Separation and characterization of bioactive polysaccharides from Caulerpa lentillifera

Caulerpa lentillifera is a green seaweed rich in polysaccharides (20–64% of dry weight) that exhibits antioxidant, antibacterial, anticoagulant, and alpha-glucosidase inhibitory activities. This study aimed to separate and characterize bioactive polysaccharides from C. lentillifera. Fresh algae, which contain approximately 95% water with polysaccharides as a major component, were directly extracted using a hydraulic press. The crude extract was subsequently filtered through 0.2 µm and 10 kDa membranes to obtain high-molecular-weight polysaccharides (HMWPs) and lowmolecular-weight polysaccharides (LMWPs), respectively. HMWPs (1,108-2,421 kDa) contained 69.28% total sugars, 13.49% sulfate, 2.92% uronic acid, and 2.30 mg gallic acid equivalent (GAE)/g extract of total phenolics, whereas LMWPs (8.6-44.3 kDa) contained 42.18% total sugars, 8.41% sulfate, 6.04% uronic acid and 11.52 mg gallic acid equivalent (GAE)/g extract of total phenolics. The antioxidant activities, evaluated using DPPH, ABTS, FIC, LPO, and FRAP assays, revealed that LMWPs exhibited approximately two-fold stronger antioxidant activities than HMWPs. Their enhanced antioxidant properties may be attributed to their lower molecular weight and higher phenolic content, which increase their reactivity toward free radicals. These findings suggest that polysaccharides from C. lentillifera, particularly LMWPs, have potential as natural bioactive ingredients for health-promoting applications.

Keywords: Caulerpa lentillifera, Polysaccharides, Molecular weight, Bioactive compound; Antioxidant activity