Computational identification and antifungal bioassay reveals phytosterols as potential inhibitor of <i>Alternaria arborescens</i>

<i>Alternaria arborescens</i> is a major pathogen for crops like tomato, tangerine and so on and its control is mostly dependent on the application of chemical agents. Plants as the sources of natural products are very attractive option for developing eco-friendly and natural antifungal agents. In this study, we modeled three-dimensional structure of chorismate synthase (CS) enzyme from <i>A. arborescens</i>. Docking studies of phytosterols, namely, γ-sitosterol and β-sitosterol, with CS showed them to be potential inhibitor of CS. To explore the stability and conformational flexibility of all the <i>AaCS</i> complex systems, molecular dynamics simulations were performed. None of the putative inhibitors as well as β- and γ-sitosterol showed interaction with the FMNH₂ binding pocket of the tomato CS (major host of <i>A. arborescens</i>) indicating their suitability as antifungal compounds inhibiting the shikimate pathway without causing any harm to the host. An <i>in vivo</i> antifungal bioassay showed a significant reduction in fungal growth in the presence of β-sitosterol (500 ppm) which resulted in ∼23% and ∼17% reduction in fungal fresh and dry weight, respectively, at 8 days after inoculation. This study provides experimental evidence establishing natural sterols like β-sitosterol can be useful in curbing <i>A. arborescens</i> damage in an eco-friendly manner. Communicated by Ramaswamy H. Sarma

树状链格孢（Alternaria arborescens）是番茄、柑橘等多种作物的重要致病菌，其防控目前主要依赖化学药剂施用。植物作为天然产物的来源，是开发环保型天然抗真菌剂的极具吸引力的选择。本研究对树状链格孢的分支酸合酶（chorismate synthase, CS）开展了三维结构建模。针对植物甾醇（phytosterols）类化合物γ-谷甾醇与β-谷甾醇进行的分子对接（molecular docking）研究显示，二者均可作为该酶的潜在抑制剂。为探究所有树状链格孢分支酸合酶（AaCS）复合物体系的稳定性与构象柔性，本研究实施了分子动力学模拟（molecular dynamics simulations）实验。结果表明，所有候选抑制剂以及β-谷甾醇与γ-谷甾醇，均未与作为树状链格孢主要宿主的番茄CS的还原型黄素单核苷酸（FMNH₂）结合口袋产生相互作用，提示这类化合物可通过抑制莽草酸途径（shikimate pathway）发挥抗真菌活性，且不会对宿主造成损害。体内（in vivo）抗真菌生物活性实验显示，施加500 ppm的β-谷甾醇可显著抑制真菌生长：接种8天后，真菌鲜重与干重分别降低约23%与17%。本研究通过实验证据证实，β-谷甾醇等天然甾醇类物质可通过环保方式有效防控树状链格孢对作物的危害。本文由Ramaswamy H. Sarma通讯。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于通过计算建模和实验验证，研究植物甾醇作为Alternaria arborescens真菌的潜在抑制剂。它涉及分支酸合酶的三维结构建模、分子对接和动力学模拟，以及体内抗真菌生物测定，证明β-谷甾醇能有效抑制真菌生长。数据集属于生物化学和药理学领域，旨在为开发环保型抗真菌剂提供实验依据。