Oxidative stress and chronic inflammation are major contributors to skin photoaging, highlighting the need for natural antioxidants with multifunctional bioactivities. This study developed an ultrasound-assisted extraction (UAE) strategy to recover an astaxanthin-rich extract from the underutilized freshwater macroalga Chara corallina and evaluated its antioxidant, anti-inflammatory, and anti-photoaging properties. Different solvent systems were evaluated for extraction efficiency, and astaxanthin-equivalent recovery was quantified by high-performance liquid chromatography with photodiode array detection (HPLC–PDA). Antioxidant activity was evaluated using the DPPH radical scavenging assay, whereas biological activities were assessed in human dermal fibroblasts and RAW264.7 macrophages using cell viability assays, quantitative real-time PCR, and extracellular matrix-related enzyme inhibition assays. The selected solvent system (48% ethanol in ethyl acetate) provided the highest astaxanthin-equivalent recovery (0.2598 ± 0.0086% w/w). The selected CCE exhibited DPPH radical-scavenging activity, modulated antioxidant- and inflammation-associated gene expression, increased COL1A2 mRNA expression, and inhibited collagenase, elastase, and hyaluronidase within the evaluated concentration range. HPLC–PDA analysis revealed a chromatographic component with retention-time and UV–visible spectral characteristics corresponding to those of an authentic astaxanthin reference standard; however, comprehensive structural and phytochemical characterization was not performed. Because CCE is a chemically complex extract, the observed biological responses cannot be attributed exclusively to astaxanthin. Overall, these findings provide an initial basis for further investigation of C. corallina as an underexplored freshwater source of carotenoid-containing bioactive extracts rather than establishing it as a commercially competitive source of natural astaxanthin.

Mannan-oligosaccharides (MOS) may influence microbial and immune-related processes, but evidence concerning palm kernel meal (PKM)-derived MOS-containing products in goats remains limited. The experimental product was a chemically heterogeneous PKM-derived hydrolysate in which M2–M6 oligosaccharides were identified by HPLC–RID; residual sugars and other soluble constituents were also present. Twenty growing male goats received 0, 2.5, 5.0, or 10.0 g hydrolysate/goat/day (n = 5 per treatment) for 90 days. Feed intake, growth, hematological and serum biochemical indices, circulating immune indicators, peripheral blood leukocyte gene expression, and selected ruminal measures were evaluated. Immune and gene-expression outcomes were measured in prefeeding blood collected on Day 90. Ruminal pH and acetate, propionate, and butyrate were measured in a single rumen-fluid sample collected 3 h after feeding on Day 90. Serum IgA showed a positive linear association with supplementation level, whereas IL-1β and IL-6 showed negative associations; these remained significant after false-discovery-rate correction (q = 0.036, 0.012, and 0.012, respectively). Selected immune-related transcripts also differed among treatments, but these endpoint patterns do not establish coordinated immunological regulation or a specific mechanism. Propionate and butyrate showed nominal positive linear associations, whereas the acetate-to-propionate ratio showed a nominal negative association (raw p = 0.028, 0.021, and 0.018, respectively); none remained significant after correction (q = 0.056 for each). Ruminal pH, the sum of the three measured VFA concentrations, feed intake, and growth did not differ detectably. No overt clinical abnormalities requiring veterinary intervention were observed, but the study was not powered to establish safety. These preliminary between-group endpoint associations concern the complete heterogeneous hydrolysate and cannot be attributed specifically to M2–M6 oligosaccharides. Larger, adequately powered studies with pretreatment and repeated measurements are required.