Abstract: The paper is aimed to check anti-UVR and anti-oxidant ability of natural sun-screen compounds, the main contents is mycosporine-like amino acids (MAAs), which was extracted from Porphyra haitanensis by 80%, 90%,100% methanol, respectively. The results showed that 80% methanol was the best concentration for extracting MAAs in Porphyra haitanensis. The extracted compounds had the potent UV shield ability because of obvious absorption peak under UVR waveband (280-400 nm). For analyzing the sun block results, the compounds were mixed into the anti-sun lotion (Zirantang, SPF=18) according to the ratio (mg∶mg) of 1∶5, 1∶10, 1∶20 and 1∶30 respectively and then we calculated the sun protection factor (SPF). The data showed these compounds improved the anti-UVR ability of anti-sun lotion very well. The SPF was 22 (1∶30), 43 (1∶20), 87 (1∶10) and 114 (1∶5), respectively. These compounds also had the ability to eliminate reactive oxygen species, 12.82% of DPPH and 0.58% of hydroxyl radical can be cleared up by these compounds. The data in our paper showed the compounds extracted from Porphyra haitanensis can be used for sun-screen cosmetic．

Key words: anti-oxidant, methanol, Porphyra haitanensis, sun-screen, UV absorbing compounds