Fungal products. Part IX. Gibberellins A16, A36, A37, A41, and A42 from Gibberella fujikuroi

Abstract

Several new metabolites from the culture filtrates of Gibberella fujikuroi, strain TP70, are described. These include gibberellin A₁₆(4), hitherto known only as the methyl ester, an anhydride (C₁₉H₂₄O₄), and gibberellins A₃₆[(16)(20)] and A₃₇(31). Structure [(16)(20)] was deduced for gibberellin A₃₆ from spectroscopic data and confirmed by chemical correlation with gibberellin A₁₃(9). The δ-lactone (31), obtained by reduction of gibberellin A₃₆, was identical with gibberellin A₃₇, previously isolated as the glucosyl ester from seed of Phaseolus vulgaris. The occurrence of gibberellin A₃₇ in culture filtrates of the fungus was established by g.l.c.–mass spectrometry.

Gibberellin A₁₃ hydrate (13) and gibberellin A₁₄ hydrate (14) were also isolated, and allocated the gibberellin numbers A₄₁ and A₄₂.