In this study, inhibitory effects of the aqueous and ethanolic leaf extracts obtained from marshmallow (A. officinalis) were evaluated against Alternaria spp., pathogenic on Citrus. The marshmallow leaf extracts were added to potato dextrose agar medium at various concentrations and antifungal effect of the extracts against three species of Alternaria pathogenic on citrus was tested in vitro and in vivo. The ethanolic leaf extract revealed significant inhibitory effect on the mycelial growth of all fungal species and complete inhibition on spore germination of the pathogens at 100 mg mL⁻¹ concentration, similar to those of the fungicide tested. Microscopic analysis revealed that the extract caused morphological changes, including abnormal hyphal morphology with a rough surface and shriveled hyphae. The HPLC analysis revealed the presence of phenolic/flavonoid compounds, including chlorogenic acid, quercetin, benzoic acid, apegenin, cinnamic acid, ferulic acid and Kaempferol. Results of enzyme activity assays revealed that the activity of cellulase, amylase, protease and pectinase reduced in the samples treated with the ethanolic extract. The ethanolic leaf extract protected Citrus sinensis (orange) fruits against the pathogens and reduced lesion diameter of Alternaria disease in a concentration dependent manner. The concentrations of 50 and 100 mg mL⁻¹ were the most effective in reducing lesion diameters on citrus fruits campared to the control. Both in vitro and in vivo assays revealed potential of marshmallow ethanolic leaf extract to be used as a safe and eco-friendly protectant of citrus fruits against Alternaria spp. as destructive pre- and post-harvest fungal parhogens. Future research seems to be necessary to investigate antifungal effect of the major components detected in marshmallow leaf extract and determine the best formulation to increase its efficiency against phytopathogens.

在这项研究中，评估了从棉花糖 ( A. officinalis ) 中提取的含水和乙醇叶提取物对柑橘属致病性链格孢属 ( Alternaria spp. ) 的抑制作用。将棉花糖叶提取物以不同浓度添加到马铃薯葡萄糖琼脂培养基中，并在体外和体内测试了提取物对三种柑橘属致病链格孢菌的抗真菌作用。乙醇叶提取物显示对所有真菌物种的菌丝体生长有显着抑制作用，并在 100 mg mL ^{-1 时}完全抑制病原体的孢子萌发浓度，与测试的杀菌剂的浓度相似。显微分析表明，提取物引起了形态学变化，包括表面粗糙的异常菌丝形态和枯萎的菌丝。HPLC 分析表明存在酚类/黄酮类化合物，包括绿原酸、槲皮素、苯甲酸、芹菜素、肉桂酸、阿魏酸和山奈酚。酶活性测定结果显示，用乙醇提取物处理的样品中纤维素酶、淀粉酶、蛋白酶和果胶酶的活性降低。乙醇叶提取物以浓度依赖性方式保护柑橘（橙色）果实免受病原体侵害并减小链格孢病的病灶直径。50 和 100 mg mL ^-1的浓度是最有效地减少与对照相比的柑橘类水果的病斑直径。体外和体内试验均表明，棉花糖乙醇叶提取物可用作柑橘类水果对抗链格孢属（Alternaria spp）的安全环保保护剂。作为破坏性的收获前和收获后真菌parhogens。未来的研究似乎有必要研究棉花糖叶提取物中检测到的主要成分的抗真菌作用，并确定最佳配方以提高其对抗植物病原体的效率。