Asporyergosterol (1), a new steroid with an E double bond between C-17 and C-20, was identified from the culture extracts of Aspergillus oryzae, an endophytic fungus isolated from the marine red alga Heterosiphonia japonica. Moreover, four known steroids including (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (2), (22E,24R)-3β-hydroxyergosta-5,8,22-trien-7-one (3), (22E,24R)-ergosta-7,22-dien-3β,5α,6β-triol (4), and (22E,24R)-5α,8α-epidioxyergosta-6,22-dien-3β-ol (5) were isolated. Structures of these compounds were unambiguously established by spectroscopic techniques and by comparison with literature values. All the isolates exhibited low activity to modulate acetylcholinesterase (AChE).
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