Carbon dots (CDs) were synthesized from phloroglucinol (PG) by simple heat treatment at 220–230 °C in the atmosphere without catalysts and solvents. PG-CDs heated at 220–230 °C could be completely dissolved in environmentally friendly water and exhibited a photoluminescence (PL) peak at 485 nm with 85 nm of the full width at half maximum (FWHM). The water-soluble polymer-dot-like PG-CDs were estimated to be 1.6–3.2 nm in size, and exhibited a wide range of PL wavelength at 370–630 nm. Since the PG-CDs are water-soluble materials, PG-CDs could be homogeneously mixed with a polymer such as polyvinylpyrrolidone (PVP) in water as a solvent, and PG-CDs/PVP films were prepared. The films exhibited PL characteristics that convert ultraviolet light at 350 nm to visible light above 400 nm. Thus, using PG as the raw material which has widely been produced industrially, the water-soluble fluorescent PG-CDs/PVP films could be prepared at a low cost by environmentally friendly methods.

The seaweed Ecklonia cava, a brown algae abundant in JeJu Island, South Korea, has large amounts of the polyphenol compound phloroglucinol (PG, 1,3,5-trihydroxybenzene), which has been proposed to exert interesting biological properties including antioxidant and radioprotective effects against ionizing radiation-induced damages in various cells and tissues. To identify antioxidant and radioprotective effects of PG in skin tissues, we exposed mice to 8.5 Gy whole body irradiation (WBI) at day 6 after depilation with and without PG treatment. In PG treated cases, PG was applied twice, once at 17.8 hours before and then at the time of WBI. At 8 hours after WBI, a reduction in the formation of thiobarbituric acid-reactive substrates (TBARS) was observed in the PG treated group. Upon western blot analysis, PG treatment overexpressed the MnSOD, catalase, and GPx-1, although the difference was not significant. In parallel with the results of western blot analysis, the percentage of MnSOD-and catalase-positive cells was significantly increased at 8 and 24 hours after WBI, while no significant difference was observed over 48 hours in PG treated skins. Moreover, PG treatment increased the percentage of Ki-67 positive cells compared with that of irradiated only mice at 8 hours after WBI. Our results suggest that PG is effective at attenuating oxidative stress, and that the promotion of antioxidant enzymes such as MnSOD and catalase may be an important aspect for its radioprotection in skin.