PPAGHGel) was prepared by crosslinking a polyphosphoramidate glycoconjugate (PPAG) with hexamethylene diisocyanate (HMDI) under mild conditions. Poly(oxyethylene H-phosphonate) (POEHP) was used as a precursor and was converted into PPAG via the Staudinger reaction with glucose-containing azide (2-p-azidobenzamide-2-deoxy-1,3,4,6-tetra-O-trimethylsilyl-α-D-glucopyranose). Then, crosslinking of PPAG was performed to yield PPAGHGel, which was thoroughly characterized. The gel showed a gel fraction of 83%, a swelling degree of 1426 ± 98%, and G″ = 1560 ± 65 Pa. The gel was fully degraded by alkaline phosphatase (400 U/L, pH 9) in 19 days, while hydrolytically, up to 52% degradation was observed under similar conditions. Multivalent studies of the obtained hydrogel with lectin–Concanavalin A were performed. PPAGHGel binds 92% of Concanavalin A within 24 h and the complex remains stable until the amount of glucose reaches 0.3 mM. PPAGHGel acts as a stabilizer for silver nanoparticles (12 nm). SEM shows pores measuring 10 µm (surface) and 0.1 mm (interior) with capillary channels, confirming the gel’s suitability for biosensors, drug delivery, or wound dressings. The cytotoxic (IC50) and cell-adhesive properties of the obtained hydrogel were investigated on human cell lines (HeLa). Antibacterial activity tests were also performed with gel containing silver nanoparticles against skin-associated pathogenic bacteria. The results show that PPAGHGel possesses excellent biocompatibility, non-adhesive properties and antibacterial activity.