The Anti-melanogenesis Activities of Some Selected Brown Macroalgae from Northern Coasts of the Persian Gulf

Abstract Melanogenesis is a biological process which led to the synthesis of melanin pigment. Abnormal melanin production results in melasma, solar lentigo, post inflammatory melanoderma, etc. In this study, we examined the potential inhibitory effects of 17 brown macroalgae from Persian Gulf on melanogenesis. The effects of various concentrations (100, 250 and 500 µg/mL) of methanolic extracts of macroalgae belonging to four genera (including: Padina, Colpomonia, Cystoseira and Sargassum) were studied on oxidation of L-Dopa by mushroom tyrosinase. Subsequently, the activity of macroalgae with high inhibitory effect on monophenolase activity of mushroom tyrosinase and zebrafish was investigated using L-tyrosine as a substrate. Anti-melanogenesis effects of algae extracts were studied on zebrafish as an alternative in vivo model. Kojic acid was used as a positive control. All the tested macroalgae showed inhibitory effect on activities of diphenolase and monophenolase (of mushroom tyrosinase). P. boergesinii exhibited the most in vivo anti-tyrosinase activity compared with other samples. P. boergesenii inhibited zebrafish tyrosinase more potent than kojic acid (83% vs 50% inhibition for kojic acid). Moreover, it reduced melanin synthesis in zebrafish 42% (kojic acid: 50%).

Antioxidant properties of some filamentous green algae (Chaetomorpha Genus)

The antioxidant activity and the contents of total phenolics and flavonoids were quantified in the methanolic extracts of four Chaetomorpha species including C. aerea, C. crassa, C. linum and C. brachygona. Eight samples of Chaetomorpha plants were collected from five locations along the northern coasts of the Persian Gulf in south of Iran from December 2010 until October 2011. Methanolic extracts of the seaweeds were assessed for their antioxidant activity using DPPH radical scavenging assay. C. linum showed highest antioxidant potential with a relatively low IC50 (1.484 ± 0.168 mg mL-1), the highest flavonoid content (18.177 ± 2.238 mg RE g-1 ) and a relatively high content of phenolics (2.895 ± 0.415 mg GAE g-1) in comparison with the other species. C. crassa, which was collected from two different areas, showed lowest antioxidant activity and lowest phenolics and flavonoid contents than other species. Results revealed that IC50, total phenolics and flavonoid content were influenced by the time of collection and location. Also there were positive correlations between the phenolic and flavonoid contents with DPPH radical scavenging activity (p<0.01). The results suggested that some of these filamentous green seaweeds possessed antioxidant potential, which could be considered for future applications in medicine, food or cosmetic industries.