Merulidial (Compound 1) is an antibiotic and cytotoxic agent characterized by a sesquiterpene dialdehyde structure. It effectively inhibits the spore germination and mycelial growth of the wood-decaying basidiomycete Heterobasidion annosum (H. annosum) and the saprophytic fungus Cladosporium cucumerinum (C. cucumerinum). Additionally, Merulidial suppresses DNA synthesis in various bacteria, algae, and ECA cells. It exhibits strong anticancer activity, with IC50 values of 20 μg/mL for ECA cells and 10 μg/mL for L1210 cells.

Merulidial (Compound 1), at a concentration of 25 mg/mL, significantly inhibits the growth of mycelium over 3-5 days, forming inhibition zones of 4-7 mm in width for [C. cucumerinum] and 15-19 mm for [H. annosum]. Additionally, Merulidial at 6.3-25 μg/mL over 24 hours strongly hinders the germination of [H. annosum] mycelial spores at concentrations of 12.5 and 25 μg/mL, and delays germination at 6.3 μg/mL, while it has a weaker effect on [C. cucumerinum], delaying spore germination by at least 48 hours. In the Ames test, Merulidial (50 μg/plate) demonstrates mutagenic activity against mutant strains TA98, TA2637, and TA100, with mutation rates of 0.62, 0.28, and 1.5 revertants/nmol, respectively.