Obtaining high-added value compounds from agricultural waste receives increasing attention, as it can both improve resource utilization efficiency and reduce waste generation. In this study, polysaccharides are extracted from the discarded roots of Abelmoschus manihot (L.) by the high-efficiency ultrasound-assisted extraction (UAE). The optimized condition was determined as solid–liquid ratio SL ratio = 1:20, temperature T = 30 °C and time T = 40 min, achieving an extraction yield of 13.41%. Composition analysis revealed that glucose (Glc, 44.65%), rhamnose (Rha, 26.30%), galacturonic acid (GalA, 12.50%) and galactose (Gal, 9.86%) are the major monosaccharides of the extract. The extract showed a low degree of esterification (DE) value of 40.95%, and its Fourier-transform infrared (FT−IR) spectrum exhibited several characteristic peaks of polysaccharides. Inspired by the wide cosmetic applications of polysaccharides, the skincare effect of the extract was evaluated via the moisture retention, total phenolic content (TPC) quantification, 2,2-Diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging activity, anti-hyaluronidase and anti-elastase activity experiments. The extract solutions demonstrated a 48 h moisture retention rate of 10.75%, which is superior to that of commercially available moisturizer hyaluronic acid (HA). Moreover, both the TPC value of 16.16 mg GAE/g (dw) and DPPH-free radical scavenging activity of 89.20% at the concentration of 2 mg/mL indicated the strong anti-oxidant properties of the extract. Furthermore, the anti-hyaluronidase activity and moderate anti-elastase activity were determined as 72.16% and 42.02%, respectively. In general, in vitro skincare effect experiments suggest moisturizing, anti-oxidant, anti-radical and anti-aging activities of the A. manihot root extract, indicating its potential applications in the cosmetic industry.

Abelmoschus manihot (L.) flowers are widely used in traditional Chinese medicine, whereas the roots are often discarded as agricultural waste. The compact cellular and tissue architecture of the roots hinders the release of intracellular metabolites, thus impeding their reutilization. Here, enzyme-assisted ultrasonic extraction was developed to obtain a polysaccharide-rich crude extract from A. manihot roots. Orthogonal optimization identified pH 4.5, a temperature of 60 °C and a cellulase dosage of 6% (w/w) as the optimal extraction conditions, giving an extraction yield of 21.59%. The phenol–sulfuric acid assay indicated a total carbohydrate content of 75.09% (glucose equivalents). Structural analysis by Fourier transform infrared (FT−IR) confirmed the presence of characteristic polysaccharide functional groups, while monosaccharide composition analysis via high-performance liquid chromatography (HPLC) revealed the major components of glucose, glucuronic acid, rhamnose, galacturonic acid, etc. Inspired by the traditional use of A. manihot extract in papermaking, its preliminary hair care-related properties were further evaluated. At a concentration of 30 mg/mL, the extract solution inhibited Malassezia furfur growth by 84%, reduced wet and dry combing work by 16.93% and 30.86%, and increased tensile strength and tensile fracture energy by 13.04% and 14.84%, respectively. Scanning electron microscope (SEM) images suggested smoother hair fiber surfaces after treatment. These results highlight the extract’s great potential for hair care cosmetic products.