Objective:To find out and compare the in vitro antioxidant and tyrosinase inhibitory activities of two species of mangrove plants.Methods:Mangrove samples were harvested at the shoreline on the island of Weno,Chuuk State in Micronesia.The phenol content,antioxidant activity(based on DPPH-free radical scavenging)and tyrosinase inhibitory activity in different tissues(leaves,barks and roots)of Rhizophora stylosa(R.stylosa)and Sonneratia alba(S.alba),collected from the island of Weno.Results:Total phenol content ranged from 4.87 to 11.96 mg per g of freeze dried samples.The highest antioxidant activity was observed in R.styiosa bark(85.5%).The highest tyrosinase inhibitory activity was found in S.alba bark.Also,total phenol content and antioxidant activity were higher in methanol extracts than in aqueous extracts.Conclusions:Taken together,the results of this study proved that mangroves can be excellent sources of antioxidant compounds. Objective: To find out and compare the in vitro antioxidant and tyrosinase inhibitory activities of two species of mangrove plants. Methods: Mangrove samples were harvested at the shoreline on the island of Weno, Chuuk State in Micronesia. The phenol content, antioxidant activity (based on DPPH-free radical scavenging) and tyrosinase inhibitory activity in different tissues (leaves, barks and roots) of Rhizophora stylosa (R. stylosa) and Sonneratia alba (S.alba), collected from the island of Weno. Results: Total phenol content ranged from 4.87 to 11.96 mg per g of freeze dried samples. The highest antioxidant activity was observed in R.styiosa bark (85.5%). The highest tyrosinase inhibitory activity was found in S.alba bark. Also, total phenol content and antioxidant activity were higher in methanol extracts than in aqueous extracts. Conclusions: Taken together, the results of this study proved that mangroves can be excellent sources of antioxidant compounds.