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PC-56

Unprecedented spirolactones from an oyster-derived fungal strain

Westerdykella dispersa Ca4-13

2
1
1
Shu-Jung Huang, Li-Kwan Chang, Su-Jung Hsu, George Hsiao,* ,3,4 Tzong-Huei Lee* ,1

1 Institute of Fisheries Science, College of Life Science, National Taiwan University, Taipei,
Taiwan
2 Department of Biochemical Science and Technology, College of Life Science, National
Taiwan University, Taipei, Taiwan
3 Department of Pharmacology, School of Medicine, College of Medicine, Taipei Medical
University, Taipei, Taiwan
4 Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University,
Taipei, Taiwan
* E-mail: geohsiao@tmu.edu.tw (G.H.); thlee1@ntu.edu.tw (T.-H.L.)

Abstract
Chemical investigation on the liquid-state fermented products of the fungal
strain Westerdykella dispersa Ca4-13 isolated from edible oysters Crassostrea
angulata collected from Yunlin county, Taiwan resulted in the isolation and identification of
seven chemical entities. Their structures were elucidated by spectroscopic analysis to be
westeroic acid A (1), westeroic acid B (2), westeroic acid C (3), auranticin A (4), auranticin B
(5), pilobolusone C (6), and epi-radicinol (7). Among these, westeroic acid A (1), a polyketide
with a γ-lactone functionality, and westeroic acid B (2) and westeroic acid C (3), two rare
polyketides with a 6/6-spiro-linked δ-lactone moiety, were previously undescribed compounds
with distinctive structural features. The plausible biosynthetic pathway of 2 and 3 was
speculated to arise from two C14 analogues of 1 via bio-Diels–Alder reaction. Compounds 1, 2,
3, and 7 exhibited anti-inflammatory activities with IC50 values ranging from 9.9 μM to 11.3
μM. Compound 5 exhibited anti-Epstein-Barr virus (EBV) activity with an EC50 value of 38.1
μM.

Keywords: Westerdykella dispersa; Westeroic acid; Anti‑inflammatory activity; Anti-EBV;
Fungus