Three resorcylic acid lactones from an endophyte, Leptosphaeria sp

Three new resorcylic acid lactone derivatives, viz., spirolasiodiplodin (1), (3S,4S)-9-oxo-de-O-methyllasiodiplodin (2), and (3S,5R)-9-oxo-de-O-methyllasiodiplodin (3), along with two known compounds, viz., (3S)-dihydroresorcylide (4) and alternariol-2,4-dimethylether (5), were isolated from Leptosphaeria sp. S-55, an endophyte. The structures of these undescribed compounds, including their absolute configurations, were elucidated using the NMR, UV, infra-red, HRESITOFMS, and ECD data. Compounds 1 and 4 exhibited root elongation inhibitory activity against chickweed (Stellaria media), presenting LC₅₀ values of 40.2 and 44.7 µg/mL, respectively.