The antifungal metabolite (I) obtained from Acrostalagmus NRRL-3481 has a similar structure to those of plant growth inhivitors, inumakilactones and nagilactones, of Podocarpus genus. It was made clear that (I) had, in fact, the same extent of activity as those. Although compound (I) has a nobel C-16 carbon skeleton, this was considered as terpenoid origin from the inspection of the structural feature. This study was done for the purpose of elucidation of biosynthetic pathway of (I). From the culture of Acrostalagmus, three new metabolites were isolated, and these structures were determined as (IV), (VIII), and (IX) by spectral studies and direct comparison with an authentic sample. In order to elucidate whether the precursor of (I) is a sesquiterpenoid or a diterpenoid, the incorporation experiments of [2-^<13>C]acetate and [2-^<14>C, 5-^3H_2]mevalonate were carried out, and the compound (I) was revealed to arise from a diterpenoid precursor such as labdadienol.
