Work

Antifungal activity and potential mechanisms of two new bafilomycin analogues from Streptomyces sp. TH30 against tomato early blight

Year: 2026

Type: article

Abstract: BACKGROUND Tomato early blight, which is caused by the pathogenic fungus Alternaria solani , poses a serious threat to global tomato cultivation and yield. This situation underscores the urgent need for innovative, eco‐friendly biocontrol approaches. RESULTS In the present work, a strain designated as Streptomyces sp. TH30 was isolated from tomato rhizosphere soil. This strain exhibited notable antagonistic activity against A. solani , suppressing its mycelial growth by 71.3% in a dual‐culture assay. Chemical examination of the TH30 fermentation broth yielded two new bafilomycin analogues, bafilomycin H ( 1 ) with a unique furan ring group and 19‐ O ‐methylhygrolidin ( 2 ), together with the known compound halichomycin ( 3 ). Their structures were unequivocally established through integrated spectroscopic analyses (1D/2D NMR, HRESIMS) and comparison with previously reported data. Compounds 1 and 2 displayed pronounced antifungal potency against A. solani , with EC 50 values determined to be 0.9 mg L −1 and 2.0 mg L −1 , respectively. These compounds exert antifungal effects by compromising cell membrane integrity, inducing electrolyte efflux, and disrupting redox homeostasis, as manifested by elevated malondialdehyde (MDA) content and altered SOD, CAT, and PPO activities. Molecular docking analyses indicated that both 1 and 2 may bind to Fks1, a critical enzyme in the fungal cell wall biosynthetic pathway. In pot experiments, both compounds significantly reduced disease severity and incidence, with 1 showing complete suppression of early blight at 10 mg L −1 . CONCLUSION These findings demonstrate that bafilomycin analogues from Streptomyces sp. TH30 represent promising candidates for the development of novel biofungicides against tomato early blight. © 2026 Society of Chemical Industry.

Source: Pest Management Science

DOI: 10.1002/ps.70913