Structures of two novel heterocyclics from Whitmania pigra.

Two new heterocyclics, named hirudonucleodisulfide A (1) and hirudonucleodisulfide B (2), were isolated from the dried material of Whitmania pigra Whitman. Their structures were elucidated by various spectroscopic means in combination with X-ray crystallographic analysis. A biological assay in vitro against anoxic injury demonstrated that 1 and 2 have moderately anti-anoxic activity with EC (50) values of 27.01 +/- 2.23 microg/mL and 19.54 +/- 1.53 microg/mL, respectively.