Abstract
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 Hübner than 1. In particular, 15 showed potent insecticidal activity with an IC50 value of 89 μM, comparable to the positive control azadirachtin (IC50 = 70 μM). 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 μM. 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.
Highlights
Cotton bollworm (Helicoverpa armigera Hübner) is one of the most destructive agricultural pests known
H. armigera is native to Africa, Asia, Europe, and Australasia and has become the most globally widespread species of Helicoverpa [3]
H. armigera Hübner is responsible for about two billion dollars in direct economic losses each year [4]
Summary
Cotton bollworm (Helicoverpa armigera Hübner) is one of the most destructive agricultural pests known. H. armigera Hübner is responsible for about two billion dollars in direct economic losses each year [4] It has developed resistance against newer chemistries and conventional insecticides because of the extensive use of these chemical insecticides [5]. Introducing structural modifications to MNPs is one important strategy for drug development initiatives to improve bioavailability, enhance bidrug development initiatives to improve ological activity and reduce toxicity [8]. Griseofulvin and its analogues have been rigorously studied and and some structure–activity relationships (SARs) clearly identified [16,17]. SAR study geodin (1) exerts weak insecticidal activity [19].
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