2.4.4. PANIKI\_4 (TSRR0002\_D-12) *Halichondria* sp.

The microfractionated extract PANIKI\_4 (injection volume 1 and 2 μL, 1 mg/mL) was rescreened against *S. tritici*. Only the 2 μL injection volume replicate produced one active zone (Figure S10), which could be assigned to a compound of *m*/*z* 317.2112 [M + H]<sup>+</sup> corresponding to the molecular formula of C20H28O3. The fragmentation pattern of the compound does not allow for clear assignment of substructural frameworks. The UV absorption maximum was detected at 220 nm. A database search of the molecular formula retrieved a sesquiterpene compound, namely 20-hydroxyhaterumadienone (Figure 5), as plausible candidate for tentative structure assignment. 20-hydroxyhaterumadienone is a cytotoxic compound reported from *Dysidea* sp. [22].
