In this study, valuable polyhydroxynaphthoquinone (PHNQ) pigments were recovered from sea urchin food waste and were investigated as a potential bioactive ingredient for cosmeceuticals. The crude PHNQ pigment extract from 4 Vietnam sea urchins, Diadema setosum, Diadema savignyi, Stomopneustes variolaris, and Tripneustes gratilla, exhibited effective 2,2-diphenyl-1-picryl-hydrazyl-hydrate scavenging activity, tyrosinase inhibitory activity, and antibacterial activity. The moisturizing cream with 0.5% of PHNQ pigments from D. setosum and Tripneustes gratilla sea urchins showed no dermal irritation over 14 days of mouse skin test. Four major active components in PHNQ were identified via high-performance liquid chromatography coupled with diode array detector and mass spectrometry. Echinochrome A contributed considerably to the antioxidant activity of the extracts while those containing echinochrome A and spinochrome E were significantly active against various bacteria. The promising results laid the foundation for establishing a novel process from food waste to innovative biomaterial and formulating eco-friendly skincare products with PHNQ components from sea urchins as precious ingredient.

In this study, the structural characteristics of a polysaccharide extracted from the Ulva fasciata green seaweed were determined using the chemical composition analytical methods combined with IR, MS, and NMR spectra. The results showed that the polysaccharide consists of two major repeating disaccharide units designated as ulvanobiuronic acid 3-sulfate type A (A3s) [→4)-β-D-GlcA-(1 → 4)-α-L-Rha 3S-(1→] and type B (B3s) [→4)-α-LIdoA-(1 → 4)-α-L-Rha 3s(1→]. This kind of polysaccharide exhibited a significant in vitro antioxidant activity. This study demonstrated that the Ulva fasciata green algae can be considered as a source of bioactive ulvan.

Antioxidant activities and total phenolic content of ethanolic extract of 41 marine algae species including red, brown and green algae from central coast of Vietnam were evaluated. The extract of Sargassum polycystum, Chnoospora implexa, Chnoospora minima demonstrated great DPPH radical scavenging activity with EC50 values (0.08, 0.2; 0.26 mg dry extract/L; respectively), extract from Dictyota dichotoma was found to be highest total antioxidant capacity (19.6 mg ascorbic acid equivalent/g dry seaweed) and Sargassum microcystum exhibited highest ferric reducing activity (23.1 mg Fe 2+ equivalent/g dry seaweed). We found that only green algae showed a linear correlation between total phenolic content and antioxidant activities.