Design, Semisynthesis, Insecticidal and Antibacterial Activities of a Series of Marine-Derived Geodin Derivatives and Their Preliminary Structure-Activity Relationships

To enhance the biological activity of the natural product geodin (1), isolated from the marine-derived fungus Aspergillus sp., a series of new ether derivatives (2-37) was designed and semisynthesized using a high-yielding one-step reaction. In addition, the insecticidal and antibacterial activities of all geodin congeners were evaluated systematically. Most of these derivatives showed better insecticidal activities against Helicoverpa armigera Hubner than 1. In particular, 15 showed potent insecticidal activity with an IC50 value of 89 mu M, comparable to the positive control azadirachtin (IC50 = 70 mu M). Additionally, 5, 12, 13, 16, 30 and 33 showed strong antibacterial activity against Staphylococcus aureus and Aeromonas salmonicida with MIC values in the range of 1.15-4.93 mu M. The preliminary structure-activity relationships indicated that the introduction of halogenated benzyl especially fluorobenzyl, into 1 and substitution of 4-OH could be key factors in increasing the insecticidal and antibacterial activities of geodin.

Automated summary

To enhance the biological activity of geodin, a natural product from marine-derived fungus, a series of new ether derivatives were designed and synthesized. These derivatives showed improved insecticidal activity against Helicoverpa armigera and strong antibacterial activity against Staphylococcus aureus and Aeromonas salmonicida. The introduction of halogenated benzyl and substitution of 4-OH were found to be key factors in increasing the activity of geodin.