The uncommon macrocyclic polydisulfides, trans-3,3'-dihydroxy-1,5,1',5'-tetrathiacyclodecane (1), cis-3,3'-dihydroxy-1,5,1',5'-tetrathiacyclodecane (2), along with five known related cyclic disulfides, gymnorrhizol (3), neogymnorrhizol (4), bruguiesulfurol (5), brugierol (6), and isobrugierol (7), were isolated from the mangrove Bruguiera gymnorrhiza collected from Guangdong Province, China. Structures of compounds 1 and 2 were determined by extensive analysis of their spectroscopic data, by comparison of their NMR spectroscopic data with those of the co-occurring known compounds, as well as by single-crystal Xray diffraction analysis. A possible biogenetic origin was also proposed. (C) 2009 Published by Elsevier Ltd.